Reactions of α-Sulfenyl-N-anions with Nitrogen Participation. Reactions of N-Substituted Sulfenylamide Salts with Isothiocyanates

Reaction of N-aroyl- and N-arylsulfonylarenesulfenylamide salts with aryl isothiocyanates in acetone results in salts of N-arenesulfenyl-N-aroyl(arylsulfonyl)-N'-arylthioureas that in the presence of mineral acids are transformed into the corresponding thioureas.     

Mesomere Kationen. IV—13C-NMR-Spektren von Uronium-, Thiouronium- und Guanidiniumsalzen,sowie einigen Guanidinen

The ¹³C chemical shifts of uronium-, thiouronium- and guanidinum salts are reported, and compared with the shifts of the corresponding uncharged ureas, thioureas and guanidines. The shifts for the aromatic carbon atoms in these compounds compared with related phenols and thiophenols give insight into the charge distribution in the systems.     

Synthesis and characterization of tetraphenylphosphonium salts of N-phosphorylated thioureas and bis-thioureas

Russian Chemical Bulletin - Tetraphenylphosphonium salts of N-phosphorylated thioureas and bio-thioureas were synthesized by the reactions of their sodium salts with PPh4Br in 96% aqueous EtOH. The...     

Synthesis of 2-Methyl-4-quinolyl Isothiocyanate

A procedure has been developed for the synthesis of substituted 2-methylquinolin-4-ylthiuronium salts by reaction of 2-methyl-4-chloroquinoline with N-substituted thioureas. Alkaline hydrolysis of these salts yields 2-methyl-4-quinolyl isothiocyanate instead of the expected 2-methylquinoline-4-thiol.     

Determination of mixtures containing amines and thioureas

A convenient and accurate method has been described for the analysis, on the same sample solution, of mixture of amines and thioureas. The mixture solution is first analyzed for amines by an acidimetric titration. The titrated solution is acidified with more aqueous acid and then analyzed for thioureas by an oxidimetric titration. The method has been successfully applied to the analysis, also on the same sample solution, of mixtures containing isocyanates and thioureas. A known excess of standard n-butylamine added to the mixture solution in diemthylformamide converts the isocyanates to the corresponding disubstituted ureas. Acidimetric titration of the excess of amine followed by iodatometric titration of thiourea present enable the mixture to be analyzed for both the components. The methods described are reliable and have wide applications.     

A convenient method for the synthesis of substituted thioureas

A convenient method for the synthesis of substituted thioureas by the reaction of primary amines with molybdenum dialkyl dithiocarbamates has been developed. Primary amines on reaction with 0.5 equiv of molybdenum xanthate produce the corresponding thioureas in moderate to good yields in short times. Similar reactions with propargylamine or 2-aminoethanol produce cyclic thiaoxazolidine and oxazolidine derivatives, respectively.     

Synthesis of 1- and 5-Aryl-2,4-benzothiazepines. 25th Communication on Seven-membered Heterocycles

α-Aryl-o-xylyl dibromides 1 reacted with thioureas to give the mono-isothiouronium salts 2 , bis-isothiouronium salts 4 being formed as by-products in some cases. Compounds 2 , which readily reacted with water or alcohols to form 3 , were cyclized with Na₂CO₃ in anhydrous acetone to yield 5-aryl-2,4-benzothiazepines 5, 6 and 7 , but the 2′-chlorophenyl-derivative 21 exceptionally cyclized to the cyclobutene 20 . The 1-aryl-2,4-benzothiazepines 14, 15 and 16 were prepared unequivocally by acid-catalysed cyclizations of thioureas 13 and 19 .     

A facile method for the preparation of carbodiimides from thioureas and (Boc)2O

A concise method for the preparation of carbodiimides from thioureas using di-tert-butyl dicarbonate [(Boc)₂O] as the dehydrosulfurizative reagent has been developed. Using DMAP as the catalyst, a variety of symmetric and asymmetric 1,3-diaryl thioureas were converted into the corresponding carbodiimides efficiently in a short time.     

