A diastereoselective route to 2,5-diaryl-3,4-disubstituted tetrahydrofuran lignans: protection free synthesis of (+)-galbelgin and (+)-galbacin†
Abstract
An efficient and protection free asymmetric synthesis has been reported for all-trans variant 2,5-diaryl-3,4-disubstituted tetrahydrofuran lignans in seven steps from N-succinyl-2-oxazolidinone. (+)-Galbelgin and (+)-galbacin were synthesized in very good overall yields by this route where diastereoselective aldol reaction, stereoselective C-alkylation over O-alkylation and Friedel–Crafts reaction serve as key steps.