Michael reactions on conformationally flexible methyl 3-C-nitro-hex-2-enopyranoside derivatives
摘要:
Dimethyl malonate and dibenzoylmethane attacked the C-2 position of the title 3-nitro-2-enopyranosides from the side opposite the anomeric methoxyl group to afford the 3-enopyranosides (S(N)2' products). In the case of 2,4-pentanedione and ethyl acetoacetate, further intramolecular cyclization occurred to yield dihydropyran derivatives. (C) 2000 Elsevier Science Ltd. All rights reserved.