William A. Hada

A simple method for the formation of cyclopropylamines: the first synthesis of tricyclopropylamine

Abstract A mild, one-step method to cyclopropylate amines is described. Treatment of a variety of secondary and primary amines with [(1-ethoxycyclopropyl)oxy]trimethylsilane and sodium cyanoborohydride in methanol gave mono- and dicyclopropylamines in good yield. Sterically hindered di- and tricyclopropylamines, including the previously unreported tricyclopropylamine, were prepared using this method. The pKas of some mono-, di- and tricyclopropylamines were measured showing a reduction of ∼1–2 pKa unit per added cyclopropyl group.

Pyrazolinone-piperidine dipeptide growth hormone secretagogues (GHSs) : Discovery of capromorelin

Novel pyrazolinone-piperidine dipeptide derivatives were synthesized and evaluated as growth hormone secretagogues (GHSs). Two analogues, capromorelin (5, CP-424391-18, hGHS-R1a K(i)=7 nM, rat pituicyte EC(50)=3 nM) and the des-methyl analogue 5c (hGHS-R1a K(i)=17 nM, rat pituicyte EC(50)=3 nM), increased plasma GH levels in an anesthesized rat model, with ED(50) values less than 0.05 mg/kg iv. Capromorelin showed enhanced intestinal absorption in rodent models and exhibited superior pharmacokinetic properties, including high bioavailabilities in two animal species [F(rat)=65%, F(dog)=44%]. This short-duration GHS was orally active in canine models and was selected as a development candidate for the treatment of musculoskeletal frailty in elderly adults.

Discovery and biological characterization of capromorelin analogues with extended half-lives

New tert-butyl, picolyl and fluorinated analogues of capromorelin (3), a short-acting growth hormone secretagogue (GHS), were prepared as part of a program to identify long-acting GHSs that increase 24-h plasma IGF-1 levels. Compounds 4c and 4d (ACD LogD values >or=2.9) displayed extended plasma elimination half-lives in dogs, primarily due to high volumes of distribution, but showed weak GH secretagogue activities in rats (ED(50)s>10 mg/kg). A less lipophilic derivative 4 (ACD LogD=1.6) exhibited a shorter canine half-life, but stimulated GH secretion in two animal species. Repeat oral dosing of 4 in dogs for 29 days (6 mg/kg) resulted in a significant down-regulation of the post dose GH response and a 60 and 40% increase in IGF-1 levels relative to pre-dose levels at the 8- and 24-h post dose time points. Compound 4 (CP-464709-18) has been selected as a development candidate for the treatment of frailty.

Molecular Characterization of Novel and Selective Peroxisome Proliferator-Activated Receptor α Agonists with Robust Hypolipidemic Activity in Vivo

The nuclear receptor peroxisome proliferator-activated receptor α (PPARα) is recognized as the primary target of the fibrate class of hypolipidemic drugs and mediates lipid lowering in part by activating a transcriptional cascade that induces genes involved in the catabolism of lipids. We report here the characterization of three novel PPARα agonists with therapeutic potential for treating dyslipidemia. These structurally related compounds display potent and selective binding to human PPARα and support robust recruitment of coactivator peptides in vitro. These compounds markedly potentiate chimeric transcription systems in cell-based assays and strikingly lower serum triglycerides in vivo. The transcription networks induced by these selective PPARα agonists were assessed by transcriptional profiling of mouse liver after short- and long-term treatment. The induction of several known PPARα target genes involved with fatty acid metabolism were observed, reflecting the expected pharmacology associated with PPARα activation. We also noted the down-regulation of a number of genes related to immune cell function, the acute phase response, and glucose metabolism, suggesting that these compounds may have anti-inflammatory action in the mammalian liver. Whereas these compounds are efficacious in acute preclinical models, extended safety studies and further clinical testing will be required before the full therapeutic promise of a selective PPARα agonist is realized.

Rational design, synthesis, and X-ray structure of renin inhibitors with extended P1 sidechains

Abstract Structural information from a complex of a tetrapeptide renin inhibitor, CP-85, 339, with human renin, led to the design of inhibitors with extended P1 groups that span the S1-S3 active site pocket. A m-biphenyl sidechain at P1 and glycine at P3 led to a 160X increase in potency over the analogous phenyl compound. A crystal structure of this compound in complex with recombinant human renin (rHR) was solved.

An efficient synthesis of enantiomerically enriched aryllactic esters

Abstract An efficient synthesis of enantiomerically enriched aryllactic esters or acids has been established. Darzens condensation of arylaldehydes with ethyl chloroacetate followed by catalytic hydrogenation gave racemic aryllactic esters. Enzyme catalyzed (lipase PS-30, Amano) hydrolysis or acetylation provided enantiomerically enriched products. EEs of 65–99% were obtained without optimization of resolution conditions. This route is compatible with a variety of heterocycles and multigram quantities of enantiomerically enriched materials have been prepared. These chiral synthons are useful for the preparation of renin inhibitors as well as other therapeutic agents.

Synthesis and pharmacological profile of two novel heterocyclic chromanols, CP-80,798 and CP-85,958, as potent LTD4 receptor antagonists

Abstract The development of two novel LTD 4 receptor antagonists as clinical candidates for the treatment of asthma is described. The first generation compound, CP-80,798, was found to be a balanced 5-lipoxygenase inhibitor (5-LOI)/LTD 4 antagonist (LTD 4 -A), while the second generation compound, CP-85,958, is a selective LTD 4 antagonist.

Structure of 3,4-dihydroxy-2-thiophenecarboxylic acid ethyl ester in the crystal and solution states

The structure of 3,4-dihydroxy-2-thiophenecarboxylic acid ethyl ester was proven by NMR and X-ray crystallographic. Under all conditions assessed, this compound existed as the dihydroxy tautomer 2.

3-Substituted-4-hydroxy-7-chromanylacetic acid derivatives as antagonists of the leukotriene B4 (LTB4) receptor

The SAR of a series of 7-chromanylacetic acids has been investigated with the aim of identifying potent and selective LTB4 receptor antagonists. We found optimal activity in derivatives with c~,c~-disubstitution on the acetic acid and a C-4 hydroxy group and a C-3 lipophilic group on the chromane ring. CP-105696 (43), which contains a 4-phenylbenzyl C-3 substituent, was selected for development. ~ 1997 Elsevier Science lad. LTB4 is a potent chemoattractant for granulocytes (e.g., neutrophils and eosinophils) and stimulates functional responses such as secretion and cytokine synthesis in these cells as well as in mononuclear cells and lymphocytes. Its presence in relevant tissues has implicated it to be a likely mediator in a number of inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, psoriasis, and asthma. Receptor antagonists of LTB4 are thus expected to be useful therapeutics tbr these diseases. To date, compounds from several structural classes have been discovered to display LTB4 antagonismJ During the course of our investigations on leukotriene D4 antagonists, we observed that certain chromanol derivatives displayed modest LTB4 antagonism in addition to LTD4 antagonism. We also noted that of all the NSAIDs examined, only the propionic acid class showed any significant parallel between their ability to block (3H) LTB4 binding to high affinity receptors on guinea pig spleen membranes and their ability to inhibit LTB4-induced human neutrophil chemotaxis} These observations led us to prepare hybrid molecules with the aim of identifying potent and selective LTB4 antagonists. Accordingly, the propionic acid derivatives 1