Rhodium-Catalyzed Pyridylation of Alkynamides with Pyridylboronic Acids: A Route to Functionalized Enamides.

Abstract

The catalytic direct hydroarylation of alkynamides is a highly efficient approach for accessing functionalized trisubstituted arylalkenes with amide groups. Herein, we report a rhodium-catalyzed pyridylation of alkynamides with pyridylboronic acids, producing a variety of primary, secondary, and tertiary enamides with high yields (up to 94 %). This reaction demonstrates broad tolerance towards various alkyl and aryl functional groups, providing convenient access to a diverse array of alkenylpyridine derivatives. To demonstrate potential applications in late-stage hydropyridylation, we synthesized α,β-unsaturated ketones, aldehydes, and esters with high yields from the pyridylation product of Weinreb amides. This indirect expansion of the substrate scope enhances the practicality of this strategy. Additionally, the α,β-unsaturated ketone obtained can be further reduced to yield a chiral alcohol with a 99 % ee, further demonstrating the versatility and potential utility of this approach.