Oxygenated-1,2-cyclohexadienes and their unsubstituted counterpart can be generated under mild conditions by fluoride-induced desilylation and undergo intermolecular [2 + 2]-cycloaddition reactions with a variety of alkene traps to afford bicyclo[4.2.0]octenes. Both styrenes and electron-deficient olefins react in good conversion and with complete regioselectivity in favor of cyclobutane formation at the unsubstituted C2/C3 carbons of the C1-substituted cyclic allenes. Diastereoselectivities are modest (1.1–5.7:1) with a preference for the exo-isomer.

Abstract1,2‐Cyclohexadienes generated under mild fluoride‐mediated desilylative conditions undergo efficient intramolecular [2+2] trapping, providing tricyclic alkylidene cyclobutanes with complete diastereoselectivity for the cis‐fused products. Pendent styrenes or electron‐deficient olefins can trap simple 1,2‐cyclohexadienes or their oxygenated counterparts, with 14 substrates being disclosed. Reactions proceed at ambient temperature using just cesium fluoride in up to 91 % yield, and the necessary precursors are easily accessed from substituted 2‐bromocyclohexenones. Multiple synthetic routes have been developed to install the appropriate functional groups required for [2+2] trapping.

The spring-loaded tension of a cyclic allene expedites synthesis of a natural product