The synthesis of hexahydrooxoepithiopyridinedicarboximides by the reaction of thioamides with N-substituted maleimides

The synthesis of hexahydrooxoepithiopyridinedicarboxyimide (5: X₂ = N-Ph) by the reaction of thioamides 1 with N-substituted maleimide ( 2a ) was examined. The reaction of primary thioamides, such as thiobenzamide and p-toluthioamide with N-phenylmaleimide gives compounds 5 together with corresponding 4-hydroxy-1,3-thiazoles 4 . However, a similar reaction of secondary thioamides, such as N-methylthioacetamide, thiobenzanilide, with N-phenylmaleimide did not provide compounds 5 without addition of acid. The reaction pathway and the configuration of 5 were also investigated.     

Synthesis of Optically Active Isothiazole Derivatives from L-(α)-Amino Acids

Summary. Several enantiomerically pure 3,5-disubstituted isothiazol-5-ylideneamine hydrobromides were prepared by oxidation of chiral 3-amino-2,3-unsaturated thioamides. The starting thioamides derived from natural L-α-amino acids represent a novel group of synthetically useful chiral reactants.     

Unexpected mass spectral skeletal rearrangements in aromatic thioamides

Interesting skeletal rearrangements, resulting in the formation of unexpected fragments, have been noticed in the mass spectra of aromatic thioamides of cyclic amines such as piperidine, morpholine and pyrrolidine. Suitable mechanisms, based on mass analysed ion kinetic energy spectra, high voltage scan spectra and high resolution data, have been proposed for the formation of [M? SH]⁺ ions and the fragment at m/z (103+R) in the mass spectra of these compounds. The mass spectra of the thioamides of non-cyclic amines and the thioamides of aliphatic acids contain peaks corresponding to a four-centred skeletal rearrangement followed by the elimination of either the thioalkoxy or the thiophenoxy radical from the molecular ions.     

Study on the antioxidant activity and quantification of thioamides based on nitrogen five-membered heterocycles by the kinetic technique

The antioxidant activity of heterocyclic thioamides based on imidazole, triazole, tetrazole, thiazole, thiazoline, and thiadiazole is estimated by spectrophotometry using the rate constant of reaction with the chromogenic radical 2,2′-diphenyl-1-picrylhydrazyl. The rate constant of direct transfer of a hydrogen atom to the radical in carbon tetrachloride is maximal for 1-methylimidazoline-2-thione. The protective antioxidant effect of the preparations in ethanol falls down abruptly from 4-phenylthiazoline-2-thione (k = 1.06 × 10⁴ M⁻¹min⁻¹) to the thioamides based on triazole and thiazoline (k ∼ 20 M⁻¹min⁻¹). In acetonitrile, thiazole derivatives show the most substantial antioxidant activity, k = n ×10⁴ M⁻¹min⁻¹, which goes down to zero if the aromaticity of the heterocycle is broken. As established, for the pseudo first order reaction between thioamides and the chromogenic radical, the reaction rate linearly depends on the concentration of thioamides. A spectrophotometry kinetic method for the quantification of heteroaromatic thioamides is elaborated.     

Synthesen von Heterocyclen, 124. Mitt.: Über Reaktionen des Isatosäureanhydrids mit Thioamiden und Amiden

Zusammenfassung Beim Verschmelzen von Isatosäureanhydrid (1) mit Thioamiden bilden sich 2-substit.-4(3H)-Chinazolinone (3a-h).

---

Syntheses of heterocycles, CXXIV.: Reaction of isatoic anhydride with thioamides and amides

The reaction of isatoic anhydride with thioamides yields 2-substituted 4(3H)-quinazolinones (3a-h).

     

Synthesis and Use of 2H‐Azirin‐3‐amines as Dipeptide Synthons

The synthesis of the new 2H‐azirin‐3‐amines (‘3‐amino‐2H‐azirines') 11, 20, 28 , and 33 as dipeptide synthons is described. The reactions of the starting amides with Lawesson reagent gave the corresponding thioamides, and consecutive treatment with COCl₂, 1,4‐diazabicyclo[2.2.2]octane (DABCO), and NaN₃ led to the desired products. It is shown that these 2H‐azirin‐3‐amines can conveniently be used as building blocks of the dipeptides Aib‐(Me)Axx (Axx=alanine, valine), Aib‐Homoproline, and Iva‐Pro in the synthesis of several model peptides. However, some limitations apply for the synthesis of such 2H‐azirin‐3‐amines. The starting material for the azirine synthesis, the corresponding thioamides, cannot generally be synthesized, and the 2H‐azirin‐3‐amines could not be obtained in all cases from the thioamides prepared.     

