Metal catalyzed deoxygenation by carbon monoxide of o-substituted nitrobenzenes. Synthesis of 1,4-dihydro-2H-3,1-benzoxazin- 2-one derivatives
作者:S. Cenini、S. Console、C. Crotti、S. Tollari
DOI:10.1016/0022-328x(93)83021-m
日期:1993.6
The reductive carbonylation of o-nitrobenzylalcohols, o-NO2C6H4CR1R2OH [R1 = R2 = H (1); R1 = R2 = CH3 (2); R1 = H, R2 = CH3 (3); R1 - H, R2 = C6H5 (4)], catalyzed by ruthenium and palladium-based catalytic systems gives the corresponding 1,4-dihydro-2H-3,1-benzoxazin-2-one derivatives, 1a-4a. Reaction conditions used were 20-60 atm of carbon monoxide and 100-170-degrees-C. The palladium catalyst has been shown to be by far superior to the ruthenium catalyst in this reaction as far as selectivity is concerned. By carbonylation of o-nitrophenethylalcohol (5) with the palladium system as catalyst a mixture of the monomeric 5a and dimeric 5b cyclic carbamates has been obtained.