作者:Mukund P. Sibi、Prasad K. Deshpande
DOI:10.1039/a908747h
日期:——
A differentially functionalized succinic acid unit 6 undergoes alkylation with excellent regio- and high stereocontrol at the carbon α to the imide to furnish the alkylated product 7 in 60â83% yield. Selective removal of the imide provides 8 in 80â90% yields. Curtius rearrangement of 8 with retention of stereochemistry provides N-protected β-amino acids (9) in 70â83% yields. Alternatively, selective deprotection of the ester group followed by Curtius rearrangement provides isomeric β-amino acids 14a, 14b, and 14e in good yields. The methodology has been successfully applied to the synthesis of N-Boc-iturinic acid and 2-methyl-3-aminopropanoic acid, components of the antifungal peptide iturin and the cytotoxic depsipeptide cryptophycin respectively.
差异官能化的琥珀酸单元 6 在酰亚胺的碳 α 处以优异的区域和高立体控制进行烷基化,以 60-83% 的产率提供烷基化产物 7。选择性去除酰亚胺可提供 8 至 80% 至 90% 的产率。保留立体化学的 8 的 Curtius 重排提供了 N 保护的 β-氨基酸 (9),产率为 70–83%。或者,选择性脱保护酯基团,然后进行 Curtius 重排,以良好的产率提供异构 β-氨基酸 14a、14b 和 14e。该方法已成功应用于 N-Boc-ituric 酸和 2-甲基-3-氨基丙酸的合成,它们分别是抗真菌肽 iturin 和细胞毒性缩肽 Cryptophycin 的成分。