Retracted: Palladium‐Catalyzed Decarboxylative Selective Acylation of 4 H ‐Benzo[ d ][1,3]oxazin‐4‐one Derivatives with α‐Oxo Carboxylic acids via Preferential Cyclic Imine‐ N ‐Directed Aryl C−H Activation

The benzoxazine scaffolds are of much interest as they are found in a large array of natural products and pharmaceutical drugs with diverse activities. We have developed a palladium‐catalyzed decarboxylative selective mono‐ and bis‐acylation of 4 H ‐benzo[ d ][1,3]oxazin‐4‐one derivatives with α‐oxo carboxylic acids via preferential cyclic imine‐ N ‐directed C−H activation. 2‐Aryl‐4 H ‐benzo[ d ][1,3]oxazin‐4‐one was acylated with a variety of substituted phenylglyoxylic acids to produce the corresponding products. It was observed that electron‐donating groups (CH 3 , OCH 3 ) at any position of the aromatic ring of phenylglyoxylic acid provided good to excellent yields, whereas phenylglyoxylic acids containing electron‐withdrawing groups (COCH 3 , CN, NO 2 ) gave the products in moderate yields. Interestingly when the reaction was performed with silver triflate (AgOTf) in place of silver nitrate (AgNO 3 ) in the presence of 4 equivalents of glyoxylic acid, the bis‐acylated product was obtained together with a small amount of mono‐acylated product. This is the first report of acylation of 2‐aryl‐4 H ‐benzo[ d ][1,3]oxazin‐4‐ones via C−H activation. The notable features of this reaction are acylation with more challenging heteroarene‐oxo carboxylic acids and alkyl oxo carboxylic acids. This new protocol provides an easy and efficient access to a variety of o ‐acyl‐4 H ‐benzo[ d ][1,3]oxazin‐4‐one derivatives which are of pharmaceutical importance.