Cycloalkylmethyl radicals. Part 7. - Electron paramagnetic resonance characterisation of axial and equatorial centres in seven-membered alicyclic molecules

Andrew C. Hindson, John C. Walton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The EPR spectra of cycloheptylmethyl, cyclohept-4-enylmethyl and 1,3-dioxacyclohept-5-enylmethyl radicals have been observed. The cycloheptylmethyl radical spectrum shows only a single, average conformation, but for the cycloheptene and dioxacycloheptene rings the CH2. group proved to be a useful probe of the conformations. The preferred conformation of the 1,3-dioxacycloheptene ring was found to depend on the type of substitution at C(2). For the 2-CH2. radical, twist-boat and chair conformers were observed with an Arrhenius activation barrier to inversion of 5 kcal mol-1. For the 2-CH3, 2-CH2.2 radical the main conformation was the twist-boat. For the 2-Ph, 2-CH2. radical the main conformation was the chair; the rotation of the CH2. group was found to be restricted by a barrier of ca. 7.5 kcal mol-1, probably because of steric interaction from two syn axial hydrogens on C(4) and C(7).

Original languageEnglish
Pages (from-to)3237-3241
Number of pages5
JournalJournal of the Chemical Society, Faraday Transactions
Volume86
Issue number19
DOIs
Publication statusPublished - 1 Dec 1990

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