Synthesis and Pesticidal Properties of Thio and Seleno Analogs of Some Common Urea Herbicides

Thio and seleno analogs of fenuron, isoproturon, chlorotoluron, metoxuron, monuron, and diuron were synthesized from the corresponding aryl amines. Their reaction with thiophosgene leads to isothiocyanates. Aryl amines were also converted (via isocyanides) to isoselenocyanates. The reaction of both isothio- and isoselenocyanates with dimethylamine affords the corresponding thio and seleno analogs of the above-mentioned urea herbicides. Herbicidal activity of the synthesized compounds was slightly lower than the activity of the parent urea herbicides. The thio and seleno analogs as well as the parent ureas showed good fungicidal activity at a concentration of 200 ppm against selected fungi.     

Photoinduced intramolecular cyclization of o-ethenylaryl isocyanides with organic disulfides mediated by diphenyl ditelluride

Photoinduced reaction of o-ethenylaryl isocyanides with organic disulfides in the presence of diphenyl ditellurides affords the corresponding bisthiolated indole derivatives via a radical cyclization process. The cyclization can proceed at room temperature upon visible-light irradiation and exhibits good tolerance to functional groups. Several organic disulfides also can be employed for this cyclization, and the corresponding bisthiolated indole derivatives are obtained selectively. In addition, the photoinduced reaction of o-ethenylaryl isocyanides with bis(2-aminophenyl) disulfide affords tetracyclic compounds in one portion.     

Simple and efficient copper-catalyzed S-arylation of diaryl disulfides with triarylbismuthanes under aerobic conditions

Novel and simple copper-catalyzed C(aryl)-S bond formation of diaryl disulfides with bismuth reagents is described. Reactions of diaryl disulfides with triarylbismuthanes in the presence of CuOAc (10 mol %) and 1,10-phenanthroline (10 mol %) under aerobic conditions led to the formation of unsymmetrical diaryl sulfides in satisfactory yields. The reaction is atom-economic and all three aryl groups of the triarylbismuthanes and both sulfanyl groups of the diaryl disulfides could be transferred to the coupling products.     

Rhodium-catalyzed organothio exchange reaction of α-organothioketones with disulfides

RhH(PPh(3))(4) and 1,2-bis(diphenylphosphino)ethane (dppe) catalyzed the organothio exchange reaction of α-organothioketones and organic disulfides. The reaction was affected by the structure of the substrate: α-phenylthio and α-alkylthio aryl ketones reacted effectively with diaryl and dialkyl disulfides; α-phenylthio dialkyl ketones reacted with diaryl disulfides but not with dialkyl disulfides; diaryl disulfides with electron-donating p-substituents were more reactive than those with electron-withdrawing p-substituents.     

Carboxylphosphanes and Carboxyphosphane Chalcogenides

Abstract

Low temperature reactions of organo chloro phosphanes with carboxylic acids and their salts allow the preparation of carboxyphosphanes - mixed anhydrides of carboxylic acids with phosphinic acids. These are subject to thermal rearrangement reaction of the Michaelis-Arbusov type. Molecular oxygen converts them into carboxy-phosphorane oxides. These compounds are also obtainable by reacting organochlorophosphane oxides with carboxylates. Their thermal stability is higher than that of the P(III)compounds. Analoguous reactions of P-sulfides and selenides give the corresponding thio and seleno phosphoranes with higher thermal stability. At elevated temperatures a number of rearrangement reactions occur, thus producing phosphane oxides and phosphinic acid phosphinyl alkaryl ester. The reaction products of the following reaction sequences are discusses with regard to their NMR-, IR-, MS-spectra and hydrolytic and thermal properties:     

Laser-flash photolysis of naphthyl diselenides; reactivities of naphthylseleno radicals

Transient absorption spectra of 1-naphthylseleno (1-NaphSe˙), and 2-naphthylseleno (2-NaphSe˙) radicals, which are generated by laser-flash photolysis of the corresponding diselenides, were observed. The reactions of 1-NaphSe˙, and 2-NaphSe˙ with 2-methyl-1,3-butadiene and α-methylstyrene were investigated by following the decay rates of these seleno radicals. By both steady-state and laser-flash photolysis, it is proved that these seleno radicals add to alkenes in a reversible manner. The reaction rate constants for such reversible addition reactions were determined by conducting the reaction in the presence of O₂, which traps selectively the carbon-centered radicals formed by the addition reaction of the seleno radicals to the alkenes. The reactivity of 2-NaphSe˙ is higher than that of 1-NaphSe˙, both of which are less reactive than PhSe˙. These reactivities were interpreted with the properties of SOMO calculated by MO method. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 193–200, 1998.     

