Harnessing thia-Rh-carbenes for the enantioselective synthesis of chiral α,α-diheteroatomic carboxylic acids

Enantioselective X–H bond insertion into Rh-carbenoids offers a robust approach for constructing chiral centres with heteroatoms. However, the synthesis of carboxylic acid derivatives that have two distinct heteroatoms on the α-carbon remains highly challenging because of the difficulties in accessing suitable heteroatom-substituted metallocarbene intermediates and achieving enantioselectivity in highly polar environments. Here we present a method for enantioselective insertion of O–H or N–H bonds into an α-thia-Rh II -carbene species. This approach facilitates the synthesis of α,α-diheteroatomic carboxylic acids, a previously inaccessible chiral pool with unique electronic and structural properties. We identified two chiral proton-shuttling catalysts that enable highly enantioselective O–H or N–H insertion. This study introduces a versatile and programmable method for the enantioselective incorporation of two heteroatoms into a carbon centre. It broadens the scope of asymmetric insertion reactions and expands the chemical space of chiral carboxylic acids.