An efficient carbene organocatalyzed route to enantioenriched chromenones, bearing one tri- or difluoromethylated stereogenic center in the β position of the carbonyl group, from o-allyloxybenzaldehydes is described. The one-pot transition-metal-free transformation exhibits a broad substrate scope and excellent enantioselectivity.

The merger of two powerful synthetic strategies, i.e., asymmetric semipinacol-type rearrangement and transition-metal-catalyzed propargylic alkylation, has been achieved, delivering a range of enantioenriched cyclo- and heterocyclopentanones with α-alkynylated quaternary stereocenters. Such types of products are challenging to obtain using other methods, and their synthetic value has been demonstrated in a variety of further transformations. The work represents a distinctive mode inducing asymmetric 1,2-carbon migration and further expands the scope of propargylic substitution.

Developing innovative dynamic kinetic resolution (DKR) modes and achieving the highly regio-and enantioselective semihydrogenation of unsymmetrical α-diketones are two formidable challenges in the field of contemporary asymmetric (transfer) hydrogenation. In this work, we report the highly regio-and stereoselective asymmetric semi-transfer hydrogenation of unsymmetrical α-diketones through a unique DKR mode, which features the reduction of the carbonyl group distal from the labile stereocenter, while the proximal carbonyl remains untouched. Moreover, the protocol affords a variety of enantioenriched acyclic ketones with α-hydroxy-α′-C(sp 2 )-functional groups, which represent a new product class that has not been furnished in known arts. The utilities of the products have been demonstrated in a series of further transformations including the rapid synthesis of drug molecules. Density functional theory calculations and plenty of control experiments have also been conducted to gain more mechanistic insights into the highly selective semihydrogenation.