Palladium-Catalyzed Carbonylative Lactonization of Propargyl Alcohols with Organic Dichalcogenides and Carbon Monoxide

The reaction of propargylic alcohols with diaryl disulfides and carbon monoxide in the presence of tetrakis(triphenylphosphine)palladium leads to a novel thiolative lactonization to afford beta-(arylthio)-alpha,beta-unsaturated lactones in moderate to good yields. Similar conditions can be employed with homopropargylic alcohols, giving the corresponding delta-lactones with a beta-arylthio group successfully. The reaction using diaryl diselenides in lieu of diaryl disulfides also attains a similar one-pot thiolation/lactonization sequence to provide the corresponding beta-selenobutenolides (7).     

NONCONVENTIONAL FRIEDEL-CRAFTS CHEMISTRY III. ON THE REGIOSPECIFIC SYNTHESIS OF SPIRO[CYCLOALKANE-1,1′-ISOTHIOCHROMAN]-4′-ONE DERIVATIVES

Abstract

The reaction of 1-oxa-4-thiaspiro[4,4]nonan-2-one (4) and/or 1-oxa-4-thiaspiro[4,5]decan-2-one (5) with arenes (6) under the catalytic action of aluminum chloride afforded in all cases spiro[cycloalkane-1,1′-isothiochroman]-4′-ones (7a-g and 8a-g), [(arylcycloalkyl)thio]-acetic acid, (9a-g and 10a-g), cy-cloalkylthioacetic acids, (11 and 20) aryl cycloalkyl sulfides, (14 and 23) diaryl sulfides (15), diaryl disulfides and dicycloalkyl disulfides (13 and 22). The mechanisms of these reactions are discussed.     

Synthesis and photochemistry of a new class of photocleavable protein cross-linking reagents

A new series of photocleavable protein cross-linking reagents based on bis(maleimide) derivatives of diaryl disulfides have been synthesised. They have been functionalised with cysteine and transient absorption spectra for the photolysis reaction have been recorded by using the pump-probe technique with a time resolution of 100 femtoseconds. Photolysis of the disulfide bond yields the corresponding thiyl radicals in less than a picosecond. There is a significant amount of geminate recombination, but some of the radicals escape the solvent cage and the quantum yield for photocleavage is 30 % in water.     

Rhodium-catalyzed arylthiolation reaction of nitroalkanes, diethyl malonate, and 1,2-diphenylethanone with diaryl disulfides: control of disfavored equilibrium reaction

In the presence of catalytic amounts of RhH(PPh₃)₄ and 1,2-bis(diphenylphosphino)ethane (dppe), 1-nitroalkanes reacted with a diaryl disulfide giving 1-arylthio-1-nitroalkanes in air. The equilibrium to form thermodynamically disfavored products was shifted by the rhodium-catalyzed oxidation of thiols to disulfides and water. The thiolation reaction of cyclic nitroalkanes proceeded in high yields provided that suitable diaryl disulfides were employed depending on the substrate: di(p-chlorophenyl) disulfide was used for the thiolation reaction of 1-nitroalkanes, 1-nitrocyclopentane and 1-nitrocycloheptane with acidic α-protons (pK_a 16 and 17); di(p-methoxyphenyl) disulfide for 1-nitrocyclobutane and 1-nitrocyclohexane with less acidic α-protons (pK_a ca. 18). Related reactivities were observed in the thiolation reactions of malonate and 1,2-diphenylethanone.     

