DIASTEREOSELECTIVE 1,3-DIPOLAR CYCLOADDITIONS WITH ENANTIOPURE AZOMETHINE YLIDS

Secondary amines 2a-c, based on (4S,SS)-2,2-dimethyl-4-phenyl-1,3-diox an-5-ylamine (I), were heated with a variety of aromatic aldehydes in chlorobenzene under reflux. The in situ generated 1,3-dipols were trap ped with fumaric acid ester, fumaric acid nitrile or N-phenylmaleimide , respectively, that were present in excess in the reaction mixture. T he cycloadducts 4a-e, 5a-f were formed in 78-91% and 67-100% yield as mixture of exo/endo-isomers (endo:exo = 30-65:70-35). These isomers we re formed as diastereomerically pure compounds (de greater than or equ al to 96%). (C) 1998 Elsevier Science Ltd. All rights reserved.