The firsttotalsynthesis of aspinolide A has been achieved using ring-closing metathesis as a key step. The stereogenic centers were generated by means of hydrolytic kinetic resolution (HKR) of racemic epoxides.
The stereoselective formal synthesis of aspergillide A (1), a cytotoxic 14-membered macrolide, is disclosed. The key intermediate, a trisubstituted tetrahydropyran core is prepared by SmI(2)-induced intramolecular reductive cyclization as well as by using sequential alpha-aminooxylation, Homer-Wadsworth-Emmons olefination, and followed by Oxa-Michael cyclization. Other notable transformations in the synthesis include the use of Jacobsen's hydrolytic kinetic resolution, esterification, ring-closing metathesis (RCM), and cross-metathesis (CM) reactions. (C) 2010 Elsevier Ltd. All rights reserved.