Diastereoselective Cycloaddition of N-Lithiated Azomethine Ylides to (E)-α,β-Unsaturated Esters Bearing a C2-Symmetric Imidazolidine Chiral Controller

Article abstract of DOI:10.1021/jo00014a028

The 1,3-dipolar cycloaddition of N-metalated ylides to chiral (E)-3-(1,3-disubstituted 4,5-diphenylimidazolidin-2-yl)propenoates proceeded highly diastereoselectively.The previously unknown absolute configuration of optically pure 1,2-dianilino-1,2-diphenylethane was determined from the absolute configuration of the cycloadducts.What diastereotopic olefin face of the α,β-unsaturated ester was attacked by the ylide was found to depend dramatically upon the nature of N substituents of the chiral controller as well as upon the bulkiness of the ester moiety of the ylide.