Simple and efficient synthesis of O-unprotected glycosyl thiourea and isourea derivatives from glycosylamines

Practical, facile and high-yielding one-pot syntheses of different O-unprotected glycopyranosyl thioureas and thioureido bolaamphiphiles (two-step synthesis) and of 2-amino-4,5-dihydro-(1,2-dideoxy-β-d-glucopyranoso)[1,2-d]oxazoles (three-step synthesis) from glycopyranosylamines are reported. The method involves the preparation of O-unprotected β-d-gluco (and d-galacto)pyranosyl isothiocyanates which are in equilibrium with the corresponding 1,2-cyclic thiocarbamates, coupling with amines to afford glycosyl thioureas and treatment with yellow mercury (II) oxide to give trans-fused bicyclic isoureas. A d-gluco trehazolin analogue is prepared in this way. In situ transformation of N,N-dialkyl, N′-glucopyranosyl thioureas into the corresponding ureas is also reported.     

Facile synthesis of aliphatic isothiocyanates and thioureas on solid phase using peptide coupling reagents

Peptide coupling reagents can be used as versatile reagents for the formation of aliphatic isothiocyanates and thioureas on solid phase from the corresponding solid-phase anchored aliphatic primary amines. The formation of the thioureas is fast and highly chemoselective, and proceeds via formation of the intermediate isothiocyanate. The isothiocyanate and subsequent thiourea formation take place under standard peptide coupling conditions using carbon disulfide as the ‘amino acid’. The thioureas are released from the resin and isolated in moderate to high yields.     

Non-aqueous cerimetric determination of thioureas

Ammonium hexanitratocerate (in acetonitrile) solution has been used as an oxidimetric reagent for the visual and potentiometric determination of thiourea and its alkyl derivatives in acetonitrile medium. The thioureas are oxidized to their corresponding disulphides. The method is simple, accurate, reliable and widely applicable.     

Conversion of 2-aminomethylbenzothiazoles into imidazo[5, 1-b]benzothiazoles

A number of substituted 2-aminomethylbenzothiazoles ate synthesized. The corresponding ureas or thioureas are also obtained by reaction with arylisocyanates or arylisothiocyanates. Heating the substituted ureas or thioureas at temperatures above their melting points cyclizes them to 9-substituted 2-hydroxy- or 2-mercaptoimidazo[5, 1-b]benzothiazoles, which are derivatives of a new heterocyclic system.     

Oxidative cyclization of n‐methyl‐ and n‐benzoylpyridylthioureas. Preparation of new thiazolo[4,5‐b] and [5,4‐b] pyridine derivatives

Cyclization of N‐methyl‐ and N‐benzoylpyridylthioureas, prepared from the corresponding aminopy‐ridines, has been realized using various conditions. With bromine in acetic acid or potassium ferricyanide, the cyclization occurred on the nitrogen of the pyridine ring and pyridinium salts or 1,2,4‐fhiadiazolo[2,3‐a]pyridylidene systems were obtained. On the other hand, treatment of the thioureas with sodium methoxide in N‐methylpyrrolidinone (NMP) led to formation of fhiazolo[4,5‐b] and [5,4‐b]pyridines, which are interesting targets for biological evaluation.     

