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Racemic N-CBZ-3-fluoropyrrolidine-3-methanol (±)-1 was resolved by preparative chiral HPLC. The absolute configuration of the enantiomers of 1 was identified by vibrational circular dichroism and confirmed by chemical synthesis, which involved exchanging the CBZ protecting group of (−)-1 with Boc, followed by oxidation with RuCl3, NaIO4, activation of the resulting acid with carbonyl diimidazole and reaction with (R)-α-methylbenzylamine to give (R)-tert-butyl 3-fluoro-3-(((R)-1-phenylethyl)carbamoyl) pyrrolidine-1-carboxylate 7. The latter was compared with authentic (S)-tert-butyl 3-fluoro-3-(((R)-1-phenylethyl)carbamoyl)pyrrolidine-1-carboxylate 6 and its diastereomer 7; the configuration of diastereomer 6 was obtained by an X-ray diffraction study. This established that the enantiomer (−)-1 had an (R)-configuration.

We recently reported the discovery of preclinical CCR5 inhibitor GSK214096, 1 (J. Med. Chem. 2011, 54, 756). Detailed characterization of 1 revealed that it exists as a mixture of four separable atropisomers A-D. The two slow-interconverting pairs of rotamers A + B and C + D were separated and further characterized. HIV and CCR5-mediated chemotaxis data strongly suggest that the antiviral potency of 1 is due to rotamers A + B and not C + D. Furthermore, integrated UV, vibrational circular dichroism VCD and computational approach allowed to determine the M chirality in C + D (and P chirality in A + B). These findings imply additional avenues to be pursued toward new CCR5 antagonists.

Antiparasitic oral drugs have been associated to lipophilic molecules due to their intrinsic permeability. However, these kind of molecules are associated to numerous adverse effects, which have been extensively studied. Within the Tres Cantos Antimalarial Set (TCAMS) we have identified two small, soluble and simple hits that even presenting antiplasmodial activities in the range of 0.4-0.5 μM are able to show in vivo activity.

Finding small non-peptide molecules for G protein-coupled receptors (GPCR) whose endogenous ligands are peptides, is a very important task for medicinal chemists. Over the years, compounds mimicking peptide structures have been discovered, and scaffolds emulating peptide backbones have been designed. In our work on GPCR ligands, including cholecystokinin receptor-1 (CCKR-1) agonists, we have employed benzodiazepines as a core structure. Looking for ways to reduce molecular weight and possibly improve physical properties of GPCR ligands, we embarked on the search for molecules providing similar scaffolds to the benzodiazepine with lower molecular weight. One of our target core structures was 1,4-dihydro-[1,4]diazepine-5,7-dione. There was not, however, a known synthetic route to such molecules. Here we report the discovery of a simple and concise method for synthesis of 2-[6-(1H-indazol-3-ylmethyl)-5,7-dioxo-4-phenyl-4,5,6,7-tetrahydro-[1,4]diazepin-1-yl]-N-isopropyl-N-phenyl-acetamide as an example of a compound containing the tetrahydrodiazepine-5,7-dione core. Compounds from this series were tested in numerous GPCR assays and demonstrated activity at melanocortin 1 and 4 receptors (MC1R and MC4R). Selected compounds from this series were tested in vivo in Peptide YY (PYY)-induced food intake. Compounds dosed by intracerebroventricular and oral routes reduced PYY-induced food intake and this effect was reversed by the cyclic peptide MC4R antagonist SHU9119.

A computational and spectroscopic study of two epimers of 2-hydroxymutilin was conducted to obtain assignments for the configuration of the carbon at the 2-position. Gas-phase structural models for (R)- and (S)-2-hydroxymutilin were optimized using density functional theory (DFT). These models were validated using internuclear distances measured from 1H nuclear Overhauser effect (NOE) build-up rates in CDCl3 solution. The models were subsequently used to predict NMR parameters using the hybrid B3LYP density functional. After linear scaling, the agreement between predicted gas-phase and observed solution-state chemical shifts was sufficient for relative stereochemical assignments, with an average absolute error of 0.16 and 1.47 ppm for 1H and 13C shifts, respectively. 1H–1H and 1H–13C coupling constants were also predicted using the B3LYP functional with the aug-cc-p-VTZ-J basis set and compared to experimental values (measured by J-resolved and gradient J-HMBC experiments). The predicted coupling constants were within 10% of their experimental values in most cases, and like the chemical shielding, allowed for relative stereochemical assignments of the isomers. DFT prediction of coupling constants gave more useful information than empirical parameterizations. Although just one chiral center changes between the two isomers, with no consequent conformational change and only two affected NOE restraints, predictable effects on 20 different chemical shielding and J-coupling values were observed. Including these values in the stereochemical assignment allows for additional confirmation of the stereochemical results, using data already available in 1D 1H spectra and 2D 1H–13C correlation spectra. Electronic and vibrational circular dichroism (ECD and VCD) spectra of the two isomers are also measured and compared with theoretical predictions. VCD was especially useful for determining the absolute stereochemistry of 2-hydroxymutilin and was found to be superior to ECD in this role. The combination of computational and spectroscopic work is shown to be a useful tool in the analysis of unknown mutilin derivatives or other compounds, such as those present as minor impurities or metabolites in pharmaceutical samples.

