Enantioselective Divergent Syntheses of Diterpenoid Pyrones.

Capitalizing a synergy between late-stage C(sp 3 )-H alkynylation and a series of transition metal-catalyzed alkyne functionalization reactions, we reported herein enantioselective divergent synthesis of 10 diterpenoid pyrones within 14-16 steps starting from chiral pool enoxolone, including the first enantioselective synthesis of higginsianins A, B, D, E, and metarhizin C. Our synthesis also highlights an unprecedented biomimetic oxidative rearrangement of α-pyrone into 3(2H)-furanone, as well as applications of Echavarren C(sp 3 )-H alkynylation reaction and Toste chiral counterion-mediated Au-catalyzed intramolecular allene hydroalkoxylation in natural product synthesis.