Reduced 4-thio

Experiments made with yeast that had been killed by boiling showed that even in the presence of sugar such yeast is unable to reduce thio-acetaldehyde to ethyl mercaptan. 

When Rudolph and Fromm used thionicotinamide adenine dinucleotide (thio-DPN) as an alternate substrate for NAD+ and varied the concentration of ethanol with liver alcohol dehydrogenase [following the reaction at 342 nm, the isosbes-tic point for thio-DPN and reduced thio-DPN (thio-DPNH)], they saw what appeared to be concave upward reciprocal plots with partial substrate inhibition in the presence of thio-DPN (38). However, the asymptote intercepts appeared to decrease with increased thio-DPN concentration, which is not what the above equations predict for a case where a minimum is present in the curve. There must have been other interactions that caused the substrate inhibition by ethanol in the presence of thio-DPN. 

The solution was then heated at reflux for A hour, cooled to 70°C and 4-methylpentan-2-one (2 liters) added. The water was removed by azeotropic distillation under reduced pressure (260 torrs) and the resultant solution treated with charcoal (10 g) at 50°C. The solution was filtered and cooled to 10°C. N-[2-[ [ [5-dimethylamino)methyl-2-furanyl] methyl] thio] ethyl] -N -methyl-2-nitro-1,1 -ethenediamine (380 g) was filtered off and dried, melting point 69°C to 70°C. 

Carbonyl compounds, such as aldehydes [103, 179], (thio)ketones [31, 94, 180-183], carboxylic acids, and esters [183, 184] with 1 are reduced to alcohols after hydrolysis [5], except in stericaUy hindered cases (see Section 8.5) [185, 186]. Under the same experimental conditions the regioselective reduction of the oxirane ring with 1 gives also the corresponding alcohol [183, 187]. 

Et3SiH/TFA reduces disulfides to the corresponding mercaptans in modest yields (Eq. 340).564 Naphthyl thio ethers are reduced in rather poor yields to tetrahydronaphthalene with the combination EtjSiH/HF -OfE (Eq. 341).263 There is one report of the reduction of a diaryl sulfide to the hydrocarbon but the yield... 

The 5-methoxy seems less critical its replacement by methylthio or ethylthio groups, especially in 3,4,5-substituted compounds, has recently been explored by Jacob and Shulgin (116). Activity in this series is not reduced. Recently, the authors (117) prepared the 2- and 5-thio isosteres of DOM and DOET. With a 2-thiomethyl, activity was retained but was attenuated to about 1/20 to 1/25 of the oxygen isosteres. The 5-thiomethyl isomers possessed two to four times the activity of the thiomethyls at the 2-position. When both the 2- and 5-methoxys were replaced by thiomethyl groups, activity was essentially abolished. 

Even if the extraction of FeMoco in nmf slightly modifies the outer coordination of the MoFe7S9 cluster, in agreement with the experimental observation that the FeMo-protein can exist in the oxidized, semi-reduced and reduced forms, it exhibits two successive one-electron reductions (E st = -0.32 V and is d = -1.00 V,vj. NHE). In the absence of thio-phenol, the first reduction appears to be complicated by self-oxidation processes, whereas the presence of thiophenol apparently stabilizes the different oxidation states. 

NaSH-xH20 (0.532 g, 9.5 mmol) was added to a solution of 5-chloro-d-xylulose (0.8 g, 4.75 mmol) in distilled water (70 mL). The solution was shaken at room temperature for 3 h and kept at 4 °C overnight. The solvents were removed under reduced pressure and the crude product was purified by flash column chromatography on silica gel. 5-Thio-o-xylulofuranose was eluted with 8/2 CH2Cl2/MeOH in 61 % yield (0.48 g, 2.9 mmol) starting from 5-chloro-D-xylulose. 

Alkylation of ll-mercaptopyrido[l,2-h]cinnolin-6-ium hydroxide inner salts (e.g., 41) with ethyl bromoacetate gave ll-(ethoxycarbonylmethyl(thio derivatives 64 (R = H), which could be hydrolyzed to the ll-(carboxy-methyl)thio derivative or back to the starting compound 41 (74JHC125). Hydrolysis of the ll-bis(methoxycarbonyl)methylene 66 (R = H), and 2-cyano derivatives of 17 (R = H) in boiling HCl afforded 11-methyl and 2-carboxylic acid derivatives, respectively (74JHC125). The 2-nitro derivative of 17 (R = H) was reduced to the 2-amino derivative over Pd/C with NaBH4 in aqueous methanol, and the 2-amino group was acylated with acetic anhydride at 100°C. 

Reduced forms of these coenzymes absorb ultraviolet light near 340 nm, whereas the oxidized forms do not. For NAD at neutral pH, the maximal absorbance band (s = 18000 M cm ) occurs at 260 nm another absorbance band (s = 8000 M cm ) occurs at 230 nm. For NADH, the maximal absorbance band (s = 16900 M cm ) occurs at 259 nm a second absorbance band (s = 6220 M cm ) occurs at 339 nm two weaker bands occur at 234 and 290 nm with respective s values of 6600 M cm and 1300 M cm h The same is true for NADP and NADPH at 339 nm. Occasionally, investigators have used thio-NADH which has a much stronger absorbance around 366 nm. See Absorption Spectroscopy (Fig. 4, pg. 5) Nicotinic Acid Analogs and Coenzymes... 

IR spectroscopy has been used to study the structures of urazoles, triazolinones <66T213>, and triazolinethiones <71JCS(C)1016>. A-alkylation reduces the problem of tautomeric structures and early views in favour of the oxo and thio rather than the hydroxyl and thiol forms have been confirmed, although there are exceptions <73CPB1342>. 

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