2H-1,2,3-Diazaphospholes, prepared from various hydrazones and  phosphorus trichloride in the presence of triethylamine, react with  isoprene to give highly regioselective Diels-Alder products in good  yield.
                                    2H-1,2,3-二氮杂膦烯是在
三乙胺存在下由各种
肼基
肟与
三氯化磷反应制备的,与
异戊二烯反应可生成高区域选择性的Diels-Alder产物,且产率良好。