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Poster presentation 
237 
SYNTHESIS OF BENZO[4,5]IMIDAZO[2,1-B]QUINAZOLIN-
12(5H)-ONE 
 
S.S. Saidov
1
, В.I. Avazova
2
, Sh.Kh. Kubaev
1
, R.Ya. Okmanov
1
 
1) S.Yu. Yunusov Institute of the Chemistry of Plant Substances Academy of sciences of 
the Republic of Uzbekistan st. Mirzo-Ulugbek, 77, 100170 Tashkent 
e-mail: [e-mail] 
2) Urgench State University. Kh. Alimdjan str., 14, Urgench city, 220100, 
Uzbekistan 
Benzimidazoles are heterocyclic aromatic organic compound which have been an 
important pharmacophore and privileged structure in medicinal chemistry. Many 
substituted benzimidazoles have considerable interest as compounds with a wide 
spectrum of biological activity and low toxicity.
Recently we have studied the interaction of 2-methoxycarbonylaminobenzimidazole 
with benzoic and various aliphatic carboxylic acids of 
normal
or 
iso
-structure. In this 
case, the formation of mainly the corresponding acid amides was found [1].
Continuing similar studies, in this work we curried out interaction of 2-
methoxycarbonylaminobenzimidazole (
2
) with 2-hydroxybenzoic acid (salicylic acid, 
1
) 
boiling in DMF of equimolar amounts of starting materials, and formation of a new 
annulated product – benzimidazo-quinazolinone (
3
) was observed (Scheme 1): 
Scheme 1. Synthesis of benzo[4,5]imidazo[2,1-
b
]quinazolin-12(5
H
)-one 
Based on the product (
3
) obtained, it can be assumed that during the reaction, takes 
place regioselectively interaction of exocyclic amino group of the pre-formed 2-
aminobenzimidazole and carboxylic group of benzoic acid (
1
) to form benzoic acid 
amide; then intramolecular cyclization of this intermediate (amide) in acidic medium 
occurs with the formation of the target annelated heterocyclic product (
3
). 
For reliable refinement of the structure, X-ray structural analysis was performed: 
Figure 1. Molecular structure of benzo[4,5]imidazo[2,1-
b
]quinazolin-12(5
H
)-one, 
including atom labelling. Displacement ellipsoids are draw at the 30% probability level. 
Reference 
1. A.Sh. Abdurazakov, S.S. Saidov, R.Ya. Okmanov, Sh.Kh. Kubaev, B.Zh. 
Elmuradov. 
Egypt. J. Chem. 
2021, Vol. 64, No. 5. P.2247-2252. 
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Poster presentation 
238