Grignard Reaction of 2-Substituted-3-Cyanoquinolines

Abstract Grignard reactions of 2-morpholino and 2-methylthio-3-cyanoquinoline, 2-chloro-3-cyanoquinoline, 2-chloro-3-cyano-6-methoxyquinoline and 2-chloro-3-cyano-7-methylquinoline with alkyl or aryl magnesium halides have been studied. It was found that 2-morpholino and 2-methylthio- 3-cyanoquinolines gave 1,4-addition products followed by rapid aromatisation. 2-Chloro-3- cyanoquinoline with alkyl magnesium halides furnished 1,4-addition products but with aryl magnesium halides 1,4- and 1,2-addition products were obtained. The cyano group of 4-aryl-2-chloro- 3-cyano-1,4-dihydroquinolines was found to participate in the Grignard reaction to yield 1,2- addition products. 2-Chloro-3-cyano-6-m ethoxyquinoline with alkyl and phenyl magnesium halides yielded exclusively 1,4-addition products. Similarly with p-m ethoxyphenyl magnesium bromide, 1,4-addition products were isolated which participated in the Grignard reaction to yield the expected adducts. Unlike the other chloroquinoline derivatives, 2-chloro-3-cyano-7-methylquinoline with alkyl magnesium halide formed 1 ,2-addition products but with aryl magnesium halides, 1,4-addition products were isolated. The 4-alkyl-2-chloro-3-cyano-l,4-dihydroquinolines were unstable as compared to their 4-aryl analogs. A couple of the Grignard reaction products were found to be unstable on activated surface.