The reaction between arenediazonium tetrafluoroborates and alkaline thiocarboxylates in DMSO: A convenient access to aryl thiolesters and other aromatic sulfur derivatives

Copper(I)-Catalyzed Sandmeyer-Type S-Arylation of 1-Thiosugars with Aryldiazonium Salts under Mild Conditions

Preparation of S-aryl thioglycosides from 1-thiosugars via S-arylation was demonstrated under mild reaction conditions. A wide range of protected and unprotected 1-thiosugars derived from glucose, glucosamine, galactose, mannose, ribose, maltose, and lactose underwent cross-coupling reactions with functionalized aryldiazonium salts in the presence of copper(I) chloride and DBU. The desired products were obtained in 55-88% yields within 5 min. Various functional groups, including halogens, were tolerated under standard reaction conditions. Synthesis of the biologically relevant antidiabetic dapagliflozin S-analogue and arbutin S-analogues (tyrosinase inhibitors) was demonstrated.

A Novel Method for the Synthesis of Unsymmetrical Sulfides, Thioesters and β-thioesters

The S–S bond in disulfides was reduced by the Zn/ZrCl4 system in THF to produce sulfur anions, which react with alkyl halides, α,β-unsaturated esters and acyl chlorides or anhydrides to afford unsymmetrical sulfides, thioesters and β-thioesters, respectively.

A Convenient One-Pot Synthesis of Thiol Esters from Disulfides using a Zn/AlCl3 system

A novel synthetic procedure for the direct preparation of thiol esters from various disulfides and symmetrical anhydrides using a Zn/AlCl3 system is described.

Ytterbium Metal Promoted reaction of Disulfides with 2-Oxoimidazolidine-1-Carbonyl Chlorides

In the presence of a catalytic amount of methyl iodide, ytterbium metal can promote the reductive acylation of disulfides with 2-oxoimidazolidine-1-carbonyl chlorides to give 2-oxoimidazolidine-1-carbonyl thiolesters in good yields under neutral conditions.

Reductive Cleavage of the Sulfur–Sulfur Bond by the Samarium/Cp2TiCl2 Used for the Synthesis of S-Phenyl Thiolesters

A mild method is reported for the reductive cleavage of the sulfur–sulfur bond by the samarium/Cp2TiCl2 system to give a phenylthiolate anion species which reacts with acyl chlorides to give the corresponding S-phenyl thiolesters in good yields.

Hypervalent Iodine in Synthesis 56: A Convenient Route for the Synthesis of Thiol Esters via Palladium-Catalysed Alkylthiocarbonylation or Arylthiocarbonylation of Diaryliodonium Salts

Palladium-catalysed alkylthiocarbonylation or arylthiocarbonylation of diaryliodonium salts gives thiol esters in good yields.

Palladium-catalyzed carbonylation of thioacetates and aryl iodides for the synthesis of S-aryl thioesters

Palladium-catalyzed carbonylation of thioacetates and aryl iodides provided thioesters in good yields.

Efficient Cu-catalyzed base-free C-S coupling under conventional and microwave heating. A simple access to S-heterocycles and sulfides

S-aryl thioacetates can be prepared by reaction of inexpensive potassium thioacetate with both electron-rich and electron-poor aryl iodides under a base-free copper/ligand catalytic system. CuI as copper source affords S-aryl thioacetates in good to excellent yields, by using 1,10-phenanthroline as a ligand in toluene at 100 °C after 24 h. Under microwave irradiation the time was drastically reduced to 2 h. Both procedures are simple and involve a low-cost catalytic system. This methodology was also applied to the “one-pot” synthesis of target heterocycles, such as 3H-benzo[c][1,2]dithiol-3-one and 2-methylbenzothiazole, alkyl aryl sulfides, diaryl disulfides and asymmetric diaryl sulfides in good yields.

Nature of the Chain Propagation in the Photostimulated Reaction of 1-Bromonaphthalene with Sulfur-Centered Nucleophiles

The reactivity of -SC(NH)NH2 (1), MeCOS- (2), and PhCOS- (3) toward 1-naphthyl radicals was studied in DMSO. The photostimulated reaction of anions 1, 2, and 3 with 1-bromonaphthalene (4) after quenching with MeI renders 1-(methylthio)naphthalene (6) as a main product together with bis(1-naphthyl) sulfide (7) and naphthalene (5). The thioacetate ion (2) and thiobenzoate ion (3) were unreactive toward 4 as electron-donor under photostimulation; however, in the presence of potassium tert-butoxide anion (entrainment conditions), they gave the mentioned products 5, 6, and 7, after the addition of MeI. Quenching of the triplet state of 4 was assigned as the photoinduced initiation step, with a rate constant value of (4.6+/-0.5)x10(8) M-1 s-1 for tert-butoxide anion and a rough estimated value of (8+/-7)x10(7) M-1 s-1 for anion 1. By using hydrogen abstraction from DMSO as the competitive reaction, the absolute rate constants for the addition of anions 1, 2, and 3 to 1-naphthyl radicals have been determined to be 1.0x10(9), 1.2x10(9), and 3.5x10(9) M-1 s-1, respectively. This reactivity order is in agreement with the stability of the resulting radical anions (ArNu)*- (10-12)*-. The inhibition experiments of the photoinduced substitution reaction in the presence of radical scavengers and the global quantum yield higher than the unity are evidence of a radical chain mechanism for these substitution reactions by anions 1 and 2. Anion 3 adds to the 1-naphthyl radical, but is neither able to initiate nor to keep the propagation cycle. Evaluation of the electron-transfer driving forces for the reaction between (ArNu)*- and 4 together with the absence of a chain reaction for the anion 3 indicate that the propagation in the proposed mechanism is given by an acid-base reaction between the radical .C(O)Me or .C(NH)NH2 (13) and a base.

Efficient Synthesis of Thioesters and Amides from Aldehydes by Using an Intermolecular Radical Reaction in Water

The combination of the water-soluble radical initiator, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (VA-044) and the surfactant, cetyltrimethyl-ammonium bromide (CTAB), was found to be the most suitable condition for the effective and direct synthesis of useful active thioesters (pentafluorophenyl thioesters) in water. In addition, the direct amidation of aldehydes was achieved by the addition of the amines to the thioesterification reaction mixture in water.

“One-Pot” Two-Step Synthesis of Aryl Sulfur Compounds by Photoinduced Reactions of Thiourea Anion with Aryl Halides

[reaction: see text]. The photoinduced reactions of aryl halides with the thiourea anion afford arene thiolate ions in DMSO. These species without isolation, and by a subsequent aliphatic nucleophilic substitution, S(RN)1 reaction, oxidation, or protonation, yield aryl methyl sulfides, diaryl sulfides, diaryl disulfides, and aryl thiols with good yields (50-80%). This is a simple and convenient approach which involves the use of the commercially available and inexpensive thiourea in a "one-pot" two-step process for the synthesis of aromatic sulfur compounds.