Potassium trithiocarbonate

After extensive experimentation, it was discovered that exposure of silyl ether (+)-97 to potassium trithiocarbonate and trifluoroacetic acid in dichloromethane affords a 25 7 1 mixture of endolendo endo/exo exo/exo bisdithiepanethione products, reflecting a ca. 5 1 preference for nucleophilic approach from the endo-face of each diketopiperazine moiety. Resubjection of the isolated bisdithiepanethione diastereomers to the original reaction conditions did not result in their equilibration, indicating that the products were a result of kinetic trapping. 

Condensation, of paraldehyde with diethyl malonate, 32, 54 of a-phene thyl chloride with diphenylacetonitrile, 39, 74 of phenylacetylene with ethyl orthoformate, 39, 59 of 1-phenylbiguanide with ethyl chloroacetate, 38,1 of potassium diphenylacetonitrile with benzyl chloride, 39, 73 of potassium trithiocarbonate with potassium chloroacetate, 39, 77 of sodium acetylacetonate to tetraacetylethane, 39, 61 of sodium formylacetone with cyano-acetamide, 32, 32 of tetracyanoethylene with N,N-dimethylaniline, 39, 68 of thiophene, paraldehyde, and hydrogen chloride, 38, 86 of thiourea with furfuryl alcohol, 36,66... 

The reaction of 1,2-dichlorodiethyl ether with potassium trithiocarbonate leads to the formation of the cyclic thione (318) which on treatment with p-toluenesulfonic acid gives... 

Potassium oxalate, 34, 83 Potassium permanganate, 30, 87 31,59 Potassium phthalimide, 38, 81 Potassium sulfide, 32,103 Potassium thiobenzoate, 32,101 Potassium thiocarbonate, 39, 78 Potassium thiocyanate, 32,39,40 Potassium trithiocarbonate, 39, 78 Prins reaction, 33, 72 Propane, 1, 3-dibromo-2,2-5m-(bromo-methyl)-, 31, 82... 

Potentiometric Methods. - Potassium trithiocarbonate has been used as a reductant (-S-S- reduction cleavage) for the potentiometric (and spectrophoto-metric) determination of the disulfides of dithio-phosphinic acids in DMF-H2O medium at millimolar levels.The protonation equilibria for N,N -diethylami-nomethylenephosphonic acid (88) were elucidated from both potentiometric titration and determination of the pH dependence of the NMR chemical shift (83 ip), and protonation constants for aminoalkanephosphonates RCH(NH2)P(0)(0Et)2 and the acidity constant of di(2-ethylhexyl)thiopho-sphoric acid (111) have also been obtained potentiometrically. 

The unsubstituted l,3-dithiole-2-thione (245) can be accessed, however, by the reaction of dimethyl acetylenedicarboxylate with l,3-dithiolane-2-thione (Scheme 50) <74JOC2456>, from the reaction of sodium acetylide with carbon disulfide and elemental sulfur <64CB1298>, or by a two-step synthesis from the 1,2-dichloroethyl ethylether (246) and potassium trithiocarbonate. The intermediary 4-ethoxy-l,3-dithiolone-2-thione (247) affords, upon reaction with p-toluene sulfonic acid with concomitant loss of ethanol, the unsubstituted derivative (245) <76CC920>. 

Reduction of carbon disulfide also provides a starting point for the synthesis of these compounds. For small scale preparation the electrochemical reduction of CS2 in DMF on a platinum or mercury electrode offers a way for the preparation of 4,5-dithio-l,3-dithiole-2-thione dianion (248) (together with significant amounts of potassium trithiocarbonate (249)), which upon alkylation gives access to 4,5-bis(alkylsulfanyl)-1,3-dithiole-2-thiones (252) (Scheme 51) <74J A945,74JOC511,81JOC775). How-... 

The action of potassium trithiocarbonate on the acetylenes 533 (R = H, Me or z-Pr X = Cl, Br or TosO) results in the dithiolethiones 534, which afford butatrienes 535 on desulphurization with nickeP. ... 

Diaryliodonium salts imdergo a nucleophilic displacement reaction in [BMIM][Bp4] with potassium trithiocarbonates to give aryltrithiocarbonates (Scheme 5.2-66) [163]. The reactions in ionic liquids gave significantly higher yields (up to 75%) than in solvents such as THF, DMF, or acetonitrile. Diaryliodonium... 

The fragmentation of 2-heterosubstituted 4,7-dihydro-1,3-dithiepins (232)-(234) viacarbene (235) gave 1,3-butadiene and carbon disulfide. The tosylhydrazone (232) was synthesized by cyclization of l,4-dichlorobut-2-ene with the 5,5 -sodium-potassium salt of dithiocarbonic acid-tosyl-hydrazone, the diazo compound (233) was synthesized by careful pyrolyzation of the dry Na salt of (232), and the trithiocarbonate (234) was synthesized from l,4-dichlorobut-2-ene and potassium trithiocarbonate in DMSO. Similarly, pyrolysis of the sodium salt of benzoannelated dithiepin (236), obtained in a one-pot synthesis from a,a -dichloro-o-xylene, carbon disulfide, potassium hydroxide, and tosylhydrazide gave o-quinodimethane, which could be trapped by dienophiles, such as acrylonitrile, to give Diels-Alder product (238) (Scheme 40) <92SCi7ii>. 

Dibromobutyne was used in the preparation of cyclic trithiocarbonates with a propadiene side-chain. From potassium trithiocarbonate, a double substitution occurs in the presence of 18-c-6. 59 Sonication speeds up the reaction by a factor of 10. Without sonication, only polymers are formed. 

Synthesis.—In the course of their investigations in the field of simple trithiocarbonates, Gattow and his co-workers have prepared the cyclic trithiocarbonates (284) and (285) by reactions involving the action of methylene iodide on potassium trithiocarbonate, and the treatment of hydrogen trithiocarbonate with dimeric thiophosgene, respectively. The... 

Compounds (1), (2) and (3) have been prepared by several cyclization procedures (see [1-3,25,28,35,37,73,75,77,216,246] and refs, therein). Vinylene trithiocarbonate (la ) can be obtained in a good yield by treating potassium trithiocarbonate, KS-C(=S)-SK, with 1,2-dichloroethyl ethyl ester, ClCH2CHCl(OEt), followed by elimination of ethanol with / -toluenesulfonic acid. Vinylene trithiocarbonate... 

Desulphurization of l,2-bis(trifluoromethyl)vinylene trithiocarbonate (75), best obtained by reaction of 2,3-dichlorohexafluorobut-2-ene with potassium trithiocarbonate in dimethylformamlde, with triphenylphosphine in benzene yields the bidithiole (76) in 90% yield. The last compound is also a product of the thermal reaction between carbon disulphide and perfluorobut-2-yne, which leads to the generation of the 1,3-dithiolium caibene (77) (see p. 54). ... 

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