Rearrangements of bicyclic monoterpenes

The stereochemistry of reaction of phenylmagnesium bromide with camphor (43) has been determined. The attempted preparation of the phenyl alcohol (46) by oxymercuration of 2-phenylbornylene (72) resulted in the formation of the vinyl-mercury (81). Consequently the oxymercuration of a number of olefins was carried out to determine the vital structural features for the occurrence of vinylmercury compound formation. Attempted preparation of epoxides (49 and 50) by m-chloroperbenzoic acid oxidation of the olefin (72) gave largely 2-endo-phenyl ketone (87). An attempt to prepare the bromohydrin (90) by reaction with aqueous N-bromosuccinimide resulted in formation of the bromo-olefin (70). The exo- and endo-epoxides (49 and 50) were prepared by a novel syn-elimination reaction of the two cis-diol monotosylates (60 and 93). The acid catalysed rearrangement of the endo-epoxide (50) gave only the 2-endo-phenyl ketone (87), while the exo-epoxide (49) gave mainly the aldehyde (119). The cyclic sulphites (95a and 95b) were prepared from the cis-exo-diol (59) obtained by potassium permanganate oxidation of the olefin (72). Thermal rearrangement of the cyclic sulphites gave the aldehyde (119) and the 2-endo-pbenyl ketone (87). The greater proportion of the ketone (87) from the anti-cyclic sulphite (95a) has been rationalised in terms of the stereochemistry about the sulphur atom. A study of the thermal rearrangements of the 2,3-butane epoxides (108 and 109) with sulphur dioxide and the cyclic sulphites (116 and 117) is described