作者:Masahiko Seki、Yoshikazu Mori、Masanori Hatsuda、Shin-ichi Yamada
DOI:10.1021/jo025794+
日期:2002.8.1
(+)-Biotin (1) was synthesized in 25% overall yield over 11 steps from L-cysteine. The contiguous asymmetric centers at C-3a and C-6a were formed through a novel and highly stereoselective Lewis base-catalyzed cyanosilylation of alpha-amino aldehyde 3 to provide anti-O-TMS-cyanohydrin 4 with high stereoselectivity and in high yield (anti/syn = 92:8, 96%). Treatment of 4 with a di-Grignard reagent,
(+)-生物素(1)在11个步骤中由L-半胱氨酸合成,总产率为25%。C-3a和C-6a的连续不对称中心是通过新颖且高度立体选择性的Lewis碱催化的α-氨基醛3的氰基硅烷化反应形成的,从而提供具有高立体选择性和高收率的抗O-TMS-氰醇4(反/ syn = 92:8,96%)。用双格氏试剂,1,4-双(溴镁)丁烷,然后用二氧化碳处理4,可有效地在C-4处安装4-羧基丁基链,得到酮酸5。最后环化成双环化合物7b, 1的前体是通过钯催化的5的顺式-烯丙基碳酸酯6b分子内烯丙基胺化而实现的。