Enantioselective Direct Vinylogous Michael Addition of Functionalized Furanones to Nitroalkenes Catalyzed by an Axially Chiral Guanidine Base

The highly syn-diastereo- and enantioselective direct vinylogous Michael addition of a-thio substituted furanones with conjugate nitroalkenes was demonstrated using an axially chiral guanidine base catalyst. The method provides facile access to enantioenriched alpha,gamma-functionalized butenolides that can be further manipulated, thereby rendering them useful synthetic intermediates.