Methyl 3-Amino-1H-indole-2-carboxylates in the Synthesis of 5H-Pyrimido[5,4-b] indole Derivatives

Abstract

Reactions of methyl 3-amino-1H-indole-2-carboxylates with aryl isocyanates, aryl isothiocyanates, and cyan amides led to the formation of 5H-pyrimido[5,4-b]indole derivatives. In the reaction with isocyanates formed 3-aryl-1H-pyrimido[5,4-b]indole-2,4(3H,5H)-diones that were involved into the alkylation at two nitrogen atoms. The reaction with isothiocyanates afforded-aryl-2-thioxo-2,3-dihydro-1H pyrimido[5,4-b]indol-4(5H)- ones undergoing alkylation at the sulfur atom. The reactions with benzoylcyanamide and N-(4,6-dimethylpyrimidin-2-yl) cyanamide resulted in N-(4-oxo-4,5-dihydro-3H-pyri ido-[5,4-b]indol-2-yl) benzamides and 2-(4,6-dimethylpyri midin-2-ylamino)-3H-pyrimido[5,4-b]indol-4(5H)-ones respectively