Irradiation of solutions of β-hydroxycobaloximes e.g. (2), (5), (9) and (13) derived from epoxy olefins [e.g. (1), (8) and (12)] and cobalt(I) dimethylglyoxime, using a sunlamp at room temperature, leads to facile cyclisation producing cycloalkanols e.g. (4), (6), (10) and (14). By contrast, only the products viz (3), (7) and (11) of dehydrocobaltation are produced when the same β-hydroxycobaloximes
An oximinotrifluoromethylation of unactivated alkenes was developed via trifluoromethyl radical-induced intramolecular remote oximino migration under mild reaction conditions.
Complete Control of Regioselectivity in the Intramolecular [2 + 2] Photocycloaddition of 2-Alkenyl-3(2<i>H</i>)-furanones by the Length of the Side Chain
The 2-(omega-alkenyl)-substituted 2-methyl-3(2H)-furanones 2a and 2b were prepared from biacetyl (3) in four reaction steps and in overall yields of 20% and 21%, respectively. They underwent a clean intramolecular [2 + 2] photocycloaddition upon irradiation at lambda = 350 nm. Whereas compound 2a reacted in the expected manner and yielded 7-oxabicyclo[3.2.1.0(3,6)]octane 7 (87% yield), the regioselectivity