Synthesis and in vitro antimicrobial activity of novel N-(6-chlorobenzo[d]thiazol-2-yl) hydrazine carboxamide derivatives of benzothiazole class

Figures & data

Scheme 1.  Synthetic pathways to N-(6-chlorobenzo[d]thiazol-2-yl) hydrazine carboxamide.

Scheme 2.  Synthetic route for the title compounds.

Table 1.  Physicochemical data of N-(6-chlorobenzo[d]thiazol-2-yl)hydrazine carboxamide derivatives (6a–g, 7a–g, 8).

Comp.	R	Yield (%)	M.P. (°C)	Molecular Weight	Molecular Formula	Rf
6a		74	240	384.87	C16H9ClN6S2	0.7
6b		71	254	419.31	C16H8Cl2N6S2	0.6
6c		68	248	453.76	C16H17Cl3N6S2	0.9
6d		71	282	398.89	C16H17Cl3N6S2	0.8
6e		66	288	442.90	C18H11ClN6O2S2	0.7
6f		76	218	400.87	C16H9ClN6OS2	0.6
6g		63	116	429.86	C16H17Cl3N6S2	0.7
7a		67	262	328.78	C15H9 ClN4OS	0.8
7b		64	234	363.22	C15H8 Cl2N4OS	0.6
7c		66	249	397.67	C15H7 Cl3N4OS	0.7
7d		65	232	342.80	C16H11 ClN4OS	0.8
7e		64	246	386.81	C17H11 ClN4O3S	0.7
7f		73	261	344.78	C15H9ClN4O2S	0.8
7g		67	223	373.77	C15H8ClN5O3S	0.6
8	—	74	234	284.75	C9H5ClN4OS2	0.8

Elemental analysis were found to be within ± 0.4% of theoretical values.

Table 2.  Antibacterial activity of the title compounds (6a–g, 7a–g and 8).

Compounds	MIC in µg/mL and zone of inhibition in mm
	Escherichia coli	Staphylococcus aureus	Pseudomonas aeruginosa	Klebsiella pneumoniae
6a	25 (16–20)	50 (11–15)	50 (11–15)	50 (11–15)
6b	100 (<10)	100 (<10)	100 (<10)	100 (<10)
6c	12.5 (21–25)	25 (16–20)	12.5 (21–25)	12.5 (21–25)
6d	12.5 (21–25)	25 (16–20)	12.5 (21–25)	12.5 (21–25)
6e	100 (<10)	100 (<10)	100 (<10)	100 (<10)
6f	25 (16–20)	25 (16–20)	50(11–15)	25 (16–20)
6g	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)	25 (16–20)
7a	12.5 (21–25)	25 (16–20)	25 (16–20)	25 (16–20)
7b	100 (<10)	100 (<10)	100 (<10)	100 (<10)
7c	12.5 (21–25)	25 (16–20)	12.5 (21–25)	12.5 (21–25)
7d	25 (16–20)	50 (11–15)	50 (11–15)	50 (11–15)
7e	100 (<10)	100 (<10)	100 (<10)	100 (<10)
7f	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)	25 (16–20)
7g	25 (16–20)	50 (11–15)	50 (11–15)	50 (11–15)
8	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)
Ofloxacin	6.25 (26–30)	6.25 (26–30)	6.25 (26–30)	6.25 (26–30)

The figures in the table show the MIC (Minimum Inhibitory Concentration) values in µg/mL and the corresponding zone of inhibition in mm.

Table 3.  Antifungal activity of the title compounds (6a–g, 7a–g and 8).

Compounds	MIC in µg/mL and zone of inhibition in mm
	Candida albicans	Aspergillus niger	Aspergillus flavus	Monascus purpureus	Penicillium citrinum
6a	50 (11–15)	25 (16–20)	50 (11–15)	50 (11–15)	50 (11–15)
6b	100 (<10)	100 (<10)	100 (<10)	100 (<10)	100 (<10)
6c	12.5 (21–25)	25 (16–20)	12.5 (21–25)	25 (16–20)	12.5 (21–25)
6d	12.5 (21–25)	25 (16–20)	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)
6e	100 (<10)	100 (<10)	100 (<10)	100 (<10)	100 (<10)
6f	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)	25 (16–20)	25 (16–20)
6g	50 (11–15)	50 (11–15)	25 (16–20)	25 (16–20)	50 (11–15)
7a	25 (16–20)	50 (11–15)	25 (16–20)	25 (16–20)	50 (11–15)
7b	100 (<10)	100 (<10)	100 (<10)	100 (<10)	100 (<10)
7c	50 (11–15)	25 (16–20)	25 (16–20)	50 (11–15)	50 (11–15)
7d	50 (11–15)	50 (11–15)	50 (11–15)	25 (16–20)	50 (11–15)
7e	12.5 (21–25)	12.5 (21–25)	25 (16–20)	25 (16–20)	12.5 (21–25)
7f	100 (<10)	100 (<10)	100 (<10)	100 (<10)	100 (<10)
7g	25(16–20)	25 (16–20)	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)
8	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)	12.5 (21–25)
Ketoconazole	6.25 (26–30)	6.25 (26–30)	6.25 (26–30)	6.25 (26–30)	6.25 (26–30)

The figures in the table show the MIC (minimum inhibitory concentration) values in µg/mL and the corresponding zone of inhibition in mm.