Copper(I)-Catalyzed Conjugate Addition/Enantioselective Protonation with Selenols and α-Substituted α,β-Unsaturated Thioamides

Herein, a copper(I)-catalyzed asymmetric conjugate addition/protonation with selenols and α-substituted α,β-unsaturated thioamides is disclosed, which affords a series of chiral selenides in high to excellent enantioselectivity. As for both selenols and α-substituted α,β-unsaturated thioamides, the reaction enjoys broad substrate scopes. The present catalytic system is also successfully applied to asymmetric selenation of β-substituted α,β-unsaturated thioamides. A [Cu-(R,R_P)-TANIAPHOS]-SePh species is characterized by its ⁷⁷Se NMR spectra, which gives a chemical shift at δ 462 ppm. Moreover, a {[Cu-(R)-TOL-BINAP]-SePh}₂ species is characterized by X-ray analysis, which confirms the formation of Cu−Se bond in the reaction. Finally, the transformations of the thioamide group to amine and thioester are demonstrated to be straightforward.     

Hybrid Palladium Catalyst Assembled from Chiral Phosphoric Acid and Thioamide for Enantioselective β-C(sp3)−H Arylation

A hybrid palladium catalyst assembled from a chiral phosphoric acid (CPA) and thioamide enables a highly efficient and enantioselective β-C(sp³)−H functionalization of thioamides (up to 99 % yield, 97 % ee). A kinetic resolution of unsymmetrical thioamides by intermolecular C(sp³)−H arylation can be achieved with high s-factors. Mechanistic investigations have revealed that stereocontrol is achieved by embedding the substrate in a robust chiral cavity defined by the bulky CPA and a neutral thioamide ligand.     

13C n.m.r. spectra of some thiobenzamides. Correlation between 13C and 1H n.m.r. spectra and signal assignments of syn and anti CH2 groups

¹³C n.m.r. spectra of a series of N,N-disubstituted thioamides have been recorded and signal assignments were performed. Separate signals are observed for methylene groups fixed on the nitrogen atom. Since the carbon atom syn to the thiocarbonyl sulfur resonates at higher field than the anti carbon, the syn-anti assignment in ¹H n.m.r. is easily obtained by selective double irradiation. This method, which is rapid and reliable, affords a rather general solution to the interesting problem of resonance assignments in tertiary amides and thioamides (and in analogous molecules such as oximes and nitrosamines).     

Heteroaromatic thioamides: Structure and stability of charge transfer complexes with iodine, antithyroid activity

The review generalizes the structural studies on the products of the interaction of antithyroid preparations (heteroaromatic thioamides) with iodine. The n-σ* adducts of imidazol, thiazol, oxazole, pyridine, uracil derivatives with molecular iodine, iodinium salts, and also disulfides formed as a result of thione oxidation in iodine-coordinating solvents are considered. Based on mainly single crystal X-ray diffraction and Raman spectroscopy data, the structural parameters of iodine molecular complexes are shown to be highly sensitive to changes in the type of a heteroatom and substituents in the heteroring. The effect of the structure of heteroaromatic thioamides on their antithyroid activity is analyzed.     

Studies on thioamido-platinum complexes: Stabilization of platinum in its higher oxidation state

Summary The reducing power of thioamides and related compounds being often rationalised in terms of a thiol structure for the thioamido-form, it would be expected thatN-disubstituted thioamides should be able to complex platinum in its higher oxidation state. The platinum(IV) complexes of dimethylthioformamide (dmtf) and tetramethylthiourea (tmtu) are described and characterised by x.p.s. and n.m.r. spectroscopy. This paper also reports some findings concerning class II mixed-valence (Pt^II/Pt^IV) thioamide complexes.     

Hybrid Palladium Catalyst Assembled from Chiral Phosphoric Acid and Thioamide for Enantioselective β‐C(sp3)−H Arylation

A hybrid palladium catalyst assembled from a chiral phosphoric acid (CPA) and thioamide enables a highly efficient and enantioselective β‐C(sp³)?H functionalization of thioamides (up to 99 % yield, 97 % ee). A kinetic resolution of unsymmetrical thioamides by intermolecular C(sp³)?H arylation can be achieved with high s‐factors. Mechanistic investigations have revealed that stereocontrol is achieved by embedding the substrate in a robust chiral cavity defined by the bulky CPA and a neutral thioamide ligand.     

