28,994 results match your criteria Organic Letters [Journal]


Synthesis of Quinazoline and Quinazolinone Derivatives via Ligand-Promoted Ruthenium-Catalyzed Dehydrogenative and Deaminative Coupling Reaction of 2-Aminophenyl Ketones and 2-Aminobenzamides with Amines.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 United States.

The in situ formed ruthenium catalytic system ([Ru]/L) was found to be highly selective for the dehydrogenative coupling reaction of 2-aminophenyl ketones with amines to form quinazoline products. The deaminative coupling reaction of 2-aminobenzamides with amines led to the efficient formation of quinazolinone products. The catalytic coupling method provides an efficient synthesis of quinazoline and quinazolinone derivatives without using any reactive reagents or forming any toxic byproducts. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01082DOI Listing

Synthesis of Sugar-Based Enones and Their Transformation into 3,5-Disubstituted Furans and 2-Acyl-Substituted 1,2,3-Trideoxy Sugars in the Presence of Lewis Acids.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Natural Product Chemistry Division , Indian Institute of Integrative Medicine (IIIM) , Jammu 180001 , India.

Pd-catalyzed carbonylative cross-coupling reactions of 2-iodoglycals have been developed for the synthesis of sugar-based arylones and ynones using formic acid as the carbonyl source. Whereas acetyl-protected arylones lead to the formation of highly substituted furan derivatives in the presence of Lewis acid, benzyl-protected arylones furnished the 3-deoxy sugar derivative. In the presence of nucleophiles, an attack took place on the C-1 or C-3 carbon regio- and stereoselectively depending on the nature of the nucleophiles. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b00680
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b00680DOI Listing
April 2019
3 Reads

Rapid Construction of Fused Heteropolycyclic Aromatics via Palladium-Catalyzed Domino Arylations of Imidazopyridine Derivatives.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering , East China University of Science & Technology , 130 Meilong Road , Shanghai 200237 , China.

By using diaryliodonium salts, a novel approach of a palladium-catalyzed cascade of diarylation/intramolecular dehydrogenative coupling reaction has been developed in the synthesis of phenanthro-imidazopyridine fused heteropolycycles. The method can tolerate various substrates, and the target products were rapidly constructed in one pot. Furthermore, studies of the detailed reaction mechanism provide an insight into the C-H functionalization of 2-aryl-imidazopyridine derivatives and the C-C bond formations in the presence of palladium catalyst. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00761DOI Listing

Sulfur-Containing, Quinodimethane-Embedded Acene Analogue with Nine Consecutively Fused Six-Membered Rings.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543.

Linear quinodimethane-embedded acene analogue 9L was synthesized, and its quinoidal structure was confirmed by X-ray crystallographic analysis. The multiple oxidation states of 9L could be achieved. Its dication is a triplet diradical, and its tetracation can be regarded as the isoelectronic structure of the nonacene, which was validated by experiments and theoretical calculations. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b00805
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b00805DOI Listing
April 2019
1 Read

Manganese(I)-Catalyzed Synthesis of Fused Eight- and Four-Membered Carbocycles via C-H Activation and Pericyclic Reactions.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023 , China.

Pericyclic reactions have allowed facile construction of complex cycles. On the other hand, metal-catalyzed C-H activation has been established as an important strategy for rapid synthesis of complex structures. The two areas are integrated in Mn(I)-catalyzed redox-neutral coupling of 3-alkenyl- and 3-allylindoles with propargylic carbonates, which occurred via C-H allenylation with subsequent pericyclic reactions to afford fused eight- and four-membered carbocycles, respectively. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b01139
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b01139DOI Listing
April 2019
1 Read

Design of Phosphinic Acid Catalysts with the Closest Stereogenicity at the α-Position: Synthesis and Application of α-Stereogenic Perfluoroalkyl Phosphinic Acid Catalysts.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Department of Chemical Science and Engineering, School of Materials and Chemical Technology , Tokyo Institute of Technology , O-okayama, Meguro-ku , Tokyo 152-8552 , Japan.

Chiral C-symmetric phosphinic acids were designed based on sterically demanding and helical chiral perfluoroalkyl groups at the closest α-position advancing asymmetric reaction environment and catalytic activity. The perfluoroalkyl catalysts, [(CF)F] and [(CF)F] phosphinic acids, were synthesized via a stereoselective addition/cyclization sequence of methyl phosphinate and deoxofluorination. These new classes of Brønsted acid catalysts were applied to an asymmetric Friedel-Crafts reaction to give up to 89% yield and 82% R-enantioselectivity, which is higher than those obtained with the parent phosphoric acid (42% and 55. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01131DOI Listing

Synthesis of Alkynyl Sulfides by Copper-Catalyzed Thiolation of Terminal Alkynes Using Thiosulfonates.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering , Tokyo Medical and Dental University (TMDU) , 2-3-10 Kanda-Surugadai , Chiyoda-ku, Tokyo 101-0062 , Japan.

