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A macrocycle provides diverse functionality and stereochemical complexity in a conformationally preorganized ring structure, and it occupies a unique chemical space in drug discovery. However, the synthetic challenge to access this structural class is high and hinders the exploration of macrocycles. In this study, efficient synthetic routes to macrocyclized betulin derivatives have been established. The macrocycle containing compounds showed equal potency compared to bevirimat in multiple HIV-1 antiviral assays. The synthesis and biological evaluation of this novel series of HIV-1 maturation inhibitors will be discussed.

A series of 2-anilinothiazolones were prepared as inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). The most potent compounds contained a 2-chloro or 2-fluoro group on the aniline ring with an isopropyl substituent on the 5-position of the thiazolone ring (compounds 2 and 3, respectively). The binding mode was determined through the X-ray co-crystal structure of the enzyme with compound 3. This compound was also approximately 70-fold selective over 11beta-HSD2 and was orally bioavailable in rat pharmacokinetic studies. However, compound 3 was >580-fold less active in the 11beta-HSD1 cell assay when tested in the presence of 3% human serum albumin.

The bradykinin B1 receptor is induced following tissue injury and/or inflammation. Antagonists of this receptor have been studied as promising candidates for treatment of chronic pain. We have identified aryl sulfonamides containing a chiral chroman diamine moiety that are potent antagonists of the human B1 receptor. Our previously communicated lead, compound 2, served as a proof-of-concept molecule, but suffered from poor pharmacokinetic properties. With guidance from metabolic profiling, we performed structure-activity relationship studies and have identified potent analogs of 2. Variation of the sulfonamide moiety revealed a preference for 3- and 3,4-disubstituted aryl sulfonamides, while bulky secondary and tertiary amines were preferred at the benzylic amine position for potency at the B1 receptor. Modifying the beta-amino acid core of the molecule lead to the discovery of highly potent compounds with improved in vitro pharmacokinetic properties. The most potent analog at the human receptor, compound 38, was also active in a rabbit B1 receptor cellular assay. Furthermore, compound 38 displayed in vivo activity in two rabbit models, a pharmacodynamic model with a blood pressure readout and an efficacy model of inflammatory pain.

A thiazole derivative, 2-(2,6-dichlorobenzyl)-N-(4-isopropylphenyl) thiazole-4-carboxamide (1), was identified as a TRPV1 antagonist. We synthesized various thiazole analogs and evaluated them for their ability to block capsaicin- or acid-induced calcium influx in TRPV1-expressing CHO cells. The IC50 values of the most potent antagonists were ca. 0.050 μM in these assays.

The biological activity for a set of melanocortin-4 receptor (MC4R) agonists containing a piperazine core with an ortho-substituted aryl sulfonamide is described. Compounds from this set had binding and functional activities at MC4R less than 30 nM. The most selective compound in this series was >25,000-fold more potent at MC4R than MC3R, and 490-fold more potent at MC4R than MC5R. This compound also reduced food intake after oral dosing at 25, 50, and 100 mg kg−1 in fasted mice.

Novel αvβ3 antagonists based on the N-aryl-γ-lactam scaffold were prepared. SAR studies led to the identification of potent antagonists for αvβ3 receptor with excellent selectivity against the structurally related αIIbβ3 receptor. Additional interactions of N-aryl-γ-lactam derivatives with αvβ3 were found when compared to c(-RGDf[NMe]V-) peptide antagonist. The effects of the conformation and configuration of the γ-lactam core on the binding were also assessed.

Neuropeptide Y (NPY) has been shown to play an important role in the regulation of food intake and energy balance. Pharmacological data suggests that the Y5 receptor subtype contributes to the effects of NPY on appetite, and therefore a Y5 antagonist might be a useful therapeutic agent for the treatment of obesity. In attempts to identify potential Y5 antagonists, a series of pyrrolo[3, 2-d]pyrimidine derivatives was prepared and evaluated for their ability to bind to Y5 receptors in vitro. We report here the synthesis and initial structure-activity relationship investigations for this class of compounds. The target compounds were prepared by a variety of synthetic routes designed to modify both the substitution and the heterocyclic core of the pyrrolo[3,2-d]pyrimidine lead 1. In addition to identifying several potent Y5 antagonists for evaluation as potential antiobesity agents, a pharmacophore model for the human Y5 receptor is presented.

