A Simple Approach to Vicinal Pyrrolylphosphane Aldehydes

Abstract

ABSTRACTA simple approach to vicinal pyrrolylphosphane aldehydes was developed. The reaction of Alder's dimer 1 with a set of pyrrolylphosphane derivatives—its oxides, sulfides, and selenides—was studied in detail. While Alder's dimer reacted with phosphane oxides and sulfides at the O and S atoms, phosphane selenides 4a–c were found to be suitable for the introduction of the formyl group into the pyrrole ring. The reaction of highly electrophilic Alder's dimer with pyrrolylphosphane selenides proceeded predominantly at the pyrrolyl nuclei, affording the corresponding aldehydes. The phosphoroselenoyl groups of aldehydes 11 were reduced either with Raney Ni or hexamethylphosphorustriamide under mild conditions, affording pyrrolylphosphane aldehydes 12.