A mild and odorless copper-catalyzed thiolation of terminal alkynes with thiosulfonates is described. The broad substrate scope provides convenient access to a wide variety of sulfur-containing heterocycles. In particular, divergent benzoheteroles are efficiently prepared in a simple manner by thiolation of ethynylbenzenes bearing ortho-nucleophilic functional groups followed by iodocyclization. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b00875
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b00875DOI Listing
April 2019
5 Reads

Functionalization at Will of Rim-Differentiated Pillar[5]arenes.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Institute for Molecular Design and Synthesis, School of Pharmaceutical Science & Technology , Tianjin University , 92 Weijin Road, Nankai District , Tianjin , 300072 , People's Republic of China.

The development of an efficient synthetic route toward rim-differentiated C-symmetric pillar[5]arenes (P[5]s), whose two rims are decorated with different chemical functionalities, opens up successive transformations of this macrocyclic scaffold. This paper describes a gram-scale synthesis of a C-symmetric penta-hydroxy P[5] precursor, and a range of highly efficient reactions that allow functionalizing either rim at will via, e.g. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01123DOI Listing

Palladium-Catalyzed Regioselective Syn-Chloropalladation-Olefin Insertion-Oxidative Chlorination Cascade: Synthesis of Dichlorinated Tetrahydroquinolines.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Department of Chemistry, School of Chemical and Biotechnology , SASTRA Deemed University , Thanjavur - 613401 , Tamil Nadu India.

A palladium catalyzed cascade process involving syn-chloropalladation, intramolecular olefin insertion, and oxidative C-Cl bond formation reactions was demonstrated for the synthesis of dichlorinated tetrahydroquinolines in high yields (up to 93%). The N-propargyl arylamines having a tethered α,β-unsaturated carbonyl moiety underwent a regioselective syn-chloropalladation followed by a Heck-type reaction to deliver the tetrahydroquinoline scaffold. The rare insertion of the second chlorine atom was rationalized comprising a Pd catalytic cycle and oxidative cleavage of the C-Pd bond. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b01295
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b01295DOI Listing
April 2019
1 Read

Tandem Pd-Catalyzed Intermolecular Allylic Alkylation/Allylic Dearomatization Reaction of Benzoylmethyl pyridines, Pyrazines, and Quinolines.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

School of Chemistry and Molecular Engineering , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , China.

An efficient synthesis of nitrogen-containing heterocycles via Pd-catalyzed tandem allylic alkylation and dearomatization reactions was reported. In this reaction design, heteroarenes such as pyridines, pyrazines, and quinolines serve as bis-nucleophiles by installing a benzoyl group at the C2 benzylic position. With but-2-ene-1,4-diyl dimethyl dicarbonate as the bis-electrophile, the tandem Pd-catalyzed intermolecular allylic alkylation/allylic dearomatization reaction of benzoylmethyl-substituted heteroarenes has been developed. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01060DOI Listing
April 2019
1 Read

Metal-Free Directed Diastereoselective C2,C3-Cyclopropanation of Substituted Indoles with Diazoesters.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Department of Chemistry , Indian Institute of Technology Madras , Chennai 600036 , India.

A metal-free directed C2,C3-cyclopropanation of suitably substituted indoles with α-diazo esters has been accomplished for the diastereoselective synthesis of cyclopropane-fused indolines in good yield. This method works well with a wide range of differently substituted α-diazo esters as well as indole derivatives and shown excellent compatibility for diverse directing group like pyridyl, pyrimidyl, acyl, and urea derivatives. Furthermore, the preliminary mechanistic investigation revealed the importance of directing group for the developed transformation. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01197DOI Listing
April 2019
1 Read

Vagiallene, a Rearranged C Acetogenin from Laurencia obtusa.

Org Lett 2019 Apr 19. Epub 2019 Apr 19.

Section of Pharmacognosy and Chemistry of Natural Products, Department of Pharmacy , National and Kapodistrian University of Athens , Panepistimiopolis Zografou , Athens 15771 , Greece.

