Chain-ring-chain tautomerism in 2-aryl-substituted hexahydropyrimidines and 1H-2,3-dihydroperimidines. Does it appear?

A series of 2-aryl substituted hexahydropyrimidines and perimidines were synthesized from aromatic aldehydes and substituted 1,3-propanediamines or 1,8-naphthalenediamine. The ¹H and ¹³C NMR spectra showed that 2-arylperimidines and 2-aryl-4,4,6-trimethylhexahydropyrimidines exist exclusively in ring forms even in DMSO solutions, whereas 2-aryl-4-methylhexahydropyrimidines undergo chain-ring-chain tautomerism with a good linear correlation between the ring-chain equilibrium constants (log K, where K=[ring]/[chain]) and the Hammett-Brown σ⁺ parameters of the aromatic substituents. 4,4,6-Trimethylhexahydropyrimidines underwent complete and irreversible ring opening in CF₃COOH solutions giving two different chain forms.     

Synthesis of 1-heterarylisoquinolines by cyclization of nitrilium salts

1-Heteraryl substituted 3,4-dihydroisoquinolines and their aromatic analogs have been synthesized from heterocyclic carbonitriles, -phenylethyl chloride and tin(IV) chloride.M. V. Lomonosov Moscow State University, Moscow 119899. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 376–378, March, 1997.     

Arylation of adamantanamines: IX. Copper(I)-catalyzed arylation of adamantane-containing amines

Copper(I)-catalyzed arylation of 14 adamantane-containing amines with iodobenzene, 1-fluoro-4-iodobenzene, 1-iodo-4-(trifluoromethyl)benzene, and 1-iodo-4-methoxybenzene has been studied under the conditions optimized previously. The yields of the N-arylation products have been shown to depend in a complicated manner on the amine structure, steric environment of the amino group, and substituent nature in iodobenzene.     

Copper(I)‐Catalyzed Amination of Halogenopyridines with Polyamines

Cu^I‐Catalyzed amination of 2‐bromo‐, and 2‐, 3‐, and 4‐iodopyridines with tri‐ and tetraamines aimed at the synthesis of N,N′‐diheteroaryl derivatives was studied. A strong dependence of the product yields on the nature of starting compounds and the ligand used was observed. The increase in the number of ethene‐1,2‐diamine fragments in the polyamine structure led to the increase in the yields of polyheteroarylated compounds, whereas propane‐1,3‐diamine fragments favored the formation of monopyridinyl derivatives and promoted the heteroarylation of the secondary amino groups. 2‐Iodopyridine, as a more reactive compound, readily formed N,N‐diarylated products. The best yields of the target N,N′‐dipyridin‐2‐yl derivatives were 76% in the case of the triamine and 68% in the case of the tetraamine. A comparison of Cu^I‐ and Pd⁰‐mediated heteroarylation of polyamines was also presented.     

Copper(I)-catalyzed amination of halothiophenes with polyamines

Copper(I)-catalyzed hetarylation of a series of polyamines and of 4,7,10-trioxatridecane-1,13-diamine with halothiophenes has been studied with a view to obtaining the corresponding N,N′-dihetaryl derivatives. The target products can be obtained using both 3-iodothiophene in the presence of CuI/L-proline/EtCN or CuI/N,N-dimethylglycine/EtCN as catalytic system and 3-bromothiophene in the system CuI/2-(2-methyl-1-oxopropyl)cyclohexanone/DMF. The latter system is also suitable for the hetarylation of 4,7,10-trioxatridecane-1,13-diamine with 3-iodothiophene. In some cases, N-(thiophen-3-yl) derivatives have also been isolated.     

Amination of chloro-substituted heteroarenes with adamantane-containing amines

Russian Chemical Bulletin - Amination of 3,6-dichloropyridazine, chloropyrazine, 2,3and 2,6-dichloropyrazines, 2-chloroquinoxaline, 1-chloroand 1,3-dichloroisoquinolines with various...     

Nucleophilic Rearrangement of Functionally-substituted 2-Ethylpyridines

The nucleophilic rearrangement of 2'-substituted 2-ethylpyridines by the action of methylamine was studied. When the side chain has a nitrile group, the rearrangement is accompanied by intra- and intermolecular ammonolysis, leading to cyclic and linear amides, respectively. When the side-chain has an indole substituent, the rearrangement proceeds through the classical scheme.     

Cu<Superscript>I</Superscript>-catalyzed <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>’-diarylation of diamines of adamantane series

A copper(I) complex-catalyzed N,N’-diarylation of diamines based on 1,3-disubstituted adamantane, using aryl iodides bearing electron-donating and electron-withdrawing substituents, was studied. In the case of 2,2’-(adamantane-1,3-diyl)ethanediamine, the optimal catalyst system is CuI—2-(isobutyryl)cyclohexanone—Cs₂CO₃—DMF. The highest yield of diarylation product was reached in the case of 4-methoxyiodobenzene (79%). In the case of more spatially hindered adamantane-1,3-diyldimethanamine, 1,1’-binaphthalene-2,2’-diol (BINOL) should be used, with the highest yield of the target product (84%) being reached in the reaction with iodobenzene.     

Synthesis and structural characterization of cis- and trans-fused 4a,5,6,7,8,8a-hexahydro-2H,4H-1,3-benzodithiines and their 2-methyl and 2,2-dimethyl derivatives

Both cis- and trans-fused 4a,5,6,7,8,8a-hexahydro-2H,4H-1,3-benzodithiine together with their 2-methyl and 2,2-dimethyl derivatives were prepared as racemates from the appropriate dithiols obtained via multistep syntheses. The products were characterized by (1)H and (13)C NMR, mass spectrometry, and for two of the cis-fused compounds by X-ray diffraction. (1)H,(1)H vicinal coupling constants indicated that all compounds attain chair-chair conformations as their predominant conformations. All three trans-fused isomers exist in totally biased chair-chair conformations and are essentially conformationally locked, whereas the cis-fused compounds are conformationally mobile and can potentially attain either the S-in or the S-out conformation. The interconversion of the conformers is fast on the NMR time-scale at ambient temperatures, but at 213 K 4ar,5,6,7,8,8ac-hexahydro-1,3-benzodithiine freezes out into a 83:17 mixture of the S-in and S-out forms, respectively. Both 2c-methyl-4ar,5,6,7,8,8ac-hexahydro-1,3-dithiine and the dimethyl derivative adopt almost exclusively the S-in conformer at ambient temperature whereas 2t-methyl-4ar,5,6,7,8,8ac-hexahydro-1,3-dithiine is a 5:1 mixture of the S-out and S-in conformers.