A quantitative Hammett study of the magnitude of the electronic effects of a C7 substituent on the functional reactivity of N-BOC-CBI (5, RH), its impact on biological properties, details of the mechanism of the acid-catalyzed nucleophilic addition to the activated cyclopropane, and its implications on the origin of the DNA alkylation selectivity of this class of agents is detailed.

An extensive study of analogs of the potent antitumor antibiotics CC-1065 and the duocarmycins which incorporate the 1,2,9,9 a -tetrahydrocyclopropa[c]benz [e]indol-4-one (CBI) alkylation subunit are detailed. In contrast to early speculation, deep-seated modifications in the CC-1065 and duocarmycin alkylation subunits are well tolerated and the CBI-based analogs proved to be potent cytotoxic agents and efficacious antitumor compounds. Full details of studies defining a direct relationship between functional stability and in vitro cytotoxic potency are described. As such, the readily accessible CBI-based analogs were found to be four times more stable and four times more potent than the corresponding analogs containing the authentic CPI alkylation subunit of CC-1065 and comparable in potency to agents containing the authentic alkylation subunit of duocarmycin SA. Similarly, the CBI-based agents alkylate DNA with an unaltered sequence selectivity at an enhanced rate and with a greater efficiency than the corresponding CPI analog and were comparable to the corresponding analog incorporating the duocarmycin SA alkylation subunit. Systematic and extensive modifications and simplifications in the DNA binding subunits attached to CBI were explored with the comparisons of both enantiomers of CC-1065 and the duocarmycins 2 and 3 with enantiomers of 18–24, 25–29, 57–61, 62–65, 66–68, 72, 73, 78 and 79.

The product distributions produced by the photoinduced dichlorination of n-dodecane (nD) and the photoinduced monochlorination of 1 -chlorododecane (1CD) adsorbed on two pentasil zeolites (silicalite and LZ- 105) have been investigated. The results are explained in terms of a supramolecular model for which the mobile and diffusing chlorination reagents (CWC12) enter the zeolite particle from the external surface and diffuse preferentially along the linear channels of the zeolite internal surface that contain immobile adsorbed nD (or 1CD) molecules. The model assumes that the outermost layer of adsorbed substrates is attacked preferentially, that the attack occurs at the proximal end of adsorbed nD molecules closest to the extemal surface, and that, after the first chlorination, the substrate molecules in an inner layer are protected from chlorination by "blocking" molecules parked in the outer layer. The model describes each substrate molecule adsorbed on the internal surface in terms of supramolecular isomeric structures that are capable of characterizing the specific void space sites occupied by the substrate. A detailed analysis of the results allows the conclusion that the compensating cations tend to be preferentially located in the zigzag channels rather than in the linear channels or intersections and that the variation of selectivity of chlorination with experimental conditions results from redistribution of the isomeric supramolecular structures.

The discovery of novel and highly potent oxopiperazine based B1 receptor antagonists is described. Compared to the previously described arylsulfonylated (R)-3-amino-3-phenylpropionic acid series, the current compounds showed improved in vitro potency and metabolic stability. Compound 17, 2-((2R)-1-((4-methylphenyl)sulfonyl)-3-oxo-2-piperazinyl)-N-((1R)-6-(1-piperidinylmethyl)-1,2,3,4-tetrahydro-1-naphthalenyl)acetamide, showed EC50 of 10.3 nM in a rabbit biochemical challenge model. The practical syntheses of chiral arylsulfonylated oxopiperazine acetic acids are also described.

A three-histidine Zn 2+ binding site based on the carbonic anhydrase B site has been engineered into the four available sites on the light chain of the fluorescein binding antibody 4-4-20. All mutant antibodies bind fluorescein. Transition metal binding was assayed by tryptophan fluorescence quenching. Two of the four sites exhibit metal affinities consistent with complexation by three ligands. The specificity of the highest affinity site was probed by mutagenesis. For various combinations of histidine, aspartate, and glutamate residues, affinities range from -5 to -10 kcal/mol for Cu 2+ , -3 to -6.5 kcal/mol for Zn 2+ , and -3 and -5.5 kcal/mol for Cd 2+

The dominant products from the photolysis of large α-phenylcycloalkanones are the cyclophanes formed by the intramolecular para coupling of the acyl benzyl biradical intermediate. This tendency to form cyclophanes is preserved under a variety of environmental conditions (organic solvents, micelles, and zeolites)

