In the presence of a mixture of pyridine and acetic acid, dimethyl acetylenedicarboxylate condenses with malononitrile and with ethyl cyanoacetate to give, respectively, pyridinium salts I1 and 111. Under the saMe conditions dimethyl acetylenedicarboxylate and malonate esters yield two isomeric lJ1, 2, 3, 4, 5, 6, 7-octacarbo-alkoxycycloheptadienes. Aqueous potassium acetate converts these cycloheptadienes into the potassium salt of the strongly ...
