A Catalytic Michael/Horner-Wadsworth-Emmons Cascade Reaction for Enantioselective Synthesis of Thiochromenes
作者:Abhijnan Ray Choudhury、Santanu Mukherjee
DOI:10.1002/adsc.201300281
日期:2013.7.8
A catalyticenantioselective sulfa‐Michael/Horner–Wadsworth–Emmonsreactioncascade has been developed, taking advantage of phosphonate as an electrophilic activator and a traceless binding site. Using a chiral bifunctional urea derivative as the catalyst, a variety of aryl and heteroaryl substituted thiochromenes was obtained in excellent yield with a high level of enantioselectivity.
An efficient protocol for silver-catalyzed direct radical phosphonation of β-aryl-α,β-unsaturated carbonylcompounds with H-phosphites to afford trans-substituted alkenylphosphonates under microwave irradiation is described. Some notable features of this method are high efficiency, good yield, broad functional groups tolerance, commercially available and cheap catalyst.