Divergent Syntheses of (-)-Chicanine, (+)-Fragransin A, (+)-Galbelgin, (+)-Talaumidin, and (+)-Galbacin via One-Pot Homologative -Butyrolactonization.

In this study, the divergent syntheses of (-)-chicanine, (+)-fragransin A, (+)-galbelgin, (+)-talaumidin, and (+)-galbacin are detailed. In this approach, an early-stage modified Kowalski one-carbon homologation reaction is utilized to construct the central -butyrolactone framework with the two necessary ,-vicinal stereogenic centers. The two common chiral -butyrolactone intermediates were designed to be capable for assembling five different optically active tetrahydrofuran lignans from commercially available materials in a concise and effective divergent manner in five to eight steps. These five syntheses are among the shortest and highest-yielding syntheses reported to date.