Catalyst‐/Additive‐Free One‐Pot Synthesis of Oxazolidines in Water via Regioselective and Stereoselective C−H Functionalization Approach

Abstract

AbstractA catalyst‐free approach for the synthesis of oxazolidine derivatives is developed here. Though the synthesized oxazolidines contain three stereogenic centers, single diastereomer of the product is obtained. Single crystal X‐ray analysis of the product confirmed the stereochemistry. The reaction is performed by taking tetrahydroisoquinoline/cyclic benzylic amine (1 equivalent) and aromatic aldehyde (2 equivalent) in water under refluxing condition which produces excellent yield (87–96 %). With pyrrolidine as amine substrate, the reaction gives α,β‐unsaturated cyclic imines which is an example of β‐C−H functionalization of secondary amine. The proposed mechanism shows that the reaction proceeds through the formation of azomethine ylide which undergoes [3+2]‐cycloaddition reaction providing the oxazolidine product.