1978 年 98 巻 6 号 p. 802-816
Knoevenagel condensation of o-nitrobenzaldehydes (Ia-d) with ethyl 2, 4-dioxopentanoate (II) gave 3-acetyl-2, 4-dihydroxy-4-(o-nitrophenyl) crotonic acid lactones (IVa-d), which take the open-form, 3-(o-nitrobenzylidene)-2, 4-dioxopentanoic acids (IV'a-d), in a polar solvent. Reductive cyclization of IVa-d in the presence of 5% Pd-C as a catalyst gave α-hydroxy-2-methyl-3-quinolineacetic acid 1-oxides (Va-d) in a good yield. These were easily derived to esters (VIa-c, VII, and VIIIa), α-keto esters (IXa-c), α-hydroxyimino esters (Xa-c), and aldehydes (XIa-c). The reaction of VIa with acetyl chloride followed by deoxygenation with phosphorus trichloride afforded methyl α-acetoxy-2-methyl-3-quinolineacetate (XVII), which was hydrolyzed to α-hydroxy acid (XVIII). Reduction of Xa with zinc dust in acetic acid and acetic anhydride gave α-acetamido ester (XIX), which was hydrolyzed to α-quinaldylglycine (XX). The reaction of VIa with acetic anhydride gave methyl α-acetoxy-2-acetoxymethyl-3-quinolineacetate (XXI), which was oxidized to the N→oxide derivative (XXIII). Hydrolyses of XXI and XXIII gave δ-lactones (XXII, XXIV). The reaction of IVa-d with diazomethane in ether gave 3-acetyl-4-hydroxy-2-methoxy-4-(o-nitrophenyl) crotonic acid lactones (XXVIa-d), the structure of which was determined from UV spectra. Similar reductive cyclization of XXVIa-d in alcohols (R3OH) gave alkyl (R3) 1, 4-dihydro-1-hydroxy-α-methoxy-2-methyl-4-oxo-3-quinolineacetates (XXVIIa-d, XXVIIIa-XXXa) in a fairly good yield. The mechanism of the formation of quinoline N-oxide derivatives and 1, 4-dihydro-4-quinolones was discussed. Finally for biological tests, resolution of Va with cinchonidine was carried out, and its effect on Aspergillus flavus and soy beans was tested.