Synthesis and application of L-proline and R-phenylglycine derived organocatalysts for direct asymmetric Michael addition of cyclohexanone to nitroalkenes

摘要

Novel .R-phenylglycine derived organocatalysts were prepared from the reaction of Cbz-R-phenylglycine with indoline, pyrrolidine, or (S)-(-)-2-(diphenylmethyl)pyrrolidine in 3 steps. The asymmetric Michael addition of cyclohexanone to nitroolefins was investigated using R-phenylglycine derivatives along with L-prolinamides as chiral catalysts. The desired products were obtained in excellent yields with enantioselec-tivities up to 90% ee and diastereomeric ratio up to 98:2 of the syn addition product.