Addition of dibromocarbene to tricyclo[4.3.0.03,7]nona-4,8-diene (brexadiene). Synthesis of exo-4,5,10,exo-11-tetrabromotricyclo[5.4.0.03,8]undeca-5,9-diene

Addition of dibromocarbene to tricyclo[4.3.0.0 3,7 ]nona-4,8-diene (brexadiene) under phase-transfer catalysis conditions yields the only tricyclic tetrabromide, exo -4,5,10, exo -11-tetrabromotricyclo[5.4.0.0 3,8 ]undeca-5,10-diene