Dithiocarboxylic acids thioacylation

Thioacylation reactions with dithiocarboxylic acids are not limited to amines, but, employing the Mg salt, can also be carried out with hydroxylamine to give thiohydroxamic acids or with hydrazine and some substituted hydrazines to provide thiohydrazides. ... 

Thioacyl chlorides, RCSCl, are powerful thioacylating agents as is obvious from the quantitative thiobenzoylation of the only moderately nucleophilic nitrogen in thiocarbamate (13 equation 5). However, severe limitations are the difficult accessibility of thioacyl chlorides and their thermal lability. Even if they are prepared from dithiocarboxylic acids using an improved procedure, only thioaroyl chlorides, particularly PhCSCl (12), can be handled sufficiently easily to be used in synthetic work. Thus, various azoles react with (12) to furnish /V-thiobenzoyl azolides (14) in the presence of excess azole or NEts (equation 6) a particularly clean and fast reaction is achieved if IV-silylated azoles are employed. However, considering the fact that the chloride has to be prepared from the dithiocarboxylic acid, the approach of equation (4) presents a shortcut to the products. 

Thiols can also be thioacylated, in the same way as alcohols (Section 2.5.3.2), by reaction with bis-thioacyl thioanhydrides (equation 58). The preparation of aromatic as well as aliphatic thioanhydrides is possible according to novel procedures described by Kato et a/., e.g. from the corresponding dithiocarboxylic acids and DCC or 2-chloro-N-methylpyridinium iodide.Even sterically hindered di-thioesters are obtained (equation 58). ... 

In general, thiocarbonyl halides (59) function as thioacylation reagents with a variety of nucleophiles to yield the appropriate thio derivatives (60) (Scheme 31). For example, (59) on condensation with thiols, amines, potassium cyanide or potassium thiocyanide yields the corresponding thio compounds (60). Thiolocarboxylic acids (50) characteristically acylate alcohols and amines with desulfuration (Scheme 32). Dithiocarboxylic acid esters (54b) react with organolithium or Grignard reagents to give the dithioketals (61) after treatment with an alkyl halide (Scheme 33). 

In 1994, successful isolations of various alkyl and aryl selenocarboxylic acids [14] enabled them to undergo exact reactions. Reactions of selenocarboxylic acids with dicyclohexylcarbodiimide (DCC) yield the corresponding diacyl selenides 25 and selenourea 26 quantitatively (Scheme 15) [14], as in reactions of thio- [44] and dithiocarboxylic acids [45,46]. In air,selenocarboxylic acids are immediately oxidized to afford the corresponding diacyl diselenides [13, 14]. Also, thio- and dithio-carboxylic acids readily react with aryl isocyanates to give acyl carbamoyl [47,48] and thioacyl carbamoyl sulfides [49, 50], respectively. 

Many dithiocarboxylate compounds of sulfur have been reported. Bis(thioacyl) disulfides 100, dimers of dithiocarboxylate ligands, are easily synthesized by oxidative dimerization of the corresponding dithiocarboxylic acids (Scheme 26) [151-154]. Their reactivities toward cycloaddition reactions and S-S bond cleavage have been investigated [155-157]. Bis(thioacyl) trisulfides 101 and tetrasulfides 102 are also prepared by treating the dithiocarboxylic acid with SCI2 and S2CI2, respectively [135]. 

Sulfonic acid chloride Thioacyl disulfides from dithiocarboxylic acids... 

The 5-substituted 1,2,3,4-thiatriazoles 758 are prepared by the generation of intermediate azidothiocarbonyl compounds 757 followed by 1,5-electrocyclic reaction (Scheme 326). The intermediate compounds 757 have never been isolated they can be generated by treatment of derivatives of thiohydrazides 756 with either nitrous acid or with arenediazonium salts, and in reactions of thiophosgene (or dithiocarboxylates) 755 (X = Cl, SR) with either sodium- or trimethylsilyl azide (Scheme 326) . For example, thiatriazoles 760 can be prepared in high yields by the reaction of or A-thioacyl dithiophosphates 759 with sodium azide (Scheme 327) <2002J(P1)1271>. 

Thioamide synthesis from dithiocarboxylates and amines under basic conditions gives thiols as rather unpleasant parallel products. This problem is avoided by using S-thioacylated thioglycolic acids (17), as... 

The utility of various thioxo- and dithio-carboxylic anhydrides was recently reviewed by Martin and Bamikow, who pointed out that bisthioacylthioanhydrides and the mixed anhydrides of thiocarbox-ylic and diphenyldithiophosphinic acids are effective thioacylating agents for alcohols (equation 46), whereas carboxylic dithiocarboxylic anhydrides transfer an acyl group to a nucleophile. 

Sulphur and Selenium Compounds.— Nitroaryl-sulphonic acids (196) have been made by oxidative treatment of aminoaryl-sulphonic acids (197) with peracetic acid, while the useful acyl thioacyl sulphides (198) have been formed by the reaction of Na or piperidinium dithiocarboxylates (199) with acetyl chloride. 

The thioacylation of NH groups by dithiocarboxylic esters and their salts, as well as by thionocarboxylic esters, is dealt with in Section 5 of this chapter. Diphenylcyclopropenethione reacts with amines to give the cycloadducts (91), which are rearranged to the thioamides (92) when heated in benzene. Thioamides RNHC(S)CHXY are obtained from compounds with active methylene groups by reaction with A-aryldithiocarbamic acid esters, e.g. MeSC(S)NHPh, thiocarbamoyl chlorides, or C-sulphonylthioformamides,... 

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