Synthesis of Optically Active Triazolinediones and Examination of Their Utility for Inducing Asymmetry in Diels-Alder Cycloaddition Reactions

Article abstract of DOI:10.1021/jo01313a018

(S)-(-)-α-Methylbenzylamine, dehydroabietylamine, and endo-bornylamine have been transformed into the optically pure triazolinediones via the respective isocyanates and urazoles.Their ability to discriminate between diastereomeric Diels-Alder transition states was determined in the case of two dienes, 2,4-p-menthadiene and α-phellandrene, which were prepared in racemic and optically active forms of known enantiomeric purity.Exhaustive cycloaddition to these dienes gave the needed pairs of adduct <α>_D reference points against which those obtained in the asymmetric induction studies could be compared.By this technique, simple plots of <α>_D vs. diastereomeric purity served to delineate not only the level of enantioselection but also the absolute configuration of the adducts.Due in part to their exceptionally high reactivity, the triazolinediones are not sufficiently selective to permit high levels of enantioselection.Rather, their usefulness lies in their ability to achieve nondestructive resolution of various nonobivously resolvable compounds.