Molecules 2021 Mar 26;26(7). Epub 2021 Mar 26.
Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia.
An atom economical method for the preparation of variously substituted 4-pyrrolo[2,3-]oxazoles was developed on the basis of thermal isomerization of 5-(2-azirin-2-yl)oxazoles. The latter were prepared by Rh(oct) catalyzed reaction of 2-(3-aryl/heteroaryl)-2-diazoacetyl-2-azirines with a set of substituted acetonitriles, benzonitriles, acrylonitrile and fumaronitrile. According to DFT calculations the transformation of 5-(2-azirin-2-yl)oxazole to 4-pyrrolo[2,3-]oxazole occurs through the nitrenoid-like transition state to give a 3a-pyrrolo[2,3-]oxazole intermediate, followed by 1,5-H-shift. Read More