One pot three-component regioselective and diastereoselective synthesis of halogenated pyrido[2,1-b][1,3]oxazines

Three-component reactions of 3-substituted pyridines, dimethyl acetylenedicarboxylate (DMAD), and α-halo ketones led to regioselective and stereoselective synthesis of pyrido[2,1-b][1,3]oxazines in high to excellent yields under mild conditions. All the reactions gave the pyrido[2,1-b][1,3]oxazine derivatives without formation of any indolizine products.

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