Conformation et reactivite de derives (4.n.0) bicycliques a jonction trans—XXIV: Trifluoroéthanolyse du phényl-4a et du méthyl-4a tosyloxy-3a bicyclo (4.2.0) octane trans. mise en évidence d'une réaction d'élimination à partir d'union phénonium

Rate constants and reaction products for trifluoroethanolysis of transfused 4a-phenyl 3a-tosyloxy bicyclo (4.2.0) octane 1 and 4a-methyl 3a-tosyloxy bicyclo(4.2.0) octane 1' are reported. As for methanolysis, this reaction occurs through the E₁(ip) process. Nevertheless, first-formed secondary cations are rearranged before reacting, by hydride migration for 1 and 1', and phenyl migration for 1. Reaction products result from solvent or leaving group basic and nucleophilic attack on tertiary ions, and phenonium ion for 1. Elimination via phenonium ion has been established by the characterisation of a rearranged olefin (with equatorial phenyl). A mechanism for this elimination reaction is proposed.