Isothiocyanates thioamides

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... 

Most reactive metabolites produced by CYP metabolic activation are electrophilic in nature, which means that they can react easily with the nucleophiles present in the protein side chains. Several functional groups are recurrent structural features in M Bis. These groups have been reviewed by Fontana et al. [26] and can be summarized as follows terminal (co or co — 1) acetylenes, olefins, furans and thiophenes, epoxides, dichloro- and trichloroethylenes, secondary amines, benzodioxoles (methylenediox-yphenyl, MDP), conjugated structures, hydrazines, isothiocyanates, thioamides, dithiocarbamates and, in general, Michael acceptors (Scheme 11.1). 

CHEMISTRY AND DEVELOPMENTS OF jV-THIOCARBONYL CARBOHYDRATE DERIVATIVES SUGAR ISOTHIOCYANATES, THIOAMIDES, THIOUREAS, THIOCARBAMATES, AND THEIR CONJUGATES... 

N-Substituted amides can be prepared by direct attack of isocyanates on aromatic rings.The R group may be alkyl or aryl, but if the latter, dimers and trimers are also obtained. Isothiocyanates similarly give thioamides. The reaction has been carried out intramolecularly both with aralkyl isothiocyanates and acyl isothiocyanates.In the latter case, the product is easily hydrolyzable to a dicarboxylic acid this is a way of putting a carboxyl group on a ring ortho to one already there (34 is... 

The oxidation of thioamides 63 with a wide variety of oxidizing agents is a well-employed method for the synthesis of 3,5-disubstituted-l,2,4-thiadiazoles 64 <1982AHC285>. However, this method is limited mainly to arylthioamides. The most common oxidizing agents tend to be halogens, hydrogen peroxide, dimethyl sulfoxide (DMSO), and nitrous acid. Yields from these reactions are variable and depend on the thioamide, oxidant, and conditions used (Equation 19). By-products such as nitriles and isothiocyanates are usually formed. 

Reactions of isothiocyanate with nucleophiles give desired thioamides (Scheme 7). 

Addition of Grignard reagent to isothiocyanates provides secondary thioamides.24... 

Reaction of isothiocyanates with resorcinol derivatives in the presence of boron trifluoride-acetic acid complex for overnight at 0-5 °C affords the corresponding thioamides.25... 

The thiophene synthesis described herein is related to the synthesis in solution reported by Laliberte, and Medawar4 but differs in some aspects from the procedure in homogeneous phase. Laliberte and Medawar succeeded in obtaining aminothio-phenes in a one-pot reaction from acceptor-substituted acetonitriles, isothiocyanates, a-haloketones, and sodium ethoxide. In contrast to their procedure, solid-phase S-alkylation of the intermediate thioamides under basic conditions led to the formation of product mixtures. We obtained pure aminothio-phenes only when conducting the S-alkylation under neutral or slightly acidic conditions. 

A new protocol was developed for the synthesis of A-substituted thioamides, employing arenes and isothiocyanates in 1-butyl-3-methylimidazolium chloro-aluminate IL, [bmim][AlCl4], as a homogenous Lewis acid catalyst and solvent,Scheme 12. 

Phenyl isothiocyanate reacts less readily with alkynyllithium than methyl isothiocyanate. The thioamide from the reaction of CHjC=CLi with PhN=C=S is not easy to obtain in a crystalline state. 

Thiophene can react with isocyanates or isothiocyanates the products are amides or thioamides respectively. Thus with ethoxycarbonyl isocyanate or isothiocyanate the products... 

Thioamides are suitable intermediates for the preparation of amidines, thiazoles, and thiophenes. Thioamides have mainly been prepared on insoluble supports by C-acylation of enamines or C,H-acidic compounds with isothiocyanates (Entries 1-3,... 

Imidothioesters are easily obtained through 5-alkylation of thioamides, and we have noted (see Section 2.8.3) a general preparation of such compounds from isothiocyanates via addition of an organometallic and 5-alkylation. 

A large number of thioamide derivatives have been obtained by Mirek and associates by allowing substituted indolizines to react with an aryl171,172 or aroyl173 isothiocyanate in a refluxing inert solvent. If a diisocyanate or a carbodiimide is used, products such as 109 and 110 are formed.17 ... 

Substituted 2-mercapto-4//-pyrido[l,2-a]pyrimidin-4-ones 121 were prepared by the cyclization of thioamides 120, prepared from 2-pyridyl-isothiocyanate and the appropriate CH acids, in boiling ethanol by the action of sodium ethylate (81CCC2428). 

Acylation reactions can be carried out by the action of acid anhydrides [66, 67], chloroanhydrides [47, 61], isocyanates [68], isothiocyanates [68, 69] and thioamides [70]. It was shown that the reaction of aziridinyl ketone 49 with chloroacetyl chloride 50 in the presence of Et3N [61] leads to the formation of A-acyl derivative 51, whereas the alkylation product was not isolated. 

Similarly, reaction of various alkyllithium reagents on SMA s isothiocyanates is a good way to prepare the corresponding thioamides.264,265... 

Addition of isocyanates and isothiocyanates, followed by hydrolysis, yields amides, thioamides,274-277 or ureides of j8-ketoacids 82 and 83 are examples of typical intermediates in this reaction. 

Addition of a carbanion [39] or an enolate [40, 41] to methyl isothiocyanate provided an entry to a new class of biologically active thioamides, bearing sulfinyl and pyridyl groups, introduced by Rhone-Poulenc-Rorer as cellular potassium channel openers... 

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