Isothiocyanates dithiocarbamate synthesis

Similar results can be achieved by using cyanothioformamides <2002HAC291, 2002HAC611> or dithiocarbamates 861 <2005BML1877> instead of isothiocyanates, as shown by the synthesis of 2-phenyl-2-thioxo-4-quinazolinone 863 <2005BML1877>. Once again the intermediate thiourea 862 is not isolated. 

B ) facilitates removal of the imidic proton (Scheme 26). An analogous synthesis of isothiocyanates involves the action of phosgene (46) on ammonium dithiocarbamates the probable mechanism of the reaction is shown in Scheme 27. 

Even though the most widely used preparation is still the reaction of alkali isothiocyanates or alkyl and aryl isothiocyanates with a-amino carboxylic acid derivatives, the reaction of dithiocarbamic acid esters (CCX) with a-amino carboxylic acids (CCXI) has certain advantages especially in the synthesis of heterocyclically substituted imidazolidin-4-one-2-thiones (221). 

Recent examples of the application of isothiocyanates in the synthesis of dithiocarbamates include the synthesis of butyl diphenylphosphinyldithio-carbamate by the reaction of diphenylphosphinyl isothiocyanate with sodium butylmercaptide, the synthesis of methyl diethoxyphosphinyldi-thiocarbamate by the successive treatment of diethylphosphoryl isothiocyanate with hydrogen sulphide anions and methyl iodide, and the reaction between phenyl isothiocyanate and butyl dibutylthioboronite to afford the 1 1 adduct (321), which on hydrolysis is converted into butyl iV-phenyl-dithiocarbamate. The action of hydrogen sulphide on l,4-dicyanato-2,5-... 

A facile synthesis of 2,3,5-tri-O-acetyl-p-D-ribofuranosyl isothiocyanate fiom the corresponding ribosyl chloride has been detailed. 2,3,4,6-Tetia-D-acetyl- 3-D-glucopyianosyl isothiocyanate continues to be a popular reagent for preparing diastereomeric thiourea or dithiocarbamate derivatives in the reversed-phase resolution of enantiomeric amine- or thiol-... 

Synthesis.—A standard method for the preparation of G-alkyl thiocarba-mates and S-alkyl dithiocarbamates depends on the reaction of isothiocyanates with alcohols and thiols, respectively, and several new examples of its applicability have appeared during the past two years (refs. 132, 252, 634, and 635). In special cases the products, either spontaneously or promoted by a catalyst present, underwent a subsequent ring-closure reaction to form heterocycles containing the thionocarbamate or the dithiocarbamate moiety. Phenols and thiophenols reacted with isothiocyanates in a similar way. Some Oethyl selenonocarbamates have been obtained in good yields by ethanolysis of isoselenocyanates, and Mayer and his co-workers have reported on the successful synthesis of the heterocyclic... 

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