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

Indole inhibitors of human nonpancreatic secretory phospholipase A2. 1. Indole-3-acetamides

Phospholipases (PLAs) produce rate-limiting precursors in the biosynthesis of various types of biologically active lipids involved in inflammatory processes. Increased levels of human nonpancreatic secretory phospholipase A2 (hnps-PLA2) have been detected in several pathological conditions. An inhibitor of this enzyme could have therapeutic utility. A broad screening program was carried out to identify chemical structures which could inhibit hnps-PLA2. One of the lead compounds generated by the screening program was 5-methoxy-2-methyl-1-(phenylmethyl)-1H-indole-3-acetic acid (13a). We describe the syntheses, structure--activity relationships, and pharmacological activities of a series of indole-3-acetamides and related compounds derived from this lead. This SAR was undertaken with the aid of X-ray crystal structures of complexes between the inhibitors and hnps-PLA2 which were of great value in directing the SAR.

2-[2'-(Dimethylamino)ethyl]-1,2-dihydro- 3H-dibenz[de,h]isoquinoline-1,3-diones with substituents at positions 4, 8, 9, 10, and 11. Synthesis, antitumor activity, and quantitative structure-activity relationships

New 2-[2'-(dimethylamino)ethyl]-1,2-dihydro-3H-dibenz[de,h]isoquinoline-1,3- diones with substituents at the 4, 8, 9, 10, and 11 positions were synthesized. Diazonium salts prepared from aminoazonafides were key intermediates for many of the analogues. Six of the new compounds were more potent than azonafide in a panel of tumor cells including human melanoma and ovarian carcinoma and murine L1210 leukemias. Three of these compounds, the 10-OCH3, 10-OC2H5, and 10-F analogues, had better ratios of cardiotoxicity to tumor-cell toxicity than azonafide. Eight compounds were not cross-resistant with MDR L1210 leukemia, and the 10-CN analogue was more potent against solid tumor cells than leukemia cells. The 9-OH, 10-CN, and 10-F analogues had high potency against both sensitive and resistant cell lines of MFX 7 breast carcinoma and WiDr colon carcinoma and sensitivity A599 lung carcinoma. Advantages of the 10-Cl, 10-NH2, and 10-CN analogues over azonafide were apparent in P388 leukemia in mice, and the 10-CN analogue was more effective than doxorubicin in this assay. Quantitative structure-activity relationship studies revealed statistically significant correlations between DNA binding strength of 8- and 10-substituted azonafides, as measured by deltaTm, and toxicity to tumor cells. There also were correlations between substituent size, as measured by MR, and cytotoxicity for 9- and 10-substituted azonafides and between MR and deltaTm for 4- and 11-substituted azonafides. Lipophilicity of substituents (pi) correlated with cytotoxicity for 9-, 10-, and 11-substituted azonafides. These results lend support to a model in which DNA binding strength influences cytotoxic potency, and lipophilicity increases DNA binding whereas large substituents decrease it.

Bisphenolic compounds that enhance cell cation transport are found in commercial phenol red

We have isolated two bisphenolic compounds (4 and 5) that have a marked effect on K+ and Na+ concentrations in human cells from commercial preparations of the pH indicator dye phenol red (phenolsulfonphthalein). We used a bioassay to identify active chromatographic fractions from the lipophilic impurities present in phenol red, and we determined the structure of two active components (4 and 5) by 1H and 13C NMR and mass spectrometry. When added to human fibroblasts in serum-free medium, the bisphenol fluorene derivative 9,9-bis(4'-hydroxyphenyl)-3-hydroxyfluorene (5) produced a rapid loss of K+ and a gain of Na+, at low concentrations, with an EC50 between 30 and 60 ng/mL (80-160 nM). The 2- and 4-hydroxy isomers of the fluorene 5 (i.e., compounds 6 and 7), prepared by synthesis, had similar activity, although compound 6 was somewhat less potent. The bisphenol xanthene derivative 9,9-bis(4'-hydroxyphenyl)xanthene (4) elicited a similar biological response but was less potent than 5-7; it also had a strong effect on cell adhesion, causing release of cells from the plastic substrate at concentrations as low as 2-5 microg/mL (5.5-14 microM). The structures of xanthene (4) and fluorene (5) bisphenols have been confirmed by synthesis from xanthone and hydroxyfluorenone, respectively, by Friedel-Crafts alkylation with phenol. In the latter case, the desired 3-hydroxyfluorene isomer was formed in situ by rearrangement of the 1-hydroxy isomer.

