Regio- and Stereoselectivity in the 1,3-Dipolar Cycloaddition of C,N-Diarylnitrones to 3,3-Methylene-5,5-dimethyl-2-pyrrolidinone

Article abstract of DOI:10.1007/BF00823428

Regio- and stereoselectivity of the nitrone cycloaddition with 3,3-methylene-5,5-dimethyl-2-pyrrolidinone (1) is discussed.Nitrones react regioselectively with 1 to give a mixture of diastereoisomeric spiro-cycloadducts 3 and 4, in which 3 always dominates.Both 3 and 4 result from the approach which binds the carbon of the nitrone with the exocyclic carbon of 1 and the oxygen to the spiro carbon.The structure and steric configuration of the adducts have been assigned on the basis of 1H- and 13C-NMR spectroscopy, mainly by nuclear Overhauser effect difference spectroscopy.AMI calculations of the reactants were performed, the regio- and stereochemistry of the cycloaddition seems to be controlled by steric effects. Keywords. 1,3-Dipolar addition of nitrones; 3,3-Methylene-5,5-dimethyl-2-pyrrolidinone; Regio- and stereochemistry of 1,3-dipolar cycloaddition.