Total Syntheses of Naturally Occurring Seimatopolide A and Its Enantiomer from Chiral Pool Starting Materials Using a Bidirectional Strategy

摘要

Enantioselective total syntheses of both enantiomers ofnthe recently isolated decanolide natural product seimatopolide A arendescribed. The C2-symmetric building blocks (R,R)-hexa-1,5-diene-3,4-ndiol (derived from D-mannitol) and its enantiomer (derived from L-n(+)-tartrate) serve as key starting materials, which are elaborated in anbidirectional way using a selective mono-cross-metathesis, regio- andnstereoselective epoxidation, and regioselective reductive epoxide openingnto furnish the first fragment. Both enantiomers of the second fragment, 3-nhydroxypent-4-enoic acid, were conveniently obtained through a lipasecatalyzednkinetic resolution and merged with the first fragment via Shiinanesterification. An E-selective ring-closing metathesis was used to access the 10-membered lactone. A comparison of the specificnoptical rotations of synthetic seimatopolides with those reported for the natural product suggests that the originally assignedn(3R,6R,7R,9S)-configuration should be corrected to (3S,6S,7S,9R).