An entry to the synthesis of uleine-type alkaloids by Fischer indole synthesis reactions: FT-IR, NMR spectroscopy and computational study of the substituted carbazole compound

Abstract

An efficient and straightforward method for the synthesis of 2-(2,3,4,9-tetrahydro-1H-carbazole-2-yl)acetonitrile by Fischer reaction of phenylhydrazine hydrochloride acid and 2-(3-oxocyclohexyl)acetonitrile in presence of ethanol is reported. Mild reaction conditions, good yields of products, short reaction times, and operational simplicity are the advantages of this procedure. PES scan was performed to determine the stable conformers of the studied compound in the gas phase at B3LYP/6-31G(d,p) level of the theory.The1H and 1C NMR chemical shifts for each stable conformer of the studied compound were observed and simulated by the DFT method in both gas and water phases. Also, the recorded FT-IR spectrum of the studied compound wascompared with the simulated vibrational modes for each stable conformer. NBO was employed to predict the important intra-molecular interactions contributing to the lowering of the molecular stabilization energy of each stable conformer. FMO analysis and MEP diagrams were performed to predict the physicochemical and quantum chemical parameters to estimate the chemical reactivity behavior and reactive sites of each stable conformer. © 2018 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.