The reaction of norbornene with CuCl2, TlCl3·4H2O, PbCl4, SeCl4, SbCl5, and VCl4 in CCl4, CH2Cl2, or CH3CN gave a mixture of nortricyclyl chloride (1), and six isomeric dichloronorbornanes [trans-2,3-(2), exo-2-anti-7-(3), trans-2,5-(4), exo-cis-2,5-(5), exo-cis-2,3-(6), and exo-2-syn-7-(7)], the product distribution depending very much on metal chlorides and reaction conditions. The reactions did not show any participation of a chlorine molecule which may be released from metal chlorides. The ability of SeCl4 and VCl4 to chlorinate olefins was found for the first time. From a synthetic viewpoint CuCl2 was a good reagent for obtaining 2, while TlCl3·4H2O and SbCl5 were recommended for either 3 or 7. The reactions with the following metal chlorides did not give any dichloronorbornanes; SnCl4, BiCl3, TiCl4, FeCl3, NbCl5, TaCl5, and WCl6. It was revealed that isomerization of 2 or 7 to a mixture of 3, 4, and 5 occurred very rapidly by SbCl5 and smoothly by TlCl3·4H2O. The chlorination of norbornene and their products isomerization were mainly explained by assuming a chloronorbornyl cation as an intermediate.
No takes yet. Share an insight, caveat, or question.
Uemura et al. (1975) studied this question.
Synapse has enriched 4 closely related papers on similar clinical questions. Consider them for comparative context: