Asymmetric synthesis of complex tricyclo[3.2.2.0]nonenes from racemic norcaradienes: kinetic resolution via Diels–Alder reaction

Herein, the enantioselective synthesis of complex tricyclo[3.2.2.0]nonenes through the Diels–Alder reaction is reported. Utilizing racemic norcaradienes prepared from the visible-light-mediated dearomative cyclopropanation of m-xylene as dienes and enone derivatives as dienophiles, the overall process represents a kinetic asymmetric transformation in the presence of a chiral cobalt(ii) complex of chiral N,N′-dioxide. High diastereo- and enantioselectivity could be obtained in most cycloaddition processes and part racemization of norcaradiene is observed. The topographic steric maps of the catalysts were collected to rationalize the relationship between reactivity and enantioselectivity with the catalysts.