Ytterbium(II) Complex‐Catalyzed Selective Single and Double Hydrophosphination of 1,3‐Enynes

Abstract 1,3‐Enynes with conjugated alkene and alkyne moieties are attractive building blocks in synthetic chemistry. However, neither 4,1‐hydrophosphination nor dihydrophosphination of 1,3‐enynes has been reported. In this paper, the divalent ytterbium and calcium amide complexes supported by silaimine‐functionalized cyclopentadienyl ligands (C 5 Me 4 ‐Si(L)=NR) were developed, which successfully catalyzed the efficient single and double hydrophosphination of 1,3‐enynes with diarylphosphines. The hydrophosphination reactions selectively produced homoallenyl phosphines and ( E )‐propenylene diphosphines, respectively. This work demonstrated the potential of hemilabile silaimine‐Cp ligands in the supporting the efficient and selective rare‐ and alkaline‐earth catalysts.