The thermolysis of heterocyclic aminimines

Aminimines derived from six heterocyclic tertiary amines were thermolyzed in t-butyl alcohol at ca. 80°. N-Methylindoline gave a good yield of the ring-opened product, and a double elimination on 1,4,4-trimethyl-piperidine gave 3,3-dimethyl-1,4-pentadiene. The aminimine derived from quinuclidine was stable to elimination under these conditions. Simple elimination products were not obtained from N-methyl-pyrrolidine, N-methylpiperidine, or N-methyltetrahydroisoquinoline.     

The proton magnetic resonance of heterocyclic diketones

A full analysis of the 60 MHz ¹H NMR spectra of heterocyclic analogues of 1,3-indandione [N-(2-bromoethyl)-phthalimide, phthalic anhydride and thiophthalic anhydride] and of 1,2-indandione (N-methylisatin, coumarandione and 2,3-dihydrothionapthene-2,3-dione) has been carried out. The protons of the symmetric compounds resonate at lower fields than those of the asymmetric ones and the proton ortho to the CO function is more deshielded than the proton ortho to the heteroatom. Coupled Hartree-Fock perturbation theory has been applied to estimate the ring current contributions to the proton chemical shifts and to the magnetic susceptibilities. MO calculations based on the finite perturbation theory at the CNINDO levels provide information on the relative importance of σ and π pathways for the various coupling constants.     

The pyrylation of aromatic and heterocyclic compounds

Pyrylium salts having no substituents in position 4 react with aromatic and heteroaromatic compounds forming 4-aryl- and 4-heterylpyrylium derivatives. The reaction takes place through the stage of the formation of a pyran which, with an excess of the initial pyrylium salt, splits out a hydride ion, aromatizing into a trisubstituted pyrylium cation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 6, pp. 733–738, June, 1970.     

The mannich reaction with heterocyclicγ-ketones

A number ofΒ-aminomethyl-γ-piperidones have been obtained by the aminomethylation of 1, 2, 5-trimethyl-4-piperidone with formaldehyde and various secondary amines.     

Microwave-assisted conversion of aromatic heterocyclic nitriles to various heterocyclic molecules

Abstract

Dihydroimidazole (3a-c), dihydrooxazole (3d-f), benzoxazole (5a-c), benzothiazole (5d-f) and oxazolopyridine (7a-c) derivatives have been synthesized by condensation of various heterocyclic aromatic nitriles with diamine, aminoalcohal, aminophenol, aminothiophenol, and 3-aminopyridine-2-ol, respectively, under microwave irradiation and under solvent free conditions. This catalyst free and solvent free approach provided heterocyclic compounds in quantitative yields. Time taken for the condensation to occur is < 20 min.     

The reaction of certain heterocyclic azides with triphenylphosphine

Azidobenzothiazole and azidobenzimidazole and certain of its derivatives react with triphenyl-phosphine to give isolatable adducts which decompose thermally to give the corresponding phosphinimines. 2-Azidobenzoxazole gives an adduct which loses nitrogen at 15–20° and gives the phosphinimine directly. Methylation of the phosphinimines occurs at the hetero nitrogen, whereas benzoylation occurs at the exo nitrogen atom. The structures of the alkylation and aroylation products of the phosphinimines were established.     

The reaction of 2-hetarylacetonitriles with heterocyclic haloaldehydes

The reaction of 4-oxo-3,4-dihydroquinazolyl-and benzimidazolylacetonitriles with 2-chloro-2-quinolinecarbaldehydes and 1-aryl-5-chloro-3-methyl-1H-pyrazole-4-carbaldehydes gave the corresponding 3-(2-chloro-3-quinolyl)-2-(4-oxo-3,4-dihydro-2-quinazolyl)-2-propenenitriles and 3-(1-aryl-5-chloro-3-methyl-1H-4-pyrazolyl)-2-hetaryl-2-propenenitriles. Intramolecular cyclization of these compounds gives 15-oxo-15H-benzo[6,7][1,8]naphthyridino[2,1-b]quinazoline-6-carbonitriles, 1-aryl-3-methyl-11-oxo-1,11-dihydropyrazolo[4′,3′:5,6]pyrido[2,1-b]quinazoline-5-carbonitriles, and 1-aryl-3-methyl-1H-benzo[4,5]imidazo[1,2-a]pyrazolo[4,3-e]pyridine-5-carbonitriles.     

The effect of polar substituents on the heterocyclic benzoxazoles

The synthesis, characterization, and mesomorphic properties of a new type of heterocyclic compounds 1, 2 derived from benzoxazole are reported. In order to understand the relationship between the structure and the mesomorphic behavior, compounds containing a variety of polar substituents (i.e., X=H, F, Cl, Br, CH₃, CF₃, OCH₃, NO₂, CN, OH, NMe₂, COOCH₃) on the terminal end were prepared. The phase behavior of these mesogenic compounds was characterized and studied by differential scanning calorimetry (DSC) and polarization optical microscopy. The formation of mesophases was strongly dependent on the electronic and/or the steric factors of the substituents. In general, a mesophase was better induced by introduction of a polar substituent. Compounds (X=H) formed a crystalline phase, however, other compounds, except for X=OH, exhibited nematic or smectic A phases. Interestingly all compounds with electron-donating substituents (X=CH₃, OCH₃, NMe₂) exhibited nematic phases, however, other compounds with electron-withdrawing substituents (X=F, Cl, Br, CF₃, NO₂, CN, COOCH₃) formed smectic A phases. Compounds (X=NO₂, CN, COOCH₃) have higher clearing temperatures than those of other homologues, and the higher T_cl was attributed to an enhanced conjugative interaction. However, no linear correlation between the clearing temperature or the temperature range of mesophases with Hammett σ_p constants was found. The fluorescent properties of the compounds were examined. All λ_max peaks of the absorption and photoluminescence spectra of compounds occurred at ca. 348-381 and 389-478 nm, respectively. Whereas, the quantum yields of some compounds were relatively low.     

