Catalytic asymmetric synthesis of γ-butenolides by direct vinylogous reactions.

The γ-butenolide structural motif is a prominent feature in many bioactive natural products and drugs. This short review summarizes catalytic asymmetric synthesis of γ-butenolides through direct vinylogous reactions by metal complexes and organocatalysts. In light of building chiral γ-tertiary and quaternary carbon centers of butenolides, three synthetic strategies are included: 1) the reactions with furanone derivatives as nucleophiles, 2) olefination of γ,γ- disubstituted butenolides and 3) the reactions by using γ,γ-disubstituted butenolides as nucleophiles.