An asymmetric synthesis of the antibiotic (+)-negamycin (1) has been achieved, starting from commercially available (5R,6S)-4-(benzyloxycarbonyl)-5,6-diphenyl-2,3,5,6-tetrahydro-4H-1,4-oxazin-2-one (2). The synthesis involved the stabilized Wittig olefination of the lactone carbonyl group of 2 and subsequent asymmetric hydrogenation to generate the corresponding all-syn oxazine 4 with excellent diastereoselectivity
(+)-Negamycin was synthesised employing the highly diastereoselective conjugate addition of lithium (alpha-methylbenzyl)benzylamide in the key step. The synthesis was completed in 13 steps starting from ethyl 4-chloroacetoacetate with an overall yield of 24 %. Copyright (C) 1996 Elsevier Science Ltd
Synthesis of (±)-negamycin and of (±)-epinegamycin
作者:Georges Pasquet、Dominique Boucherot、William R. Pilgrim、Brian Wright
DOI:10.1016/s0040-4039(00)77742-2
日期:1980.1
Asymmetric syntheses of (+)-negamycin, (+)-3-epi-negamycin and sperabillin C via lithium amide conjugate addition
作者:Stephen G. Davies、Osamu Ichihara、Paul M. Roberts、James E. Thomson
DOI:10.1016/j.tet.2010.10.067
日期:2011.1
and enantioselective reduction of ethyl 4-chloroacetoacetate and the diastereoselective conjugateaddition of enantiopure lithium N-benzyl-N-(α-methylbenzyl)amide to an α,β-unsaturatedester have been used as the key steps in the total asymmetric syntheses of (+)-negamycin (in 13 steps and 24% overall yield), (+)-3-epi-negamycin (in 13 steps and 10% overall yield) and sperabillin C (in 17 steps and 13%