Vagiallene (1), a rearranged C acetogenin with a molecular formula and a carbon skeleton unprecedented in natural products, was isolated as a trace constituent from the organic extract of the red alga Laurencia obtusa from Lefkada island. The planar structure and the relative configuration of 1 were established on the basis of extensive analysis of its spectroscopic data, while its absolute configuration was determined by comparison of its experimental and quantum-mechanically predicted electronic circular dichroism spectra. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00897DOI Listing
April 2019
1 Read

Rhodium(III)-Catalyzed Directed C-H Dienylation of Anilides with Allenes Leads to Highly Conjugated Systems.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Department of Chemistry , Indian Institute of Science Education and Research Bhopal , Bhopal Bypass Road , Bhauri, Bhopal 462066 , Madhya Pradesh , India.

Allenes are unique coupling partners in transition-metal-catalyzed C-H functionalization leading to a variety of products via alkenylation, allenylation, allylation, and annulation reactions. The outcome is governed by both the reactivity of the allene and the formation and stability of the organometallic intermediate. An efficient Rh(III)-catalyzed, weakly coordinating group-directed dienylation of electronically unbiased allenes is developed using an N-acyl amino acid as a ligand. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00958DOI Listing
April 2019
1 Read

Visible-Light-Mediated β-C(sp)-H Amination of Glycosylimidates: En Route to Oxazoline-Fused/Spiro Nonclassical Bicyclic Sugars.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Department of Chemistry , Indian Institute of Technology Patna , Bihta 801106 , Bihar , India.

A straightforward route has been developed for the diastereoselective synthesis of nonclassical conformationally constrained oxazoline-fused and spiro bicyclic sugars bearing a quaternary center via selective β-C-H amination of appropriately positioned glycosylimidates. The desired transformation proceeds via the generation of imidate N-radicals under visible-light conditions followed regioselective intramolecular N-C bond formation. The reactions tolerate broad functional groups under the optimized conditions. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00763DOI Listing

Sequential Assembly of Morita-Baylis-Hillman Carbonates and Activated ortho-Vinylbenzaldehydes To Construct Chiral Methanobenzo[7]annulenone Frameworks.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy , Sichuan University , Chengdu 610041 , China.

The α-regioselective asymmetric [3 + 2] annulation reaction of Morita-Baylis-Hillman carbonates from isatins and activated ortho-vinylbenzaldehyses was developed by the catalysis of a chiral tertiary amine. The sequential N-heterocyclic carbene-mediated intramolecular Stetter reaction was conducted to finally furnish the bridged 5,8-methanobenzo[7]annulen-9-one architectures incorporating a spirooxindole motif with excellent stereoselectivity. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01058DOI Listing

Total Syntheses of Pleiocarpamine, Normavacurine, and C-Mavacurine.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Graduate School of Pharmaceutical Sciences , Chiba University , 1-8-1 Inohana, Chuo-ku , Chiba 260-8675 , Japan.

The total syntheses of C-mavacurine-type indole alkaloids, (±)-pleiocarpamine, (±)-normavacurine, and (±)- C-mavacurine, were accomplished. The key step in the syntheses was the cyclization between the metal carbenoid at C and the N position in a Corynanthe-type compound that was equipped with a diazo function. For this cyclization, the N modification of the substrate using an amine-borane complex was indispensable to fix the molecular conformation. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b01084
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b01084DOI Listing
April 2019
2 Reads

Intermolecular Anodic Oxidative Cross-Dehydrogenative C(sp)-N Bond-Coupling Reactions of Xanthenes with Azoles.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle , Nanchang Hangkong University , Nanchang 330063 , China.

A new anode strategy for accessing xanthen-9-azoles via an electrochemical C(sp)-H/N-H cross-coupling of xanthenes with azoles is described. This reaction proceeds efficiently with a broad scope of both xanthenes and N-H-free azoles under metal- and additional oxidant-free conditions and represents a new access to direct incorporation of important N-heterocycle units into the resulting xanthenes. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00947DOI Listing
April 2019
1 Read

Stereoselective Access to ( E)-1,3-Enynes through Pd/Cu-Catalyzed Alkyne Hydrocarbation of Allenes.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

C-TAC , UMR 8038, CNRS- Université de Paris, Faculté de Pharmacie , 4, avenue de l'Observatoire , 75006 , Paris , France.

Pd and Cu cooperate in catalyzing the alkynes hydrocarbation of allenes (AHA) giving ( E)-1,3-enynes with high yields, atom economy, and high regio-/stereoselectivities. We devised new efficient conditions and expanded the substrate scope. Experimental and computational studies support a nonorthodox Pd/Pd catalytic cycle involving an oxidative addition triggered by a stereodeterminant H transfer. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00828DOI Listing

Nickel-Catalyzed Intramolecular Direct Arylation of Imines toward Diverse Indoles.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Institut für Organische und Biomolekulare Chemie , Georg-August-Universität , Tammannstraße 2 , 37077 Göttingen , Germany.