A solid-phase synthesis of substituted benzopyranoisoxazoles is described. The six-step synthesis features a novel method of generating nitrile oxides on a polymer support followed by an intramolecular 1,3-dipolar cycloaddition with a tethered alkyne for assembly of the benzopyranoisoxazole scaffold. Furthermore, the utilization of single-bead attenuated total reflectance Fourier transform infrared (ATR-IR) microspectroscopy as an essential analytical tool for reaction optimization is highlighted.

Mycobacterium tuberculosis is a major human pathogen and the causative agent for the pulmonary disease, tuberculosis (TB). Current treatment programs to combat TB are under threat due to the emergence of multi-drug and extensively-drug resistant TB. As part of our efforts towards the discovery of new anti-tubercular leads, a number of potent tetrahydropyrazolo[1,5-a]pyrimidine-3-ca​rboxamide(THPP) and N-benzyl-6′,7′-dihydrospiro[piperidine-4,​4′-thieno[3,2-c]pyran](Spiro) analogues were recently identified against Mycobacterium tuberculosis and Mycobacterium bovis BCG through a high-throughput whole-cell screening campaign. Herein, we describe the attractive in vitro and in vivo anti-tubercular profiles of both lead series. The generation of M. tuberculosis spontaneous mutants and subsequent whole genome sequencing of several resistant mutants identified single mutations in the essential mmpL3 gene. This ‘genetic phenotype’ was further confirmed by a ‘chemical phenotype’, whereby M. bovis BCG treated with both the THPP and Spiro series resulted in the accumulation of trehalose monomycolate. In vivo efficacy evaluation of two optimized THPP and Spiro leads showed how the compounds were able to reduce >2 logs bacterial cfu counts in the lungs of infected mice.

An unexpected cyclization product was isolated in the final step of the synthesis of nevirapine, a non-nucleoside inhibitor of HIV-1 reverse transcriptase. Based on infrared spectrometry, mass spectrometry, and a number of two-dimensional nmr experiments, the structure of this product was assigned to be 2-((2′-cyclopropylamino)-3′-pyridyl)-7-methyloxazolo[5,4-b]pyridine, 9. Results of a single crystal X-ray analysis confirmed this structural assignment. This product arises from cyclization of N-(2-chloro-4-methyl-3-pyridyl)-2-(cyclopropylamine)-3-pyridinecarboxamide, 8, by displacement of the chlorine with the amide carbonyl oxygen. A competitive reaction occurs when 8 is deprotonated prior to cyclization to form nevirapine, 11-cyclopropyl-5,11-dihydro-4-methyl-6H-dipyrido[3,2-b:2′,3′-e][1,4]diazepin-6-one, 2.

Two classes of amino acid-derived heterocyclic progesterone receptor ligands were developed to address the metabolic issues posed by the dimethyl amide functionality of the lead compound (1). The tetrazole-derived ligands behaved as potent partial agonists, while the 1,2,4-triazole ligands behaved as potent full agonists.

The enzymatic glucuronidation of 3′-azido-3′-deoxythymidine (AZT) catalyzed by human liver microsomal UDP-glucuronosyltransferase (EC 2.4.1.17, UDPGT) was inhibited by a number of nucleoside analogs. The inhibitory potency of these nucleoside analogs correlated with their hydrophobicity ( r 2 = 0.90, N = 13). Since similar results were obtained with solubilized UDPGT ( r 2 = 0.87, N = 7), the affinity of the nucleosides for UDPGT was probably being assessed rather than the ability of the compounds to access the membrane-bound enzyme. Three homologous inhibitors, 3′-azido-2′,3′-dideoxyuridine (AzddU), 5-ethyl-AzddU, and 5-propyl-AzddU, were also studied as substrates of UDPGT. The substrate efficiency ( V max / K m ) of these three compounds and AZT also correlated with their hydrophobicity ( r 2 = 0.94). Sixteen drugs that are structurally unrelated to nucleosides also inhibited the glucuronidation of AZT. The mechanism of inhibition was competitive for seven compounds tested. K i , values were estimated from Dixon plots for nine other less soluble inhibitors; their mechanism of inhibition was assumed to be competitive. Since the peak physiological drug concentrations of the tested inhibitors are considerably less than their K i values, none of these compounds are expected to strongly inhibit AZT glucuronidation in humans. However, the rank order of these drugs with respect to their inhibitory potential is probenecid > chrloramphenicol > naproxen > phenylbutazone > other drugs tested.

