フロキノリン類 (第3報)

Abstract

By catalytic hydrogenation with PdO as a catalyst in alcoholic solution at oridinary temperature and pressure, dictamnine (I) and skimmianine (II) absorb one mole of hydrogen to yield respectively dihydrodictamnine, C12H11O2N, long pillars, m.p. 96-97° (picrate: yellow prisms, m.p. 183°), and dihydroskimmianine, C14H15O4N, prisms, m.p. 163° (picrate: yellow needles, m.p. 183°). Dihydroskimmianine does not absorb bromine in glacial acetic acid solution while (II) is brominated. Dihydrodictamnine and dihydroskimmianine are therefore 4-methoxy-(V) and 4, 7, 8-trimethoxy-2, 3-dihydrofuro [2, 3-b] quinoline (IV), respectively. (II) is cleaved to 3-ethylcarbostyril compound (VII) by catalytic hydrogenation with PtO2-catalyst, but (IV) cannot be hydrogenated with the same catalyst. This suggests that hydrogenolysis of the furo [2, 3-b] quinoline bases with PtO2-catalyst results in the formation of (VII) through 3-vinylcarbostyril (VI), the fission of the furan ring occurring in the 1:2-position. On hydrogenation over Raney nickel, (II) yields a mixture of (IV) and (VII). From the above facts, dihydroacronycidine by Lahey, Lamberton and Price obtained from acronycidine (III) by catalytic reduction over Raney nickel must be 4, 5, 7, 8-tetramethoxy-2, 3-dihydrofuro [2, 3-b] quinoline (VIII). Tetrahydro and hexahydro derivatives of acronidine by Lamberton and Price are considered as (Xa-Xb) and (XIa-XIb), respectively.