Rh(II)-catalyzed enantioselective synthesis of acuminatin through a C–H insertion reaction of a non-stabilized carbenoid

An efficient and practical asymmetric synthesis of the 2,3-dihydrobenzo[b]furan neolignan acuminatin was achieved by using trans-isoeugenol as the starting material. The key step is an intramolecular C–H insertion through a non-stabilized carbenoid, prepared by decomposition of a tosylhydrazone in the presence of an anthracenyl-derived cinchonidine quaternary ammonium salt as a chiral phase-transfer catalyst.