The primary photochemical process of 2,2,12-trimethylcyclododecanone ( 1a ) and 2,2,12,12-tetramethylcyclododecanone ( 1b ) is exclusively C 1 C 2 α cleavage to form biradicals 2a and 2b which then disproportionate to form enals. This contrasts with the strong preference for γ-hydrogen abstraction for the parent cyclododecanone. The preference of α cleavage over γ-hydrogen abstraction for the methyl-substituted large ring cycloalkanones is explained by the faster rate of α cleavage due to stabilization of the intermediate biradical by methyl substitution. No nuclear polarization can be observed in the photochemically induced dynamic nuclear polarization (photo-CIDNP) of 1a in the absence of radical scavengers. Measurement of the 13 C isotopic content of the photoproducts shows that the major enal product is slightly enriched in 13 C in the absence of radical scavengers through isotopomer separation via the magnetic isotope effect. However, the recovered 1a is not enriched in 13 C. The addition of radical scavengers, such as molecular oxygen, CBrCl 3 or CCl 4 , causes dramatic nuclear polarization and an increase in the 13 C enrichment of the enal product. The presence of radical scavengers opens up a competitive pathway which serves as the spin (or isotopomer) sorting process required for both the generation of T 0 S biradical CIDNP and isotope enrichment. In the absence of radical scavengers, the observation of the slight 13 C enrichment in the enal product and the absence of nuclear polarization result from the slow decarbonylation process which is fast enough to serve as an isotopomer sorting process, but not fast enough to serve as a spin sorting process.

The dominant products from the photolysis of large α-phenylcycloalkanones are the cyclophanes formed by the intramolecular para coupling of the acyl benzyl biradical intermediate. This tendency to form cyclophanes is preserved under a variety of environmental conditions (organic solvents, micelles, and zeolites)

A series of compounds containing the 2-amino-1,3-thiazol-4(5H)-one core were found to be potent inhibitors of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). One of our lead compounds from this series activated the human nuclear xenobiotic receptor, pregnane X receptor (PXR). To try and mitigate the PXR activity, we prepared analogues of our lead series that contained polar groups on the right-hand side of the thiazolone. Several analogues containing amides or alcohols appended to the C-5 position of the thiazolone showed a significant reduction in PXR activity. Through these structure-activity efforts, a compound containing a tert-alcohol group off the C-5 position, analogue (S)-33a, was found to have an 11beta-HSD1 Ki = 35 nM and negligible PXR activity. Compound (S)-33a was advanced into a pharmacodynamic model in cynomolgus monkeys, where it inhibited adipose 11beta-HSD1 activity after being orally administered.

The photochemistry of solid complexes of large ring 2-phenylcycloalkanones adsorbed in cyclodextrin cavities results in significant yields of enals as disproportionation products, at the expense of the para-rearrangement, depending on both the ring size of the cyclanone and the cavity size of the cyclodextrin. This behavior contrasts with its photoreaction in homogeneous solutions which yields predominantly para-cyclophanes.

The vanilloid receptor-1 (TRPV1 or VR1) is a member of the transient receptor potential (TRP) family of ion channels and plays a role in regulating the function of sensory nerves. A growing body of evidence demonstrates the therapeutic potential of TRPV1 modulators, particularly in the management of pain. As a result of our screening efforts, we identified (E)-3-(4-tert-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)acrylamide (1), an antagonist that blocks the capsaicin-induced and pH-induced uptake of (45)Ca(2+) in TRPV1-expressing Chinese hamster ovary cells with IC(50) values of 17 +/- 5 and 150 +/- 80 nM, respectively. In this report, we describe the synthesis and structure-activity relationship of a series of N-aryl cinnamides, the most potent of which (49a and 49b) exhibit good oral bioavailability in rats (F(oral) = 39% and 17%, respectively).

Novel alphavbeta3 antagonists based on the N-aryl-gamma-lactam scaffold were prepared. SAR studies led to the identification of potent antagonists for alphavbeta3 receptor with excellent selectivity against the structurally related alpha(IIb)beta3 receptor. Additional interactions of N-aryl-gamma-lactam derivatives with alphavbeta3 were found when compared to c(-RGDf[NMe]V-) peptide antagonist. The effects of the conformation and configuration of the gamma-lactam core on the binding were also assessed.

