1,3-Dithiole-2-thiones, synthesis

Dithiole-3-thione, 5-amino-mass spectra, 6, 787 synthesis, 6, 804, 806... 

A range of 4-substituted l,3-dithiole-2-thiones (71) and 2,6-substituted 1,4-dithiafulvalenes (73) were synthesised from 4-substimted 1,2,3-thiadiazoles (72). Reaction of (72) with NaH in a mixture of CS2 and acetonitrile led to the formation of (71), whereas absence of CS2 gave fulvalenes (73). This route was found to be very efficient for the preparation of 4-formyl-1,3-dithiole-2-thione (71 R = CHO), which was previously difficult to prepare, and thus allowed the synthesis of the novel 2,6(7)-bisformyltetraAiafulvalene (74) <96T3171>. 

In the synthesis of l,3-dithiolan-2-ones from spirocyclic intermediates, via episulfides, substituted tetrathiacyclododecane and the related pentathiacyclopentadecane were isolated in good yields <96JCS(P1)289>. Preparation and molecular dynamics studies of 2,5,8,17,20,23-hexathia[9.9]-p-cyclophane have been reported <96P4203>. The syntheses and properties of thiocrowned l,3-dithiole-2-thiones and their conversion to tetrathiafiilvenes via treatment with triethylphosphine have been described <96LA551>. 

The synthesis of halogenated TTF is most often based on the lithia-tion/electrophilic halogenation of either the TTF core itself [50] or the five-membered l,3-dithiole-2-thione [36,51]. This procedure has been recently expanded to the analogous l,3-diselenole-2-thione [52,53], allowing for the formation of a wide variety of iodo- and bromotetraselenafulvalenes or dithiadiselenafulvalenes shown in Schemes 6 and 7. 

In the synthesis of l,3-dithiole-2-thione derivatives as intermediates for electropolymerization precursors, the bicyclic 462 was found to be inert to normal cyclization conditions <1999JOC6418>. This is believed to be due to steric hindrance, from the boat conformation of the dithiin ring. Cyclization was achieved, albeit in only moderate yields, by heating with P2S3 to give the thiophene 463a or HBr/AcOH for the furan 463b (Equation 125). 

Bismorpholino disulfide (35) and related compounds are prepared from the corresponding amine (or imide) and disulfur dichloride. An elegant synthesis of the 1,3-dithiole-2-thione (36) from 35 is shown this is an example of two transfer reagents acting in concert.40... 

The base-catalyzed fragmentation of 4-alkyl-l,2,3-thiadiazoles is a useful method for the preparation of alkyne-1-thiolates <1996T3171>. These alkyne-l-thiolates can then react with carbon disulfide to afford l,3-dithiole-2-thiones. This strategy has been developed to give a synthesis of some novel tetrathiafulvene derivatives <1996T3171>. 

The synthesis, X-ray structure and solid state NMR of 4,4-dimethyl-l,2-ditellurolane 75 have been reported <98PS(136-8)291>. Chemoselective oxidation of 1,2-dithiole derivatives using dimethyldioxirane to give products such as 76 has been described <00SUL169>. Cycloaddition of dihydroquinoline-fused l,2-dithiole-3-thiones 77 with DMAD gives the spiro 1,3-dithioles 78 <99CHE587>. Dicationic thiatelluroles such as 79 have been prepared <00AG(E)1318>, anti cancer properties have been claimed for the simple dithiolopyrrolones... 

Mercaptodithiole thiones 93 were treated with sulfur monochloride and DABCO under conditions for the synthesis of tricyclic bis-dithiolothiazines from substituted diisopropylamines (see Scheme 38). Unexpectedly, in all the cases 5-chloro-l,2-dithiole-3-ones 96 were formed in high yields (2006RCB143 Scheme 47). 

On the other hand, hydroquinone (3 pmol/L) prevented the staurosporine-induced apoptosis of HL-60 and the IL-3-dependent murine myeloblastic (32D) cell line it also prevented apoptosis of the 32D cells observed in the absence of IL-3. The myeloperoxidase inhibitor indomethacin opposed the effect of hydroquinone on staurosporine-induced apoptosis of HL-60 cells (Hazel et al., 1995, 1996b). Pretreatment of human leukaemia cells ML-1 with buthionine sulfoximine (100 pmol/L for 24 h), in order to decrease their glutathione content, increased the susceptibility of these cells to hydroquinone-induced inhibition of differentiation caused by phorbol acetate pretreatment with l,2-dithiole-3-thione, which induces reduced glutathione synthesis, prevented the differentiation inhibition of hydroquinone. Treatment of DBA/2 mice with 1,2-dithiole-3-thione, which increased the activity of quinone reductase of bone-marrow stromal cells by 50%, decreased the susceptibility of these cells towards hydroquinone (Trush et al., 1996). 

Heterocyclic thiones l,3-dithiole-2-thione-4,5-dithiolate (DMIT). N. Svenstrup and J. Becher, Synthesis, 215 (1995). 

An unusual synthesis of 2-alkylthio-TA 41 consists in the ring enlargement of l,2-dithiole-3-thiones 40 in the reaction with sodium cyanide, followed by methylation (88JHC1223) (Scheme 9). The suggested mechanism is confirmed by an increase in yield of TA 41, when excess thiocyanate ion is added. 

A better synthesis of a-(l,2-dithiol-3-ylidene)ketones from thio-pyran-4-thiones consists in the reaction with sodium hydroxide in dimethylformamide (DMF), followed by ferricyanide oxidation (Eq. 3).11... 

Upon treatment with CS2 at 170°C, 4,6-dihydro thieno[3,4-d]-l,2,3-thiadiazole (70) yielded 4,6-dihydrothieno[3,4-(/]-1,3-dithiole-2-thione (71), which was a useful intermediate for the synthesis of a novel organic conductor <89TL7249>. 

Recently it has been reported that a-thio derivatives of enamines and enol ethers form 5-amino- or 5-alkoxy-l,2-dithiole-3-thiones (127a, b) by reaction with carbon disulfide (80ZOR13). Spiran compounds (128) are also formed from suitable substrates. The reaction has some similarities to an enamine synthesis below <67AG(E)294). 

Alkyl- and aryl-1,2-dithiol-3-ones (3a) are made by ring synthesis from unsaturated esters (B-66MI43100) and alkylation of these affords 3-alkoxy-l,2-dithiolylium salts (35b). The parent (3a R1 = R2 = H) is best made from the thione (3b) by treatment with mercury(II) acetate (63CB2702). 

A further efficient and general synthesis of l,3-dithiole-2-thiones (169) with a variety of functional groups is the acid-catalyzed ring closure of j8-keto f-butyl trithiocarbonates of type (261) which are readily available from a-halo ketones and sodium t-butyl trithiocarbon-ate. The intermediates (262) fragment into isobutene and l,3-dithiole-2-thiones (169) (80JOC175). 

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