Michael Addition of Heteroaromatic Compounds to Unsaturated Phosphonates and Their Reactions

Abstract

Organophosphorus compounds are synthetic targets of interest because of their value for a variety of industrial, biological and chemical uses. Therefore new or improved methods for the synthesis of phosphonates continue to attract considerable attention. In this study; it was aimed to synthesize novel heteroaromatics substituted phosphonate analogues by the Michael reaction in the presence of metal trifluorometanesulfonates (triflates) and novel phosphono-pyrrolizine derivatives by an intramolecular cyclization reaction. In the first part of the study; different vinylphosphonates were synthesized by the Knoevenagel reaction of active methylene compounds and aldehydes. In the second part of the study; vinylphosphonates including ester, ketone and cyano functional groups were used in the addition reactions of eteroaromatics in the presence of metal triflates as catalysts. The effects of solvent, temperature, catalyst type and substituents on the addition reactions were investigated and optimum reaction conditions were determined. Heteroaromatics substituted new phosphonate analogues which are important precursors for the synthesis of pyrrolizines were obtained regioselectively with Michael addition. In the last part of the study; the reaction of pyrrole substituted addition products with NaH were investigated to obtain phosphono-pyrrolizine compounds. Phosphono-pyrrolizines were obtained in high yields with ester functionalized pyrrole addition products by the intramolecular cyclization reaction. Ketone and cyano functionalized pyrrole addition products gave novel N-phosphonosubstituted rearrangement products instead of cyclization products. ii Synthesized compounds were purified by chromatographic methods and their structures were identified by 1H NMR, 13C NMR, 31P NMR, IR and HRMS techniques.