Expedient, regioselective C–H chalcogenation of 3,4-dihydro-1,4-benzoxazines using a palladium–copper catalyst†

The palladium-catalysed regioselective C–H chalcogenation of benzoxazines with disulfides and diselenides in air has been described. In this protocol, palladium acetate serves as the catalyst in conjunction with copper as an oxidizing agent. Through this approach, a wide array of sulfenylation and selenylation reactions of benzomorpholines have been effected, yielding results ranging from good to excellent. Thus, the established procedure demonstrates superb regioselectivity and a strong tolerance towards various functional groups and is suitable for gram-scale synthesis. Additionally, this synthetic approach offers a practical and convenient pathway for late-stage functionalization leading to the Rosenmund–von Braun reaction.