Hybrid agents 5-11 containing the C-terminus DNA binding domain of bleomycin A2 linked to the CBI analogue of the CC-1065 and duocarmycin DNA alkylation subunits were prepared and evaluated. The agents exhibited little or no enhancement of the DNA alkylation efficiency and in some cases the linkage resulted in diminished properties relative to the simple alkylation subunit itself. Moreover, the DNA alkylation selectivity (5'-AA > 5'-TA) of the resulting agents proved identical to that of simple derivatives of the CBI alkylation subunit, e.g. N-BOC-CBI. Thus, the linkage to the DNA binding domain of bleomycin A2 did not alter this inherent DNA alkylation selectivity to reflect a DNA binding or cleavage selectivity of bleomycin A2, nor did it reflect the greater 5- or 3.5-base-pair AT-rich selectivities observed with CC-1065 or the duocarmycins, respectively. Consistent with these observations, the cytotoxic properties of 5-11 were diminished relative to those of even simple derivatives of the CC-1065/duocarmycin alkylation subunits, e.g. N-BOC-CBI.

The synthesis and preliminary examination of CBI-CDPBO1 (2) and CBI-CDPBI1 (3), CBI analogs of CC-1065 (1) and the duocarmycins incorporating the 3-carbamoyl-1,2-dihydro-3H-pyrrolo[3,2-e]benzoxazole-7-carboxylate (CDPBO) and 3-carbamoyl-1,2-dihydro-3H-pyrrolo[3,2-e]benzimidazole-7-carboxylate (CDPBI) DNA binding subunits, are detailed. The agents contain deep-seated modifications in the DNA binding subunits of the natural products with incorporation of a nitrogen capable of functioning as a hydrogen bond acceptor (CDPBO, CDPBI) or hydrogen bond donor (CDPBI) on their inside concave face which is in intimate contact with the minor groove floor. The CDPBO subunit was prepared through use of a novel and effective MnO2-mediated oxidative coupling of 2-(benzyloxy)ethylamine with 5-hydroxyindole (4) to directly provide 2-[(benzyloxy)methyl]pyrrolo[3,2-e]benzoxazole (6, 48%) in a reaction cascade that initially proceeds with amine regioselective C4 nucleophilic addition to the in situ generated p-quinone monoimine 13. Subsequent conversion of 6 to 8 (debenzylation; MnO2-NaCN, CH3OH) and selective reduction of the fused pyrrole (Et3SiH-CF3CO2H) completed the synthesis of the 1,2-dihydro-3H-pyrrolo[3,2-e]benzoxazole-7-carboxylate ring system. The CDPBI subunit was prepared through selective C4 nitration of 22 followed by reduction of the nitro group and acid-catalyzed closure to the corresponding 2-[(benzyloxy)methyl]pyrrolo[3,2-e]benzimidazole 25. The final conversion of 25 to the 1,2-dihydro-3H-pyrrolo[3,2-e]benzimidazole-7-carboxylate ring system (CDPBI) followed the same protocols introduced for CDPBO. The DNA alkylation efficiencies of 2 and 3 were identical and both were substantially diminished relative to that of CBI-CDPI1 (40). Thus, the introduction of a single nitrogen atom in the DNA binding subunit of 40 has a pronounced and detrimental effect on the relative efficiency (100 x) of DNA alkylation. Consistent with these observations, the in vitro cytotoxic activity of (+)-2 and (+)-3 were comparable (IC50 = 200 pM, L1210) and 40 x less potent than (+)-40 (IC50 = 5 pM, L1210). In contrast to the large impact these small structural changes had on the efficiency of DNA alkylation, the selectivity of DNA alkylation by 2 and 3 was unperturbed and both agents were found to alkylate the same major sites as CBI-CDPI1 (40). The potential origin of these effects is discussed.

The three trimethylammonium salts 3–5 proved to be 100 times more efficient at alkylating DNA than 2 and exhibited DNA alkylation efficiencies identical to that of (+)-CC-1065 ( 1 ). In addition, the agents 3 and 4 exhibited DNA alkylation selectivities identical to that of 2 . This may be attributed to spatially well-defined stabilizing electrostatic interactions between the positively charged trimethylammonium salt lying on the peripheral face of the agents and the bracketing, negatively charged phosphates located in the DNA backbone that enhance the DNA noncovalent binding affinity without affecting DNA binding or alkylation selectivity. The agent 5 exhibited an altered and more discriminating AT-rich adenine N3 alkylation selectivity than 2–4 that may be attributed to the groove placement of the large trimethylammonium salt.