A Strategy for Accessing Aldehydes via Palladium-Catalyzed C-O/C-N Bond Cleavage in the Presence of Hydrosilanes

We report the catalytic reduction of both active esters and amides by selective C(acyl)-X (X=O, N) cleavage to access aldehyde functionality via a palladium-catalyzed strategy. Reactions are promoted by hydrosilanes as reducing reagents with good to excellent yields and with excellent chemoselectivity for C(acyl)-N and C(acyl)-O bond cleavage. Carboxylic acid C(acyl)-O bonds are activated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) to form triazine ester intermediates, which further react with hydrosilanes to yield aldehydes in one-pot two-step procedures. We demonstrate that C(acyl)-O cleavage/formylation offers higher yields and broader substrate scopes compared with C(acyl)-N cleavage under the same reaction conditions.