Kinetics and thermochemistry of the [2π+2σ+2σ]‐cycloaddition of quadricyclane with 2,3‐dicyano‐1,4‐benzoquinone

Two‐stage [2π+2σ+2σ]‐cycloaddition of quadricyclane ( 2 ) with 2,3‐dicyano‐1,4‐benzoquinone ( 1 ) with a huge difference in the activity of two reaction centers has been studied. In the first stage (kinetic control), the cycloaddition of 2 takes place on the activated С 2 =С 3 bond of 1 to form the monoadduct 3 , and in the second stage the cycloaddition of 2 on the С 5 =С 6 bond of the monoadduct 3 occurs by 6 orders of magnitude lower with the formation of bisadduct 4 . The structures of adducts 3 and 4 have been proved by NMR data and the X‐Ray method, respectively. The kinetics of the first and second stages, the enthalpy of dissolution of 1 in the π‐donor solvents, and the enthalpy of the reaction 1+2→3 have been measured.