Access to 2-(Het)aryl and 2-Styryl Benzoxazoles via Palladium-Catalyzed Aminocarbonylation of Aryl and Vinyl Bromides.

A sequential one-pot procedure for the synthesis of either 2-(hetero)aryl or 2-styryl benzoxazoles is reported, starting from aryl and vinyl bromides, respectively, involving an initial aminocarbonylation with 2-aminophenols as nucleophiles followed by an acid mediated ring closure to generate the heterocycle. The methodology displays a broad substrate scope in moderate to excellent yields and can be exploited for (13)C-isotope labeling. Finally, this carbonylative protocol was applied to the synthesis of a potential Alzheimer's plaque binder and a selective PPAR antagonist including site-specific labeling with (13)C-carbon monoxide.