This paper describes the development a series of peptidyl trifluoromethyl ketone inhibitors of human leukocyte elastase which are found to have excellent pharmacological profiles. Methods have been developed that allow for the synthesis of these inhibitors in stereochemically pure form. Two of these compounds, 1k and 1l, have high levels of oral bioavailability in several species. Compound 1l has entered development as ZD8321 and is presently undergoing clinical evaluation. These compounds demonstrate that peptidyl trifluoromethyl ketone inhibitors can achieve high levels of oral activity and bioavailability, and therefore they may prove useful as therapeutic agents in the treatment of diseases in which elastase is implicated.

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A systematic structure-activity exploration of the carboxylic acid region in a series of indole- or indazole-derived leukotriene antagonists 1 led to several discoveries. Use of the 3-methoxy-p-tolyl fragment (illustrated in acid 1) for connecting the indole and the acidic site provides the most potent carboxylic acids 1, tetrazoles 20, and aryl sulfonimides 21. The aryl sulfonimides are 5-500 times more potent (in vitro and/or in vivo) than the corresponding carboxylic acids 1. The o-tolyl sulfonimides such as 114 show greater oral potency than the phenyl sulfonimides at a given level of in vitro activity. Acidic keto sulfone derivatives 10 (Nu = CH-(CO2CH3)SO2Ph) mimic the activity of the sulfonimides.

A subset of antiandrogen compounds, the N-aryl-3,3,3-trifluoro-2-hydroxy-2-methylpropanamides 1, were found to activate ATP sensitive potassium channels (KATP) and represent a new class of potassium channel openers (PCOs). A structure-activity relationship was carried out on the western region of this series with the goal of obtaining an activator of the ATP sensitive potassium channel suitable for use in the treatment of urge urinary incontinence. In particular three large 4-(N-aryl) substituents, the (N-phenyl-N-methylamino)sulfonyl, benzoyl, and 4-pyridylsulfonyl moieties, yielded non-antiandrogen, KATP potassium channel openers (39, 41, and 64, respectively) that are bladder selective in an in vivo rat model that simultaneously measures bladder contractions, heart rate, and blood pressure. Substitutions of the aryl rings of 41 and 64 gave several derivatives that also display selectivity in the in vivo rat model; however, none appear to offer a substantial advantage over 41 and 64. The PCO activity of 41 and 64 resides in the (S)-(-) enantiomers. ZD6169, 41(S), has been selected into development for the treatment of urge urinary incontinence.

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Considerations of the possible similarities between leukotriene D4 and its prototypical antagonist, FPL 55712, led to the development of a new series of leukotriene antagonists incorporating a hydroxyacetophenone group (e.g., the toluic acids 16 and 18). Although considerable attention has focused on FPL 55712-derived analogues, only limited investigations into alternatives for the standard 4-acetyl-3-hydroxy-2-propylphenoxy moiety have been reported. Therefore, an extensive study of modifications to the hydroxyacetophenone portion of toluic acid 18 was undertaken. Although no viable alternative to the 3-hydroxy moiety was discovered, replacements for the 2-propyl group (34, 37) and the 4-acetyl functionality (56, 59) yielded potent antagonists. A number of compounds exhibited longer duration of action in vivo than FPL 55712.

1,6-Substituted and 3,5-substituted indoles and indazoles containing acylamino and N-arylsulfonyl amide appendages are potent antagonists of the peptidoleukotrienes LTD4 and LTE4. A compound from the 3,5-substituted indole series, N-[4-[[5-[[(cyclopentyloxy)carbonyl]amino]-1-methylindol- 3-yl]methyl]-3-methoxybenzoyl]-2-methyl-benzenesulfonamide (ICI 204,219), is undergoing clinical evaluation for asthma. Two new elements of structural diversity were introduced to this series of antagonists. An investigation of pyrrole substituents in the 1,6-substituted indoles demonstrated that substitution at C-2 was detrimental to biological activity, but the incorporation of hydrophilic groups at C-3 was beneficial. The introduction of a propionamide moiety at C-3 enhanced activity by 1 order of magnitude; N-[4-[[6-(cyclopentylacetamido)-3-[2-(N- methylcarbamoyl)ethyl]indol-1-yl]methyl]-3-methoxy- benzoyl]benzenesulfonamide (15c) has a pKB of 10.7 at the LTD4 receptor on guinea pig trachea. Modifications of the acylamino portion of the disubstituted antagonists demonstrated that a transposition of the amide CO and NH atoms was viable. N-Cyclopentylmethyl amides in both the 1,6- and 3,5-disubstituted indole series were 1 order of magnitude less potent than the corresponding cyclopentylacetamides. In both series this potency loss could be regained by the incorporation of a propionamide substituent at either C-3 or N-1, respectively. For example, N-[4-[[6-[N-(cyclopentylmethyl)carbamoyl]-3-[2-(pyrrolidin-1 - methylbenzenesulfonamide (39c) has a pKB of 9.5.