Hao Zhang

Ligand‐Promoted Borylation of C(sp3)H Bonds with Palladium(II) Catalysts

A quinoline-based ligand effectively promotes the palladium-catalyzed borylation of C(sp(3))-H bonds. Primary β-C(sp(3))-H bonds in carboxylic acid derivatives as well as secondary C(sp(3))-H bonds in a variety of carbocyclic rings, including cyclopropanes, cyclobutanes, cyclopentanes, cyclohexanes, and cycloheptanes, can thus be borylated. This directed borylation method complements existing iridium(I)- and rhodium(I)-catalyzed C-H borylation reactions in terms of scope and operational conditions.

Discovery of an oxybenzylglycine based peroxisome proliferator activated receptor alpha selective agonist 2-((3-((2-(4-chlorophenyl)-5-methyloxazol-4-yl)methoxy)benzyl)(methoxycarbonyl)amino)acetic acid (BMS-687453).

An 1,3-oxybenzylglycine based compound 2 (BMS-687453) was discovered to be a potent and selective peroxisome proliferator activated receptor (PPAR) alpha agonist, with an EC(50) of 10 nM for human PPARalpha and approximately 410-fold selectivity vs human PPARgamma in PPAR-GAL4 transactivation assays. Similar potencies and selectivity were also observed in the full length receptor co-transfection assays. Compound 2 has negligible cross-reactivity against a panel of human nuclear hormone receptors including PPARdelta. Compound 2 demonstrated an excellent pharmacological and safety profile in preclinical studies and thus was chosen as a development candidate for the treatment of atherosclerosis and dyslipidemia. The X-ray cocrystal structures of the early lead compound 12 and compound 2 in complex with PPARalpha ligand binding domain (LBD) were determined. The role of the crystal structure of compound 12 with PPARalpha in the development of the SAR that ultimately resulted in the discovery of compound 2 is discussed.

Plasma stability-dependent circulation of acyl glucuronide metabolites in humans: how circulating metabolite profiles of muraglitazar and peliglitazar can lead to misleading risk assessment.

Muraglitazar and peliglitazar, two structural analogs differing by a methyl group, are dual peroxisome proliferator-activated receptor-α/γ activators. Both compounds were extensively metabolized in humans through acyl glucuronidation to form 1-O-β-acyl glucuronide (AG) metabolites as the major drug-related components in bile, representing at least 15 to 16% of the dose after oral administration. Peliglitazar AG was the major circulating metabolite, whereas muraglitazar AG was a very minor circulating metabolite in humans. Peliglitazar AG circulated at lower concentrations in animal species than in humans. Both compounds had a similar glucuronidation rate in UDP-glucuronic acid-fortified human liver microsomal incubations and a similar metabolism rate in human hepatocytes. Muraglitazar AG and peliglitazar AG were chemically synthesized and found to be similarly oxidized through hydroxylation and O-demethylation in NADPH-fortified human liver microsomal incubations. Peliglitazar AG had a greater stability than muraglitazar AG in incubations in buffer, rat, or human plasma (pH 7.4). Incubations of muraglitazar AG or peliglitazar AG in plasma produced more aglycon than acyl migration products compared with incubations in the buffer. These data suggested that the difference in plasma stability, not differences in intrinsic formation, direct excretion, or further oxidation of muraglitazar AG or peliglitazar AG, contributed to the observed difference in the circulation of these AG metabolites in humans. The study demonstrated the difficulty in doing risk assessment based on metabolite exposure in plasma because the more reactive muraglitazar AG would not have triggered a threshold of concern based on the recent U.S. Food and Drug Administration guidance on Metabolites in Safety Testing, whereas the more stable peliglitazar AG would have.

BIOTRANSFORMATION OF CARBON-14-LABELED MURAGLITAZAR IN MALE MICE: INTERSPECIES DIFFERENCE IN METABOLIC PATHWAYS LEADING TO UNIQUE METABOLITES

Muraglitazar (Pargluva; Bristol-Myers Squibb), a dual α/γ peroxisome proliferator-activated receptor activator, is under development for treatment of type 2 diabetes. This study describes the biotransformation profile of carbon-14-labeled muraglitazar in plasma, urine, feces, and bile samples from male CD-1 mice [intact and bile duct cannulation (BDC)] after single oral doses of 1 and 40 mg/kg. The major drug-related component circulating in mouse plasma was the parent compound for up to 4 h postdose. Similar to excretion profiles of muraglitazar in humans, monkeys, and rats, urinary excretion was the minor and fecal excretion via the biliary route was the major elimination pathway for muraglitazar in mice. The parent compound was a minor component in urine, bile, and feces, indicating that muraglitazar was extensively metabolized in mice. Major biotransformation pathways of muraglitazar in mice included taurine conjugate formation, acyl glucuronidation, hydroxylation, and O-dealkylation. In addition to those metabolites previously identified in humans, monkeys, and rats (M1–M21), several unique metabolites identified in mice included taurine conjugates (M24, M25, M26a,b,c, and M31), oxazole-ring-opened metabolites (M27 and M28), glutathione conjugates (M29a,b and M30), a dihydroxylated metabolite (M32), hydroxylated metabolites (M33 and M35), and a dehydrogenated metabolite (M34). The taurine conjugate of muraglitazar, M24, was a major metabolite in mice, accounting for 12 to 15% of the total dose in BDC mice or 7 to 12% of the total dose in intact mice. None of these taurine and glutathione conjugates were found in the bile samples of humans, monkeys, or rats.

Synthesis and structure–activity relationships of 2-aryl-4-oxazolylmethoxy benzylglycines and 2-aryl-4-thiazolylmethoxy benzylglycines as novel, potent PPARα selective activators- PPARα and PPARγ selectivity modulation

The synthesis and follow-up SAR studies of our development candidate 1 by incorporating 2-aryl-4-oxazolylmethoxy and 2-aryl-4-thiazolylmethoxy moieties into the oxybenzylglycine framework of the PPARalpha/gamma dual agonist muraglitazar is described. SAR studies indicate that different substituents on the aryloxazole/thiazole moieties as well as the choice of carbamate substituent on the glycine moiety can significantly modulate the selectivity of PPARalpha versus PPARgamma. Potent, highly selective PPARalpha activators 2a and 2l, as well as PPARalpha activators with significant PPARgamma activity, such as 2s, were identified. The in vivo pharmacology of these compounds in preclinical animal models as well as their ADME profiles are discussed.

Synthesis and biological evaluation of novel pyrrolidine acid analogs as potent dual PPARα/γ agonists.

The design, synthesis and structure-activity relationships of a novel series of 3,4-disubstituted pyrrolidine acid analogs as PPAR ligands is outlined. In both the 1,3- and 1,4-oxybenzyl pyrrolidine acid series, the preferred stereochemistry was shown to be the cis-3R,4S isomer, as exemplified by the potent dual PPARα/γ agonists 3k and 4i. The N-4-trifluoromethyl-pyrimidinyl pyrrolidine acid analog 4i was efficacious in lowering fasting glucose and triglyceride levels in diabetic db/db mice.