Cu-β-CD-catalyzed C_sp-P coupling of alkynes with dialkylphosphites and phosphine oxides

In this study, an easily accessible Cu-β-CD complex has been introduced for C-P cross-coupling reactions. The Cu-β-CD complex was used to catalyze the C-P coupling of alkynes with both dialkylphosphites and phosphinoxides for the synthesis of alkynyl-phosphonates and -phosphinoxides. The results showed that the coupling reactions could be carried out with appropriate yields for both aryl and alkyl alkynes. The applicability of Cu-β-CD for the oxidative decarboxylative coupling of phenylpropiolic acid with dialkyl phosphites and diphenylphosphine oxide was also studied. XPS and cyclic voltammetry analysis of the catalyst confirmed the presence of both Cu(I) and Cu(II) in the complex structure. The reaction proceeded via the oxidative addition of dialkyl phosphites and alkynes to the catalyst, and the final C-P cross-coupling product was obtained by a reductive elimination process. The presented catalytic method allows the easier and more cost-efficient cross-coupling of alkynes with dialkylphosphites and phosphine oxides under mild and base-free conditions.