126-68-1Relevant articles and documents
Nucleoside H-phosphonates. 18. Synthesis of unprotected nucleoside 5'- H-phosphonates and nucleoside 5'-H-phosphonothioates and their conversion into the 5'-phosphorothioate and 5'-phosphorodithioate monoesters
Jankowska, Jadwiga,Sobkowska, Anna,Cieslak, Jacek,Sobkowski, Michal,Kraszewski, Adam,Stawinski, Jacek,Shugar, David
, p. 8150 - 8156 (1998)
A simple and efficient protocol for the preparation of unprotected nucleoside 5'-H-phosphonates and nucleoside 5'-H-phosphonothioates via a one- step deprotection of suitable precursors with methylamine has been developed. The synthetic utility of the unprotected nucleotide derivatives was demonstrated by converting them under mild conditions to the corresponding nucleoside 5'-phosphorothioate and nucleoside 5'-phosphorodithioate monoesters. Factors affecting oxidation of H-phosphonate, H-phosphonothioate, and phosphite derivatives with elemental sulfur are also discussed.
Zwierzak
, p. 5177,5186 (1969)
Photochemical Conversion of 2-Thioxo-1,3-dithioles into Tetrathiafulvalenes
Tsujimoto, Kazuo,Okeda, Yukihiro,Ohashi, Mamoru
, p. 1803 - 1804 (1985)
Photochemical reactions of 4,5-diphenyl-2-thioxo-1,3-dithiole in the presence of an electron donor produce tetraphenyltetrathiafulvalene.
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Michaelis
, p. 6 (1872)
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Schuetz,Jacobs
, p. 1799 (1958)
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Ando et al.
, p. 807,808 (1979)
1,2,4-Dithiazole-5-ones and 5-thiones as efficient sulfurizing agents of phosphorus(iii) compounds - A kinetic comparative study
Ponomarov, Oleksandr,Laws, Andrew P.,Hanusek, Ji?í
supporting information, p. 8868 - 8876 (2013/01/15)
The sulfurization efficiency of 25 3-substituted-1,2,4-dithiazole-5-ones and 5-thiones towards triphenyl phosphite in acetonitrile, DCM, THF and toluene at 25 °C was evaluated. All the 1,2,4-dithiazoles are much better sulfurizing reagents than commercially available agents (PADS, TETD, Beaucage's reagent). The most efficient sulfurizing agents in all solvents are 3-phenoxy (4), 3-phenylthio (5) and 3-ethoxy-1,2,4-dithiazole-5-one (1) whose reactivity is at least two orders of magnitude higher than that of other 1,2,4-dithiazoles. Contrary to a previous report, the sulfurization with 1 does not yield carbonylsulfide and ethyl cyanate as the additional reaction products but unstable ethoxythiocarbonyl isocyanate which has been trapped with 4-methoxyaniline. Similar trapping experiments have proven that the site of attack is at the sulfur adjacent to the CO group for compounds 4 and 5. The reaction pathway involves rate-limiting initial nucleophilic attack of the phosphorus at sulfur followed by decomposition of the phosphonium intermediate to the corresponding phosphorothioate and isocyanate/isothiocyanate species. The existence of the phosphonium intermediate during sulfurization of triphenyl phosphine with 3-phenyl-1,2,4-dithiazole-5-thione (7a) was proven using kinetic studies. From the Hammett and Bronsted correlations and from other kinetic measurements it was concluded that the transition-state structure is almost apolar for the most reactive 1,2,4-dithiazoles whereas a polar structure resembling a zwitter-ionic intermediate may be more appropriate for the least reactive 1,2,4-dithiazoles. The extent of P-S bond formation and S-S bond cleavage is very similar in all reaction series but it gradually decreases with the reactivity of the 1,2,4-dithiazole derivatives.
Alkali metal ion catalysis and inhibition in nucleophilic displacement reactions at phosphorus centers: Ethyl and methyl paraoxon and ethyl and methyl parathion
Um, Ik-Hwan,Shin, Young-Hee,Lee, Seung-Eun,Yang, Kiyull,Buncel, Erwin
, p. 923 - 930 (2008/09/18)
(Chemical Equation Presented) We report on the ethanolysis of the P=O and P=S compounds ethyl and methyl paraoxon (1a and 1b) and ethyl and methyl parathion (2a and 2b). Plots of spectrophotometrically measured rate constants, kobsd versus [MOEt], the alkali ethoxide concentration, show distinct upward and downward curvatures, pointing to the importance of ion-pairing phenomena and a differential reactivity of free ions and ion pairs. Three types of reactivity and selectivity patterns have been discerned: (1) For the P=O compounds 1a and 1b, LiOEt > NaOEt > KOEt > EtO-; (2) for the P=S compound 2a, KOEt > EtO- > NaOEt > LiOEt; (3) for P=S, 2b, 18C6-crown-complexed KOEt > KOEt = EtO- > NaOEt > LiOEt. These selectivity patterns are characteristic of both catalysis and inhibition by alkali-metal cations depending on the nature of the electrophilic center, P=O vs P=S, and the metal cation. Ground-state (GS) vs transition-state (TS) stabilization energies shed light on the catalytic and inhibitory tendencies. The unprecedented catalytic behavior of crowned-K+ for the reaction of 2b is noteworthy. Modeling reveals an extreme steric interaction for the reaction of 2a with crowned-K+, which is responsible for the absence of catalysis in this system. Overall, P=O exhibits greater reactivity than P=S, increasing from 50- to 60-fold with free EtO- and up to 2000-fold with LiOEt, reflecting an intrinsic P=O vs P=S reactivity difference (thio effect). The origin of reactivity and selectivity differences in these systems is discussed on the basis of competing electrostatic effects and solvational requirements as function of anionic electric field strength and cation size (Eisenman's theory).
Mechanism of the sulfurisation of phosphines and phosphites using 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride)
Hanusek, Jiri,Russell, Mark A.,Laws, Andrew P.,Jansa, Petr,Atherton, John H.,Fettes, Kevin,Page, Michael I.
, p. 478 - 484 (2008/03/27)
Contrary to a previous report, the sulfurisation of phosphorus(iii) derivatives by 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride) does not yield carbon disulfide and cyanamide as the additional reaction products. The reaction of xanthane hydride with triphenyl phosphine or trimethyl phosphite yields triphenyl phosphine sulfide or trimethyl thiophosphate, respectively, and thiocarbamoyl isothiocyanate which has been trapped with nucleophiles. The reaction pathway involves initial nucleophilic attack of the phosphorus at sulfur next to the thiocarbonyl group of xanthane hydride followed by decomposition of the phosphonium intermediate formed to products. The Hammett ρ-values for the sulfurisation of substituted triphenyl phosphines and triphenyl phosphites in acetonitrile are ～ -1.0. The entropies of activation are very negative (-114 ± 15 J mol-1 K-1) with little dependence on solvent which is consistent with a bimolecular association step leading to the transition state. The negative values of ΔS ≠ and ρ values indicate that the rate limiting step of the sulfurisation reaction is formation of the phosphonium ion intermediate which has an early transition state with little covalent bond formation. The site of nucleophilic attack has been also confirmed using computational calculations. The Royal Society of Chemistry 2007.
