119174-33-3

Thiol-ene and thiol-yne photomediated conjugations have received substantial attention in research and in practice. Herein is presented the photodisulfidation of alkenes based on the radical-mediated 1:1 reaction of a disulfide and a vinyl ether, which provides an additional route for the formation of the types of sulfides seen in thiol-ene and thiol-yne polymers. Although similar linkages are formed, this approach starting with disulfides is expected to have benefits over the thiol-ene and thiol-yne reactions including extended shelf life of disulfides compared to thiols, reduced shrinkage stress, and increased refractive index of the resulting materials. It was determined that vinyl ethers were the only alkenes capable of undergoing photodisulfidation under ambient conditions and in reasonable timescales. The reaction between vinyl ethers and disulfides performed well in a variety of solvents providing modest to excellent yields (100% for bis(1-methylacetate) disulfide (DSMA)/triethyleneglycol divinylether (TEGDVE)) for numerous disulfide substrates evaluated. It was determined that the mechanism of the photodisulfidation reaction involves an auto-propagating cycle of thiyl radicals which add into either end of a vinyl ether to form thio-ether and thio-acetal linkages in the final product. Finally, although the reaction rate is slower than that of the thiol-ene reaction, the photodisulfidation reaction proceeds relatively rapidly under the explored conditions.

Homotaurine and a series of 1-substituted homotaurines were readily synthesized in satisfactory to good yields via the Michael addition of thioacetic acid to aliphatic and aromatic α,β-unsaturated nitriles followed by lithium aluminum hydride mediated reduction and performic acid oxidation. The synthesis of 1,1-disubstituted homotaurines was attempted with β,β-disubstituted acrylonitriles as starting materials but failed due to steric hindrance. The current process is an efficient method for the synthesis of 1-substituted homotaurines. Georg Thieme Verlag Stuttgart New York.

Compounds of formula (I) and their pharmaceutically acceptable salts are provided as well as processes for the manufacture of such compounds. The compounds are useful in the treatment or prevention of inflammatory and allergic diseases.

The potency and selectivity of a series of 5-hetero-2-iminohexahydroazepines were examined as inhibitors of the three human NOS isoforms. The effect of ring substitution of the 5-carbon for a heteroatom is presented. Potencies (IC50's) for these inhibitors are in the low micromolar range for hi-NOS with some examples exhibiting a 500× selectivity versus hec-NOS.

The conversion of a wide variety of halides to thioesters by reaction with potassium thiocetate under mild conditions is described, and the generality of the method is demonstrated.

In an effort to obtain a more potent and specific immunotoxin for cancer therapy, we designed a series of heterobifunctional linkers characterized by a thioimidate group linked to a S-acetyl thiol (4, 5) or substituted aryldithio group (6-10). These ligands were synthesized by a Pinner-type process from the corresponding nitrile derivatives obtained by thiol- disulphide exchange reaction, reaction with substituted benzene-sulphenyl chloride, or other known procedures. To check the reagent of choice for immunoconjugate preparation, we studied thioldisulphide exchange kinetics between the intermediate nitrile derivatives and cysteine. Among the tested aryldithio derivatives (6-10), we selected ethyl 3-(4-carboxamido- phenyldithio)propionthioimidate (CDPT, 9) for further studies. By analyzing the rate of incorporation of the linkers 4, 5, and 9 in a model immunoglobulin G protein, we found similar results with CDPT 9 and ethyl S- acetyl 3-mercaptopropionthioimidate ester hydrochloride (AMPT, 5) because both reagents showed a linear correlation between the number of introduced thiol groups and factors such as time and protein and reagent concentrations. Comparison of the two acetylthio-derivative ligands 4 and 5 showed that AMPT 5 was more stable toward deacetylation than ethyl S-acetyl 2- mercaptopropionthioimidate ester hydrochloride (AMAT, 4). By comparing the kinetic and biological parameters of seven new thioimidate linkers, we found that two of these (CDPT and AMPT) could be superior ligands for protein- protein conjugation. They offer advantages over the commercially available compounds, such as minimal perturbation of the protein structure, controlled reactivity, and good stability.

The addition reactions of thiol anions to form adducts with acrylonitrile (1), 1-chloroacrylonitrile (2), and fumaronitrile (3) and the corresponding elimination reactions were examined in aqueous solution, generally containing 8.3percent Me2SO at 25 deg C.Deuterium exchange into the methanethiol and thiosalicylate adducts of 1 is faster than elimination.Deuterium exchange causes biphasic kinetics for elimination reactions in D2O of the p-nitrothiophenol, but not of the pentafluorothiophenol, adducts 1 and 2.The kinetic solvent deuterium isotope effects of knHOH/knDOD = 2.0 for addition of thiosalicylate to form 3 and 1.1-1.2 for addition of β-mercaptoethanol and thioacetic acid anions to form 1 are smaller than the product discrimination isotope effects of kH/kD = 3.2, 2.8 and 3.2 for these reactions.These differences show that the reactions proceed through a carbanion intermediate that is protonated faster than it expels basic thiol anions.These results exclude a concerted mechanism for addition-elimination with a concurrent, separate exchange reaction.The solvent kinetic deuterium isotope effect is 3.9 for the addition of thionitrobenzoate dianion to form 3.Buffer catalysis of elimination becomes more significant with more acidic leaving groups and is larger for 3 than for 1 with a given leaving group.The results show that the rate-limiting step changes from addition-elimination of the thiol anion to proton transfer with decreasing pKa of the thiol; the same change is favored by addition of CN to the α-position for a given thiol.The effect of the α-CN group is attributed to conjugation with the developing double bond in the transition state for elimination.The Broensted slope is β = 0.90 for rate-limiting deprotonation of the pentafluorothiophenol adduct 3 and Broensted-type plots against the pKa of the leaving group have slopes of β1g = -0.25 and -0.54 for predominantly rate-limiting deprotonation and leaving group expulsion, respectively.