Starch xanthate–polyethylenimine reaction mechanisms

The chemical nature of starch xanthate (SX)–polyethylenimine (PEI) reaction products has been studied because of their effectiveness as wet-end additives for improving strength properties of paper. Model compounds, in conjunction with ultraviolet, infrared, and chemical analyses, served to elucidate SX–PEI reaction mechanisms. Aqueous solutions of SX (degrees of substitution 0.1–0.5) were titrated with PEI at pH 5–7 (25–30°C) to form SX–PEI flocculent precipitates that were determined to be polyelectrolyte complexes. However, when solutions of SX–PEI were kept at pH 10–12, products were formed that included dithiocarbamic acid salts in major quantities, PEI thioureas, and minor quantities of O-starch PEI thinocarbamate. Acid precipitation of these SX–PEI polymeric reaction products from their alkaline solutions, which contained residual xanthate and PEI, also yielded polyelectrolyte complexes. Model systems suggest that PEI thiuram disulfide and starch xanthide, possible products of air oxidation, could be present in minor amounts and would react rapidly with PEI to yield thioureas and thioncarbamates, respectively. Apparently, mixtures of xanthate and amine gave (1) dithiocarbamic acid salts from both xanthate groups and CS₂ (decomposition from xanthate), (2) thioureas from both dithiocarbamic acid salts and thiuram disulfide, and (3) thioncarbamates, principally from xanthate as opposed to xanthide.     

Thiocarbamyolation of amine-containing compounds

Thiocarbamoylation of primary and secondary aliphatic amines with tetramethylthiuram disulfide in various solvents at different temperatures was studied. At 110°C, the reactions with primary amines afforded mixed,N,N-dimethyl-N′-alkyl(cycloalkyl)thioureas and symmetricalN,N′-dialkyl(cycloalkyl)thioureas as the final products, while the reactions with secondary amines gave mixtures of dithiocarbamate salts with “symmetrical” derivatives predominating.     

C-S Bond-Forming Reactions of Barbiturylbromide with Isothiocarbamides in Aqueous Media

The C-S cross coupling of pharmaceutically active barbituric acid derivatives has been achieved by the interaction of selective monobromobarbituric acid with thioureas in an aqueous medium. This method is applicable for simple thiourea as well as monosubstituted thioureas, and corresponding products are obtained in good yield.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Thiazolium-Substituted Gem-Bisphosphonates

Abstract

Heterocyclic derivatives of gem-bisphosphonates exhibit various biological activities. We have found that thiazolium substituted bisphosphonic acids can be obtained by two-step synthesis from amino-bisphosphonates (I). Reaction of (I) with isothiocyanates in alkohol in the presence of triethylamine led to corresponding thioureas (II) obtained as natrium or triethylamonium salts [1]. Further treatment of (II) with α-bromoketones give aminothiazoles (III) with a good yield. As a rule only less hindered nitrogen atom is involved into the cyclization with formation of one from two of possible isomers.     

Bismuth(III) nitrate pentahydrate: a convenient and selective reagent for conversion of thiocarbonyls to their carbonyl compounds

A variety of thioamides and thioureas are rapidly transformed to their oxo derivatives with Bi(NO₃)₃·5H₂O in excellent yields. However, thiono esters and thioketones are converted to their corresponding carbonyl compounds in only poor yields. Bi(NO₃)₃·5H₂O is relatively non-toxic, insensitive to air and inexpensive. These features coupled with the selective deprotection of thioamides and thioureas in the presence of thiono esters and thioketones make this method an attractive alternative to the existing routes for deprotection of thiocarbonyl compounds.     

New tetrasubstituted thioureas containing the 1-iminoethyl moiety

The reactions of 1,1,3-trisubstituted thioureas with acetonitrile afforded the corresponding tetrasubstituted thioureas containing the N-(1-iminoethyl) moiety.     

Stereoselective synthesis of (Z)-enethiols and their derivatives: vinylic S(N)2 reaction of (E)-alkenyl(phenyl)-lambda3-iodanes with thioamides

[reaction: see text]. Exposure of (E)-beta-alkylvinyl(phenyl)-lambda3-iodanes to thioamides in dichloromethane at room temperature was found to result in a bimolecular nucleophilic substitution (S(N)2) at the vinylic carbon atom to give inverted (Z)-enethiols and/or (Z)-S-vinylthioimidonium salts. Vinylic S(N)2 reactions with thioureas are also discussed.