Xanthogenate reaction

Esters of Dithioc arbonic Acid — Xanthogenate Reaction (Detection and Identification)... 

Xanthates (or xanthogenates), t.g., CS(OR)SK, are formed by the reaction between carbon disulphide and an alcoholic solution of potassium hydroxide, for example ... 

The reaction of chloroformates with sodium xanthates results in the formation of alkyl xanthogen formates that are useful as flotation agents in extraction of metals from their ores (48). 

Upon thermolysis of xanthates (xanthogenates) 1 olefins 2 can be obtained, together with gaseous carbon oxysulfide COS 3 and a thiol RSH 4. This decomposition process is called the Chugaev reaction, another common transcription for the name of its discoverer is Tschugaeff. 

Omeprazole was prepared [19] by reaction of 4-methoxy-o-phenyl-enediamine 1 with potassium ethyl xanthogenate 2 to give 5-methoxy-2-mercapto-lH-benzimidazole 3. Treatment of compound 3 with 3,5-dimethyl-4-methoxy-2-chloromethyl pyridine 4 in sodium hydroxide... 

A simple method for the preparation of l,3-dithiol-2-ones 196 using radical methodology has been reported [95CC1429]. The reaction involves heating of diisopropyl xanthogen disulfide 193 with a terminal alkyne at 80 °C in the presence of a radical initiator. The reaction conditions are compatible with a variety of functional groups on the alkyne. 

Bis-(2-bromo-(l-bromomethyl-l-methyl)ethyl)pyridine 78 is a precursor for tetrapodal ligands. Its reaction with an excess of potassium 0-ethyl xanthogenate in DMSO at 70 °C (72 h) gave 2,6-bis-(3-methylthietan-3-yl)pyridine 79 (Equation 24) <2002ZN1256>. The yield of the product was not reported. 

Sulfur can be introduced into a diazonium salt by the SN1 reaction shown in Figure 5.51. In order to prevent the reagent from effecting a double (rather than a mono-) arylation at the sulfur atom, potassium xanthogenate instead of sodium sulfide is used as the sulfur nucleophile. The resulting S-aryl xanthogenate C is hydrolyzed. In this way diarylsulfide-free aryl thiol B is obtained. 

Tertiary iodides and bromides usually are reduced (defunctionalized) with Bu3SnH or (Me3Si)3SiH via a radical chain reaction, as discussed in Section 1.9. Primary and secondary alkyl iodides, bromides, and xanthogenates can be reduced with the same reagents under the same conditions via the same radical mechanism. 

The l,3-dithiol-2-ones 511 were conveniently prepared in a one-step reaction involving diisopropyl xanthogen disulfide 510 and terminal alkyl and aryl alkynes in the presence of radical initiators (Scheme 73) <1995GC1429,1998H(48)2003>. This synthetic strategy was also applied to the preparation of the quinoxaline derivatives 512 <1997J(P1)801>. 

In the seccHid part, surveys concerning telechelk telomers ate mentioned. The different telc ens used and their known transfer-constants are supplied alijAatic and aromatic disulfides, disubstituted benzoyl disulfides, functional xanthogens and polyhalogenated compounds. Also novel monoaddition reactions of functional monomers onto both end groups of dithiols and ditrichloromethyl compounds are summarized. 

Fokina et al. [90] studied the modification of xanthogens according to the reaction ... 

Despite the high temperatures required for acetate and xanthogenate pyrolysis, the accessibility of these compounds from the corresponding alcohols provides for a useful route to alkenes. One advantage is that as no acidic or basic reagents are required, rearrangement reactions, which can interfere with alcohol dehydration, are avoided. For example, pyrolysis of lactol acetates has been used to prepare 4,5-dihy-drofurans, as illustrated in equation (58), - and pyrolysis of the corresponding thionocarbonate was used to dehydrate alcohol (128 Scheme 38). 

Thioxo derivatives are available from 1,8-naphthalenediamines in reactions with carbon disulfide or potassium xanthate (xanthogenate). In fusion reactions with ammonium thiocyanate or thiourea, mixtures of the 2-amino derivative and the thione can be formed. Thiation reactions in the carbocyclic system correspond to those in naphthalene chemistry. 

An ingenious solution to the problem of slowly reacting (weakly basic) o-aminonitriles was to replace the carbon disulfide by potassium O-ethyl dithiocarbonate ( xanthogenate ) (EtO—CS2K),188 which slowly liberates carbon disulfide above 110°C. Thus, 2-amino-5-nitrobenzonitrile gave an excellent yield of 6-nitroquinazoline-2,4-dithione when boiled with this salt in butanol for 4 hr.189 Excellent yields of 8-azapurine-2,6-dithione and its 9-methyl and 9-benzyl derivatives were similarly obtained.179 For more reluctant reactions, boiling dimethylformamide proved to be a useful solvent.189... 

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