An efficient nickel-catalyzed intramolecular direct arylation of imines with challenging aryl chlorides has been developed. The versatile nickel catalysis made use of easily accessible imines and delivered diversely decorated 2-arylindoles of considerable importance to biological and medicinal chemistry. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00600DOI Listing

Enantioselective [4 + 2]-Annulation of Azlactones with Copper-Allenylidenes under Cooperative Catalysis: Synthesis of α-Quaternary α-Acylaminoamides.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Department of Organic Chemistry , Indian Institute of Science , Bangalore - 560012 , India.

The first enantioselective decarboxylative [4 + 2]-annulation of ethynyl benzoxazinanones with azlactones has been developed under cooperative copper and bifunctional tertiary aminourea catalysis. This direct and modular approach combines dipolar copper-allenylidene intermediates with azlactone enolates and allows for the synthesis of α-quaternary α-acylaminoamides as a single diastereomer generally in high yields with good to excellent enantioselectivities (up to 99:1 er). Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01103DOI Listing
April 2019
1 Read

Rhenium-Catalyzed Regioselective ortho-Alkenylation and [3 + 2 + 1] Cycloaddition of Phenols with Internal Alkynes.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , 3-1-1 Tsushimanaka, Kita-ku , Okayama 700-8530 , Japan.

An operationally simple and direct rhenium-catalyzed ortho-alkenylation ( C-alkenylation) of unprotected phenols with alkynes was developed. The protocol provided ortho-alkenylphenols exclusively, and formation of para- or multiply alkenylated phenols and hydrophenoxylation ( O-alkenylation) products were not observed. The [3 + 2 + 1] cycloaddition of phenols and two alkynes via ortho-alkenylation was also demonstrated, in which the alkynes functioned as both two- and one-carbon units. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01214DOI Listing
April 2019
1 Read

Synthesis of HDAC Substrate Peptidomimetic Inhibitors Using Fmoc Amino Acids Incorporating Zinc-Binding Groups.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

School of Chemistry , University of Glasgow , Joseph Black Building, University Avenue , Glasgow G12 8QQ , U.K.

Syntheses of Fmoc amino acids having zinc-binding groups were prepared and incorporated into substrate inhibitor H3K27 peptides using Fmoc/Bu solid-phase peptide synthesis (SPPS). Peptide 11, prepared using Fmoc-Asu(NHOBu)-OH, is a potent inhibitor (IC = 390 nM) of the core NuRD corepressor complex (HDAC1-MTA1-RBBP4). The Fmoc amino acids have the potential to facilitate the rapid preparation of substrate peptidomimetic inhibitor (SPI) libraries in the search for selective HDAC inhibitors. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00885DOI Listing
April 2019
1 Read

Phase-Transfer-Catalyzed, Enantioselective Vinylogous Conjugate Addition-Cyclization of Olefinic Azlactones To Access Multifunctionalized Chiral Cyclohexenones.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering , Henan Normal University , Xinxiang , Henan 453007 , P.R. China.

An asymmetric, phase-transfer-catalyzed vinylogous conjugate addition-vinylogous cyclization cascade of olefinic azlactones with 4-nitro-5-styrylisoxazoles is reported. In the presence of an l- tert-leucine-derived urea-quaternary ammonium salt as a bifunctional phase-transfer catalyst and KF, two series of valuable optically pure cyclohexenones featuring two and three stereocenters were obtained in high yields with good to excellent enantio- and diastereoselectivities. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01001DOI Listing

General Oxidative Aryl C-P Bond Formation through Palladium-Catalyzed Decarbonylative Coupling of Aroylhydrazides with P(O)H Compounds.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba , Ibaraki 305-8565 , Japan.

Oxidative C-C/P-H cross-coupling is achieved via Pd-catalyzed decarbonylative cross-coupling of aroylhydrazides with P(O)H compounds. The unique cooperative reaction system, especially the Brønsted acid and bidentate phosphine ligand, allows the selective activation of the inert C-C bond and the suppression of the undesired oxidation and coordination of >P(O)-H compounds, leading to a general oxidative synthesis of aryl phosphorus compounds from easily available substrates. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b00922
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b00922DOI Listing
April 2019
2 Reads

Co(II)-Catalyzed Regioselective Pyridine C-H Coupling with Diazoacetates.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510641 , China.

