Synthesis, Characterization And Anti-Proliferation Study Of Some Benzimidazole Derivatives

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Date
2010
Authors
Al–Douh, Mohammed Hadi Saeed
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Publisher
Universiti Sains Malaysia
Abstract
Four different types of compounds were successfully synthesized and characterized. The syntheses of these compounds involved benzylation, addition elimination and cyclization reactions. The structures of the synthesized compounds were confirmed by melting points, FTIR, HRMS, 1D and 2D NMR spectroscopy and X–ray crystallography. The first type of these compounds is 2-benzyloxy-3- methoxybenzaldehyde 75, which was synthesized by the reaction of o-vanillin with benzyl bromide in acetone as the solvent and K2CO3 as a base in the presence of tetra-n-butylammonium iodide (TBAI) as catalyst. The second type of the studied compounds is 2-amino-N-benzylidene benzeneamines 76 and 82, which were synthesized from the reaction of o-phenylenediamine with o-vanillin or 75 in dichloromethane at cold conditions. Both 1H–1H COSY and HMBC NMR experiments were performed to further confirm the assigned peaks of compounds in CDCl3, CD2Cl2 and acetone-d6. Some effect from those six– and five–membered illusory rings, which were formed from the intramolecular hydrogen bonding between N–H in the amino ring and the N atom in N=C–H bond and O–H with N atom of N=C–H of 76 or between N–H in the amino ring and the N atom in N=C–H bond and the bond of the methine C–H of 82 with oxygen atom in the benzyloxy ring. The crystal structures of both 76 and 82 confirmed the hydrogen bonds by using the X–ray crystallographic analysis. The third type of the studied compounds is bis- Schiff bases 79, 80 and 81, which are formed from the reaction between o-vanillin with o-, m- and p-phenylenediamines, respectively, by a tetrahedral mechanism or addition/elimination mechanism. The crystal structures of those bis-Schiff bases confirmed six–membered illusory rings, which formed from the intramolecular hydrogen bonding between N=C–H bonds and O–H groups of the trisubstituted rings by using the X–ray crystallographic analysis.
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Keywords
Synthesis, characterization and anti-proliferation , of some benzimidazole derivatives
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