Synthesis of New Functionally Substituted Pyrazoles and Indoles Based on Acetophenones with Carbamate Moiety

By condensation of acetophenones containing a carbamate moiety with phenylhydrazine in ethanol, the corresponding phenylhydrazones were obtained, which, under the action of the Vilsmeier–Haack reagent, were converted into methyl N-[2(3,4)-(4-formyl-1-phenyl-1H-pyrazol-3-yl)phenyl]carbamates in yields of 79–83%. By boiling 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, 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 were obtained in yields of 50–54%. 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-3yl]phenyl}carbamate in 61 and 75% yields, respectively. Treatment of phenylhydrazones with boron trifluoride etherate in glacial acetic acid acid upon heating leads to the formation of methyl N-[2(3,4)-(1H-indol-2-yl)phenyl]carbamates in yields of 84–86%. Based on methyl N-[4-(1H-indol-2-yl)phenyl]carbamate, 3-nitroso-, 3-aminoand 3-methoxycarbonylamino derivatives were obtained.

acetophenones with carbamate moiety, phenylhydrazones, Vilsmeier–Haack reaction, Fischer indole cyclization reaction, 1,3-diaryl-4-formyl-substituted pyrazoles, three-component condensation of 4-formylpyrazole with aphenylcarbamate fragment with thiourea, ethyl acetoacetate orethyl cyanoacetate, 2-aryl-substituted indoles with carbamate function and their functionalization at 3 position