GT-2331 [(+)-1] is one of the most potent members of a class of chiral drug substances used to regulate the synthesis and release of histamine by the histamine H3 receptor, and as such, is an important biomarker for pharmaceutical companies conducting research in this field. In addition to overall structural features, the bioactivity of this molecule has also been found to be highly dependent on absolute stereochemistry, making the reliable assignment of this property a necessity. X-ray diffraction studies have provided conflicting data, leaving its three-dimensional structure uncertain. In view of this, its absolute configuration was investigated by vibrational circular dichroism. Results from this study provided independent assignment of this important molecule as the (1S,2S)-enantiomer. Chirality, 2007. © 2007 Wiley-Liss, Inc.

2-(Anilinomethyl)imidazolines with 2'-esters or 2'-amides are potent agonists of the cloned human alpha(1)-adrenoceptors in vitro. The size and shape of the ortho substituent can have significant effects on the potency, efficacy, and subtype selectivity of these 2-(anilinomethyl)imidazolines. alpha(1A)-subtype selective agonists have been identified.

A series of phthalimide and isoindolinone derivatives bridged to 4-(1,2-benzisothiazol-3-yl)-1-piperazinyl was prepared. The compounds were evaluated in vitro at dopamine D2 and serotonin 5-HT1a and 5-HT2 receptors and in vivo for their ability to antagonize the apomorphine-induced climbing response in mice. The effects of bridge length and conformation on the biological activity of these potential antipsychotic agents are discussed. A four-carbon spacer provided optimal activity within the two homologous series. Conformational investigations of the lead compound, isoindolinone 2, were conducted in an attempt to account for the superior activity observed for the butyl derivatives. On the basis of NMR and molecular modeling studies, two types of folded structures were proposed and several conformationally restrained analogues were synthesized. In general, restrictions incorporated within the linking bridge were detrimental to activity.

The binding of two isomeric 2-[(chysenylmethyl)amino]-2-methyl- 1 ,3-propanediols (AMAPs) to the biopolymer poly(dG-dC)"poly(dG-dC) was studied using Raman spectroscopy. The Raman spectra of the bound AMAPs were obtained by subtracting the Raman spectrum of the biopolymer in buffered aqueous solution from those recorded for the AMAP-DNA binary complexes. The difference method applied here has been used in other studies to obtain spectra of small molecules bound to macromolecules of biological origin (Yue, K.T. et al., J. Raman Spectrosc., 20, 541-545, 1989, and references therein). Due to the extremely low number of Raman active lines observed in the spectra of these AMAPs, it was also possible to study perturbations in the Raman spectrum of the complexed biopolymer. Spectroscopic data indicated that both AMAPs intercalate with DNA, in agreement with viscometric measurements for these compounds; however, some differences were observed in the Raman spectra of DNA complexed with these drugs, suggesting that the specific AMAP-DNA binding interactions are different.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

While incorporating oxazoles into known PPARy agonist an unexpected 6,5,6-tricylic lactam was isolated as the major product.

Reversed-phase high-performance liquid chromatography (HPLC) was used to measure the lipophilicities of a series of biphenyl acids and their non-acid precursors. Values obtained by HPLC for the precursors were as predicted from the calculated lipophilicity values. For biphenyl acids, a systematic deviation in the correlation of calculated log P and log k′ was observed (hydrogen-bond acceptors and non-hydrogen-bonding substituents described two separate lines in the correlaton). An explanation of these results is presented, based on steric effects which control the way the biphenhyl acids interact with the stationary phase.

Capacity ratios (k') for a set of small organic compounds of miscellaneous structure were measured under a variety of reversed-phase liquid chromatoghraphic conditions. The capacity ratios from these experiments were correlated with the binding of these solutes to bovine serum albumin (BSA). Hydrophobic binding of small molecules to BSA is considered to be a nonspecific process (i.e., requiring no special orientation or restriction of movement of the solute molecules) and serves as a model for the hydrophobic binding of small molecules to other macromolecules, such as hemoglobin and ribonuclease. Standard deviations from these correlations were compared using the null hypothesis to determine the set of chromatographic conditions giving the best correlation with the binding constants. The null hypothesis was again applied to compare the correlation of the best chromatographic data with binding to the correlation of the binding data with the octanol-water partition coefficients of these compounds. ...