A Co(II)-catalyzed pyridyl C-H bond carbenoid insertion with α-diazoacetates has been realized. This transformation features a highly regioselective C-C bond formation at the C3-position of pyridines, providing an efficient access to diverse α-aryl-α-pyridylacetates. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01196DOI Listing
April 2019
1 Read

Oxidative Rearrangement of Primary Amines Using PhI(OAc) and CsCO.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Graduate School of Pharmaceutical Sciences , Osaka University , 1-6 Yamada-oka , Suita , Osaka 565-0871 , Japan.

An oxidative rearrangement of primary amines mediated by a hypervalent iodine(III) reagent is herein reported. The combination of PhI(OAc) and CsCO proves highly efficient at inducing the direct 1,2-C to N migration of primary amines, which can be applied to the preparation of both acyclic and cyclic amines. A mechanistic study shows that the rearrangement proceeds via a concerted mechanism. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00559DOI Listing
April 2019
1 Read

Revisiting Furodiindolines: One-Pot Synthesis of Furodiindolines Using Indole 2,3-Epoxide Surrogates and Their Synthetic Applications.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Faculty of Pharmaceutical Sciences , Health Sciences University of Hokkaido , Ishikari-tobetsu, Hokkaido 0610293 , Japan.

Furodiindolines have emerged as versatile intermediates in various transformations, which are easily obtained from indole 2,3-epoxide surrogates via a one-pot procedure and allowed access to heterocyclic compounds with structural diversity and complexity. Four types of transformations from the furodiindolines have been achieved: (i) dehydrative rearrangement to afford 2,3'-biindoles, (ii) hydrolysis/cyclization to give 3,4-disubstituted quinolines, (iii) ring-opening/cyclization to give pyrroloindolines, and (iv) aminal cleavage to give a 3,3-disubstituted 2-oxindole. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01108DOI Listing
April 2019
1 Read

Pd-Catalyzed Site-Selective C(sp)-H Olefination and Alkynylation of Phenylalanine Residues in Peptides.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Jiangsu Key Laboratory for Functional Substances of Chinese Medicine, Stake Key Laboratory Cultivation Base for TCM Quality and Efficacy, School of Pharmacy , Nanjing University of Chinese Medicine , Nanjing 210023 , China.

Pd-catalyzed site-selective C(sp)-H olefination and alkynylation of phenylalanine residues in peptides are described. The amino acids within the peptides are used as native bidentate directing groups to facilitate C-H functionalization. This protocol would provide appealing strategies for the postsynthetic modification of peptides. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00987DOI Listing
April 2019
1 Read

Cu(OAc)-Triggered Cascade Reaction of Malonate-Tethered Acyl Oximes with Indoles, Indole-2-alcohols, and Indole-2-carboxamides.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering , Changzhou University , 1 Gehu Road , Changzhou , Jiangsu 213164 , China.

A Cu(OAc)-promoted cascade reaction of malonate-tetherd acyl oximes with indoles, indole-2-alcohols, or indole-2-carboxmides provides facile access to polysubstituted 3-pyrrolin-2-ones. The reaction features the generation of two adjacent electrophilic centers at the same time as cyclization to lactam. The subsequent double addition with nucleophiles followed by oxidation realizes the difunctionalization of the imine sp-carbon and the adjacent α-sp-carbon. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00849DOI Listing

Alkynylboration Reaction Leading to Boron-Containing π-Extended cis-Stilbenes as a Highly Tunable Fluorophore.

Org Lett 2019 Apr 18. Epub 2019 Apr 18.

Graduate School of Pharmaceutical Sciences , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-0033 , Japan.

An unprecedented boron-containing fluorophore, π-extended cis-stilbene, obtained via alkynylboration reaction of alkynamide is reported. Boron-containing π-extended cis-stilbenes emit fluorescence with high quantum yields in the solid state and exhibit aggregation-induced emission enhancement. The broad substrate scope of the alkynylboration reaction offers facile access to electronically diverse structures, enabling fine-tuning of light absorption/emission characteristics. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b01132
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b01132DOI Listing
April 2019
1 Read

Metal-Free Aerobic Oxidative Selective C-C Bond Cleavage in Heteroaryl-Containing Primary and Secondary Alcohols.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

State Key Laboratory of Biotherapy and Cancer Center, West China Hospital , Sichuan University , Chengdu , Sichuan 610041 , China.

