The selectivity of attack by the hydroxyl radical on myoinositol, and the importance of stereoelectronic factors upon radical rearrangement: an electron spin resonance conformational-analysis study

Abstract

E.s.r. spectroscopy has been employed to show that the reaction of ·OH with the model substrate myoinositol is unselective; at pH 4, e.s.r. signals of all possible radicals produced by C–H abstraction are detected. A conformational analysis based on the hyperfine splittings is presented. The rates of acid-catalysed rearrangement of the radicals have been measured; the radical with an axial β-hydroxy-group is shown to lose water with a rate constant (ca. 3 × 10⁶ dm³ mol^–1 s^–1) which is considerably greater than those of the radicals with only equatorial β-hydroxy-groups. This is interpreted in terms of a significant stereoelectronic requirement for rearrangement.