Determination of the Absolute Configuration of Gliomasolide D through Total Syntheses of the C-17 Epimers

Abstract

The absolute configuration at C-17, the carbon bearing the distal hydroxy group of the 14-membered natural product gliomasolide D, was assigned as R by comparison of C NMR shifts and specific rotation values of the epimers at C-17. The first total synthesis of gliomasolide D along with its C-17 epimer, regioselective macrocyclization (18 membered vs 14 membered), and regioselective Wacker oxidation are highlights of the present work.

Marine natural products

“…268) while the absolute conguration of gliomasolide D was determined as 735 via synthesis of the C-17 epimers. 269 Total synthesis of the bicyclic polyketide lactone, protulactone A, originally obtained from a sediment-derived Aspergillus sp., has been achieved and resulted in determination of the absolute conguration as 736 (ref. 270) and asymmetric total synthesis of the azaphilone derivative felinone A (Beauveria felina) resulted in revision of the absolute conguration to 737.…”