TRIP-Catalyzed Asymmetric Synthesis of (+)-Yatein, (−)-α-Conidendrin, (+)-Isostegane, and (+)-Neoisostegane

The asymmetric allylation under the assistance of catalytic amounts of 3,3′-bis­(2,4,6-triisopropylphenyl)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate (TRIP) allows the concise construction of the lignan scaffold from simple aldehydes and allylic bromides with full control of the two formed stereocenters. This young methodology has been employed to synthesize four naturally and pharmaceutically active lignans. Members of the dibenzylbutyrolactone, the tetraline, and the dibenzocyclooctadiene classes have been synthesized in 40–47% overall yield along four-step synthetic routes.