53082-15-8Relevant articles and documents
The chemistry of small-ring compounds. Part 48. Oxidation of cyclopropylidenecycloalkanes with singlet oxygen
Heuvel, C. J. M. van den,,Steinberg, H.,Boer, Th. J. de
, p. 145 - 152 (2007/10/02)
Cyclopropylidenecyclohexane undergoes the ene reaction with singulet oxygen.The migrating allylic hydrogen originates exclusively from the cyclohexane ring and therefore the hydroperoxy group becomes attached to the cyclopropane ring.Since the O-O bond in cyclopropyl peroxy systems is weak, the reaction product undergoes homolysis even at -50 deg C and this also triggers rupture of the small ring.The resulting radical pair, consisting of 7 and the hydroxyl radical, recombines to form unsaturated β-hydroxy ketone 8 and the di-α,β-unsaturated ketone 9 (cf.Scheme 2).As a model for a cyclopropylidenecycloalkane containing no active allylic hydrogen, the adamantyl derivative 10 was subjected to photo-oxidation.In this case, the product is lactone 11 (yields in Table I), formed by early ring enlargement, i.e. before O-O rupture, as outlined in Scheme 4.The zwitter ion 15a isomerises to the key intermediate carbonyl oxide 17 and, as a result of the presence of the cyclobutane ring, this can rearrange to lactone 11 in various ways (cf.Scheme 5 and 6).By photo-oxygenation in 18O-labelled acetone, zwitter ion 17 is trapped by the solvent as an unstable ozonide which decomposes with formation of 18O-labelled lactone (Scheme 7).Photo-oxygenation in the presence of TCNE gives exclusively ketone 12 by deoxygenation of 17 (Scheme 4).