A transition-metal-free aerobic oxidative selective C-C bond-cleavage reaction in primary and secondary heteroaryl alcohols is reported. This reaction was highly efficient and tolerated various heteroaryl alcohols, generating a carboxylic acid derivative and a neutral heteroaromatic compound. Experimental studies combined with density functional theory calculations revealed the mechanism underlying the selective C-C bond cleavage. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00563DOI Listing

Electrochemical Radical Formyloxylation-Bromination, -Chlorination, and -Trifluoromethylation of Alkenes.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

College of Chemistry and Chemical Engineering , Northwest Normal University , 967 Anning East Road , Lanzhou 730070 , China.

Given the versatility and value of the structurally diverse organohalides and CF-containing compounds in organic synthesis, we reported a green, oxidant-free electrochemical method using undivided electrochemical cells for radical bromination, chlorination and trifluoromethylation-formyloxylation of the various alkenes with readily available halogen radical (NaCl, NaBr), trifluoromethyl radical (CFSONa) sources, and DMF as formyloxylation reagents. The protocol is operationally simple and robust and the Cl, Br or CF was directly oxidized at the anode, obviating the need for exogenous chemical oxidants. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00867DOI Listing

Solvent-Dependent Enantiodivergence in anti-Selective Catalytic Asymmetric Nitroaldol Reactions.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Institute of Microbial Chemistry (BIKAKEN) , 3-14-23 Kamiosaki , Shinagawa-ku, Tokyo 141-0021 , Japan.

anti-Selective catalytic asymmetric nitroaldol reactions of α-keto esters promoted by a heterogeneous Nd/Na heterobimetallic catalyst exhibited a significant, unexpected disparity in enantioselection that was solvent-dependent. This phenomenon exclusively occurred when the stereogenic center of a diamide ligand had the smallest substituent (Me group, derived from l-Ala), which behaved uniquely in comparison with other structurally similar ligands to provide antipodal products under otherwise identical conditions. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b00982
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b00982DOI Listing
April 2019
2 Reads

Enantioselective Gold(I)-Catalyzed Heterocyclization-Intermolecular Exo [4 + 3]-Cycloaddition Reactions for the Synthesis of Chiral Oxa-Bridged Benzocycloheptanes.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry , East China Normal University , 3663 North Zhongshan Road , Shanghai 200062 , P.R. China.

The highly exo- and enantioselective gold-catalyzed tandem heterocyclization/[4 + 3] cycloaddition of 2-(1-alkynyl)-2-alken-1-ones and 1,3-diphenylisobenzofuran was implemented by utilizing Ming-Phos, which provides a facile access to chiral seven-membered oxa-bridged rings in 80-98% yield with high exo selectivity ( exo/ endo up to 50:1) and up to 97% ee. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00537DOI Listing

Escherichia coli Strain Designed for Characterizing in Vivo Functions of Nicotinamide Adenine Dinucleotide Analogues.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Division of Biotechnology , Dalian Institute of Chemical Physics , CAS, Dalian 116023 , China.

An Escherichia coli strain was constructed for the efficient import of nicotinamide adenine dinucleotide (NAD) analogues into cells by limiting extracellular degradation while expressing an efficient NAD importer. In vivo functions of three NAD analogues were characterized. Nicotinamide hypoxanthine dinucleotide was identified as an inhibitor of NAD synthesis. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00935DOI Listing

Azaindenocorannulenes: Synthesis, Properties, and Chirality.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Health Science Platform , Tianjin University , 92 Weijin Road , Nankai District, Tianjin 300072 , P. R. China.

Palladium-catalyzed intramolecular arylation provides bowl-shaped azaindenocorannulenes 7-9. Crystals of 8 show bowl-in-bowl columnar stacking. A substituent model rationalizes the first reduction potential of 18 related molecular bowls. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b00718
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b00718DOI Listing
April 2019
1 Read

Synthesis of C14-Desmethylene Corialactone D and Discovery of Inhibitors of Nerve Growth Factor Mediated Neurite Outgrowth.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Department of Chemistry , Dartmouth College , Burke Laboratory, Hanover , New Hampshire 03755 , United States.

An asymmetric synthesis of C14-desmethylene corialactone D is described on the basis of strategic application of a metallacycle-mediated annulative cross-coupling reaction, a Still [2,3]-Wittig rearrangement, and Morken's hydroxyl-directed diboration reaction. While representing a convenient approach to access novel compositions of matter inspired by the sesquiterpenoid natural product class (including classic natural product synthesis targets including the picrotaxanes and dendrobine), these studies have led to the discovery of natural product-inspired agents that inhibit nerve growth factor (NGF)-mediated neurite outgrowth in PC-12 cells. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00921DOI Listing

Visible-Light-Promoted [5 + 1] Annulation Initiated by Electron-Donor-Acceptor Complexes: Synthesis of Perfluoroalkyl- s-Triazines.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Department of Chemistry , Northeast Normal University , Changchun 130024 , China.

