Metal catalyzed deoxygenation by carbon monoxide of o-substituted nitrobenzenes. Synthesis of 1,4-dihydro-2H-3,1-benzoxazin-2-one derivatives

Article abstract of DOI:10.1016/0022-328X(93)83021-M

The reductive carbonylation of o-nitrobenzylalcohols, o-NO2C6H4CR¹R²OH 1 = 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 deg C.The palladium catalyst has been shown to be 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.