Reaction of heterocyclic betaines. Synthesis of a new heterocyclic system

A new condensed heterocyclic system, viz., 1,3,7,9-tetra-oxo-2,8-diphenyl-6-formylpyrimido [3,4-a]pyrimido[4,5-dloxazine, was synthesized, and its electronic and PMR spectra were recorded. Factors that affect the orientation of nucleophilic substitution in betaines of the pyrimidine series with aliphatic amines are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 993–995, July, 1980.     

The stereochemistry of the protonated forms of heterocyclic bases

The configurational and conformational ratios of protonated 2,4-dimethyl- and 1,2,4-trimethyl-1,2,3,4-tetrahydrobenzofuro[3,2-c]pyridines and their conjugate bases were studied by PMR spectroscopy. The trimethyl derivatives have a 1,4-trans configuration. The equilibrium concentrations of the epimeric salts in solution were determined. In the crystalline state the salts exist in the form of the energetically more favorable epimer, which in solution has a completely equatorial conformation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1081–1086, August, 1978.     

Fluorosulfonyl-containing heterocyclic compounds

Salts of hexafluorodimethylmethionic andα-hydrohexafluoro-2-propane-2-sulfonic acids, the amide of the latter, and a number of sulfones containingα-hydrohexafluoroisopropyl, pentafluoroisopropenyl,Β,Β,Β-trifluoroethyl, and methyl groups were obtained by alkaline hydrolysis, alcoholysis, and ammonolysis of hexafluorodimethyl sulfonene trimer.     

Stereochemistry of heterocyclic compounds

Summary On the basis of a number of chemical reactions, views are expressed on the possible steric structure of 1, 2, 5-trimethyl-4-ethyl-4-piperidinol isomers (I,, ), the corresponding acetylenic alcohols (II, ,), and certain piperidine derivatives obtained from them.     

Fluorosulfonyl-containing heterocyclic compounds

Hexafluoroisobutenylidene sulfate is a sulfotrioxidizing agent with respect to various olefins; methylenemethionic acid is formed in the case of ethylene, while the corresponding-sulfones are formed in the case of tetrafluoroethylene and vinylidene fluoride. 2,2-Difluoro-2-hydroxy-ethanesulfonic acid sultone is characterized by a capacity for anionotropic transformations; a number of sulfoacetic acid derivatives were obtained on the basis of this sultone.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 178–182, February, 1973.     

Hydrosilylation of heterocyclic aldehydes

The hydrosilylation of O-, S-, and N-heterocyclic aldehydes with triethylsilane has been studied in the presence of different metal complex catalysts and the corresponding silyl ethers of hetarylcarbinols obtained. The rhodium complexes Rh(PPh₃)₃Cl and [Et₃PhCH₂N]RhCl₄ have been found to be the most efficient catalysts for these reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp, 31–36, January, 1987.     

Investigation of heterocyclic quinones

It is shown that copper ions catalyze the amination of 6-morpholino(piperidino)quinoline-5,8-quinone with secondary amines at the C₂ atom. The role of bidentate copper complexes in this process is discussed.See [1] for communication XXVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1672–1676, December, 1976.     

Investigation of heterocyclic quinones

Substitution of the methyl group by an amine residue to give 2,8-dipiperidino-4-hydroxy-quinazoline-5, 6-quinone occurs in the oxidative animation of 2-methyl-6-hydroxy-4-quinazolone in the presence of a Cu²⁺-piperidine complex. The possible mechanism of the reaction is discussed.See [1] for communication XX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1697–1699, December, 1973.     

The synthesis of derivatives of new tetracyclic heterocyclic systems pyrazolo-bis-azolopyridazines

The synthesis of new tetracyclic systems and new stable tautomers of known systems 11H- 13 and 10H-imidazo[1, 2-b]pyrazolo[4, 3-d]-s-triazolo[3, 4-f]pyridazine 16 , 9H-pyrazolo[3, 4-d]bis-s-triazolo[4, 3-6:5′,1-f]-pyridazine 15 , 10H-pyrazolo[3, 4-d]bis-s-triazolo[4, 3-b:3′,4′-f]pyridazine 17 , and 10H-pyrazolo[4, 3-d)bis-s-triazolo[4, 3-6:5′,1′-f]pvridazine 18 is described.     

Investigation of heterocyclic quinones

Oxidation of 4-substituted 2-phenyl-6-hydroxyquinazolines with oxygen in the presence of a Cu²⁺-secondary amine complex gave N-substituted 2-phenyl-4,8-diaminoquinazoline-5,6-quniones, which form diquinazolino[6,5-d:8,7-b]furan-7,8-quinones on acid hydrolysis.See [1] for communication XIX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1403–1408, October, 1973.     

The analysis of some heterocyclic compounds

The mass spectra of some relatively simple sulphur compounds have been obtained. Comments upon the McLafferty rearrangement are reported.     

Fluorosulfonyl-containing heterocyclic compounds

Depending on the conditions, -hydrohexafluoroisobutyric anhydride, hexafluorodimethylketene, or hexafluoroisobutenylidene sulfate is formed in the sulfotrioxidation of -hydrohexafluoroisobutyric acid. The sulfotrioxidation of -hydrohexafluoroisobutyric anhydride similarly gives hexafluorodimethylketene or hexafluoroisobutenylidene sulfate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 13–15, January, 1973.