作者:Rajendra P. Jain、Robert M. Williams
DOI:10.1021/jo025636i
日期:2002.9.1
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
从市售(5R,6S)-4-(苄氧羰基)-5,6-二苯基-2,3,5,6-四氢-(5R,6S)-4-化合物开始实现了抗生素(+)-新霉素(1)的不对称合成4H-1,4-恶嗪-2-酮(2)。合成过程包括2的内酯羰基的稳定Wittig烯化反应和随后的不对称氢化反应,以产生具有出色的非对映选择性的相应的全合成恶嗪4。将4转化为β-烷氧基亚胺7和随后的CeCl3促进的螯合控制的烯丙基化7生成具有良好的对映体选择性的相应的高烯丙胺8,可以很容易地在11步中以25%的总产率将其转化为(+)-新霉素(1) 。