Convergent Synthetic Routes to Orthogonally Fused Conjugated Oligomers Directed toward Molecular Scale Electronic Device Applications

This paper describes the synthetic organic phase of a project directed toward the construction of molecular scale electronic devices. Outlined is a convergent synthetic route to orthogonally fused conjugated organic oligomers. The final systems are to have a potentially conducting chain fused perpendicularly to a second potentially conducting chain via a sigma bonded network. One of the core segments synthesized is based on a spirobithiophene moiety with a central silicon atom. It is formed by a zirconium-promoted bis(bicyclization) of a tetrapropargylsilane. The second core is a 9,9'-spirobifluorene system. Terminal halide groups provide the linkage points for further extension of the chains via Pd-catalyzed or Pd/Cu-catalyzed cross coupling methods. All four branching arms are affixed to the core in a single operation, thus making the syntheses highly convergent. In the cases of the larger functionalized systems, alkyl substituents on the thiophenes afford soluble materials. In order to prepare the molecules with >50 Å lengths, an iterative divergent/convergent approach had to be utilized for the construction of oligo(thiophene-ethynylene) branching arms. Organopalladium-catalyzed procedures are used extensively for the syntheses of the orthogonally fused compounds.

Palladium-Catalyzed Cross-Coupling of Organoboron Compounds with Iodonium Salts and Iodanes

The palladium-catalyzed cross-coupling reaction of iodinanes (iodonium salts and iodanes) with organoboron compounds to form carbon-carbon bonds was achieved at ambient temperature under aqueous conditions in the absence of base. Coupling of phenylboronic acid with diphenyliodonium tetrafluoroborate in the presence of Pd(PPh(3))(4) (0.2 mol %) or Pd(OAc)(2) (0.2 mol %) under aqueous conditions gave biphenyl in almost quantitative yield. Under the same conditions, substituted boronic acids, boronates, and trialkylboranes were readily coupled with diaryl-, alkenyl-, and alkynyliodonium salts. Finally, the iodanes ArI(OH)OTs underwent cross-coupling with boronic acids, boronates, and trialkylboranes to afford biphenyls and aryl-substituted alkenes.

Synthesis and Hydrogen Bonding Capabilities of Biphenyl-Based Amino Acids Designed To Nucleate beta-Sheet Structure

The syntheses of 3'-(aminoethyl)-2-biphenylpropionic acid (1) and 2-amino-3'-biphenylcarboxylic acid (2) are described. These residues were designed to nucleate beta-sheet structure in aqueous solution when incorporated into small, amphiphilic peptides in place of the backbone of the i + 1 and i + 2 residues of the beta-turn. N-Benzyl-3'-(2-(benzylamido)ethyl)-2-biphenylpropamide (3) and N-benzyl-(2-benzylamido)-3'-biphenylamide (4) were synthesized and studied as model compounds to investigate the hydrogen-bonding capabilities of residues 1 and 2, respectively. The X-ray crystal structure of 3 indicates that a 13-membered intramolecular hydrogen-bonded ring is formed, while the remaining amide proton and carbonyl are involved in intermolecular hydrogen bonding. Infrared and variable-temperature NMR experiments indicate that, in solution (CH(2)Cl(2)), 3 exists as an equilibrium mixture of the 13- and the 15-membered intramolecularly hydrogen-bonded conformers with the 15-membered ring conformer being favored. Amide 4 was shown to exist in solution (CH(2)Cl(2)) as an equilibrium mixture of the 11-membered intramolecular hydrogen-bonded ring and a nonbonded conformation. No contribution from the 9-membered hydrogen-bonded ring conformation was observed. The X-ray crystal structure of 4 indicated the absence of intramolecular hydrogen bonding in the solid state.

Synthesis and structure-activity relationships of phenylenebis(methylene)-linked bis-tetraazamacrocycles that inhibit human immunodeficiency virus replication. 2. Effect of heteroaromatic linkers on the activity of bicyclams

A series of bicyclam analogs connected through a heteroaromatic linker have been synthesized and evaluated for their inhibitory effects on HIV-1 (IIIB) and HIV-2 (ROD) replication in MT-4 cells. The activity of pyridine- and pyrazine-linked bicyclams was found to be highly dependent upon the substitution of the heteroaromatic linker connecting the cyclam rings. For example, 2,6- and 3,5-pyridine-linked bicyclams were potent inhibitors of HIV-1 and HIV-2 replication, whereas the 2,5- and 2,4-substituted pyridine-linked compounds exhibited substantially reduced activity and, in addition, were found to be highly toxic to MT-4 cells. We have subsequently discovered that these effects are not unique; amino-substituted linkers also have the potential to deactivate phenylenebis(methylene)-linked bicyclams. A model is proposed to explain the deactivating effects of the pyridine group in certain substitution patterns based on the ability of the pyridine nitrogen to participate in pendant conformations (complexation) with the adjacent azamacrocyclic ring, which may involve hydrogen bonding or coordination to a transition metal. The introduction of a sterically hindering group such as phenyl at the 6-position of the 2,4-substituted pyridine-linked bicyclam appears to prevent pendant conformations, providing an analog with comparable anti-HIV-1 and anti-HIV-2 activities to the parent m-phenylenebis(methylene)-linked bicyclam. The results of this study have been used to develop a quantitative structure-activity relationship model with improved predictive capability in order to aid the design of antiviral bis-azamacrocyclic analogs.