Triphenylphosphine Sulfide as an Efficient Ligand in CuAAC to Synthesize 4-Phosphinyl-1,2,3-Triazoles

Triphenylphosphine sulfide ligand (L1) exhibited excellent catalytic performance in the copper-catalyzed azide–alkyne cycloaddition (CuAAC) of ethynyldiphenylphosphine oxide (1) and azides (2), affording functionalized 4-phosphinyl-1,2,3-triazoles (3) in good yields. L1 showed superior performance to triphenylphosphine oxide, triphenylphosphine, and the sulfide ligands examined, possibly owing to suitable coordination of its P=S moiety to Cu. And, the products could be transformed to 4-phosphanyl-1,2,3-triazoles (4) and 1-benzyl-substituted 1,2,3-triazoles (5) by reduction and dephosphinylation, respectively. This [Cu]/L1-catalyzed protocol, the first example of the application of triphenylphosphine sulfide as a ligand in CuAAC, featured the following advantages: low catalyst loading, relatively short reaction time, broad functional group tolerance, high yields, and facile scalability.