The Palladium-Catalyzed Cross-Coupling Reaction of Phenylboronic Acid with Haloarenes in the Presence of Bases

On the mechanism of palladium-catalyzed coupling of haloaryls to biaryls in water with zinc

[reaction: see text] Kinetics and process parameters of coupling and hydro-dehalogenation reactions of chloroaryls are studied in the presence of zinc, water, and catalytic Pd/C. Good yields are obtained for the coupling of chlorobenzene, 4-chlorotoluene, and 4-chloro-1,1,1-trifluorotoluene. It is shown that water is actually one of the reagents, reacting with zinc in the presence of palladium to give zinc oxide and hydrogen gas, which then regenerates the Pd0 catalyst for the coupling reaction.

Structure-activity relationships and pharmacokinetic analysis for a series of potent, systemically available biphenylsulfonamide matrix metalloproteinase inhibitors

A series of biphenylsulfonamide derivatives of (S)-2-(biphenyl-4-sulfonylamino)-3-methylbutyric acid (5) were prepared and evaluated for their ability to inhibit matrix metalloproteinases (MMPs). For this series of compounds, our objective was to systematically replace substituents appended to the biphenyl and alpha-position of 5 with structurally diverse functionalities to assess the effects these changes have on biological and pharmacokinetic activity. The ensuing structure-activity relationship (SAR) studies showed that biphenylsulfonamides substituted with bromine in the 4'-position (11c) significantly improved in vitro activity and exhibited superior pharmacokinetics (C(max), t(1/2), AUCs), relative to compound 5. Varying the lipophilicity of the alpha-position by replacing the isopropyl group of 11c with a variety of substituents, in general, maintained potency versus MMP-2, -3, and -13 but decreased the oral systemic availability. Subsequent evaluation of its enantiomer, 11c', showed that both compounds were equally effective MMP inhibitors. In contrast, the corresponding hydroxamic acid enantiomeric pair, 16a (S-isomer) and 16a' (R-isomer), stereoselectivity inhibited MMPs. For the first time in this series, 16a' provided nanomolar potency against MMP-1, -7, and -9 (IC(50)'s = 110, 140, and 18 nM, respectively), whereas 16a was less potent against these MMPs (IC(50)'s = 24, 78, and 84 microM, respectively). However, unlike 11c, compound 16a' afforded very low plasma concentrations following a single 5 mg/kg oral dose in rat. Subsequent X-ray crystal structures of the catalytic domain of stromelysin (MMP-3CD) complexed with inhibitors from closely related series established the differences in the binding mode of carboxylic acid-based inhibitors (11c,c') relative to the corresponding hydroxamic acids (16a,a').

Palladium-catalyzed borylation of aryl halides or triflates with dialkoxyborane: A novel and facile synthetic route to arylboronates

A direct borylation of aryl halides or triflates with dialkoxyborane was investigated. The coupling reaction of pinacolborane with aryl halides or triflates in the presence of a catalytic amount of PdCl(2)(dppf) together with a base provided arylboronates in high yields. The product distributions were strongly dependent on the base employed, and the tertiary amine, especially Et(3)N, was effective for the selective formation of the boron-carbon bond. The reaction conditions were so mild that arylboronates having a variety of functional groups such as carbonyl, cyano, and nitro groups were readily prepared.

New class of biphenylene dibenzazocinones as potent ligands for the human EP1 prostanoid receptor

A new class of potent and selective ligands for the human EP1 prostanoid receptor is described. SAR studies reported herein allowed the identification of several potent dibenzazocinones bearing an acylsulfonamide side chain. The binding affinity of these compounds on all eight human prostanoid receptors is reported.

Imidazole substituted biphenyls: a new class of highly potent and in vivo active inhibitors of P450 17 as potential therapeutics for treatment of prostate cancer

3- And 4-imidazol-1-yl-methyl substituted biphenyl compounds (named as meta- and para-substituted compounds) were synthesized bearing additional substituents in 3'-/4'-position as inhibitors of P450 17 (17alpha-hydroxylase-C17,20-lyase). P450 17 is the key enzyme of androgen biosynthesis. Its inhibition is a novel therapeutic strategy for treatment of prostate cancer (PC). Twenty-nine compounds were synthesized by Ar-Mg-Br, Negishi or Suzuki aryl-aryl cross coupling and tested toward human and rat enzyme. Most of the compounds showed moderate to excellent activity against one of the enzymes (0.087 microM < or = IC50 < or = 7.7 microM (ketoconazole: 0.74 microM) for the human enzyme, 0.63 microM < or = IC50 < or = 32 microM (ketoconazole: 67 microM) for the rat enzyme). Interestingly, strong species differences were observed. In addition compounds were tested for inhibition toward P450 arom. The 3-imidazol-1-yl-methyl substituted compounds showed good inhibitory activity of P450 arom, while for the 4-substituted compounds negligible inhibition was found. For the most active group of P450 17 inhibitors, (i.e. the 4-imidazol-1-yl-methyl substituted compounds) a QSAR study was performed for inhibition of the human enzyme leading to the result that a hydrophilic substituent in 3'-/4'-position is very important. The most promising compounds (with respect to activity toward both enzymes) were tested in vivo using SD-rats for reduction of plasma testosterone concentrations 2 and 6 h after single i.p. application. The fluorine substituted compound 8c decreased the testosterone plasma concentration to castration level (after 2 h; 5 mg/kg) showing a biological half live of about 6 h.

Design and synthesis of isoxazoline derivatives as factor Xa inhibitors. 1

Thrombosis is a major cause of mortality in the industrialized world. Therefore, the prevention of blood coagulation has become a major target for new therapeutic agents. One attractive approach is the inhibition of factor Xa (FXa), the enzyme directly responsible for prothrombin activation. We report a series of novel biaryl-substituted isoxazoline derivatives in which the biaryl moiety was designed to interact with the S(4) aryl-binding domain of the FXa active site. Several of the compounds herein have low nanomolar affinity for FXa, have good in vitro selectivity for FXa, and show potent antithrombotic efficacy in vivo. The three most potent compounds (33, 35, and 37) have inhibition constants for human FXa of 3.9, 2.3, and 0.83 nM, respectively, and ID(50)'s ranging from 0.15 to 0.26 micromol/kg/h in the rabbit arterio-venous thrombosis model.

Terphenyl cyclooxygenase-2 (COX-2) inhibitors: optimization of the central ring and o-biphenyl analogs

The discovery of terphenyl derivatives as highly selective COX-2 inhibitors resulted from our efforts to overcome poor pharmacokinetics demonstrated by the COX-2 selective diarylthiophene DuP 697 [2-bromo-4-(4'-sulfonylmethyl)phenyl-5-(4'-fluoro)phenylthiophe ne]. Detailed SAR related to the ortho-biphenyls and variants of the central ring are described herein.

Development of chloromethylated SynPhasetrade mark crowns and their use in Pd(0) mediated cross-coupling reactions

We report the convenient generation of chloromethylated polystyrene surfaces (Merrifield linker)3 on SynPhasetrade mark crowns. It was demonstrated that these novel surfaces can be successfully employed for peptide chemistry as well as Pd(0) mediated cross-couplings. Copyright 1998 John Wiley & Sons, Inc.