Abstract
Reactions of various substituted quinoline 1-oxides with cyanogen bromide in ethanol were investigated. The corresponding ethyl N-(8-quinolyl) carbamates were formed in most cases, but their yields were rather low except reactions of N-oxides of 4-quinolinol (If), 4-aminoquinoline (Ig), 2-quinolinol (IXf), 5-nitroquinoline (XXVI) and 6-chloroquinoline (XXX). In addition to 8-quinolylcarbamates, 2-quinolylcarbamates (VIc and VIe) were obtained from reactions of 4-ethoxyquinoline 1-oxide (Ic) and lepidine 1-oxide (Ie), and further the 6-quinolylcarbamate (VII) was also isolated in the latter case. The reaction of 4-quinolinol 1-oxide (If) gave the 3-quinolylcarbamate (VIII) as the main product besides 8-quinolyl derivatives, IIf and IIi. 2-Imino-1, 2, 4-oxadiazolo [2, 3-α] quinoline hydrobromide (XVI) was produced without the participation of ethanol in a good yield of 65% from the reaction of 2-aminoquinoline 1-oxide (IXg). From 8-ethoxycarbonylaminoquinoline 1-oxide (XX), a small amount of 2, 8-bis (ethoxycarbonylamino)-quinoline (XXI) was obtained. The features and mechanisms of some reactions were also discussed.
