Pd-Catalyzed Decarboxylative Cyclization of Trifluoromethyl Vinyl Benzoxazinanones with Sulfur Ylides: Access to Trifluoromethyl Dihydroquinolines.

An unprecedented Pd-catalyzed decarboxylative cyclization of 4-trifluoromethyl-4-vinyl benzoxazinanones (4) with sulfur ylides (2) is reported. While the reactions of 4-vinyl/4-CF3 benzoxazinanones (1a/1c) with 2 furnished the 3-vinyl/3-CF3 indolines (3a/3c), via an attack on the C1 carbon of the π-allyl/benzyl zwitterionic intermediates, 4 was converted into 4-trifluoromethyl-dihydroquinolines (5) in good yields via an attack on the C3 carbon of the π-allyl intermediate. The corresponding methyl-substituted analogues afford different products via an attack on the C2 carbon.