Disulfides sodium borohydride

Sodium or potassium hydrogen sulfite reacts with several thiiranes to give disulfides of /3-mercaptosulfonic acid salts (76EGP122086). Potassium thiocyanate in dimethylformamide or aqueous ethanol isomerizes thiiranes (Scheme 84) (72CJC3930). 1,2-Dithiols are obtained by treatment of thiiranes with NaBH2S3 obtained from sodium borohydride and sulfur (73TL1401). 

Ueno and coworkers49 have developed a procedure for the synthesis of chiral sulfinic acids. Treatment of (R)-( + )-23 with disulfide 24 and tributylphosphine in THF gave (S)-( — )-25. Compound 25 was oxidized with potassium permanganate to the sulfone, which was then reduced to the sulfinic acid, (S)-( — )-26, by treatment with sodium borohydride. Conversion of 26 or an analog to an ester would lead to diastereomers. If these epimers could be separated, then they would offer a path to homochiral sulfoxides with stereogenic carbon and sulfur atoms. 

Sodium hydrogen telluride, (NaTeH), prepared in situ from the reaction of tellurium powder with an aqueous ethanol solution of sodium borohydride, is an effective reducing reagent for many functionalities, such as azide, sulfoxide, disulfide, activated C=C bonds, nitroxide, and so forth. Water is a convenient solvent for these transformations.28 A variety of functional groups including aldehydes, ketones, olefins, nitroxides, and azides are also reduced by sodium hypophosphite buffer solution.29... 

Williams and Rastetter also accomplished an elegant synthesis of ( )-hyalodendrin (83) in 1980 [39]. Beginning with the sarcosine anhydride-derived enolic aldehyde 78, silyl protection of the enal enabled alkylation of the glycine center with benzyl bromide and thiolation using LDA and monoclinic sulfur a la Schmidt. After protection of the thiol with methylsulfenyl chloride and deprotection of the silyl ether, the enol was sulfenylated with triphenylmethyl chlorodisulfide to afford bis(disulfide) 82 as a 2 1 mixture of diastereomers favoring the anti isomer. Reduction of the disulfides with sodium borohydride and oxidation with KI3 in pyridine afforded ( )-hyalodendrin (83) in 29 % yield (Scheme 9.4). 

The X-ray crystal structure of 6-chloro-2,3-dihydro-7-methyl-5-methyIene-2//, 3H, 5H- l,4-dithiepin-l,l,4,4-tetraoxide has been published and a short intermolecular contact across an inversion centre noted <00AX(Qel09>. An experimentally direct and efficient approach to 1,3-dithiepins has been reported using 1 qi-alkyldihalides and carbon disulfide and sodium borohydride, to generate the sulfide nucleophile . 

Disulfides can be either reduced to two thiols or desulfurized. The former reaction was achieved in high yields using lithium aluminium hydride [680, 681], lithium triethylborohydride [100] and sodium borohydride [682]. 

Sulfur dioxide also can be reduced by hydrogen, carbon, carbon monoxide, carbon disulfide, certain metals, metal hydrides, and sodium borohydride when heated at high temperatures ... 

Thiacyclols have been extensively investigated since 1968, when Rothe and Steinberger first demonstrated the formation of such compounds [68AG(E)884]. A thiacyclol related to the peptide portion of the ergot alkaloids (50) has been prepared [80JCS(P1)1499]. The disulfide (58) (racemic 2S, 5S, 11R and 2R, 5R, 1 IS) was reduced with sodium borohydride in DMF at 0°C, to give the racemic thiacyclol (59) in good yield. 

Reductive amination of benzaldehyde with (R)-81 provided the corresponding benzyl amine, which was reductively alkylated with formaldehyde to give 82 (Scheme H) " Compound 82 was debenzylated by hydrogenation in the presence of Pearlman s catalyst to afford frovatriptan ((/J)-6). Alternatively, monomethylation of amine (/ )-81 was affected by treatment with carbon disulfide and dicyclohexylcarbodiimide in pyridine to provide isothiocyanate 83, which was reduced with sodium borohydride to give (l )-6. 

Only a few samples exist for this type of ring synthesis. Thus, a straightforward synthesis of dithiepanes and benzodithiepanes, for example, 229 and 66a, was achieved by treatment of a corresponding 1,4-dibromo or diiodo compound with carbon disulfide activated by sodium borohydride (Scheme 67) <20000L1133>. 

