Carbon disulfide with nucleophiles

A variety of other reactions of carbon disulfide with nucleophiles are presented in a review (252). In the last 10 years a number of new 1,1-dithio ligands have been synthesized, and the chemistry of others has been explored in detail. 

FIGURE 8. Reaction of carbon disulfide with nucleophilic center in an amino acid. Modified from Cohen et... 

Dithio acids and dithiols are formed by reaction of carbon disulfide with various nucleophiles (Z or Z ), as follows. 

A major class of sulfur-containing ligands is obtained by the general reaction of carbon disulfide with various nucleophiles. These ligands can be classified into two categories the uninegative 1,1-dithioacids and the dinegativc 1,1-dithiolates (Fig. 1). 

The reaction of carbon disulfide with various nucleophiles such as NR2, CR3, OR", and SR gives rise to the general class of 1,1-dithio ligands of the general formula "S2C-X. These ligands have been discussed up to 1969 in a previous review (153). Since then various new reactions of CS2 and nucleophiles and new 1,1-dithio ligands have appeared. 

J. H. Rigby, Vinyl Isocyanates as Useful Building Blocks for Alkaloid Synthesis, Synlett 2000, 1-12. W. D. Rudorf, Reactions of Carbon Disulfide with C-Nucleophiles, Sulfur Rep. 1991, 11, 51-141. 

Hydrazine as Nucleophile. Reaction of hydrazine and carbon dioxide or carbon disulfide gives, respectively, hydrazinecarboxyhc acid [471-31-8], NH2NHCOOH, and hydrazinecarbodithioic acid [471-32-9], NH2NHCSSH, in the form of the hydrazinium salts. These compounds are useful starting materials for further synthesis. For example, if carbon disulfide reacts with hydrazine in basic medium with an alkyl haUde, an alkyl dithiocarbazate ester is obtained in a one-step reaction ... 

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. 

Isonitrile complexes, having a similar electronic structure to carbonyl complexes, can also react with nucleophiles. Amino-substituted carbene complexes can be prepared in this way (Figure 2.6) [109-112]. Complexes of acceptor-substituted isonitriles can undergo 1,3-dipolar cycloaddition reactions with aldehydes, electron-poor olefins [113], isocyanates [114,115], carbon disulfide [115], etc., to yield heterocycloalkylidene complexes (Figure 2.6). 

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. 

The reaction of 2-aminobenzyl alcohol 376 with 2-chloro-4,5-dihydroimidazole afforded [2-(4,5-dihydro-177-imidazol-2-ylideneamino)phenyl]methanol hydrochloride 377, which upon treatment with carbon disulfide gave l-(477-3,l-benzoxazin-2-yl)imidazolidine-2-thione 378 (Scheme 71). The assumed reaction mechanism involved the initial formation of the dithiocarbamate 379, which underwent intramolecular nucleophilic addition to furnish the unstable thiazetidine 380. By nucleophilic attack of the hydroxy group on the carbon atom of the thiazetidine ring, thiocarbamate derivative 381 was formed, which gave the final 3,1-benzoxazine 378 by an intramolecular cyclocondensation with the evolution of H2S <2006H(68)687>. 

Amino-l,2,4-thiadiazoles 191 are obtained when ether is used (249), while 5-alkylthio-1,2,3-triazoles 192 result when the reaction is carried out in THF (250). Reaction of 3 with carbon disulfide leads to 5-alkylthio-l,2,3-thiadiazoles 193 (251). While 3 can act as a synthetic equivalent of the RC—N—N synthon (R = H, SiMea) in all these reactions, it should be emphasized that it does not react by a concerted 1,3-dipolar cycloaddition but rather by a stepwise polar mechanism. The highly nucleophilic character of 3 can account for why diazomethane and... 

Nucleophilic substitution of the 4-chloro group of the 4-pyranotriazines 103 with hydrazine gives the 4-hydrazino-triazines 104, which can be further elaborated to the corresponding azides 105 or cyclized upon reaction with formic acid or carbon disulfide to give the triazolotriazines 106 or thioxotriazolotriazines 107, respectively (Scheme 11) <2005HC0495>. 

The 4-aminopyrimidines 367 and 368 were prepared by the reaction of the benzylidene malononitriles with thiourea or S-methylisothiourea, respectively. Nucleophilic substitution at the 2-position of 368 with hydrazine gave the 2-hydrazino derivative 369, whose treatment with carbon disulfide yielded the triazolopyrimidine 373 rather than its isomeric compound [83ZN(B)1686]. Heating 369 with benzoyl chloride in anhydrous dioxane,... 

Isothioureas can be prepared on insoluble supports by S-alkylation or S-arylation of thioureas (Entry 7, Table 14.6). Further methods for the preparation of isothioureas on insoluble supports include the N-alkylation of polystyrene-bound, A/,/V -di(alkoxy-carbonyl)isothioureas with aliphatic alcohols by Mitsunobu reaction (Entry 7, Table 14.6) and the addition of thiols to resin-bound carbodiimides [7]. Resin-bound dithio-carbamates, which can easily be prepared from Merrifield resin, carbon disulfide, and amines [76], react with phosgene to yield chlorothioformamidines, which can be converted into isothioureas by treatment with amines (Entry 8, Table 14.6). The conversion of support-bound a-amino acids into thioureas can be accompanied by the release of thiohydantoins into solution (see Section 15.9). The rate of this cyclization depends, however, on the type of linker used and on the nucleophilicity of the intermediate thiourea. 

Characteristic of the heavy metal complexes is their carbon disulfide elimination, yielding mixed thiol-thioxanthato complexes with trimeric structures and thiol bridges.139 The facile nucleophilic substitution of RS by R2N is interesting.113114... 

For example, the distonic anion radical of cyclopentadienylidene trimethylen-emethane reacts under mass spectrometer gaseous-phase conditions with carbon disulfide by sulfur abstraction and with nitric oxide by NO-radical addition. The first reaction characterizes the distonic anion radical mentioned as a nucleophile bearing a negative charged moiety. The second reaction describes the same anion radical as a species having a group with radical unsaturation (Zhao et al. 1996). 

A method used to prepare four of six possible thienopyridines (1992S528, 1997S949, 1998S1095) holds considerable promise. In particular, the synthesis of thieno[2,3-6]pyridine derivatives 31 and 32 involves the reaction of 2-chloro-3-(cyanomethyl)pyridine (33) and ethyl 2-chloro-3-pyridylacetate (34) with hetero-cumulenes, such as carbon disulfide and phenyl isothiocyanate. The reaction proceeds through the formation of the corresponding dianions 35 and 36 followed by cyclization through intramolecular nucleophilic substitution of the chlorine atom. 

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