Carbohydr Res 2016 Mar 6;422:1-4. Epub 2016 Jan 6.
Department of Chemistry and Biochemistry, BIO5, The University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721, USA. Electronic address:
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Carbohydr Res 2012 Apr 28;351:121-5. Epub 2012 Jan 28.
Carl S. Marvel Laboratories, Department of Chemistry & Biochemistry, The University of Arizona, Tucson, AZ 85721, USA.
A simplified method for the preparation of Fmoc-serine and Fmoc-threonine glycosides for use in O-linked glycopeptide synthesis is described. Lewis acids promote glycoside formation, but also promote undesired reactions of the glycoside products. Use of 'minimally competent' Lewis acids such as InBr(3) promotes the desired activation catalytically, and with greatly reduced side products from sugar peracetates. Read More
J Org Chem 2014 Apr 8;79(8):3427-39. Epub 2014 Apr 8.
Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research , S.A.S. Nagar, Punjab 160062, India.
Conventional solution-phase synthesis of thioglycosides from glycosyl acetates and thiols in the presence of In(III) triflate as reported for benzyl thioglucoside failed when applied to the synthesis of phenolic and alkyl thioglycosides. But, it was achieved in high efficiency and diastereospecificity with ease by solvent-free grinding in a ball mill. The acetates in turn were also obtained by the homogenization of free sugars with stoichiometric amounts of acetic anhydride and catalytic In(OTf)3 in the mill as neat products. Read More
J Org Chem 2012 Jun 30;77(12):5255-70. Epub 2012 May 30.
State Key Laboratory of Natural and Biomimetic Drugs and School of Pharmaceutical Sciences, Peking University, Xue Yuan Road No. 38, Beijing 100191, China.
Catalytic or stoichiometric amounts of Lewis acids were found to be very effective α-directing additives in the stereoselective glycosylations of diverse 2,3-O-carbonate-protected glucose and galactose thioglycoside donors by preactivation protocol. The poor stereoselectivities of 4,6-di-O-acetyl-2,3-O-carbonate protected thioglycoside donors in glycosyl coupling reactions were greatly improved, and excellent α-stereoselectivities were achieved by the addition of 0.2 equiv of BF(3)·OEt(2). Read More
Carbohydr Res 2011 Apr 21;346(5):534-9. Epub 2011 Jan 21.
Department of Chemistry, Jadavpur University, Kolkata 700 032, India.
Glycosides and thioglycosides based on monosaccharides in reaction with benzaldehyde dimethylacetal or p-methoxybenzaldehyde dimethyl acetal undergo FeCl(3)-catalyzed (20 mol%) regioselective 4,6-O-arylidenation producing the corresponding acetals in high yields. FeCl(3) also mediates acetalation of glycosides and thioglycosides of cellobiose, maltose, and lactose affording the corresponding 4',6'-O-benzylidene acetals, which were isolated after their acetylation in situ with acetic anhydride and pyridine. The combined yields (two steps) of these final products are also high (61-84%). Read More