NEW PROCESSES FOR THE HALOFLUORINATION OF NORBORNADIENE. STRUCTURAL REEXAMINATION OF THE PRODUCTS. EVIDENCE FOR EXLUSIVE EXO ATTACK BY ELECTROPHILES.

Article abstract of DOI:10.1016/S0040-4020(01)85985-8

The bromofluorination of norbornadiene using NBS in the presence of the new fluorinating agent Et3N/3HF leads to a 3:2 mixture of 3-exo-bromo-5-exo-fluoronortricyclane 1 and 3-exo-bromo-5-endo-fluoronortricyclane 2.The structures of these compounds were proven by independent syntheses and extensive NMR spectroscopic studies.The structure (3-endo-bromo-5-exo-fluoronortricyclane) given for the minor compound in the literature was revised especially in terms of the comparison of ³J_CF coupling constants in the 13C NMR spectra of both compounds.No evidence for an endo attack of the bromonium species on norbornadiene as stated in the literature was observed.