Carbon disulfide isothiocyanates

This type of synthesis, which was investigated by Cook and Heilbron (323) and Takahashi (393, 394) between 1947 and 1953, gives 5-aminothiazoles variously substituted in the 2-position by reacting an aminonitrile with salts and esters of dithioacids, carbon disulfide, carbon oxysulfide, and isothiocyanates under exceptionally mild conditions. 

Chemical Properties The formation of salts with acids is the most characteristic reaction of amines. Since the amines are soluble in organic solvents and the salts are usually not soluble, acidic products can be conveniendy separated by the reaction with an amine, the unshared electron pair on the amine nitrogen acting as proton acceptor. Amines are good nucleophiles reactions of amines at the nitrogen atom have as a first step the formation of a bond with the unshared electron pair of nitrogen, eg, reactions with acid anhydrides, haUdes, and esters, with carbon dioxide or carbon disulfide, and with isocyanic or isothiocyanic acid derivatives. 

The reaction of 3-hydrazinophenanthro[9,10-e][l,2,4]triazine 742 with carbon disulfide, thiourea, phenyl isothiocyanate, urea, and phenyl isocyanate led [77ZN(B)569] to the formation of phenanthro[9,10-e][l,2,4]-triazolo[4,3-/j][l,2,4]triazines 743. Alkylation of 743 in aqueous alkaline... 

The synthesis of 987 from 985 via 986 has been reported (83S759) by reaction of 985 with aryl isothiocyanates under neutral conditions. The reaction of 4-amino-6-anilino[l,2,4]triazine 988 with methyl iodide and then carbon disulfide gave 989 (90MI3, 90MI9). 

Salts of dithiocarbamic acid can be prepared by the addition of primary or secondary amines to carbon disulfide. This reaction is similar to 16-9. Hydrogen sulfide can be eliminated from the product, directly or indirectly, to give isothiocyanates (RNCS). Isothiocyanates can be obtained directly by the reaction of primary amines and CS2 in pyridine in the presence of DCC. ° In the presence of diphenyl phosphite and pyridine, primary amines add to CO2 and to CS2 to give, respectively, symmetrically substituted ureas and thioureas ... 

Biphilicylides 117 can enter in cyclocondensations with carboxylic acid chlorides, carbon disulfide, and acyl isothiocyanates [126]. Certain corresponding heterocychc products 118 obtained are described for the first time (Y =N(CO)Ph Y=S) and are precursors of the new l-(2-phenylthiazol-5-yl)-5-phenyltetrazole 119 (Scheme 33). 

ZHANG Y, WADE K L, PRESTERA T and TALALAY p (1996) Quantitative determination of isothiocyanates, dithiocarbamates, carbon disulfide, and related thiocarbonyl compounds by cyclocondensation with 1,2-benzenedithioT, Anal Biochem, 239 160-67. 

Corriu et al. also described an alternative synthetic method for internally coordinated silanethiones starting from the pentacoordinated diaminosilanes.28 As shown in Scheme 9, the pentacoordinated diaminosilanes 32 are allowed to react with sulfur-containing heterocumulenes such as carbon disulfide or phenyl isothiocyanate to give the corresponding insertion products 33, which undergo thermal decomposition to produce the corresponding silanethiones 31, 34, and 35.28... 

The thiadiazolopyrimidine derivative 39 reacts with ethoxycarbonyl isothiocyanate and carbon disulfide. In the former case the bicyclic derivative 40 is formed, and with the latter reagent the pyrimido dithiazole 41 is formed (Scheme 4) <2004JHC99>. 

Amidines and cyclic amidines are also converted into 1,2,4-thiadiazoles by reaction with isothiocyanates, imino-sulfenyl chlorides, di- and trichloromethyl sulfenyl chlorides, and carbon disulfide in the presence of sulfur. Ureas, thioureas, guanidines, carbodiimides, and cyanimides react with chlorocarbonylsulfenyl chloride to produce 1,2,4-thiadiazol-5-one derivatives in another example of a type B synthesis <1996CHEC-II(4)307>. 

Amidrazones react with carbon disulfide or isothiocyanates to give W-imidoylthiohydrazide intermediates that can be isolated and cyclized to afford 1,3,4-thiadiazoles (see Section 5.10.9.1.1). In some cases, the W-imidoylthiohydrazides are not isolated prior to cyclization and l,3,4-thiadiazol-2-thiols or 2-thiones are formed directly (e.g., Equation 55) <2004CHE1185>. 

The synthesis of thioureas has been accomplished in several manners by using isothiocyanate, carbon disulfide, hydrogen sulfide and KSCN (potassium thiocyanate). 

Carbon disulfide, the all sulfur equivalent of isothiocyanates, was found to react with benzimidazole 127 very rapidly under microwave irradiation to produce 128 <00TL5857>. 

Itoh and co-workers reported the ruthenium(n)-catalyzed [2 + 2 + 2]-cycloaddition of 1,6-diynes with isocyanates to afford the corresponding bicyclic pyridones 163 (Scheme 72).356 357 For previously reported ruthenium-catalyzed [2 + 2 + 2]-cycloaddition of 1,6-diynes see Refs 358 and 358a, and for theoretical calculations of the cyclocotrimer-ization of alkynes with isocyanates, isothiocyanates, and carbon disulfide see Refs 359 and 359a. 

