Reactions of Conjugate Phosphinyl- and Phosphonyl-Nitroso Alkenes with Enamines. Preparation of <i>N</i>-Hydroxypyrrole Derivatives

The synthesis of highly functionalized N-hydroxypyrrole derivatives by the formal [3+2] cycloaddition reaction of enamines and nitroso alkenes derived from phosphine oxides and phosphonates is reported. Intermediate phosphorylated nitrones, whose formation can be explained by a conjugate addition of enamines to phosphorylated nitroso alkenes and formation of the five-membered heterocycles, are isolated.