Syntheses and utilizations of pyrroline-nitroxide- and tetrahydropyridine-nitroxide-based α-ketophosphonates, β-ketophosphonates, and a bisphosphonate

Five- and six-membered cyclic nitroxides containing α-ketophosphonates were obtained from the corresponding paramagnetic acyl chlorides via the Arbuzov reaction, while those containing β-ketophosphonates were obtained from the appropriate 1-alkynylphosphonates via PdCl2-catalyzed hydration. These new paramagnetic phosphorus compounds proved to be useful reagents in C–C and C=C bond-forming reactions and in functional group transformation reactions, namely, reduction, phospha-Brook rearrangement, and Regitz diazo transfer reactions. The synthesis of a paramagnetic geminal bisphosphonate was also reported.