Valence-bond isomer chemistry. Part V. Hexafluorobicyclo[2.2.0]-hexa-2,5-diene and its derivatives as dipolarophiles

Abstract

Hexafluorobicyclo[2.2.0]hexa-2,5-diene is an active dipolarophile, reacting with the representative 1,3-dipoles phenyl azide. diazomethane, 2,2,2-trifluorodiazoethane. 2,4,6-trimethylbenzonitrile oxide, and benzonitrile N-phenylimide to give 1 : 1 adducts, and mixtures of 1 : 2 adducts. Related compounds are similarly reactive, addition to the CF:CF double bond of 2-methoxypentafluorobicyclo [2.2.0]hexa-2,5-diene, and of exo-5,6-dibromohexa-fluorobicyclo [2.2.0]hex-2-ene, occurring with phenyl azide and with 2,4,6-trimethylbenzonitrile oxide, respectively. ¹⁹F N.m.r. studies indicate that reaction occurs by exo-addition to the bicyclo-compounds.

The phenyl azide adducts, 1,2,3,4,5,6-hexafluoro-9-phenyl-7,8,9-triazatricyclo[4.3.0.0^2,5]nona-3,7-diene and 1,2,3,5,6,7-hexafluoro-4,10-diphenyl-4,8,9,10-tetra-azatetracyclo[5.3.0.0^2,6.0^3,5]dec-8-ene, lose nitrogen upon u.v. photolysis in acetone solution, to give the derived aziridines.