Access to benzo-fused nine-membered heterocyclic alkenes with a trifluoromethyl carbinol moiety a double decarboxylative formal ring-expansion process under palladium catalysis.

Direct access to pharmaceutically attractive benzo-fused nine-membered heterocyclic alkenes with a trifluoromethyl carbinol moiety was achieved a palladium-catalyzed double-decarboxylative formal ring-expansion process from six-membered trifluoromethyl benzo[][1,3]oxazinones to nine-membered trifluoromethyl benzo[][1,5]oxazonines in the presence of vinylethylene carbonates . Generation of a Pd-π-allyl zwitterionic intermediate was proposed in the catalytic cycle. The trifluoromethyl group in the benzoxazinanones plays an important role throughout the transformation. Diastereoselective chemical transformations of products were also demonstrated.