The reaction of gamma-phosphonyloximes with Lawesson's reagent leads to a variety of new 1,2,5-oxazaphospholine derivatives. The reaction shows regioselectivity and gives a mixture of two diastereoisomers. The steric factors influencing the regioselectivity of the reaction are discussed and a mechanism accounting for the formation of the new compounds is proposed.
PS-BEMP was used as a heterogeneous catalyst for the phospha-Michael addition of phosphorus nucleophiles to a variety of electron-poor alkenes. The addition reactions were generally performed with equimolar amounts of reagents under solvent free conditions. The protocol proved to be very efficient for the addition to aromatic, non-aromatic and cyclic ketones, giving good yields (78–85%) in all cases
Highly Enantioselective 1,4-Addition of Diethyl Phosphite to Enones Using a Dinuclear Zn Catalyst
作者:Depeng Zhao、Ye Yuan、Albert S. C. Chan、Rui Wang
DOI:10.1002/chem.200802688
日期:2009.3.9
Zinc benefits: The first catalytic asymmetric phospha‐Michael addition of enones has been developed. Under mild reaction conditions, the γ‐oxo phosphonates could be obtained in high yields (up to 99 %) with excellent enantioselectivities (93–99 % ee; see scheme). The strategy makes the asymmetric synthesis of biologically important phosphonate compounds more accessible.