Catalytic Asymmetric Hydrophosphinylation of α,β-Unsaturated N-Acylpyrroles: Application of Dialkyl Phosphine Oxides in Enantioselective Synthesis of Chiral Phosphine Oxides or Phosphines
摘要:
Dialkyl phosphine oxides were introduced in catalytic asymmetric transformations for the first time. An unprecedented phospha-Michael reaction of dialkyl phosphine oxide with alpha,beta-unsaturated N-acylpyrroles was disclosed. Excellent enantioselectivities (94-99% ee) and chemical yields (up to 99%) were achieved with a broad substrate scope of the N-acylpyrroles. Importantly, pyridine was found to be critical to achieve good results for the present reaction.
Enantioselective conjugate hydrocyanation of α,β-unsaturated N-acylpyrroles with the combined use of Me3SiCN, LiCN, and HCN has been developed in the presence of a chiral lithium(I) phosphoryl phenoxide catalyst. This reaction is useful for a variety of N-acylpyrroles, including previously unreported substrates, such as heteroaryl and halogen-substituted N-cinnamoylpyrroles. A gram-scale reaction and