A diastereodivergent strategy for the asymmetric syntheses of (−)-martinellic acid and (−)-4-epi-martinellic acid
作者:Stephen G. Davies、Ai M. Fletcher、James A. Lee、Thomas J.A. Lorkin、Paul M. Roberts、James E. Thomson
DOI:10.1016/j.tet.2013.09.013
日期:2013.11
Asymmetric syntheses of (−)-martinellic acid and (−)-4-epi-martinellic acid were achieved in 20 steps from commercially available starting materials using a diastereodivergent strategy. The conjugate addition of lithium (R)-N-allyl-N-(α-methyl-p-methoxybenzyl)amide to tert-butyl (E)-3-[2′-(N,N-diallylamino)-5′-bromophenyl]propenoate and alkylation of the resultant β-amino ester with methyl bromoacetate
的不对称合成( - ) - martinellic酸和( - ) - 4-外延-martinellic苯甲酸在20步从使用diastereodivergent策略市售原料来实现。共轭加成锂([R )- ñ -allyl- ñ - (α -甲基p甲氧基苄基)酰胺叔丁基(ë)-3- [2' - (Ñ,Ñ-diallylamino)-5'-溴-苯基]丙烯酸甲酯,并用溴乙酸甲酯得到的β氨基酯的烷基化,使用以分别安装C(9B)和C(3a)的立构中心,关键步骤。随后环化为相应的吡咯并喹啉-2-酮并还原C(4)-羰基,然后进行两个互补的烯化反应和分子内迈克尔加成反应,这两个分子都形成了该三环分子结构的C(4)-顶基> 99:1博士 ( - ) - martinellic酸,并且对于第一次,( - ) - 4-提供访问这些模板随后阐述外延-martinellic酸。