Diastereofacial selectivity studies on 3-alkenyl-4,5-diphenyl-4,5-dihydroisoxazoles

摘要: Epoxidation of 3-(1-phenylethenyl)-4,5-diphenyl-4,5-dihydroisoxazole and 3-ethenyl-4,5-diphenyl-4,5-dihydroisoxazole occurred with 74% diastereomer excess (de) 66% de, respectively. Catalytic cis-hydroxylation the 3-(1-phenylethenyl) dihydroisoxazole afforded a diol 80% de. Cycloaddition reactions same alkenyl dihydroisoxazoles bromonitrile oxide phenylsulfonylcarbonitrile 10-46%de; opposite diastereomers were preferred in 3-ethenyl- 3-(1-phenylethenyl)dihydroisoxazoles. These results are rationalized based on combination two factors: preference for s-trans heterodiene conformer attack anti to C-4 phenyl group all but one case