5-(Halomethyl)-2-pyranones as Irreversible Inhibitors of a-Chymotrypsin

William A. Boulanger, John A. Katzenellenbogen

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A series of 5-(halomethyl)-2-pyranones were prepared and assayed as potential mechanism-based inhibitors of chymotrypsin, in order to test whether substitution of a suitable electron-withdrawing group at position 5 in a 2-pyranone can activate the ring for catalytic hydrolysis, as well as form a mechanism-based inhibitor. 3-Benzyl-5-(chloromethyl)-2-pyranone (3) and 3-(1-naphthylmethyl)-5-(chloromethyl)-2-pyranone (4) rapidly and irreversibly inactivate chymotrypsin with high efficiency (I/E = 2.0 for 3 and 1.38 for 4). However, evidence for their formation of an acyl enzyme is lacking, and thus they may simply be active-site alkylating agents. 6-Methyl substitution on 4, or replacement of the chloromethyl of 3 with CF3, prevents inactivation. Since 6-bromo substitution is capable of ring activation, but 5-bromo substitution (3-benzyl-5-bromo-2-pyranone (11)) is not, the 5-position of the pyrone does not appear to affect catalytic hydrolysis.

Original languageEnglish (US)
Pages (from-to)1483-1487
Number of pages5
JournalJournal of Medicinal Chemistry
Issue number8
StatePublished - 1986

ASJC Scopus subject areas

  • Molecular Medicine
  • Drug Discovery


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