The hfi parameters and structure of radical-anions of substituted tetra- and pentafluorobenzenes. Theory and experiment (OD ESR)

Optically detected electron spin resonance (OD ESR) of radical pairs has been employed to take ESR spectra of short-lived radical-anions of substituted fluorobenzenes in liquid non-polar solutions at nearly room temperatures. The quantum-chemical hfi analysis has taken into account possible manifestations of pseudo-Jahn—Teller effects. As shown by comparison with experiment,C₆F₅OCH⁻₃, p-H-C₆F₄OCH⁻₃ and p-(CH₃)₂-C₆F⁻₄ are pseudo-π-radicals with non-planar distortions. A peculiar feature of these radicals is that their structure corresponds to the Jahn—Teller stabilization of excited Π* states. The effect results from a stronger interaction of the Σ* state with Π* than with the ground Π state, because the SOMO space localizations coincide in the Σ* and Π* states.     

Spectra and structure of mercury derivatives of primary nitramines

The mercury derivatives of primary nitramines were proved by molecular spectroscopy and quantum-chemical calculations to be covalent compounds. The mercury atom was found to be coordinated to the amine nitrogen atom.     

A theoretical study for the structure of propranolol and some fluorinated derivatives

This paper reports on studies of the theoretical geometrical structure of propranolol and three of its fluorinated derivatives: 1-(2,2,2-trifluoroethylamino)-3-(1-naphthyloxy)-2-propanol [trifluoroethyl-propranolol], 1-(2,2,3,3.3-pentafluoropropylamino)-3-(1-naphthyloxy)-2-propanol [pentafluoropropyl-propranolol], and 1-(2,2,3,3,4,4,4-heptafluorobutylamino)-3-(1-naphthyloxy)-2-propanol [heptafluorobutyl-propranolol]. The semiempirical method AM1 was used to optimize the structures. In the minimum energy state the geometries of the naphthyl moiety and the non-fluorinated portions of the analogs are quite similar to that of the parent. Dipole moments, charge density distributions, and electrostatic potential distributions all point to the significance of the ether oxygen in all four compounds and the increasing contribution of the side-chain terminal to the activity of the molecule with increasing number of fluorines.     

New highly fluorinated phenazine derivatives: Correlation between crystal structure and NMR spectroscopy

New highly fluorinated derivatives of phenazine which are difficult to obtain in other ways, namely 1,2,2,3,4-pentafluoro-10-(2,3,4,5,6-pentafluorophenyl)-2,10-dihydrophenazine (2) and its hydrolyzed product 1,3,4-trifluoro-10-(2,3,4,5,6-pentafluorophenyl)-2(10H)-phenazinone (3), were both synthesized and characterized by means of single-crystal X-ray analysis and ¹H, ¹⁹F NMR spectroscopy. Correlation between the results of X-ray analysis and NMR spectroscopy is established. The formation mechanism of 2 involving oxidation of a cobalt complex bearing two noninnocent o-benzosemiquinonediiminato(1-) ligands is proposed.     

Electrosynthesis of fluorinated indole derivatives

Anodic fluorination of various N-acetyl-3-substituted indole derivatives was successfully carried out in Et₄NF-4HF/MeCN to provide the corresponding trans-2,3-difluoro-2,3-dihydroindoles exclusively or selectively. Treatment of difluorinated products with a base provided monofluoroindole derivatives or monofluoroindoline derivative depending on the substituents at the 3-position.     

Rotational isomers of the radical-anions of 2-carbonyl-containing derivatives of 5-nitrofuran

The radical-anions of 2-carbonyl-containing derivatives of 5-nitrofuran were obtained by electrochemical generation. Their ESR spectra indicate the existence of a mixture of O,O-cis and O,O-trans rotational isomers. The parameters of the isomers were identified by INDO calculations. The more polar form (the cis isomer) is more stable in polar media.DeceasedTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 14–21, January, 1987.The authors thank A. V. Il'yasov (A. E. Arbuzov, IOFKh [Institute of Organic and Physical Chemistry], Kazan' Branch, Academy of Sciences of the USSR) for assistance in the ESR experiment with temperature regulation.     

