Sulfur Transfer Reagent Research Articles

Thermodynamic and kinetic properties of scandium (I) ion reacting with SCO in gas phase

Abstract Theoretical studies on the thermodynamic and kinetic properties of the reactions of scandium (I) ion with the sulfur-transfer reagent SCO via the C-O bond activation pathway have been carried out over the temperature range of 200-1200 K using the DFT/B3LYP method, general statistical thermodynamics, and Eyring transition state theory with Wigner correction. The relevant reactions include reaction 1 1Sc+ + SCO → 1IM1 → 1TS1 → 1IM2 (Step 1) → 1TS2 → 1IM3 → 1ScO+ + 1CS (Step 2), and reaction 2 3Sc+ + SCO → 3IM1 → CP → 1IM2 → 1TS2 → 1IM3 → 1ScO+ +1CS in which the spin multiplicity changes from the triplet state to the singlet state in the crossing region. It was concluded that the order of the equilibrium constants (K) and the reaction rate constants (k) are consistent with that of their corresponding exoergic energies, ΔE, and reaction barriers, respectively. Step 2 of reaction 1 is both thermodynamically and kinetically favored over the whole temperature range. Moreover, both Reaction 1 and reaction 2 are exothermic and spontaneous processes in which their entropy increases, and the magnitudes of their thermodynamic values all decrease with increasing temperature.

Thermodynamic and Kinetic Aspects of the Reactions of Titanium(I) ion with the Sulfurtransfer Reagent SCO via the C22O Bond Activation Pathway

Theoretical studies on the thermodynamic and kinetic aspects of the reactions of Ti+ ion with the sulfur-transfer reagent SCO via the C22O bond activation pathway have been carried out over the temperature range 200 — 1200K using the DFT=B3LYP method, general statistical thermodynamics and Eyring transition state theory with the Wigner correction. The relevant reactions comprise: reaction 1 [Formula: see text], and reaction 2 [Formula: see text] in which the spin multiplicity changes from the quartet state to the doublet state in the crossing region. It is concluded that the order of the equilibrium constants (K) and the reaction rate constants (k) are consistent with that of their corresponding exoergic energies DE and reaction barriers, respectively, and their differences at low temperature are larger than those at high temperature. Step 2 of reaction 1 is both thermodynamically and kinetically favoured over the entire temperature range. Moreover, both reactions 1 and 2 are exothermic and proceed spontaneously in which their entropy increases, and the magnitudes of their thermodynamic constants all decrease with rising temperature. The calculated DH8, DG8, and DS8 values of the two reactions are relatively similar. However, because reactants 4Ti+ and SCO have a lower energy than that of reactants 2Ti+ and SCO, it is reaction 2, in which the quartet state is changed to the doublet state through intersystem crossing, which should be seen as dominant.

Facile one-pot synthesis of thio and selenourea derivatives: A new class of potent urease inhibitors

A facile, one-pot synthesis of thio and selenourea derivatives from amines using tetrathiomolybdate 1 and tetraselenotungstate 2 as sulfur and selenium transfer reagents, respectively, is reported. The compounds were tested for their activity as urease inhibitors and some of the compounds showed potent activity in the nanomolar range towards jack bean urease.

Regio‐ and Stereospecific Synthesis of β‐Sulfonamidodisulfides and β‐Sulfonamidosulfides from Aziridines Using Tetrathiomolybdate as a Sulfur Transfer Reagent.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Novel chalcogenides of thymidine and uridine: synthesis, properties and applications

A facile and efficient methodology has been developed for the synthesis of dithymidine and di-uridine derived disulfides using benzyltriethylammonium tetrathiomolybdate as a sulfur transfer reagent. However, a similar reaction of thymidine derivative with tetraethylammonium tetraselenotungstate as a selenium transfer reagent resulted in the formation of an unexpected cyclic diselenide. The disulfide derivatives of nucleosides have been used as precursors in a tandem disulfide cleavage-Michael addition/ring opening reactions to construct aminoacid and carbocyclic derivatives of nucleosides.

