Total Synthesis of Gymnothelignan K via a One-Pot Homologative?-Butyrolactonization

Thefirst total synthesis of tetrahydrofuran dilignangymnothelignan K is disclosed. The approach is based onimplementing an early stage one-carbon homologative lactoniza-tion, which we recently disclosed, for constructing the gamma-butyrolactone scaffold with the requisite beta,gamma-trans-vicinal stereo-centers. Other salient features of the synthesis include the acid-promoted dimerization and the Suzuki-Miyaura cross-couplingreaction to install the challenging diaryl skeleton that permits theeffective assembly of the optically active gymnothelignan K in 8steps from commercially available materials