Free radical ring expansion and subsequent reactions of intermediary carbon radicals
Alkyl radicals, derived from ethyl 1-(bromoalkyl)-2-oxocyclo-alkanecarboxylates or from the corresponding thiohydroxamic esters, undergo a ring expansion reaction and subsequent intermoleculaar addition/elimination reactions. Thus, in the reaction of ethyl 1-(bromomethyl)-2-oxocycloalkanecarboxylates 4 with allytributyltin 5 a ring enlargement for one carbon occurs and by subsequent addition/elimination reactions ethyl 1-allyl-3-oxocycloalkanecarboxylates 6 were obrtained in 45-65% yields. By thermal decomposition of thiohydroxamic esters of ω̄-(1-carbethoxy-2-oxocycloalkyl)-alkanoic acids 13 and 16 a ring expansion for one or three carbon atoms takes place and α,β-unsaturated-γ-keto ester of type 14 and 17, respectively, were obtained in 10-60% yields, accompained with 2-thiazolyl-alkylthio ethers 18.
Keywords:Allytributyltin / Free radicals / Ring expension / Thiohydroxamic esters
Source:Journal of the Serbian Chemical Society, 1996, 61, 11, 1095-1105
- Serbian Chemical Society