Ethane-1,2-dithiolates

Magnesium triflate and zinc triflate are outstanding catalysts for the intro duction of the thioketal group for the protection of the ketone function [126] The reaction of a variety of ketones with ethane 1,2-dithiol in the presence of these triflates proceeds under mild conditions to form the corresponding thioketals in high yield (equation 62)... 

The procedure for the preparation of a dithiolane from a hydroxy-methylene derivative of a ketone and ethylene dithiotosylate (ethane-1,2-dithiol di-p-toluenesulfonate) can be varied to produce dithianes when the latter reagent is replaced by trimethylene dithiotosylate.8,4 The dithiotosylates also react with enamine derivatives to produce dithiaspiro compounds.4,5... 

Mesylation of alcohol 14 and hydrolysis of the acetal with oxalic acid leads to the key decalone 16 which cyclises in the presence of NaH in dioxane to afford twistanone 17 in quantitative yields. The elimination of the carbonyl group was carried out by an alternative method to the Wolff-Kishner reduction, which involves the thioacetalisation of the twistanone (18) with ethane-1,2-dithiol and removal of the resulting thioacetal by Raney nickel in boiling ethanol (62% yield). 

The vapor sample under investigation may not eontain only one kind of speeies. It is desirable to learn as mueh as possible about the vapor composition from independent sources, but here the different experimental conditions need to be taken into account. For this reason, the vapor composition is yet another unknown to be determined in the electron diffraction analysis. Impurities may hinder the analysis in varying degrees depending on their own ability to scatter electrons and on the distribution of their own intemuclear distances. In case of a conformational equilibrium of, say, two conformers of the same molecule may make the analysis more difficult but the results more rewarding at the same time. The analysis of ethane-1,2-dithiol data collected at the temperature of 343 kelvin revealed the presence of 62% of the anti form and 38% of the gauche form as far as the S-C-C-S framework was concerned. The radial distributions calculated for a set of models and the experimental distribution in Figure 6 serve as illustration. 

Figure 6. Ethane-1,2-dithiol has a mixture of the anti (a) and gauche (g) forms at the experimental temperature of 343 K, with respect to the S-C-C-S framework. The top three curves were calculated for models, the bottom curve is the experimental radial distribution.

The stoichiometric equivalents of halofluorides have been recently applied to transform alkylene dithioacetals into gcm-difluorides.70-71 Dithioacetals such as 1,3-dithiolanes and 1,3-dithianes arc readily obtained from the corresponding carbonyl compounds by the reaction with ethane-1,2-dithiol or propane-1,3-dithiol in the presence of the complexes boron trifluoride-bis(acetic acid) or boron trifluoride-diethyl ether. Using a two-step procedure, a range of aldehydes and ketones can be converted into gem-difluorides under mild conditions. 

By allowing a slurry of (PPh4)Na[VO(edt)2] 2EtOH (edt2 = ethane-1,2-dithiolate) in MeCN to react with (Me3Si)2S, orange-brown crystals were obtained.656 They contain [VS(edt)2]2-, whose structure is essentially identical with [VO(edt)2]2" (see Section 33.5.6.3). The difference between V=0 and V—S is 0.462 A. 

Chromium(II) is in planar coordination (71) in [NEt4]2[Cr(S2C2H4)2] (ju j K = 4.95 BM in MeCN), which separates as a violet solid when ether is added, after stirring for several days, to a mixture of CrCl2, sodium ethane-1,2-dithiolate and [NMe4]Cl.220... 

The fully saturated 1,4-dithiepane system can be prepared by reactions of propane-1,3-dithiol with 1,2-dibromoethane, and of ethane-1,2-dithiol with 1,3-dihalopropanes (72HC(26)598, p. 619). 

To the AzLeu-peptide-PAM 47 (0.1 mmol) in DMF/CH2C12 (1 3) was added Boc-Tyr[Bzl(2,6-Cl2)]-H (2.12 g, 0.5 mmol) in the presence of NaOAc (0.164 g, 2 mmol) and molecular sieves. The reaction was stirred for 5 h at rt and the coupling step was repeated to obtain the protected iminoaza peptide-PAM 48. A standard deprotection and cleavage procedure (TMSOTf/TFA), with thioanisole and ethane-1,2-dithiol as scavengers afforded the crude deprotected iminoaza peptide 49. The yield was estimated at about 45%. Fractions determined to be pure by analytical RP-HPLC are pooled, concentrated under reduced pressure and lyophilized to yield the iminoaza peptide 49 as a white powder (>95% pure), which was checked by TOF-MS calcd, 1253.48 [M +1]+ found, 1252.60. 

The reaction of ( r-Cp)2TiCl2 with ZnCl2 and ethane-1,2-dithiol has been shown to yield the novel complex (125).855... 

Keywords ketone, aldehyde, ethane-1,2-dithiol, neutral alumina surface, dithio-acetal, 1,3-dithiolane... 

To a freshly prepared catalyst (1 g, 0.2 mmol of iodine) under stilling, a mixture of benzaldehyde la (2 mmol) and ethane-1,2-dithiol (2.2 mmol) was added and stirring continued for 10 min or till the reaction was complete. For TLC monitoring, a small amount of the solid reaction mixture was taken out with a spatula and washed with a little amount of ethyl acetate to get a solution. On completion the reaction mixture was loaded on a short column of silica gel (60 to 120 mesh) and eluted with ethyl acetate. The organic layer was washed with a dilute solution of sodium thiosulfate followed by water and dried over anhydrous sodium sulfate. Evaporation of the solvent under reduced pressure and purification of the residue by column chromatography yielded the pure product. 

The reaction of aldehydes or ketones with ethane-1,2-dithiol or propane-1,3-dithiol to form 1,3-dithiolanes or 1,3-dithianes is an important reaction, as these compounds under suitable conditions are acyl anion equivalents (see Section 5.9, p. 626). These cyclic dithioacetals have been less used as protective groups, though when required are formed in high yield in the presence of boron trifluoride-etherate.138... 

Troponeacetals (e.g., 409) are formed, by means of dimethyl sulfite, from tetracyclic triazoles (145) or pyrazine [67LA(705)169], whereas mercaptali-zation of thienotropones by ethane-1,2-dithiol fails [85JCS(P1)983],... 

Organotin 1,2-dithiolate complexes were featured in many studies the ligands used include aliphatic derivatives, e.g. ethane-1,2-dithiolate -SCH2CH2S-(EDT), -SCH2CHMeS-, alkenyl derivatives, e.g. -SCH=CHS-, maleonitriledithiolate (MNT), aryl derivatives, 1,2--SC6H4S (BDT) and toluene-3,4-dithiolate (TDT), as well as heterocyclic derivatives, l,3-dithiane-2-one-4,5-dithiolate (DMIO) and l,3-dithiane-2-thione-4,5-dithiolate (DMIT)191. 

Ethoxycarbonyl)-1 -cyanoethylene-2,2-dithiolate Ethane-1,2-dithiolate Ethylenediaminetetraacetic acid Emission... 

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