Synthesis and structural determination of the C33–C42 fragment of symbiodinolide

Abstract

Symbiodinolide ( 1) is a polyol macrolide with a molecular weight of 2859 mu. As one of the degradation reactions, cross-metathesis of 2, which is a methyl ester of 1, with ethylene was performed to give the C33–C42 degraded fragment 4. The absolute configuration of 4 was estimated to be (36 S,40 S) by Mosher method. Stereoselective synthesis of 4 was achieved in 14 steps from l-aspartic acid. Synthetic bis-( S)- and ( R)-MTPA esters exhibited the spectroscopic data identical with those of bis-( S)- and ( R)-MTPA esters derived from the degraded fragment 4. Thus, the absolute stereochemistry of 4 was elucidated to be (36 S,40 S).