Synthesis of New Functionally Substituted Pyrazoles and Indoles from Acetophenones with a Carbamate Moiety

The condensation of acetophenones containing a carbamate moiety with phenylhydrazine in ethanol was used to obtain the corresponding phenylhydrazones, which were further converted into methyl N-[2(3,4)-(4-formyl-1-phenyl-1H-pyrazol-3-yl)phenyl]carbamates in yields of 79–83% via the Vilsmeier–Haack reaction. Refluxing methyl N-[4-(4-formyl-1-phenyl-1H-pyrazol-3-yl)phenyl]carbamate with barbituric and thiobarbituric acids in ethanol in the presence of triethylamine gave methyl N-[4-(1-phenyl-4-{[2,4,6-trioxotetrahydro-5(2H)-pyrimidinylidene]methyl}-1H-pyrazol-3-yl)phenyl]carbamate and methyl N-[4-(4-{[4,6-dioxo-2-thioxotetrahydro-5(2H)-pyrimidinylidene]methyl}-1-phenyl-1H-pyrazol-3-yl)phenyl]carbamate in yields of 50–54%. The three-component condensation of methyl N-[4-(4-formyl-1-phenyl-1H-pyrazol-3-yl)phenyl]carbamate with thiourea and ethyl acetoacetate or ethyl cyanoacetate under reflux in ethanol afforded ethyl 4-(3-{4-[(methoxycarbonyl)amino]phenyl}-1-phenyl-1H-pyrazol-4-yl)-6-methyl-2-thioxo-1,2,3,4-tetrahydro-5-pyrimidinecarboxylate and methyl N-{4-[4-(6-oxo-2-thioxo-5-cyano-1,2,3,6-tetrahydro-4-pyrimidinyl)-1-phenyl-1H-pyrazol-3-yl]phenyl}carbamate in yields of 61 and 75% yields, respectively. Treatment of the synthesized phenylhydrazones with boron trifluoride etherate in glacial acetic acid under heating resulted in the formation of methyl N-[2(3,4)-(1H-indol-2-yl)phenyl]carbamates in yields of 84–86%. 3-Nitroso-, 3-amino-, and 3-methoxycarbonylamino derivatives of methyl N-[4-(1H-indol-2-yl)phenyl]carbamate were also prepared.