Rapid and efficient microwave assisted method for the regioselective synthesis of 8,8′‐methylene‐bis‐4‐oxo‐1H and 2H‐chromeno[4,3‐C]pyrazoles

A series of methylenebis(phenyl-1,5-benzothiazepine)s 4 and methylenebis(benzofuryl-1,5-benzothiazepine)s 5 were prepared by the reaction of methylene-bis-chalcones 3 with 2-aminothiophenol for 4 and followed by the condensation with chloroacetone for 5. The structures of the synthesized compounds have been confirmed by their IR, 1 H NMR, 13 C NMR, MS and elemental analyses. All the synthesized compounds were tested for their antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. To elucidate the essential structural requirements for the antimicrobial activity, the preliminary structure-activity relationship has been described. Among the compounds tested, the dimeric compounds 4f, 4g, 5f and 5g were found to be most active against Bacillus subtilis, Bacillus sphaericus, Staphylococcus aureus, Klebsiella aerogenes and Chromobacterium violaceum. Similarly these dimeric compounds showed potent antifungal activity against Candida albicans, Aspergillus fumigatus, Trichophyton rubrum, and Trichophyton mentagrophytes. It is interesting to note that the dimeric compounds with substituents of heterocyclic ring at the 4th position of benzothiazepine system displayed notable antibacterial activity equal to that of streptomycin and penicillin. Further, the activity of all the dimeric compounds was compared with that of their monomeric compounds, and it is interesting to note that almost all the dimeric compounds showed enhanced activity than their monomeric compounds. Experimental Apparatus and reagentsMelting points were determined on a Fisher-Johns melting point apparatus and are uncorrected. The purities of the compounds were checked using precoated TLC plates. IR spectra were recorded on a Perkin-Elmer FTIR 5000 spectrometer, using KBr pellets. 1 H, 13 C NMR spectra in DMSO-d 6 were recorded on a Varian Gemini 300 MHz spectrometer and the chemical shifts (δ) were reported using TMS as an internal standard. Mass spectra were obtained on a VG micromass 7070H spectrometer. Elemental analyses were performed on a Perkin-Elmer CHN elemental analyzer. All the solvents and chemicals were purchased from Sigma-Aldrich chemical company and used without further purification.General procedure for the synthesis of methylenebis(chalcone)s (3a-3g)

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Synthesis and in vitro study of a new class of methylene‐bis‐4,6‐diarylbenzo[d]isoxazoles as potential antifungal agents

Srinivas

Nagaraj

Reddy

2009

Journal of Heterocyclic Chem

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A new class of methylene‐bis‐4,6‐diarylbenzo[d]isoxazoles 8a, 8b, 8c, 8d, 8e, 8f, 8g, 8h, 8i was synthesized by the reaction of methylene‐bis‐aryl‐6‐hydroxymethylene‐2‐cyclohexenone 6 with hydroxylamine hydrochloride, followed by aromatization with DDQ. Chemical structures of the newly synthesized compounds were elucidated by their IR, 1H NMR, 13C NMR, MS, and elemental analyses. Furthermore, all the compounds were screened for their antifungal activity against various fungi and compared with their monomeric compounds. Among the synthesized compounds, 8b, 8g, and 8i were found to be the most active against Candida albicans (ATCC 10231), Aspergillus fumigatus (HIC 6094), Trichophyton rubrum (IFO 9185), and Trichophyton mentagrophytes (IFO 40996). It is interesting to note that the compounds 8a, 8g, and 8i showed fungicidal activity toward C. albicans at the concentration of 3.12 μg/mL, which is less than the concentration of standard Amphotericin B. J. Heterocyclic Chem., 46, 497 (2009).

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Rapid and efficient microwave assisted method for the regioselective synthesis of 8,8′‐methylene‐bis‐4‐oxo‐1H and 2H‐chromeno[4,3‐C]pyrazoles

Cited by 9 publications

References 28 publications

ChemInform Abstract: Rapid and Efficient Microwave Assisted Method for the Regioselective Synthesis of 8,8′‐Methylene‐bis‐4‐oxo‐1H and 2H‐Chromeno[4,3‐c]pyrazoles.

ChemInform Abstract: Rapid and Efficient Microwave Assisted Method for the Regioselective Synthesis of 8,8′‐Methylene‐bis‐4‐oxo‐1H and 2H‐Chromeno[4,3‐c]pyrazoles.

Synthesis and in vitro Study of Novel Methylenebis(phenyl‐ 1,5‐benzothiazepine)s and Methylenebis(benzofuryl‐1,5‐benzothiazepine)s as Antimicrobial Agents

Synthesis and in vitro study of a new class of methylene‐bis‐4,6‐diarylbenzo[d]isoxazoles as potential antifungal agents

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