Palladium-Catalyzed Self- and Cross-Dimerization Annulation of β-CF3-1,3-Enynamides: An Access to Functionalized Bicyclo[4.2.0]trienes.

An efficient and general method for the synthesis of highly functionalized bicyclo[4.2.0]trienes via a palladium-catalyzed self-dimerization annulation of β-CF3-1,3-enynamides and cross-dimerization annulation of β-CF3-1,3-enynamides with 1,3-enynes was developed. β-CF3-1,3-enynamides bearing a Ts group were identified as optimal reagents for cross-dimerization of two different enynes. In all cases, the reactions proceeded in a regiospecific manner, affording highly functionalized bicyclo[4.2.0]trienes which are challenging to prepare via conventional approaches. Further synthetic transformations of the bicyclo[4.2.0]trienes were explored, highlighting their distinctive reactivity profile and outlining their application in diverse syntheses.