Ring-Size-Selective Enyne Metathesis as a Tool for Desymmetrization of an EnantiopureC2-Symmetric Building Block
摘要:
The enantiomerically pure C-2-syrnmetrical hexa-1,5-diene-3,4-diol is selectively monopropargylated. The products undergo ring-closing enyne metathesis to give exclusively dihydropyrans as single stereoisomers. An unprotected hydroxy group is identified as the factor controlling the ring-size selectivity.
Ring-Size-Selective Enyne Metathesis as a Tool for Desymmetrization of an EnantiopureC2-Symmetric Building Block
摘要:
The enantiomerically pure C-2-syrnmetrical hexa-1,5-diene-3,4-diol is selectively monopropargylated. The products undergo ring-closing enyne metathesis to give exclusively dihydropyrans as single stereoisomers. An unprotected hydroxy group is identified as the factor controlling the ring-size selectivity.
The first totalsynthesis of Cleistenolide, a novel natural product recently isolated from the Annonaceae species Cleistochlamys kirkii Oliver, is described. The synthesis proceeds in six steps and 18% overall yield, starting from an enantiopure C2-symmetric building block and using a Sharpless epoxidation, a selective epoxide opening, and a ring-closing metathesis reaction.