- Nonenzymatic Dynamic Kinetic Resolution of in situ Generated Hemithioacetals: Access to 1,3-Disubstituted Phthalans
-
The first nonenzymatic DKR reaction of hemithioacetals is developed. Hemithioacetals were formed in situ via thiol addition and subsequently underwent an intramolecular oxa-Michael reaction. The scope of the reaction was quite broad ranging from aliphatic to aromatic substituents and 1,3-disubstituted-1,3-dihyroisobenzofuran products were obtained in good yields with moderate diastereoselectivities and high enantioselectivities. (Figure presented.).
- Nath, Utpal,Chowdhury, Deepan,Pan, Subhas Chandra
-
supporting information
p. 1628 - 1633
(2018/03/21)
-
- Phosphorus Pentasulfide Mediated Conversion of Primary Carbamates into Thiols
-
In this paper, we report a method for the conversion of primary carbamates into thiols in the presence of phosphorus pentasulfide (P 2 S 5) in refluxing toluene. Presently, no method exists in the literature for conversion of carbamates into thiols and, to the best of our knowledge, it is the first report for this type of conversion. This method presents an indirect route for the conversion of alcohols into thiols via their carbamate derivatives that may be useful in the total synthesis of compounds containing a thiol functionality.
- Maurya, Chandra Kant,Gupta, Pradeep Kumar
-
p. 1649 - 1651
(2017/08/11)
-
- Phosphorus pentasulfide mediated conversion of organic thiocyanates to thiols
-
In this paper we report an efficient and mild procedure for the conversion of organic thiocyanates to thiols in the presence of phosphorus pentasulfide (P2S5) in refluxing toluene. The method avoids the use of expensive and hazardous transition metals and harsh reducing agents, as required by reported methods, and provides an attractive alternative to the existing methods for the conversion of organic thiocyanates to thiols.
- Maurya, Chandra Kant,Mazumder, Avik,Gupta, Pradeep Kumar
-
supporting information
p. 1184 - 1188
(2017/07/03)
-
- Preparation and in-vitro evaluation of 4-benzylsulfanylpyridine-2- carbohydrazides as potential antituberculosis agents
-
A set of 4-benzylsulfanylpyridine-2-carbohydrazides was synthesized and evaluated for in vitro antimycobacterial activity against Mycobacterium tuberculosis, non-tuberculous mycobacteria, and multidrug-resistant M. tuberculosis. The activities expressed as the minimum inhibitory concentration (MIC) fall into a range of 2 to 125 μmol/L, most often 4 to 32 μmol/L. The results revealed that the substituents on the benzyl moiety do not influence the antimycobacterial efficacy. The substances exhibited similar activities against sensitive and resistant strains of M. tuberculosis. Furthermore, compounds show low antiproliferative effect and cytotoxicity.
- Herzigova, Petra,Klimesova, Vera,Palat, Karel,Kaustova, Jarmila,Dahse, Hans-Martin,Moellmann, Ute
-
body text
p. 394 - 404
(2009/11/30)
-
- Electron transfer to sulfides and disulfides: Intrinsic barriers and relationship between heterogeneous and homogeneous electron-transfer kinetics
-
The electron-acceptor properties of series of related sulfides and disulfides were investigated in N,N-dimethylformamide with homogeneous (redox catalysis) and/or heterogeneous (cyclic voltammetry and convolution analysis) electrochemical techniques. The electron-transfer rate constants were determined as a function of the reaction free energy and the corresponding intrinsic barriers were determined. The dependence of relevant thermodynamic and kinetic parameters on substituents was assessed. The kinetic data were also analyzed in relation to corresponding data pertaining to reduction of diaryl disulfides. All investigated reductions take place by stepwise dissociative electron transfer (DET) which causes cleavage of the Calkyl-S or S-S bond. A generalized picture of how the intrinsic electron-transfer barrier depends on molecular features, ring substituents, and the presence of spacers between the frangible bond and aromatic groups was established. The reduction mechanism was found to undergo a progressive (and now predictable) transition between common stepwise DET and DET proceeding through formation of loose radical anions. The intrinsic barriers were compared with available results for ET to several classes of dissociative- and nondissociative-type acceptors, and this led to verification that the heterogeneous and the homogeneous data correlate as predicted by the Hush theory.
