Biomedical subjects
Publications and source records attributed to Mina Tamura.
[reaction: see text] Beta-nitroenamine having a formyl group behaves as the synthetic equivalent of unstable nitromalonaldehyde upon treatment with ketones under basic conditions and leads to 2,6-disubstituted 4-nitrophenols. The present method is safer than the conventional one using sodium nitromalonaldehyde and enables the preparation of hitherto unknown nitrophenols.
beta-Nitroenamines having a formyl group at the beta-position behave as the synthetic equivalent of unstable nitromalonaldehyde, which is a useful synthon for syntheses of versatile nitro compounds. High solubility of the nitroenamines into general organic solvents enables us to conduct reactions in the organic media accompanied by easy experimental manipulations and considerable safety. When nitroenamines are treated with 1,2-bifunctional nucleophiles such as hydrazines, hydroxylamine and glycine ester, nitrated pyrazoles, isoxazole and pyrrole-2-carboxylate were readily prepared. This methodology was also applicable to guanidines and 1,2-diamines, leading to pyrimidines and 1,4-diazepines, respectively.
The acyl group of an alpha-aryl-beta-keto ester was readily transferred to N-, O-, and S-nucleophiles. The transacylation from arylated diethyl 3-oxoglutarate to amines led to unsymmetrical malonic acid amide esters in high yields. The present reaction proceeded under mild conditions without formation of detectable byproducts. Only simple experimental manipulations were required. This reaction was also found to be sensitive to steric factors, which enabled the chemoselective monoacylation of diamines and amino alcohols without any modifications such as protection.
The title compounds are readily available by ring transformation of nitropyrimidione with active methylene compounds in the presence of ammonium acetate.