The development of a method for determining hydrophobicity constants for small, organic molecules by reversed-phase liquid chromatography (RPLC) is presented. The method uses capacity ratios measured at a number of different compositions of methanol to obtain derived values, denoted log k'w, upon which a new scale of hydrophobicity constants can be developed. This scale eliminates potential problems such as peak inversion that hamper RPLC methods using isocratic data to estimate hydrophobicity. The differential hydrogen bond effect observed in most correlations of RPLC data with logarithms of octanol-water partition coefficients (log Po/w) for compounds of opposite net hydrogen bonding capabilities (noncongeners) was minimized by adding trace quantities of n-decylamine and 1-octanol to the eluent and using an octyl-modified silica gel stationary phase. Values of log k'w are shown to be largely column-independent as long as the hydrophobic properties of columns are similar. The correlation of log k'w values with the logarithms of bovine serum albumin binding constants (log 1/C) is shown to be statistically indistinguishable from the correlation of log 1/C with log Po/w, indicating that this data models log 1/C as well as log Po/w for these compounds. Additionally, the chromatographic system is automatable and thus capable of higher sample throughput than measurements of log Po/w by the shake-flask method.

A highly deactivated octadecyl-bonded silica column and a mobile phase consisting of an water-methanol mixture in the range of blood pH and ionic strength are used to correlate log kappa' with biological activity for a series of sulfonamides and barbiturates. The results were compared to literature methods by using retention volume (VR) and retention indexes (I). For the nine sulfonamides tested, log VR and log kappa' were used with and without correction for ionization. For each biological end point (protein binding and minimum inhibitor concentration against Eschericia coli from two sources) and each independent variable (log kappa' and log VR) the residual standard derivation for the regression was determined. the standard derivations were compared in an F test for each of 12 relevant regressions. Log kappa' was statistically superior in for cases, while log VR was superior in one case. Overall, the methods were statistically indistinguishable. Log kappa' values and I values for 15 barbiturates were regressed against three biological end points [hypnotic activity (the minimum effective dose in rabbits), inhibition of Arbacia egg cell division, and inhibition of rat brain respiration]. Standard deviations were compared by an F test, and the two methods were indistinguishable as far as the goodness of biological correlations are concerned. Procedures for controlling the column's activity are presented. Choices for an appropriate mobile phase are discussed, and a method of calculating pH and ionic strength in a methanol-aqueous mobile phase is presented.

The dynamic range of a polycratic reversed-phase liquid chromatographic (RPLC) method for measuring hydrophobicity constants (log k ′ w ) for non-ionic, organic molecules was examined. Evidence is presented that indicates that the differential hydrogen bonding effect present in most RPLC methods has been minimized by selection of appropriate stationary and mobile phase conditions. Thus, values of log k ′ w determined for compounds of different net hydrogen bonding properties (non-congeners) can be compared directly. Results indicate that noncongeners congeners with hydrophobicities varying between −0.20 ≤ log k ′ w ≤ 5.27 can be measured by this procedure. Additionally, the net hydrogen bonding property of any solute molecule can be predicted from the chromatographic experiment. Finally, the suppression of hydrogen-bonding discrimination effects in this method is shown to be a result of the low levels of octanol and alkylamine added to the mobile phase.

Technical report: Presented is a methodology that was developed for quick determination of phenol, cresol, and zylenol concentrations in coal gasifier condensates. Application of the methodology is outlined. Blinds analysis was used to validate the methodology. In the method, condensate is monitored by ultraviolet absorbance at 215 nm. (11 references, 2 tables)

A highly deactivated octadecyl-bonded silica column and a mobile phase consisting of an water-methanol mixture in the range of blood pH and ionic strength are used to correlate log kappa' with biological activity for a series of sulfonamides and barbiturates. The results were compared to literature methods by using retention volume (VR) and retention indexes (I). For the nine sulfonamides tested, log VR and log kappa' were used with and without correction for ionization. For each biological end point (protein binding and minimum inhibitor concentration against Eschericia coli from two sources) and each independent variable (log kappa' and log VR) the residual standard derivation for the regression was determined. the standard derivations were compared in an F test for each of 12 relevant regressions. Log kappa' was statistically superior in for cases, while log VR was superior in one case. Overall, the methods were statistically indistinguishable. Log kappa' values and I values for 15 barbiturates were regressed against three biological end points [hypnotic activity (the minimum effective dose in rabbits), inhibition of Arbacia egg cell division, and inhibition of rat brain respiration]. Standard deviations were compared by an F test, and the two methods were indistinguishable as far as the goodness of biological correlations are concerned. Procedures for controlling the column's activity are presented. Choices for an appropriate mobile phase are discussed, and a method of calculating pH and ionic strength in a methanol-aqueous mobile phase is presented.