Novel synthesis of [1]-benzothiepino[5,4-b]pyridine-3-carbonitriles and their anti-inflammatory properties

Bioorg Med Chem. 2007 Mar 15;15(6):2403-13. doi: 10.1016/j.bmc.2007.01.015. Epub 2007 Jan 17.

Abstract

Reaction of 4-arylmethylene-3,4-dihydro-[1]-benzothiepin-5(2H)-ones 1 with malononitrile in the appropriate alcohol in the presence of sodium afforded the 2-alkoxy-4-aryl-5,6-dihydro-[1]-benzothiepino[5,4-b]pyridine-3-carbonitriles 2 and not the isomeric forms [1]-benzothiepino[4,5-c]pyridine-1-carbonitriles 3 in high regioselective manner. The assumed structure of 2 was inferred through independent synthetic reaction of 3,4-dihydro-[1]-benzothiepin-5(2H)-one (4) with ylidenemalononitriles 5 under the same applied reaction conditions and confirmed by single crystal X-ray diffraction studies. However, reaction of 4 with arylidenecyanothioacetamides 6 in refluxing ethanol in the presence of basic catalyst (piperidine or morpholine) does not afford the expected 4-aryl-3-cyano-5,6-dihydro-[1]-benzothiepino[5,4-b]pyridine-2(1H)-thiones 7 and instead 4-aryl-3,5-dicyano-6-thioxo-2(1H)-pyridinethiolate monohydrates were isolated as piperidinium or morpholinium salts 8. On the other hand, reaction of 6 with cyanothioacetamide in the presence of a sufficient amount of basic catalyst yielded exclusively 2-amino-4-aryl-3,5-dicyano-2-pyridinethiolates as piperidinium or morpholinium salts 9. Meanwhile, 7 were prepared through the reaction of 1 with cyanothioacetamide in refluxing ethanol in the presence of a catalytic amount of piperidine. Anti-inflammatory activity screening of the prepared compounds using in vivo acute carrageenan-induced paw oedema in rats exhibited that all the tested compounds possess considerable activity. In addition, few synthesized derivatives reveal remarkable anti-inflammatory properties (2d, k, l) comparable with indomethacin which was used as a reference standard during the pharmacological activity screening studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / chemical synthesis
  • Anti-Inflammatory Agents, Non-Steroidal / chemistry
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology*
  • Benzothiepins / chemistry*
  • Carrageenan / toxicity
  • Edema / chemically induced
  • Edema / prevention & control
  • Female
  • Male
  • Molecular Structure
  • Nitriles / chemical synthesis*
  • Nitriles / chemistry
  • Nitriles / pharmacology
  • Pyridines / chemical synthesis*
  • Pyridines / chemistry
  • Pyridines / pharmacology
  • Rats
  • Rats, Wistar
  • Structure-Activity Relationship

Substances

  • Anti-Inflammatory Agents, Non-Steroidal
  • Benzothiepins
  • Nitriles
  • Pyridines
  • pyridine-3-carbonitrile
  • Carrageenan