Calimsiz Selçuk, Morales Ramos Angel I, Lipton Mark A
Department of Chemistry and Cancer Center, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084, USA.
J Org Chem. 2006 Aug 18;71(17):6351-6. doi: 10.1021/jo060351h.
Two possible isomers of the natural product callipeltin E (1, 5) were synthesized by using an Fmoc-based solid-phase strategy in 7 steps, in 20% and 26% overall yields, respectively. The (1)H NMR spectrum of synthetic 5 correlated closely with that of the natural product, whereas that of 1 did not, providing confirmation of the configurational reassignment of the N-terminal residue of callipeltin E as D-allothreonine. This result strongly implies that the corresponding residue in the closely related cyclic depsipeptides callipeltins A and B should also be considered a D-allothreonine residue.
采用基于Fmoc的固相策略，分7步合成了天然产物callipeltin E（1,5）的两种可能异构体，总产率分别为20%和26%。合成的5的¹H NMR谱与天然产物的谱紧密相关，而1的谱则不相关，这证实了callipeltin E的N端残基构型重新分配为D-别苏氨酸。该结果强烈表明，在密切相关的环缩肽callipeltins A和B中相应的残基也应被视为D-别苏氨酸残基。
