Substituent Effects for the Benzene Ring on Solvolysis of 3,4-Benzotricyclo[4.3.1.01,6]dec-3-en-2-yl p-Nitrobenzoate

Preparations of anti-4′-substituted 3,4-benzotricyclo[4. 3. 1. 01,6]dec-3-en-2-yl p-nitrobenzoates (1a–d) are described. The solvolysis of these esters was examined in 80% aqueous acetone. The rates were relatively high but the sensitivity to substituents on the benzene ring was low in comparison with other secondary systems. It is considered that σ-participation rather than π-conjugation might contribute to the rate accelerative effect. In the presence of a base, 1a–d gave anti-alcohol (12a–d) (13 to 17%), syn-alcohol (13a–d) (31 to 78%), and tert-alcohol (14a–d) (5 to 54%). The product distributions are explained in terms of a nonclassical homonaphthalenium cation (24).