2-Thiophenecarboxaldehyde → HCID 54408924, compound

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Reaction Steps

A solution of 5,6,7,8-tetrahydro-2-methyl-3-quinolinecarboxylic acid ethyl ester as prepared in Preparation I (3.66 g) in acetic anhydride (10 ml) is treated with sodium acetate (1.37 g) and 2-thiophenecarboxaldehyde (2.24 g). The solution is heated at reflux temperature for 56 hours. The cooled mixture is diluted with toluene, filtered and the filtrate evaporated to a solid residue. The residue is triturated with hexane and filtered to yield a residue of 5,6,7,8-tetrahydro-2-methyl-8-(2-thienylmethylene)-3-quinoline carboxylic acid ethyl ester (1.91 g) m.p. 117° C.-118° C. The filtrate residue is purified on silica gel (70 g) with 9:1 Skelly B:ethyl acetate as eluent. Fractions 7-13, 20 ml each, provide additional 5,6,7,8-tetrahydro-2-methyl-8-(2-thienylmethylene)-3-quinoline carboxylic acid ethyl ester (0.73 g). An analytical sample, m.p. 117° C.-118° C. is obtained by hexane recrystallization.

Provenance & Evidence