COMMUNICATION. B-THIOACYLTHIO-9-BBN AS A THIOACYLATING REAGENT

Abstract

Convenient syntheses of S-aryldithioesters and thioamides are described: thus, thiols and amines are readily thioacylated with the S-borondithioester formed in situ, by the mild reaction of a dithioacid with 9-BBN.     

The. Synthesis and chelation properties of N-substituted amidrazones and related azines containing the 2-pyridyl group

The. preparation and properties of certain N-substituted amidrazones from thioamides containing the 2-pyridyl group and the azines derived from them by reaction with benzaldehyde and 2-pyridinecarboxaldehyde is described.     

Annelation of the thiazole ring to 1,2,4-triazines by tandem AN—AN or SN H—SN H reactions

The reactions of 3-aryl-1,2,4-triazines with aromatic thioamides and 4-arylthiosemicarbazides in acetic anhydride at room temperature afforded cyclic products of the tandem nucleophilic addition reactions, viz., tetrahydrothiazolo[4,5-e]-annelated 1,2,4-triazines, in good yields. The latter underwent aromatization in the presence of potassium permanganate.     

The reactions of C-methylheterocycles with thionyl chloride. Part 3. The transformation of some five-and six-membered heterocycles

Reactions of various five-and six-membered C-methylheterocycles with hot thionyl chloride gave chlorothio intermediates which were not characterized but which gave 1,2,4-thiadiazole derivatives when reacted with amidines and gave thioamides when reacted with amines. When 2,3-dimethyl-6-ethoxycarbonylimidazo-[4,5-b]pyridine ( 26 ) was treated with thionyl chloride a trisulphane 27 was isolated.     

A new rearrangement of spiro[indane-1,3′-thiophene] and spiro[naphthalene-1,3′-thiophene] derivatives accompanied by opening of the cycloalkane ring

Abstract  

The new thioamides 2-oxoindane-1-carbothioamides and 2-oxo-1,2,3,4-tetrahydronaphthalene-1-carbothioamides underwent conjugated addition to (E)-β-nitrostyrenes followed by cyclization to give products containing 5-hydroxyimino-2-aryliminothiophene rings spiro-annulated to the 2-indanone or 2-tetralone system. On treatment with hydrochloric acid in boiling methanol the compounds underwent a new rearrangement, involving transformation of the 2-aryliminothiophene ring to a pyrrole and an opening of the alicyclic ring in the proximity of the carbonyl group, affording 2-(1,3-diaryl-2-oxo-5-thioxopyrrol-4-yl)benzeneacetic or 2-(1,3-diaryl-2-oxo-5-thioxopyrrol-4-yl)benzenepropanoic acid methyl esters. The structures of two selected pyrrole derivatives were determined by X-ray crystal analyses. The thioamides derived from 2-indanone showed unexpected reactivity towards primary alcohols and underwent conversion to 2-hydroxy-1H-indene-3-thiocarboxylic acid O-esters.     

Ion chemistry of phthalamic acids. III. The origin of [M ? 1]+ ions under electron impact

Electron impact mass spectra and collisional activation/mass-analysed ion kinetic energy spectra of some phthalamic acids and their deuterium labelled analogues suggested that the genesis of [M ? 1]⁺ ions is due to the loss of an aromatic hydrogen ortho to the amidic group, as for aromatic amides and thioamides.     

Synthesis of novel c-hetero-fused thiophene derivatives

An efficient synthesis of novel 5-(4-nitrophenyl)-2-benzoxazol-2-yl-c-hetero-fused thiophenes was achieved by the condensation of 5-(4-nitrophenyl)-2-benzoxazol-2-yl-3,4-dichlorothiophene with ethylene glycol, ethylenediamine, substituted thioamides and 2-mercaptobenzimidazole using sodium carbonate in refluxing dimethyl formamide.     

Ligand Properties of Thioamides and Their N- and N,N'-Derivatives

A series of nonempirical calculations by the Hartree-Fock method with full geometry optimization for a number of N- and N,N'-derivatives of thioamides which are potential functional groups for sorbents for extraction of platinum metals from technological solutions. The ligands all prefer to coordinate to platinum metal ions by the sulfur atom (soft Lewis base) at an angle to the sulfur-oxygen bond.