- Meneses, Ana Belen,Antonello, Sabrina,Arevalo, Maria Carmen,Gonzalez, Concepcion Carmen,Sharma, Jadab,Wallette, Andrea N.,Workentin, Mark S.,Maran, Flavio
-
p. 7983 - 7995
(2008/04/01)
-
- Thioacetate deprotection
-
A method of thioacetate deprotection by providing a compound of the formula R1—S—CO—R2, and reacting the compound with a quaternary ammonium cyanide salt in the presence of a protic solvent in an inert atmosphere to convert the compound to a product of the formula R1—SH. R1 is an organic group in which the bonding to sulfur is through a saturated carbon, and R2 is an aliphatic group.
- -
-
-
- 5-HYDROXYINDOLE-3-CARBOXYLATES DERIVATIVES AND THEIR USE
-
The present invention relates to 5-hydroxy-indole-3-carboxylate derivatives of formula I , or racemic mixture or optical isomers or pharmaceutically acceptable salts and/or hydrates thereof, wherein: substitutents R 1 , R 2 , Z, X and Y are as defined in the description. The compounds of formula I can be useful for preparation of medicament for treatment and/or prophylaxis of virus infections, especially for preparation of medicament for anti-HBV (Hepatitis B virus) and anti-HIV (Human immunodeficiency virus).
- -
-
Page/Page column 14
(2010/11/25)
-
- Aliphatic thioacetate deprotection using catalytic tetrabutylammonium cyanide
-
A series of thiol-functionalized organic compounds were selected to analyze the scope and efficiency of a new thioacetate deprotection method using catalytic tetrabutylammonium cyanide (TBACN) to effect the transformation of a thioacetate group to a free thiol in the presence of a protic solvent. Particularly attractive are the mild reaction and workup conditions, reduced byproduct formation typically seen using literature methods and yields of greater than 80% for the free aliphatic thiols. This method is effective on aliphatic thiols with trityl, benzyl, p-halo-benzyl, phenethyl, phenoxyethyl, and cyclohexylethyl structural moieties, but it is not effective with thiophenols.
- Holmes, Brian T.,Snow, Arthur W.
-
p. 12339 - 12342
(2007/10/03)
-
- Mechanism of the Solution-Phase Reaction of Alkyl Sulfides Atomic Hydrogen. Reduction via a 9-S-3 Radical Intermediate
-
The low selectivity of benzyl alkyl sulfide fragmentation subsequent to its reaction with atomic hydrogen is indicative of a reaction that proceeds via an early transition state. The competitive reduction of a series of substituted-benzyl alkyl sulfides was insensitive to the substituent on the aromatic ring (ρ = -0.13, r = 0.99). The relative rates of fragmentation of a series of the substituted-benzyl alkyl sulfides gave a V-shaped Hammett plot. Both electron-donating and electron-withdrawing groups destabilized the transition state (ρ = +0.99, r = 0.999; ρ = -0.82, r = 0.992). Since the relative rates of disappearance of the alkyl benzyl sulfides are not substituent dependent, but the relative rates of fragmentation are, a 9-S-3 intermediate is preferred as the structure leading to products.
- Tanner, Dennis D.,Koppula, Sudha,Kandanarachchi, Pramod
-
p. 4210 - 4215
(2007/10/03)
-
- Sulfur-containing imidazoles
-
Novel imidazole mercaptals of the formula STR1 wherein each m is independently zero or one; and R1 and R2 each are independently selected from (lower)alkyl, cycloalkyl, cycloalkyl(lower)alkyl, phenyl, phenyl(lower)alkyl, thienyl, thienyl(lower)alkyl, pyridyl and pyridyl(lower)alkyl, in which the phenyl and heterocyclic rings optionally may contain from 1 to 3 substituents, and acid addition salts thereof, are useful antimicrobial agents.
- -
-
-
- Correlation pKa - activitee catalitique des thiols dans la reeaction d'hydrolyse de l'aceetate de p-nitropheenyle
-
The kinetic study of the hydrolysis of p-nitrophenylacetate in the presence of primary thiols indicates the thiolate anion as the sole catalytic species.Comparison of the true second order constants (kRS-) reveals that purely aliphatic primary thiols behave differently from aromatic α-substituted primary thiols.In the latter group a correlation can be established between the true second order rate constants and the pKSH values by means of the Broensted equation log kRS- = βpKSH + C, with β equal to 0.40 and C equal to -0.85.
- Brembilla, Alain,Roizard, Denis,Schoenleber, Jacqueline,Lochon, Pierre
-
p. 2330 - 2336
(2007/10/02)
-