This compound can be obtained by two related ways: 1) By cyclization of ethyl 6-chlorocoumarin-3-carboxylate (I) and N-methyl-4-piperiodone (II) by means of sodium acetate in refluxing ethanol, followed by a treatment with refluxing concentrated hydrochloric acid. 2) The cyclization of (I) and (II) by means of ammonium acetate in refluxing ethanol, followed by a treatment with cool concentrated hydrochloric acid gives the lactam od the ethyl monoester of 4a-amino-8-chloro-2-methyl-1,2,3,4,4a,10a-hexahydro(10H)-benzopyrano[3,2-c]pyrid-10-ylmalonic acid (III), which is hydrolyzed with KOH in refluxing ethanol-water to give the corresponding free acid (IV). Finally, this compound is decarboxylated by a treatment with NaHCO3 in refluxing water.
The Grignard condensation of 2,3-dichloroiodobenzene (I) with CO2 by means of Mg / ether gives 2,3-dichlorobenzoic acid (II), which is converted to the corresponding acyl chloride (III) by refluxing with SOCl2.The reaction of (III) with cuprous cyanide and KI in refluxing xylene yields 2,3-dichlorobenzoyl cyanide (IV). Finally, this compound is cyclized with aminoguanidine (V) in DMSO.