Rhodium-catalyzed disulfide exchange reaction

A system of RhH(PPh3)4, trifluoromethanesulfonic acid, and (p-tol)3P catalyzes the disulfide exchange reaction. Treatment of two symmetrical dialkyl disulfides with the catalyst provides an equilibrium mixture of three disulfides within 15 min in refluxing acetone. The catalyst is active after reaching the equilibrium, and addition of a disulfide to the mixture changes the ratio of the products. The use of 4 mol equiv excess of one of the disulfides provides the unsymmetrical disulfide in a yield exceeding 80%. Disulfide-containing peptides also undergo an exchange reaction. The reactions of diaryl disulfides and dialkyl disulfides are even faster, and reach equilibrium within 5 min at room temperature in the presence of the rhodium complex and 1,2-bis(diphenylphosphino)ethane (dppe). This exchange reaction is considerably affected by the substituents on the disulfides. Treatment of diphenyl disulfide, di(p-tolyl) disulfide, and bis(sec-butyl) disulfide yields phenyl p-tolyl disulfide at room temperature with unchanged bis(sec-butyl) disulfide; random disproportionation occurs at reflux. The rhodium catalysis can be used for the exchange reaction of disulfides and diselenides giving selenosulfides as well as disulfides and ditellurides giving tellurinosulfides.     

Radical arylation of acetyl-substituted thioureas

Conclusions The reaction of N-acetylthiourea with phenyl and p-tolyl radicals leads to diaryl disulfides and 2-methyl -4-thioaryl-6-acetamido-s-triazines.A scheme was proposed for the formation of substituted s-triazines by the successive transformation of the intermediate radicals.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2591–2593, November, 1982.     

Modular CeCl3·7H2O-catalyzed multi-component synthesis of 1,2,3,4-tetrasubstituted pyrroles under microwave irradiation and their further trichloroisocyanuric acid-mediated conversion into 5-sulfenylpyrrole derivatives

A modular, multicomponent synthesis of 1,2,3,4-tetrasubstituted pyrroles promoted by the inexpensive CeCl₃·7H₂O, is reported. The reaction was carried out under microwave irradiation, affording good yields of products in short time. Scope and limitations were explored and a plausible reaction mechanism is discussed. The resulting heterocycles were smoothly and efficiently converted into their corresponding 5-arylsulfenyl derivatives by reaction with diaryl disulfides and trichloroisocyanuric acid in EtOAc.     

MODERN FRIEDEL–CRAFTS CHEMISTRY. XIV. ON THE CYCLIZATION OF SELECTED ARYL HYDROXYALKYL SULFIDES

Abstract

The feasibility of cycloalkylation reactions in the presence of Friedel–Crafts catalysts was demonstrated in a number of aryl hydroxyalkyl sulfides (1–5), and benzyl hydroxyalkyl sulfides (6–7). Treatment of compounds (1–7) with Friedel-Crafts catalysts gave diaryl disulfides, diaryl sulfides, arene thiols, chlorohydrins, aryl chloroalkyl sulfides, aryl alkenyl sulfides and cyclization products. It is noteworthy to mention that cyclization products were isolated only in cases where the hydroxyl group is linked to a tertiary carbon atom as in compounds 3 and 7.

A suitable reaction pathway is suggested to rationalize the formation of the various reaction products.     

Chemistry of trichlorofluoromethane: synthesis of chlorofluoromethyl phenyl sulfone and fluoromethyl phenyl sulfone and some of their reactions.

It was observed that the reaction of CFCl3 with thiophenoxide gave only 10% of the corresponding thioether. On the other hand, these thioethers could be prepared in excellent yield from diaryl disulfides and CFCl3 in the presence of sodium hydroxymethanesulfinate in aqueous DMF at 4 atm pressure of nitrogen. Dechlorination of the thioether (PhSCFCl2) with different reducing agents were studied. Most of the reducing agents eliminated both fluorine and chlorine functionalities or gave the hydrolyzed products. But its sulfone on treatment with Zinc in methanol gave monochlorofluoromethyl and fluoromethyl phenyl sulfone in good yields. Darzens reaction of these compounds was also studied.     

