A new catalytic procedure for atom-transfer radical addition (ATRA) and cyclization (ATRC) reactions is described. The combination of the ruthenium(III) complex [RuCl(2)Cp*(PPh3)] (Cp*: pentamethylcyclopentadienyl) with magnesium allows these reactions to be performed under mild conditions with high efficiency. In most cases, the catalyst concentrations required are significantly lower than those used
Several omega-alkenyl dichloroacetates cyclize in moderate to excellent yields to 3,5-dichloro-oxocan-2-ones (8-membered ring lactones) when heated in benzene at 80-180-degrees-C in the presence of a catalytic amount of the cuprous chloride 2,2'-bipyridine complex.
Synthesis of medium-sized lactones by the copper(I)chloride/2,2′-bipyridine-catalyzed cyclization of di- and trichloroacetates
作者:Frank O.H. Pirrung、Henk Hiemstra、W. Nico Speckamp、Bernard Kaptein、Hans E. Schoemaker
DOI:10.1016/s0040-4020(01)89549-1
日期:1994.1
Medium-sized lactones (eight- to eleven-membered rings) are efficiently formed by Cu(bpy)Cl catalyzed cyclization of various alkenyl di- and trichloroacetates at temperatures between 80 and 190°C in 1,2-dichloroethane or benzene as solvents. The mechanism of the alkene addition reaction is best understood as a chlorine atom transfer process through radical type intermediates. Exclusive endo-cyclization