Total synthesis of N-methylsansalvamide A was accomplished in solution phase by a convergent approach. An N-Boc-tri-depsipepide 6 and a dipeptide ester 10 were prepared in the yield of 89% and 91%, respectively. Cyclization of the linear penta-depsipetide was achieved with PyBOP and DIPEA in DMF-CH2Cl2.
Shou Xin LIU Yan Lou GENG Xia TIAN Xiao Li ZHEN Jian Rong HAN
Tumescenamide A (1), isolated from Streptomyces tumescens YM23-20, consists of a cyclic depsipeptideand a side-chain 2,4-dimethylheptanoate (Dmh). Herein, we report the first total synthesis of tumescenamide A (1) and establish its stereochemistry. The configuration of Dmh is 2S,4S and, notably, the configuration of Val is revised as D. In addition, a mild and practical method for the β-elimination of derivatives ofserine and threonine by using nano-K_(2)CO_(3) as a base was established. A highly stereoselective synthesis ofthe Dmh substructure was also developed.
