(endo)-5-(2-haloethyl)-2-norbornene. A new radical probe.

(endo)-5-(2-haloethyl)-2-norbornenes have been synthesized, and their corresponding radicals generated by reaction with sodium, magnesium, sodium naphthalenide and tri-n-butyltin hydride in the presence of AIBN to produce both straight chain and cyclized products. This probe cyclizes substantially faster than the often used 5-hexenyl halide probes.