Regio- and Stereospecific Synthesis of β-Sulfonamidodisulfides and β-Sulfonamidosulfides from Aziridines using Tetrathiomolybdate as a Sulfur Transfer Reagent

A comprehensive study of a general and effective one-step procedure for the synthesis of beta-sulfonamidodisulfides directly from N-tosyl aziridines in a regio- and stereospecific manner under neutral conditions without the use of any Lewis acid or base has been reported. This methodology is extended to the synthesis of an optically pure cyclic seven-membered disulfide 29. Synthesis of a variety of beta-sulfonamidosulfides involving tandem, multistep reactions in one pot is also reported.

New conformationally locked thioderivatives of mannose: synthesis, applications, and mechanistic studies

Tetrathiomolybdate has been used as an efficient sulfur-transfer reagent in the synthesis of a number of thiolevomannosan derivatives having an axial-rich 1 C 4 conformation. An unprecedented synthesis of a novel thioorthoester and its synthetic utility in glycosylation has been demonstrated. This is a general and efficient method for the synthesis of conformationally locked thiosugars.

Heterocyclic Chemistry of Sulfur Chlorides — Fast Ways to Complex Heterocycles.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis of Thioglycosides by Tetrathiomolybdate‐Mediated Michael Additions of Masked Thiolates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chemistry of tetrathiomolybdate and tetraselenotungstate: Applications in carbohydrate chemistry

Abstract An efficient one pot synthesis of thio and selenolevoglucosans from 1,6-diactivated carbohydrate derivatives has been achieved using benzyltriethylammonium tetrathiomolybdate, [BnNEt3]2MoS4, as a sulfur transfer reagent and tetraethylammonium tetraselenotungstate, [Et4N]2WSe4, as a selenium transfer reagent, respectively. The methodology has also been extended to the synthesis of 1,5-epithio and 1,5-episeleno pentoses.

Advances in the Applications of Polymer‐Supported Reagents for Organic Synthesis

AbstractFor Abstract see ChemInform Abstract in Full Text.

The correct formulation of the sulfur transfer reagent benzyltriethylammonium tetracosathioheptamolybdate

The recently reported sulfur transfer reagent benzyltriethylammonium tetracosathioheptamolybdate [(PhCH 2)N(C 2H 5) 3] 6[Mo 7S 24] [ Tetrahedron Lett. 2003, 44, 887] is correctly formulated as benzyltriethylammonium tetrathiomolybdate [(PhCH 2)N(C 2H 5) 3] 2[MoS 4]. The correct formulation explains the unusual sulfur transfer properties of [(PhCH 2)N(C 2H 5) 3] 6[Mo 7S 24] observed in the earlier work.

Chemistry of Tetrathiomolybdate and Tetraselenotungstate: Applications in Carbohydrate and Peptide Chemistry

The reagents, benzyltriethylammonium tetrathiomolybdate, [BnNEt3]2MoS4 1 [1] and tetraethylammonium tetra­selenotungstate [Et4N]2WSe4 2 have been shown to be useful for sulfur and selenium transfer reactions respectively in organic synthesis. Preparation of disulfides from alkyl halides, [2] ring opening of epoxides, [3] tandem sulfur transfer-reduction-Michael addition [4] in one step, reduction of aryl azides to amines [5] and alkyl azides to imines [5] have been reported from our laboratory using the reagent tetrathiomolybdate 1. Tetrathiomolybdate 1 is also used for the selective deprotection of propargyloxycarbonyl (Poc) protective group for amines [6] in peptides and for alcohols [7] in carbohydrate chemistry. Recently, regio­selective reduction of anomeric azides [8] to amines using the reagent 1 has been reported. Reagent 1 has also been used, as a sulfur transfer reagent, for the synthesis of phosphorothioate oligonucleotides. [9] Large quantities of 1 can be prepared from ammonium tetrathiomolybdate and benzyltriethylammonium chloride. [2a]

Solid Phase Synthesis of Phosphorothioate Oligonucleotides Utilizing Diethyldithiocarbonate Disulfide (DDD) as an Efficient Sulfur Transfer Reagent

Diethyldithiodicarbonate (DDD), a cheap and easily prepared compound, is found to be a rapid and efficient sulfurizing reagent in solid phase synthesis of phosphorothioate oligodeoxyribonucleotides via the phosphoramidite approach. Product yield and quality based on IP-LC-MS compares well with high quality oligonucleotides synthesized using phenylacetyl disulfide (PADS) which is being used for manufacture of our antisense drugs.

