Synthesis, Characterization And Anti-Proliferation Study Of Some Benzimidazole Derivatives
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Date
2010
Authors
Al–Douh, Mohammed Hadi Saeed
Journal Title
Journal ISSN
Volume Title
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.
Description
Keywords
Synthesis, characterization and anti-proliferation , of some benzimidazole derivatives