A visible-light-promoted electron-donor-acceptor (EDA) complex-initiated [5 + 1] annulation between biguanides and perfluoroalkyl halides for the construction of perfluoroalkyl- s-triazines has been developed. It was found that both visible light and dioxygen in the air are favorable for the reaction. A radical-polar crossover mechanism was proposed, in which sequential SET, radical combination, HF elimination, electrocyclization, and aromatization are involved. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00655DOI Listing
April 2019
1 Read

Rhodium-Catalyzed Nitrene/Alkyne Metathesis: An Enantioselective Process for the Synthesis of N-Heterocycles.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

College of Chemistry, Chemical Engineering and Materials Science , Soochow University , Suzhou 215123 , China.

A chiral dirhodium-carboxylates-catalyzed asymmetric nitrene/alkyne metathesis (NAM) cascade reaction of alkyne-tethered sulfamates has been developed, which provides a general access to the synthesis of tricyclic N-heterocycles in good yields and excellent enantioselectivity. The chiral dirhodium catalyst not only promotes the nitrene/alkyne metathesis (NAM) to generate the key α-imino metal carbene intermediate but also is responsible for the observed asymmetric induction in the terminating [2,3]-sigmatropic rearrangement of oxonium ylide species. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01074DOI Listing

Organic Letters Global Enterprise.

Authors:
Erick M Carreira

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00974DOI Listing
April 2019
1 Read

Metal-Free Site-Specific Hydroxyalkylation of Imidazo[1,2- a]pyridines with Alcohols through Radical Reaction.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

College of Chemistry , Nanchang University , Nanchang 330031 , P.R. China.

An effective approach to realize the direct hydroxyalkylation of imidazo[1,2- a]pyridines with alcohols promoted by di- tert-butyl peroxide was described without any metal catalyst. It is the first time that the dehydrogenative C(sp)-C(sp) coupling of imidazo[1,2- a]pyridines with alcohols occurred regioselectively at the C-5 position of imidazo[1,2- a]pyridines. Multisubstituted imidazopyridine derivatives were smoothly synthesized in moderate to good yields. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b01212
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b01212DOI Listing
April 2019
1 Read

Deaminative Reductive Arylation Enabled by Nickel/Photoredox Dual Catalysis.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Roy and Diana Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104-6323 , United States.

Described is a cross-electrophilic, deaminative coupling strategy harnessing Katritzky salts as a new species of electrophile in Ni/photoredox dual catalytic reductive cross-coupling reactions. Distinguishing features of this arylation protocol include its mild reaction conditions, high chemoselectivity, and adaptability to a variety of complex substrates [i.e. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01097DOI Listing
April 2019
1 Read

Cu(I)-Catalyzed Intramolecular Tandem Cyclization of N-Indole-Tethered Cyclopropenes: Synthesis of Functionalized Hydrogenated Diazabenzo[ a]cyclopenta[ cd]azulene Derivatives.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Key Laboratory for Advanced Materials and Institute of Fine Chemicals, School of Chemistry & Molecular Engineering , East China University of Science and Technology , 130 Mei Long Road , Shanghai 200237 , People's Republic of China.

A Cu(I)-catalyzed [3 + 2] intramolecular cycloaddition reaction of N-indole-tethered cyclopropenes is presented in this paper. This reaction starts from the formation of π-allyl cationic intermediate or its resonance-stabilized metal carbenoid intermediate upon activation of cyclopropene with Cu(I) catalyst and a Friedel-Crafts-type cyclization to give functionalized hydrogenated diazabenzo[ a]cyclopenta[ cd]azulenes in good to excellent yields along with moderate to good dr values. The asymmetric variant of this cycloaddition reaction can be realized, giving the desired products with moderate ee values. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00864DOI Listing

Iridium-Catalyzed α-Methylation of α-Aryl Esters Using Methanol as the C1 Source.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering , Kansai University , Suita , Osaka 564-8680 , Japan.

IrCl(cod)]/dppe-catalyzed α-methylation of aryl esters using methanol as the C1 source was developed. This methylation process is useful in several fields including organic chemistry, biochemistry, and medicinal chemistry. Readily available methanol as methylation reagent was successfully adapted. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01025DOI Listing
April 2019
1 Read

Regioselective trans-Carboboration of Propargyl Alcohols.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Max-Planck-Institut für Kohlenforschung , 45470 Mülheim/Ruhr , Germany.

