Synthesis and exploration of QSAR model of 2-methyl-3-[2-(2-methylprop-1-en-1-yl)-1H-benzimidazol-1-yl]pyrimido[1,2-a]benzimidazol-4(3H)-one as potential antibacterial agents

Figures & data

Figure 1.  Structure of synthesized 2-methyl-3-[2-(2-methylprop-1-en-1-yl)-1H-benzimidazol-1-yl]pyrimido[1,2-a]benzimidazol-4(3H)-one (4a–r).

Scheme 1.  Generation of 3-methylbuta-1,2-dien-1-ylidene (dimethylvinylidene carbene) intermediate.

Scheme 2.  An overview of synthesis of 2-methyl-3-[2-(2-methylprop-1-en-1-yl)-1H-benzimidazol-1-yl]pyrimido[1,2-a]benzimidazol-4(3H)-one (4a–r).

Table 1.  The in vitro antimicrobial inhibition activities of 2-methyl-3-[2-(2-methylprop-1-en-1-yl)-1H-benzimidazol-1-yl]pyrimido[1,2-a]benzimidazol-4(3H)-one (4a–r).

S. No.	Entry	R	pIC50
			P. diminuta	B. subtilis	E. Coli	S. aureus
1	4a	-H	−3.0934	−3.2574	−3.1746	−3.3222
2	4b	4-OC2H5	−1.1761	−1.3617	−1.2553	−1.4472
3	4c	6-C2H5	−1.5563	−1.7243	−1.6532	−1.7634
4	4d	6-NO2	−2.1303	−2.2900	−2.2041	−2.3617
5	4e	4-OCH3	−2.2304	−2.3802	−2.3222	−2.4698
6	4f	4-Cl	−2.4232	−2.5843	−2.5119	−2.6532
7	4g	6-OH	−3.1761	−3.3426	−3.2565	−3.4108
8	4h	4-COOH	−2.4624	−2.6021	−2.5441	−2.6902
9	4i	4-CH3	−2.5315	−2.6928	−2.6021	−2.7559
10	4j	4-OH	−3.1303	−3.3118	−3.2041	−3.3598
11	4k	6-CH3	−2.5740	−2.7380	−2.6628	−2.8162
12	4l	6-OCH3	−2.3324	−2.4843	−2.4393	−2.5563
13	4m	4-NO2	−1.9542	−2.1139	−2.0607	−2.1903
14	4n	4-C2H5	−1.3424	−1.5441	−1.4472	−1.6232
15	4o	4-Br	−1.7634	−1.9294	−1.8751	−2.0253
16	4p	5-CH3	−2.6021	−2.7076	−2.6284	−2.8062
17	4q	5-Cl	−2.5575	−2.6857	−2.5911	−2.7324
18	4r	5-OCH3	−2.3617	−2.4698	−2.3802	−2.5441
19	A	--	−3.2175	−3.3802	−3.2742	−3.4150

A, Ampicilline.

Figure 2.  PM3 optimized geometry of more active 2-methyl-3-[2-(2-methylprop-1-en-1-yl)- 1H-benzimidazol -1-yl]pyrimido[1,2-a]benzimidazol-4(3H)-one.