A new one-pot synthesis of alkynylphosphonates

A method for the palladium-catalyzed synthesis of alkynylphosphonates from 1,l-dibromo-l-alkenes has been developed. In general, the best catalyst sys tem for this transformation was found to be Pd(OAc)(2), dppf, H-phosphonate , propylene oxide, DMF, 80 degreesC, The reaction appears tolerant of a ran ge of functional groups in both the 1,l-dibromo-l-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.