Reagents 1,2-ethanedithiol

Related Reagents. 1,2-Ethanedithiol Ethanethiol Methane-thiol. 

Lactones can be protected as dithiolane derivatives using a method that is analogous to ketone protection. The required reagent is readily prepared from trimethyl-aluminum and ethanedithiol. 

Scheme 5. Reaction conditions i, reductive amination ii, protection of amino group iii, Collins reagent iv, Ph3F CHCioH2i" v, hydrolysis vi, Hg(OAc>2 vii, NaBH4 viii, l-decen-3-one ix, ethanedithiol x, Raney Ni xi, HCl-EtOH.

Peptide synthesis reagents such as diisopropylcarbodiimide (DIC), benzotriazole-1-yl-oxy-tris-pyrrolidino-phosphonium hexafluorophosphate (PyBOP), bromo-tris-pyrrolidino-phosphonium hexafluorophosphate (PyBroP), 2-(lH-benzotriazole-l-yl)-l,l,3,3-tetramethyluronium hexafluorophosphate (HBTU), 1-hydroxybenzotriazole (FlOBt), piperidine, A-methylmorpholine (NMM), trifluoroacetic acid (TEA), triisopropylsilane (TIS), A -diisopropylethylamine (DIPEA, DIEA), l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,2-ethanedithiol (EDT), and 4-dimethylaminopyridine (DMAP) may be obtained from Sigma-Aldrich, Chemlmpex, and Novabiochem. 

Cyclization of enone (9) in hexane with boron trifluorideetherate in presence of 1,2-ethanedithiol, followed by hydrolysis with mercury (II) chloride in acetonitrile, yielded the cis-isomer (10) (16%) and transisomer (11) (28%). Reduction of (10) with lithium aluminium hydride in tetrahydrofuran followed by acetylation with acetic anhydride and pyridine gave two epimeric acetates (12) (32%) and (13) (52%) whose configuration was determined by NMR spectroscopy. Oxidation of (12) with Jones reagent afforded ketone (14) which was converted to the a, 3-unsaturated ketone (15) by bromination with pyridinium tribromide in dichloromethane followed by dehydrobromination with lithium carbonate and lithium bromide in dimethylformamide. Ketone (15), on catalytic hydrogenation with Pd-C in the presence of perchloric acid, produced compound (16) (72%) and (14) (17%). The compound (16) was converted to alcohol (17) by reduction with lithium aluminium hydride. 

Peptide synthesis reagents and materials Use NovaSyn TGR resin (Novabiochem) for C-terminal amide synthesis and Fmoc amino acid monomers (Novabiochem) including Fmoc-Arg(Pbf)-OH, Fmoc-Asn(Trt)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Gln(Trt)-OH, Finoc-Glu(OfBu)-OH, Fmoc-His(Trt)-OH, Fmoc-Lys(Boc)-OH, and Fmoc-Trp(Boc)-OH. Other peptide synthesis reagents are as for PNA (above) with the addition of 1,2-ethanedithiol (EDT, >98%, Fluka). A Phenomenex Jupiter C-18 column (analytical and semi-preparative) may be used for reversed-phase HPLC. 

The reagent is prepared by reaction of BCIj with i, 2-ethanedithiol at —78°. ... 

One of the effective reagents for highly chemoselective dithioacetalization of carbonyl compounds is ceric ammonium nitrate (CAN) in chloroform. When a mixture of benzaldehyde and acetophenone was allowed to react with 1,2-ethanedithiol and a catalytic amount of CAN, the 1,3-dithiolane derived from the aldehyde was obtained in 84% yield while the ketone was recovered unchanged. It is noteworthy that aromatic ketones, 7-lactones, and acylic ketones did not react at all under these conditions and even at elevated temperatures for longer reaction times <1995T7823>. 

Treatment of a mixture of a carbonyl compound and 1,2-ethanedithiol in dry dichloromethane at room temperature with anhydrous zirconium(iv) chloride dispersed on silica gel gave excellent yields (96-99%) of the respective 1,3-dithiolanes. The high reactivity of this reagent was also observed in the case of less reactive aromatic ketones at room temperature and a,(3-unsaturated aldehydes such as cinnamaldehyde 556 (Equation 74) <1996TL4621>. 

Cleavage of the peptides from the resin support and concomitant deprotection of the amino acid side chains was achieved in reagent R (TFA thioanisole 1,2-ethanedithiol anisole = 90 5 3 2) at room temperature for 6 h. This was followed by removal of the exhausted resin by filtration and precipitation of the peptide product in cold ether. The precipitate was allowed to settle overnight at -20 °C and then washed 3x with cold ether and dried under high vacuum. 

Although Hauptmann showed in parallel experiments that better yields of thioketals are obtained with this reagent than with ethanedithiol, propanedithiol has been used to only a limited extent, - for example ... 

Characterization of carbonyl compounds. Since it does not possess the evil odor of 1,2-ethanedithiol but condenses readily with aldehydes and ketones under acid catalysis, the reagent is useful for the preparation of characterizing derivatives. Aldehydes and ketones can be dilferentiated by their rate of reaction with the reagent. I. Shashak and B. D, Btrgmann,./. chrm. Stic. C, 100.5 (1966)... 

Ketones (see also Carbonyl compounds) N,N-Dimethylglycinehydrazide hydrochloride. Ethanedithiol. Girard s reagent. 5-lodo-2,4-dinitrophenylhydrazine. Lithium dimethylamino-sulfonylmethide. 8-Mercaptoethanol. Propane-1,3-dithiol. Propane-1,3-dithiol di-p-toluene-sulfonate. 

Reaction of 1,2-ethanedithiol with boron trifluoride dimetbylsulfide complex gives (367) which is a useful reagent for the one-step conversion of carboxylic acids RCO2H into 1,3-dithiolanes (368) (Equation (77)) <89MI 312-01>. 

Condensation of ethane-12-dithiol [1, 1220, before references]. Coffen13 states that trifluoroacetic acid is an excellent reagent for the condensation of ketones with ethanedithiol to form ethylenethioketals. He found, however, that in the absence of a carbonyl compound the acid condenses with ethanedithiol to produce in high yield the crystalline orthothiol ester formulated. 

Reagents i, KOBu ii, AcjO-py iii, ethanedithiol-HCI iv, Zn-AcOH v, Raney nickel vi, KjCOj-MeOH vii, LiAlH viii, A-chlorosuccinimide ix, NaOMe. 

Cleavage of 2-haloethyl esters. This reagent, prepared from sodium hydride and ethanedithiol, cleaves 2-haloethyl esters selectively in 80-95% yield (four examples). Compare Sodium trithiocarbonate, this volume. 

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