Synthesis, molecular and crystalline structure of 8-formylharmine

Abstract

For the first time, synthesis of 8-formylharmine by the Vilsmeier reaction was carried out. 8-Formylharmine was obtained by treating alkaloid harmine with dichloromethoxymethane in the presence of SnCl4.The yield of the target product was 64 %. The structure of the obtained compound was established on the basis of 1H and 13C NMR spectroscopy as well as mass-spectrometry data. The crystalline structure of 8-formylharmine was determined by X-ray diffraction. It has been shown that the replacement of the hydrogen atom in the harmine molecule with a formyl group occurs at the C8 atom. It was revealed that the methoxy group at the C7 atom changes its orientation to the opposite one as compared to the orientation in the harmine molecule and its salts due to the mutual Van der Waals repulsion of the methoxy and formyl groups. A weak intramolecular hydrogen bond was found in the crystal between the O2 atom of the formyl group and the hydrogen atom of the secondary amino group. It was shown that molecules in the crystal form an intermolecular hydrogen bond between the same atoms (О2 and НN9A), as a result of which dimers are formed.