Optimization of alpha-ketooxazole inhibitors of fatty acid amide hydrolase.
A series of alpha-ketooxazoles containing conformational constraints in the flexible C2 acyl side chain of 2 (OL-135) and representative oxazole C5 substituents were prepared and examined as inhibitors of fatty acid amide hydrolase (FAAH). Exceptionally potent and selective FAAH inhibitors emerged from the series (e.g., 6, Ki = 200 and 260 pM for rat and rhFAAH). With simple and small C5 oxazole substituents, each series bearing a biphenylethyl, phenoxyphenethyl, or (phenoxymethyl)phenethyl C2 side chain was found to follow a well-defined linear relationship between -log Ki and Hammett sigmap of a magnitude (rho = 2.7-3.0) that indicates that the substituent electronic effect dominates, confirming its fundamental importance to the series and further establishing its predictive value. Just as significantly, the nature of the C5 oxazole substituent substantially impacts the selectivity of the inhibitors whereas the effect of the C2 acyl chain was more subtle but still significant even in the small series examined. Combination of these independent features, which display generalized trends across a range of inhibitor series, simultaneously improves FAAH potency and selectivity and can provide exquisitely selective and potent FAAH inhibitors.
Kimball
F Scott
FS
Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Romero
F Anthony
FA
Ezzili
Cyrine
C
Garfunkle
Joie
J
Rayl
Thomas J
TJ
Hochstatter
Dustin G
DG
Hwang
Inkyu
I
Boger
Dale L
DL
D000581:Amidohydrolases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D000818:Animals; D001713:Biphenyl Compounds / Q000138:chemical synthesis / Q000737:chemistry; D006801:Humans; D008968:Molecular Conformation; D010080:Oxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D010647:Phenyl Ethers / Q000138:chemical synthesis / Q000737:chemistry; D051381:Rats; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D013329:Structure-Activity Relationship; D000099252:Fatty Acid Amide Hydrolases
D000581:Amidohydrolases; D001713:Biphenyl Compounds; D010080:Oxazoles; D010647:Phenyl Ethers; D011994:Recombinant Proteins; D000099252:Fatty Acid Amide Hydrolases