RING-CLOSURE OF THE 6-METHYLENECYCLODECYL RADICAL

Treatment of the dithiocarbonate, 10a, derived from 6-methylenecyclodecanol, with tributylstannane affords a mixture of the cis- and trans- isomers of 9-methyldecahydro-naphthalene, in which the former predominates, but no methylenecyclodecane. The reaction involves the extremely rapid, stereoselective transannular cyclisation of the 6-methylene-cyclodecyl radical (2b). Generation of 2b by thermolysis of the tert-butyl perester, 12b, in the presence of 1,1,3,3-tetramethylisoindolinyl-2-oxyl (T·.) gives both cyclised (15, 16) and uncyclised (14) products. The usual treatment of the data gives kc≈ 3 × 1010 s-1 at 80°C, where kcis the rate constant for cyclisation of 2b. © 1991.