反应详情

Each of the Rilyazines RL-1 through RL-4 may be synthesized according to the procedure of Scheme 1. Furo[3,4-b]pyridine-5,7-dione is reacted with ethanol in the presence of an acid, such as H2SO4, resulting in diethyl pyridine-2,3-dicarboxylate (1), which is then reacted with freshly-prepared pyridin-2-yl lithium to afford ethyl 2-picolinoylnicotinate (2) and ethyl 3-picolinoylpicolinate (3). Separation of the isomers (2) and (3) by chromatography and their reactions with cyclohexylhdrazine hydrochloride affords the ketone-Rilyazines RL-1 and RL-3, which may then be converted to the corresponding thione-Rilyazines RL-2 and RL-4 by reaction with Lawesson reagent.