For a related example of a ruthenium(II)-catalyzed cycloaddition of 1,6-diynes with isothiocyanates and carbon disulfide, see Yamamoto, Y. Takagishi, H. Itoh, K. J. Am. Chem. Soc. 2002, 124, 28-29. 

Aryl-3-phenacylthio-l,2,4-triazoles 122 react with carbon disulfide and aryl isothiocyanates to give 5-aryl-3//-[l,2,4]triazolo[3,4-f][l,2,4]dithiazole-3-thiones and the 3-arylimino derivatives 123 (Equation 35) <1983ABC1017>. 

Transformation of the thiadiazolopyrimidine compound 138 to the fused dithiazole 140 also follows a fairly complicated pathway <2004JHC99>. When the derivative 138 is treated with carbon disulfide, a cyclization reminiscent of 1,3-dipolar cyclization takes place with the reagent acting as a dipolarophile to give a />OT-fused tricyclic intermediate containing a hypervalent sulfur atom 139. This intermediate can undergo isothiocyanate elimination to furnish 140. It is interesting to note that the sulfur atom of the thione moiety in the product is derived from carbon disulfide. 

Most of the cyclizations of the five-membered ring relating this type of fused [l,2,4]triazines concern the synthesis of [l,3,4]thiadiazolo[2,3-c][l,2,4]triazines. These synthetic approaches are similar in respect to the starting compound, which is a substituted 4-amino-3-mercapto[l,2,4]triazine-5(477)one 218 in each case. The ring-closure reactions can be classified into four related categories according to the reagent used aldehyde, isothiocyanate, carbon disulfide, or an acid. 

Scheme 44 also shows two further synthetic routes to [l,3,4]thiadiazolo[2,3-c][l,2,4]triazinones. Reaction of the 3-mercapto- or 3-methylsulfanyltriazinone 221 (R1 = H or R1 = Me) with a set of isothiocyanates was reported to give the 2-amino-substituted fused ring system 222 in medium to good yield (36-84%) <1997JHC1351>. Derivative 223 was described to undergo cyclization to a fused thiadiazole 224 by treatment with carbon disulfide in the presence of potassium hydroxide in ethanol <2001PHA376>. 

The present procedure2 describes the conversion of resin-bound, primary aliphatic amines into isothiocyanates and the conversion of the latter into 3-aminothiophenes. The generation of isothiocyanates is related to known procedures,3 in which amines are first treated with carbon disulfide and the resulting dithiocarba-mates are desulfurized by treatment with a condensing agent (alkyl chloroformates, carbodiimides, lead or mercury salts, etc.). The presence of resin-bound isothiocyanates on the polystyrene support could be qualitatively ascertained by infrared spectroscopy (KBr-pellet strong absorption at 2091 cm-1). 

In carbohydrate chemistry, the most described method for the preparation of saccharidic thionocarbamates involves preliminary introduction of the amine function on a partially or non-protected saccharidic template. The condensation of amino sugars with carbon disulfide or thiophosgene leads to cyclization in 1,3-oxazolidine- or l,3-oxazine-2-thiones. This reaction involves the formation of an intermediate isothiocyanate, which reacts further with a 3- or y-located hydroxyl group. The viability and facility of this process depends on the saccharidic ring size and the inherent strain. Some major rules can be put into light from the cases studied 30... 

Saccharidic templates bearing an amino group in C-2, C-6, C-3, C-5. Generally, an amine located on non-anomeric position reacts similarly through the condensation reaction with carbon disulfide or thiophosgene, the preliminary formed isothiocyanate leads to spontaneous or base-induced cyclization into 1,3-oxazolidine- or l,3-oxazine-2-thiones, as previously mentioned. Several extensive studies are reported about the selective introduction of thionocarbamate moieties on carbohydrate scaffolds.3 22 23 320 34 38... 

On the other hand, Seto and Ogura (64BCJ1526) prepared isomeric thiazolotropone 193 as well as the 2-amino (191) and the 2-mercapto derivatives (192) from 3-aminotropolone (112) and dithiobenzoate 194, isothiocyanate, or carbon disulfide, respectively. 

Analogously, thiazolotropolones 197-200 (Schemes 47 and 48) arise from similar condensations of 5-amino-3-bromo- or 5-aminotropolones (195,203) with dithioesters 194 and 201, isothiocyanates, or carbon disulfide, respectively (62BCJ1998 63BCJ173 64BCJ1526, 64JAP64/10132). 

In 1970 ring-opening and ring-closing reactions of 2,2-dialkyl-1,3,2-dioxa- and -1,3,2-oxathia-stannolanes with carbon disulfide and phenyl isothiocyanate involving nucleophilic attack at the tin atom were discovered <70CC235>. Since these reactions are described as proceeding via a cyclic transition state they will be considered in Section 4.24.2,5.10. 

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