Bridgehead Bicyclo[4.4.0]boron Heterocycles: A One-Pot Four-Component Synthesis of Dibenzo[e,i][1,3,7,2]oxadiazaborecin-8(7H)-ones.

A one-pot four-component synthesis of 6-aryl-6H-dibenzo[e,i][1,3,7,2]oxadiazaborecin-8(7H)-ones is described. Heating a mixture of isatoic anhydride and a benzylamine afforded the corresponding anthranilamide derivative, which was condensed with a 2-hydroxybenzaldehyde and an arylboronic acid under solvent-free conditions to produce bridgehead bicyclo[4.4.0]-boron heterocycles in good to excellent yields. Single-crystal X-ray analysis conclusively confirms the structures of the obtained bridgehead bicyclic 6–6 heterocyclic compounds.