Aromatic nucleophilic substitution of hydrogen: reactions of 6-nitroquinoline with potassium cyanide and nitroalkanes

The reactions of 6-nitroquinoline 1 and potassium cyanide with methyl nitro acetate, nitroethane, 1-nitropropane, and 2-nitropropane have been carried out in the medium of dimethyl sulfoxide. H-1 NMR has been used to identify the reaction products from 6-nitroquinoline 1 with methyl nitroacetate and potassium cyanide and to determine the proportions of products in the react ion mixture. The main reaction products are 6-(methoxalylamino)quinoline-5- carbonitrile 6 and 1-aminoisoxazolo[4,3-f]quinoline 9. The reactions of 6-n itroquinoline 1 with potassium cyanide and primary nitroalkanes give, as th e main products, 3-substituted pyrido[3,2-f]quinazolin-1(2H)-ones 12a,b. Th e reaction of 6-nitroquinoline 1 and potassium cyanide with 2-nitropropane produces 3-(1-cyano-1-methylethyl)-2,3-dihydro-1H-pyrazolo[4,3-f]quinolin-1 -one 14 as the chief product. In all cases the reaction involves substituti on of the 5-hydrogen of quinoline skeleton with concomitant lowering of oxi dation number of the nitrogen atom in the original nitro group of 1. A mech anism is suggested for the reactions investigated involving 6-nitrosoquinol ine-5-carbonitrile 3 as a likely common intermediate.