AN ANOMALOUS INTRAMOLECULAR CONJUGATE ADDITION OF N-PROTECTED IMIDAZOLES TO VINYLIMINOPHOSPHORANES PROMOTED BY TETRABUTYLAMMONIUM FLUORIDE - X-RAY CRYSTAL-STRUCTURE OF E-AMINO)-5,6-DIHYDROIMIDAZO[2,1-ALPHA]ISOQUINOLINE

An anomalous intramolecular conjugate addition of N-SEM protected imid azoles to vinyliminophosphoranes proceeds efficiently in the presence of tetrabutylammonium fluoride (TBAF) to afford the corresponding fuse d imidazoles. The crystal and molecular structure of 4 have been solve d by X-Ray analysis. The crystal packing is governed by weak C-H ... X (X = O, N or aromatic pi system) hydrogen interactions because the ab sence of more polarized donor groups to form hydrogen bonds. Copyright (C) 1996 Elsevier Science Ltd