Proper choice of the base allowed trans-diboration of propargyl alcohols with B(pin) to evolve into an exquisitely regioselective procedure for net trans-carboboration. The method is modular as to the newly introduced carbon substituent (aryl, methyl, allyl, benzyl, alkynyl), which is invariably placed distal to the -OH group. Read More

View Article

Download full-text PDF

Source
http://pubs.acs.org/doi/10.1021/acs.orglett.9b01225
Publisher Site
http://dx.doi.org/10.1021/acs.orglett.9b01225DOI Listing
April 2019
1 Read

Site Selective Amide Reduction of Cyclosporine A Enables Diverse Derivation of an Important Cyclic Peptide.

Org Lett 2019 Apr 17. Epub 2019 Apr 17.

Caudill Laboratories, Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States.

Site selective amide reductions of the cyclic undecapeptide, cyclosporine A, have been developed using the combination of a heteroleptic borane catalyst and a silane reductant. Tertiary silane MeEtSiH provides two unique cyclosporine A derivatives, one of which can be readily diversified in subsequent reactions. The secondary silane EtSiH enables divergent reactivity that uses a free hydroxyl group to direct the reduction. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01245DOI Listing

Synthesis and Properties of Phospha[5]helicenes Bearing an Inner-Rim Phosphorus Center.

Org Lett 2019 Apr 16. Epub 2019 Apr 16.

Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , Singapore 637371 , Singapore.

New phospha[5]helicene derivatives featuring angular fusion of phosphole and carbohelicene moieties have been synthesized using 7-hydroxybenzo[ b]phosphole oxide as a key intermediate, which can be regioselectively prepared through one-pot multicomponent coupling. The structural behavior of the present phospha[5]helicene oxide, sulfide, and gold complex in the solid and solution states, along with DFT calculations, demonstrated close correlation between the P-centered chirality and the helical chirality as well as facile helicity inversion and equilibrium between the diastereomers in solution. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00955DOI Listing

Identification of the Amipurimycin Gene Cluster Yields Insight into the Biosynthesis of C9 Sugar Nucleoside Antibiotics.

Org Lett 2019 Apr 16. Epub 2019 Apr 16.

State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry , University of Chinese Academy of Sciences (CAS), CAS, Shanghai 200032 , China.

Feeding studies indicate a possible synthetic pattern for the N-terminal cis-aminocyclopentane carboxylic acid (ACPC) and suggest an unusual source of the high-carbon sugar skeleton of amipurimycin (APM). The biosynthetic gene cluster of APM was identified and confirmed by in vivo experiments. A C9 core intermediate was discovered from null mutants of ACPC pathway, and an ATP-grasp enzyme (ApmA8) was reconstituted in vitro for ACPC loading. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00840DOI Listing
April 2019
1 Read

Biosynthesis of Diphenyl Ethers in Fungi.

Org Lett 2019 Apr 16. Epub 2019 Apr 16.

College of Pharmaceutical Sciences , Southwest University , Chongqing 400715 , P. R. China.

A new and concise biosynthetic pathway of fungal diphenyl ethers (DPEs) has been elucidated and efficiently reconstructed in yeast. The pathway includes an unusual nonreducing polyketide synthase (NRPKS) responsible for the formation of a polyketide dimer with an ether bond linkage as well as two cofactor-independent enzymes that catalyze tandem regioselective decarboxylation reactions. Our discovery here opens a new window for utilizing fungal DPEs as a platform to design and synthesize analogues for the development of highly useful drug leads. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b00768DOI Listing
April 2019
4 Reads

[Pd(NHC)(acac)Cl]: Well-Defined, Air-Stable, and Readily Available Precatalysts for Suzuki and Buchwald-Hartwig Cross-coupling (Transamidation) of Amides and Esters by N-C/O-C Activation.

Org Lett 2019 Apr 16. Epub 2019 Apr 16.

College of Chemistry and Chemical Engineering and Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry, Ministry of Education , Shaanxi University of Science and Technology , Xi'an 710021 , China.

A general class of well-defined, air-stable, and readily available Pd(II)-NHC precatalysts (NHC = N-heterocyclic carbene) for Suzuki and Buchwald-Hartwig cross-coupling of amides (transamidation) and esters by selective N-C/O-C cleavage is reported. Since these precatalysts are highly active and the easiest to synthesize, the study clearly suggests that [Pd(NHC)(acac)Cl] should be routinely included during the development of new cross-coupling methods. An assay for in situ screening of NHC salts in this cross-coupling manifold is presented. Read More

View Article

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.orglett.9b01053DOI Listing