Thermal cyclization of ethyl α-(2-chloro-2-propenyl)-β-arylaminocrotonates in mineral oil afforded the corresponding substituted 2,4-dimethylfuro[3,2-c]quinolines instead of the expected 4-hydroxy-2-methyl-3-(2-chloro-2-propenyl)quinolines. Scheme 1.
Keywords: 4-hydroxy(amino)-2-methyl-3-(2-methylindol-3-yl)methylquinolines, 4-hydroxy(chloro)-2-methyl-3-(3-oxobutyl)quinolines, 4-hydroxy-2-methyl-3-(3-oxobutyl)quinolines thiosemicarbazones.We have previously developed a convenient method for the synthesis of differently structured 3-(3-oxobutyl)quinolines [1, 2] as suitable starting materials for conversion to different novel heterocyclic systems. In continuing these investigations of the synthesis of quinolines also containing an indole ring we have studied the reaction of the corresponding 4-hydroxy-2-methyl-3-(3-oxobutyl)quinolines with phenylhydrazine hydrochloride.Optimum conditions for the reaction have been developed. It was found that the reaction indicated can be brought about by heating equimolar mixtures of the starting components in alcoholic solution in the presence of H 2 SO 4 for 7-8 h. Evidently the reaction takes place with the formation of an intermediate phenylhydrazone and a subsequent Fischer type rearrangement to give high yields of the corresponding indolylquinolines 1a-e. N OH CH 2 CH 2 Me R Me N OH CH 2 Me R N H Me C N Me N C NH 2 S N OH CH 2 CH 2 Me O R 1a-e C H 2a-e 1, 2 a R = H, b R = 6-Me, c R = 8-Me, d R = 6-OMe, e R = 8-OMe
Fused pyridine derivatives R 0450 New Synthesis of 2,4-Dimethylfuro[3,2-c]quinolines. -2,4-Dimethylfuro[3,2-c]quinolines, e.g. (VI), are prepared from readily accessible starting compounds. -(AVETISYAN, A. A.; ALEKSANYAN, I. L.; PIVAZYAN, A. A.; Russ. J. Org. Chem. 40 (2004) 9, 1351-1352; Erevan State Univ., Erevan 375049, Armenia; Eng.) -M. Bohle 15-141
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