Thiocarbamates reactions

Reaction wifli Salts and Esters of Thiocarbamic Acid 2-Hydroxythiazoles and Derivatives... 

The reaction is carried out at low temperature in aqueous medium and then allowed to stand overnight (221). Ammonium thiocarbamate is prepared from a cold saturated solution of ammonium thiocyanate, which is gradually added to dilute sulfuric acid at 25°C. The liberated carbonyl sulfide is passed into a saturated solution of alcoholic ammonia at about 10°C (221). The fairly low yield indicates that the reaction has not been greatly developed. 

Similarly, thioalcohols and thiophenols react with isocyanates to form thiocarbamates. Although these reactions are generally found to be much slower than that of the corresponding alcohol, alkoxide catalysts have successfully been used to provide moderate levels of rate enhancement (68). 

Uses. There may be some captive use of carbonyl sulfide for production of certain thiocarbamate herbicides (qv). One patent (38) describes the reaction of diethylamine with carbonyl sulfide to form a thiocarbamate salt which is then alkylated with 4-chloroben2yl haUde to produce 3 -(4-chloroben2yl) A[,A/-diethylthiocarbamate [28249-77-6] ie, benthiocarb [28249-77-6]. Carbonyl sulfide is also reported to be useful for the preparation of abphatic polyureas. In these preparations, potassium thiocyanate and sulfuric acid are used to first generate carbonyl sulfide, COS, which then reacts with a diamine ... 

Thiocarbamates, formed by reaction of a thiol with an isocyanate, are stable in acidic and neutral solutions and are readily cleaved by basic hydrolysis. The... 

Reaction of equimolar amounts of the thiocarbamate (91) with (chlorocarbonyl)sulphenyl chloride gave l,2,4-dithiazoline-5-one (92) and the 1,2,4-thiadiazole (93) the relative amounts of (92) and (93) being very dependent on the solvent used in the reaction. The mechanism of formation of both (92) and (93) was discussed <96JOC6639>. 

Because of the higher reaction rate, 7V(3)-alkylimidazolium-A ( 1 )-carboxylates or thiocarboxylates have often been used for the synthesis of carbamates and thiocarbamates by the azolide method instead of imidazole-iV-carboxylates. 

The synthesis was carried out as a one-pot reaction in ethyl acetate. The result is actually surprising, since there are three hydroxy groups in the educt, any of which might in principle react with the imidazolide. Probably the 6/J-OH- and the 9a-OH groups are more sterically hindered than the 7/J-OH group. With ImCSIm in the presence of methylamine the corresponding thiocarbamate was obtained in 15% yield. 

Analogous to this reaction, thiocarbamates have been prepared using ImCSIm, which is generated in situ from two equivalents of imidazole, CS2, sodium hydride, and one equivalent of a thiazolium salt 2163 ... 

It is claimed that this reaction proceeds via a 2, 3 -thionocarbonate or a thiocarbamate derivative. If the 5 -OH group of uridine was not protected, the yield of the 2,2 -anhydro-l-(j -D-arabinofuranosyl)uracil was low. 

Thiocarbamate (tc, RHNCSO-) is a monodentate ambidentate ligand, and both oxygen- and sulfur-bonded forms are known for the simple pentaamminecobalt(III) complexes. These undergo redox reactions with chromium(II) ion in water via attack at the remote O or S atom of the S- and O-bound isomers respectively, with a structural trans effect suggested to direct the facile electron transfer in the former.1045 A cobalt-promoted synthesis utilizing the residual nucleophilicity of the coordinated hydroxide in [Co(NH3)5(OH)]2+ in reaction with MeNCS in (MeO)3PO solvent leads to the O-bonded monothiocarbamate, which isomerizes by an intramolecular mechanism to the S-bound isomer in water.1046... 

Zinc carbamate complexes are well known, and the structural types and stabilities can be compared with thiocarbamates and dithiocarbamates which are discussed in Sections 6.8.11.1.3 and 6.8.7.1.4482 Carbamates of zinc can be formed from the reaction of carbon dioxide with alkylzinc alkyl amides and further reaction with alkylzinc can give a distorted cubane structure.483 The tetrameric diethylcarbamate species initially formed can also be used to produce monomeric or dimeric carbamate structures in reaction with amines tetramethylethylenediamine forms a monomer [(Me2NCH2)2Zn(02CN(C2H5)2)2] with an octahedral zinc center and pyridine forms a dimer[CsH5NZn2Me(02CN(C2H5)2)3] with tetrahedral zinc centers.484... 

The preparation and reactions of V-thiocarbonyl carbohydrate derivatives, such as sugar isothiocyanates, thioamides, thioureas, thiocarbamates and their conjugates have been the subject of valuable comprehensive as well as specialized accounts, which should be consulted for details.198... 

Metal complexes, dialkyl thiophosphates and dialkyl thiocarbamates of Zn, Ni, Ba, and Ca, in particular, are widely used for the stabilization of lubricants [30-32,34]. At moderate temperatures (350 400 K), these inhibitors are less efficient than phenols, but they are more potent at higher temperatures (430 480 K). The sophisticated mechanism of action of these antioxidants involves their reactions with hydroperoxide. The interaction of hydroperoxide with metal dialkyl thiophosphates induces a cascade of reactions [5,66-69],... 

Rate Constants of Reactions of Metal Thiophosphates and Metal Thiocarbamates with Cumylhydroperoxide (Experimental Data)... 

Rate Constants of Reactions of Peroxyl Radicals with Metal Thiocarbamates and Thiophosphates in Hydrocarbon Solutions (Experimental Data)—continued... 

Organoaluminum reagents have been used in the copper-catalyzed conjugate addition to enones with some success. Iwata and co-workers (182) demonstrated that dimethoxyphenyl oxazoline (247) provides modest selectivities in the copper-catalyzed conjugate addition of trimethylaluminum to 3,4,4-trimethylcyclohexadi-enone to provide the adduct in 68% ee, Eq. 145. The use of TBSOTf is crucial to attain high conversion and selectivity in this process. Woodward and co-workers (183) subsequently reported that a Cu(I) complex of thiocarbamate 248 provides modest facial discrimination in the addition of trimethylaluminum to a linear enone to afford 245b in 51% ee, Eq. 146. The authors note that this catalyst system decomposes under the reaction conditions at ambient temperature. 

Haloarene chromium tricarbonyl complexes are activated to nucleophilic attack by thiolate anions [58, 59]. High yields of the thioethers are obtained under liquiddiquid two-phase conditions, but optimum yields are achieved under soliddiquid conditions. In many cases the thioether is produced directly but, where the reaction mixture contains thioether and its chromium complex, the thioether can be isolated by degradation of the complex with iodine or an excess of the thiol. Both 1,2- and 1,4-dichlorobenzenes yield only monothioethers, even when an excess of thiolate anion is used. In contrast, 1,3-dichlorobenzenes produce a mixture of the mono- and dithioethers [59]. Aryl allyl thioethers have been produced under catalysed Heck reaction conditions from S-allyl thiocarbamates and iodobenzene [60]. 

When thiocarbamate 3b was irradiated in a benzene solution, thiolactone 5b was isolated in 90% yield (entry 4). The solid-state photolysis also gave thiolactone 5b in 85% yield when the reaction conversion was 78% (entry 4). 

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