Solution Phase Synthesis of ISIS 2922 (Vitravene) by the Modified H‐Phosphonate Approach.

The synthesis of Vitravene, a 21-mer oligonucleotide phosphorothioate (d[Gp(s)Cp(s)Gp(s)Tp(s)Tp(s)Tp(s)Gp(s)Cp(s)Tp(s)Cp(s)Tp(s)Tp(s)Cp(s)Tp(s)Tp(s)Cp(s)Tp(s)Tp(s)Gp(s)Cp(s)G]) by the modified H-phosphonate approach in solution is reported. The synthetic strategy adopted involves the use of only four different trimer building blocks. The dimer and trimer blocks are prepared by a novel four component procedure in which the coupling agent (diphenyl phosphorochloridate 5b) and the sulfur-transfer reagent (N-[(2-cyanoethylsulfanyl)succinimide] 19) are added at the same time. Yields both of the building blocks and in the block coupling reactions are very satisfactory. The fully-protected 21-mer 38 is unblocked by a five-step procedure to give Vitravene, which is isolated as its sodium salt.

A New Reagent for the Efficient Synthesis of Disulfides from Alkyl Halides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A convenient synthesis of diacyl sulfides using a novel sulfur transfer reagent

AbstractVarious diacyl sulfides were synthesized by reaction of acyl chlorides with LiAlHSH. Reaction of glutaryl chloride with LiAlHSH afforded glutaric thioanhydride. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:633–635, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10217

Advances in the Applications of Polymer-Supported Reagents for Organic Synthesis

This chapter discusses the new developments in polymer-supported reagents, with reagents grouped by different classes of chemical transformations. Polymer-supported acids and bases have been used extensively as ion-exchange resins for purifications and reagents for synthetic transformations. Their handling properties guarantee easy manipulations allowing rapid reaction optimization and parallel synthesis development. Using acids and bases, several reactions have been carried out. Some of these include the synthesis of dihydropyrimidones, oxidations and reductions, synthesis of carboxylic acids, and hydrogenation of alkenes. The Anelli oxidation of alcohols to aldehydes and ketones has been accomplished using polymer-supported nitroxyl radical catalysts. Various polymer-supported hydrides have been applied successfully to the reductions of both carbonyl and olefin groups. The sulfur and phosphorous transfer reagents are discussed. New polymer-supported reagents for sulfide transfer have been developed to avoid exposure to malodorous and toxic sulfur reagents. The chapter also reviews various esterification and amide-coupling reagents.

A new reagent for the efficient synthesis of disulfides from alkyl halides

Benzyltriethylammonium tetracosathioheptamolybdate [(C 6H 5CH 2N(Et) 3) 6Mo 7S 24] has been found to be a superior sulfur transfer reagent for the conversion of alkyl halides to the corresponding disulfides in excellent yields under very mild reaction conditions.

Solution phase synthesis of ISIS 2922 (Vitravene) by the modified H-phosphonate approach

The synthesis of Vitravene, a 21-mer oligonucleotide phosphorothioate (d[Gp(s)Cp(s)Gp(s)Tp(s)Tp(s)Tp(s)Gp(s)Cp(s)Tp(s)Cp(s)Tp(s)Tp(s)Cp(s)Tp(s)Tp(s)Cp(s)Tp(s)Tp(s)Gp(s)Cp(s)G]) by the modified H-phosphonate approach in solution is reported. The synthetic strategy adopted involves the use of only four different trimer building blocks. The dimer and trimer blocks are prepared by a novel four component procedure in which the coupling agent (diphenyl phosphorochloridate 5b) and the sulfur-transfer reagent (N-[(2-cyanoethylsulfanyl)succinimide] 19) are added at the same time. Yields both of the building blocks and in the block coupling reactions are very satisfactory. The fully-protected 21-mer 38 is unblocked by a five-step procedure to give Vitravene, which is isolated as its sodium salt.