Enantioselective Transfer Hydrogenation of Oxocarbenium Ions Enables Asymmetric Access to α-Substituted 1,3-Dihydroisobenzofurans

Reported here is an efficient enantioselective transfer hydrogenation of cyclic oxocarbenium ions generated in situ through collapse of the corresponding acetal substrates. The asymmetric approach provides straightforward access to a variety of chiral α-aryl substituted 1,3-dihydroisobenzofurans in high yields with excellent enantioselectivities. α-Alkynyl substituted 1,3-dihydroisobenzofurans were also proved to be suitable substrates. In addition, when the reaction was performed at gram scale, the desired product was obtained in good yields with excellent enantioselectivity.