The interest in papain increased enormously after the publication by Kimmel and Smith D ] of a modification of the purification procedure of Balls and Lineweaver [5j. This modification permitted the isolation of pure papain from papaya dried latex and was used for many years as the standard method for the production of papain. The crystalline papain of Kimmel and Smith consists of three components active papain, reversibly oxidized papain, and irreversibly oxidized papain. Reversibly oxidized papain can be converted into active papain by reduction of the active-site thiol by low molecular weight thiols [10], sodium borohydride [11], or CN [12]. In active papain, the Cys-25, which is essential far catalytic activity, is present in a reduced form, while in reversibly oxidized papain the Cvs-25 forms a mixed disulfide with cysteine. Drenth et al. reported that in irreversibly oxidized papain the Cys-25 has been oxidized to the sulfuric acid... 

Gallenbeck et al. (25) has summarized the work on reductive alkylation using formaldehyde and sodium borohydride to yield dimethylated proteins. Oxidation and reduction reactions involving thiol and disulfide groups have been discussed by Ryan (13) and Feeney (11). 

REDUCTION, REAGENTS Bis(N-methylpi-perazinyl)aluminum hydride. Borane-Di-methyl sulfide. Borane-Tetrahydrofurane. Borane-Pyridine. n-Butyllithium-Diisobu-tylaluminum hydride. Calcium-Amines. Diisobutylaluminum hydride. 8-Hydroxy-quinolinedihydroboronite. Lithium aluminum hydride. Lithium 9-boratabicy-clo[3.3.1]nonane. Lithium n-butyldiisopro-pylaluminum hydride. Lithium tri-j c-butylborohydride. Lithium triethylborohy-dride. Monochloroalane. Nickel boride. 2-Phenylbenzothiazoline. Potassium 9-(2,3-dimethyl-2-butoxy)-9-boratabicy-clo[3.3.1]nonane. Raney nickel. Sodium bis(2-methoxyethoxy)aluminum hydride. Sodium borohydride. Sodium borohy-dride-Nickel chloride. Sodium borohy-dride-Praeseodymium chloride. So-dium(dimethylamino)borohydride. Sodium hydrogen telluride. Thexyl chloroborane-Dimethyl sulfide. Tri-n-butylphosphine-Diphenyl disulfide. Tri-n-butyltin hydride. Zinc-l,2-Dibromoethane. Zinc borohydride. 

Tosylamination ofalkenes, The reaction of diphenyl disulfide with chloramine-T in acetone gives, in 91% yield, an adduct of the composition (C6HsSSC6H5)(NTs)2 shown to have the structure (1) by virtue of subsequent reactions with alkenes. Thus it reacts with cyclohexene to give (2), which was reduced by sodium borohydride to (3), whose structure was established by an independent synthesis. 

Sodium borohydride reduces disulfides to thiols, which can then be used to reduce nitro groups. Based on the redox properties of 1,2-dithiolane, lipoamide (17) was used for the selective reduction of mono-substituted nitrobenzenes to the corresponding anilines. Lipoamide (17) can also be immobilized on hydrophilic polymers such as polyvinylamine, polyethyleneimine and chitosan. These polymeric reducing catalysts can be recycled and are easy to separate from the reaction mixture. The system has been used to reduce nitroarenes to anilines. ... 

Reduction of 308 with sodium borohydride gives 24% tetraphenylethylene with lithium borohydride, 75% of 2,2-diphenylethanol and 16% of 2,2-diphenylethyl disulfide with di-isobutylaluminum hydride, 39% l,l,3,3-tetraphenyl-2-propanone and 30% of benzophenone. Lithium aluminum hydride gives four products that may be formed by way of cyclopropanone intermediates. ... 

Hydrazones (140) derived from 4-amino-1-methylpiperazine can be reduced by sodium borohydride to l-arylmethylamino-4-methylpiperazine (141) (1708). 1-Methylpiperazine vacuum distilled with formalin gave bis-(l-methylpiperazinyl)-methane, which refluxed with methyl iodide in methanol formed 1,4-dimethyl-piperazine dimethiodide (1709). 1-Methylpiperazine with carbon disulfide in ethanol produced l-dithiocarboxy-4-methylpiperazine, which was reduced by lithium aluminum hydride to 1,4-dimethylpiperazine (1709). 

The mixed disulfide is readily reduced by thiols, such as j3-mercapto-ethanol, or DTT, or by sodium borohydride. 

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