Acid‐dependent Divergent Conversion of ortho‐Arylcyclopropanecarbonyl Carboxaldehydes for the Synthesis of Furanodibenzocycloheptenes and Dibenzocycloheptenes

Abstract

Abstractortho‐Arylcyclopropanecarbonyl carboxaldehydes were utilized common substrates for the synthesis of furanodibenzocycloheptenes and dibenzocycloheptenes. Excess amount of (+)‐camphorsulfonic acid ((+)‐CSA) could lead to acid‐promoted cyclopropane ring opening/cyclization reaction of the common substrates to give dibenzocycloheptene products in up to 87% yield. Alternatively, when the common precursors were treated with catalytic amount of super acid (NHTf2) resulting in the formation of furanodibenzocycloheptenes as a mixture of two regioisomeric products.