Perfluoroalkylation of 2-Thiopyrimidine Derivatives

The method of perfluoroalkylation of heterocyclic thiols and disulfides by thermolytic reaction with xenon(II) bisperfluoroalkylcarboxylates has been extended to sulfur-containing pyrimidines, including 2-mercaptopyrimidines, symmetrical disulfides, and S-trifluoroacetyl derivatives obtained from the corresponding thiols. The main reaction products are 2-SC_nF_2n+1 (n = 1, 2)-substituted pyrimidines. Their formation proceeds only via disulfides into which the initial thiols and S-trifluoroacetyl derivatives are converted in the reaction medium. Side reactions occurred in the case of trifluoromethylation linked with the perfluoroalkylation of the pyrimidine nucleus at the free 5 position (in the case of the 4,6-dimethyl derivative), or at position 4 or 4 and 5 (for unsubstituted pyrimidine). In addition, the introduction of the CF₃ group at one of the methyl substituents was confirmed by the formation of CH₂CF₃ fragment.     

Base Metal Catalyzed Isocyanide Insertions

Isocyanides are diverse C₁ building blocks considering their potential to react with nucleophiles, electrophiles, and radicals. Therefore, perhaps not surprisingly, isocyanides are highly valuable as inputs for multicomponent reactions (MCRs) and other one‐pot cascade processes. In the field of organometallic chemistry, isocyanides typically serve as ligands for transition metals. The coordination of isocyanides to metal centers alters the electronic distribution of the isocyano moiety, and reaction pathways can therefore be accessed that are not possible in the absence of the metal. The tunable reactivity of the isocyanide functional group by transition metals has evolved into numerous useful applications. Especially palladium‐catalyzed isocyanide insertion processes have emerged as powerful reactions in the past decade. However, reports on the use of earth‐abundant and cheap base metals in these types of transformations are scarce and have received far less attention. In this Minireview, we focus on these emerging base metal catalyzed reactions and highlight their potential in synthetic organic chemistry. Although mechanistic studies are still scarce, we discuss distinct proposed catalytic cycles and categorize the literature according to 1) the (hetero)atom bound to and 2) the type of bonding with the transition metal in which the (formal) insertion occurs.     

Addition of ArSSAr to carbon-carbon multiple bonds using electrochemistry

ArS(ArSSAr)⁺ (arylbis(arylthio)sulfonium ions), which were generated and accumulated by the electrochemical oxidation of diaryl disulfides (ArSSAr) in CH₂Cl₂ at −78 °C, reacted with alkenes to give the corresponding diarylthio-substituted compounds in a stereospecific manner in good yields, when the reaction was quenched with a soft nucleophile, such as allylsilanes, ketene silyl acetals, and triethylamine. A mechanism involving the initial formation of an episulfonium ion followed by ring-opening by the attack of ArSSAr has been suggested. The reactions of ArS(ArSSAr)⁺ with alkynes also took place to give 1,2-diorganothio-substitued alkenes stereoselectively under similar conditions.     

Photoreaction between benzoylthiophenes and N-BOC-tryptophan methyl ester

Drug-induced photoallergy requires as the first step formation of covalent drug-protein photoadducts. One of the key amino acids involved in this process is tryptophan (Trp). In this context, several diaryl ketones, including 2-benzoylthiophene (BT), [2-(5-benzoyl-5-thienyl)]-2-methylpropanoic methyl ester (TPA methyl ester) and 4-(2-thienylcarbonyl)phenyl]-2-methylpropanoic methyl ester (SUP methyl ester) have been irradiated in the presence of N-BOC-(L)-tryptophan methyl ester. Laser flash photolysis has allowed to detect three neutral radicals (ketyl, indolyl and skatolyl radicals) resulting from formal hydrogen-atom abstraction. This correlates well with the isolation of homodimers, as well as with cross-coupling products, in the preparative irradiation. The main cross-coupling products were in all cases lactones arising from the reaction of the Trp-derived skatolyl radicals with the corresponding ketyl radicals. These lactones were obtained as the (4R) stereoisomers with remarkable diasteroselectivity. No coupling products through the phenyl p-position of BT or TPA methyl ester were found. By contrast, ketone homodimers and cross-coupling products arising from reaction through the thienyl 5-position were obtained when using BT and SUP methyl ester; this is very interesting, because stable LAT-derived products are difficult to isolate.     

"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.