CONFORMATION ET REACTIVITE DE DERIVES (4.n.0) BICYCLIQUES A JONCTION trans-XXVII. TRIFLUOROETHANOLYSE DU TOSYLATE DE PHENYL-4a BICYCLO (4.4.0) DECANYLE-3a TRANS. IMPORTANCE DE LA COPLANEITE DES GROUPES C6H5 ET OTs POUR L'ASSISTANCE DU PHENYLE.

Article abstract of DOI:10.1016/0040-4020(80)80007-X

The reaction products from the trifluoroethanolysis of trans-fused 4a-phenyl 3a-tosyloxy bicyclo(4.4.0)decane 2 have been investigated and compared with the data previously obtained for trans-fused 4a-phenyl 3a-tosyloxy bicyclo(4.2.0)octane 1.This comparison provides strong evidence that an aryl-assisted pathway is involved in the ionisation of tosylate 2, the assisted rate being 25 times that of the competing unassisted pathway.A comparative study of the solvolytic rates in the case of several similar tosylates (differently substituted and belonging to the (4.4.0) and (4.2.0) series) allowed us to conclude in favour of phenyl-assisted ionisation process, in the case of trifluoroethanolysis of tosylate 1, though the acceleration factor is then only 11.The fact that the ratio of reaction through the assisted pathway is lower for tosylate 1 than for tosylate 2 has been attributed to a less rigorous parallelism of the C-C6H5 and C-OTs bonds implied in the formation of the bridged ion for compound 1.