A New One-Pot Synthesis of Alkynylphosphonates

A method for the palladium-catalyzed synthesis of alkynylphosphonates from 1,1-dibromo-1-alkenes has been developed. In general, the best catalyst system for this transformation was found to be Pd(OAc)2, dppf, H-phosphonate, propylene oxide, DMF, 80 °C. The reaction appears tolerant of a range of functional groups in both the 1,1-dibromo-1-alkene and H-phosphonate coupling partners. The synthesis of a backbone-modified thymidine dimer is used to illustrate the application of this methodology in the synthesis of complex target molecules.