Synthetic studies on Natural products: Total synthesis of Lycopladine A and Sphingofungin E

Abstract

The total syntheses of lycopodium and sphingofugin natural products were investigated. For lycopladine A, 3,5-dibromo-2-pyrone was used as the starting building block utilizing its regioselective Stille coupling reaction with chiral branched allylic silyl ether substituents and highly π-facial and endo-selective intramolecular Diels-Alder reaction of the resulting coupling product. In the second part, the polar head part of sphingofungin E was synthesized by developing π-facial selective dihydroxylation on the enantiomerically-enriched oxazolidinone enoate prepared by using a bisoxazoline-Cu chiral catalyst. The introduction of a bulky trityl group on oxazolidinone nitrogen allowed highly selective dihydroxylation. Subsequent protecting group swapping and functional group manipulation culminated in the synthesis of the polar head part of natural product sphingofungin E.