Unexpected formation of 3-chloro-1-hydroxy-2,6-diarylpiperidin-4-ones: Synthesis, antibacterial and antifungal activities

Figures & data

Scheme 1  Reaction route for the synthesis of 3-chloro-l-hydroxy-2,6-diarylpiperidin-4-one.

Table I.  Physical and analytical data of 3-chloro-1-hydroxy-2,6-diarylpiperidin-4-ones 18–22.

			Elemental analysis (%)
Compound	Yield (%)	m.p° C	C Found (calculated)	H Found (calculated)	N Found (calculated)	m/z (M^+.) Molecular formula
18	65	149–151	67.65 (67.69)	5.27 (5.30)	4.62 (4.64)	302 C17H16NO2Cl
19	60	160–162	69.20 (69.22)	6.07 (6.09)	4.22 (4.25)	330 C19H20NO2Cl
20	65	169–171	63.07 (63.10)	5.51 (5.53)	3.84 (3.87)	362 C19H20NO4Cl
21	55	168–170	55.07 (55.10)	3.77 (3.78)	3.75 (3.78)	371 C17H14NO2Cl3
22	70	160–162	60.45 (60.48)	4.11 (4.14)	4.13 (4.15)	338 C17H14NO2ClF2

Scheme 2  Probable reaction meachanism for the synthesis of target molecules.

Table II.  In vitro antibacterial activities (MIC) values for compounds 18–22.

	Minimum inhibitory concentration (MIC) in μg/mL
Micro organisms	Compound 18	Compound 19	Compound 20	Compound 21	Compound 22	Ciprofloxacin
S.aureus	100	12.5	100	12.5	12.5	25
β-H. streptococcus	100	100	200	12.5	25	50
V. cholerae	50	50	50	25	25	50
S. typhii	50	50	200	100	6.25	50
S. felxneri	100	200	12.5	50	50	25
E. coli	200	200	200	100	100	25
K. pneumonia	100	100	12.5	50	50	50
Pseudomonas	200	100	100	12.5	6.25	25

Table III.  In vitro antifungal activities (MIC) values for compounds 18–22.

	Minimum Inhibitory Concentration (MIC) in μg/mL
Micro organisms	Compound 18	Compound 19	Compound 20	Compound 21	Compound 22	Fluconazole
A. flavus	100	200	100	25	25	50
Mucor	200	100	50	25	12.5	50
Rhizopus	200	50	6.25	12.5	25	25
M. gypsuem	200	50	50	12.5	12.5	25