Number and structure of solvolysis intermediates. Part 1. A comparison of nucleophilic reactions on in situ generated carbocations with solvolysis reactions for 2,2-dimethyl-1-(p-methoxyphenyl)propyl cation

Abstract

2,2-Dimethyl-1-(p-methoxyphenyl)propyl cation has been generated by treatment of the corresponding chloride with AgSbF₆ in SO₂–CH₂Cl₂(20% CD₂Cl₂) at –98 °C and its ¹³C NMR spectrum observed. The reactions of the generated carbocation with methanol or phenol give products with a rearranged carbon atom skeleton and non-rearranged products with complete racemization, as expected for a typical carbocation reaction, whereas the solvolysis of the corresponding p-nitrobenzoate in phenol affords exclusively the non-rearranged products with partial retention of configuration. Such distinctions between generated carbocation reactions and the solvolysis reactions indicate that no dissociated (free) carbocation intermediate intervenes even in this solvolysis system, i.e., it is one of a few systems which have been hitherto confirmed to proceed via multiple intermediate stages.