Fully and partially fluorinated flavone derivatives

In the crystal structures of the fully and partially fluorinated flavone derivatives 5,6,7,8‐tetrafluoro‐2‐(2,3,4,5,6‐pentafluorophenyl)‐4H‐1‐benzopyran‐4‐one, C₁₅HF₉O₂, (I), and 5,6,7,8‐tetrafluoro‐2‐phenyl‐4H‐1‐benzopyran‐4‐one, C₁₅H₆F₄O₂, (II), the pentafluorophenyl group and the pyranone moiety in (I) are twisted due to repulsion of the F substituents, and a CO(δ⁻)...π(δ⁺) intermolecular interaction is observed between the carbonyl O atom and the pentafluorophenyl group. In (II), on the other hand, the phenyl group and the pyranone moiety are almost coplanar, and arene–perfluoroarene interactions are observed in the head‐to‐tail intermolecular columnar stacking between the phenyl group and the tetrafluorophenylene moiety.     

Synthesis of fluorinated 1,8-naphthyridinone derivatives

Processes for the synthesis of fluorinated 1,8-naphthyridinone derivatives including 6,7-difluoro-1,8-naphthyridin-2-one are described.     

Synthesis of fluorinated derivatives of glutethimide and aminoglutethimide

Aminoglutethimide (1), used in the treatment of hormone dependent breast cancer, interacts with enzyme complexes desmolase and aromatase. Its action is not specific and its metabolism gives rise to toxic and non-inhibitory metabolites. The work described here explores the impact of fluorine substitution within the glutethimide (2) framework, on the enzyme inhibitory properties of aminoglutethimide. Four new fluorinated derivatives (5), (6), (8) and (9) have been prepared, in which fluorine substituents have been introduced into the phenyl ring and the ethyl side chain. 4-Fluoroglutethimide (5) and 3-trifluoroglutethimide (6) were synthesised from the corresponding fluorophenylacetonitriles (10) and (14) via sequential monoethylation, Michael addition to methyl propenoate and cyclisation. An alternative strategy, devised for the synthesis of (8), involved the monoarylation of ethyl cyanoacetate, and gave rise to the intermediate (29). Incorporation of fluorine was carried out by SF₄ fluorination of the cyanoketoester (33), which was subsequently converted to the difluoroaminoglutethimide (8). For the synthesis of trifluoromethyl glutethimide (9), the trifluoromethyl group was introduced by alkylation of phenylcyanoacetate (16) with 2-iodo-1,1,1,-trifluoroethane. Preliminary enzyme inhibition results have been obtained for compounds (5), (6) and (8).     

ESR. Spectra of the Radical Anions of Cycloalkylbenzenes

Radical anions of five cycloalkylbenzenes (alkyl = propyl, butyl, pentyl, hexyl, or heptyl) have been studied by ESR. spectroscopy at ?90°C. In the case of cyclopropylbenzene, no reliable experimental data could be obtained, because of the instability of its radical anion. The spectra of the radical anions of the four higher homologues have been analysed by means of a computer program. The assignment of the coupling constants to the α-protons in the para position of the benzene ring and to the cycloalkyl ß-protons has been based on the spectra of specifically deuterated derivatives. The experimental data of the radical anion of cycloalkylbenzenes have been compared with those of the radical anions of five alkylbenzenes (alkyl = methyl, ethyl, n-propyl, isopropyl, or t-butyl), the spectra of the latter being reexamined at ?90°C. In the cycloalkyl series the degeneracy of the two benzene-type lowest antibonding orbitals is the more effectively removed the larger the substituent, whereas the reverse relation holds for the non-cyclic series. The preferred conformation of the substituents is that in which the alkyl or cycloalkyl ß-proton is near to the nodal plane of the benzene π-system, and this preference is accentuated with the increasing size of the substituent group.     

ESR. Spectra of the Radical Anion of Dimethyl-phenyl-phosphine

ESR. spectra of the radical anion (I^?) produced from dimethyl-phenyl-phosphine (I) both by electrolysis and reaction with alkali metals have been studied upon variation of temperature. The coupling constant assigned to the ³¹P nucleus depends strongly on temperature, whereas the coupling constants attributed to protons do not exhibit such a dependence. The π-spin populations at the benzene ring of I^? give evidence - in accordance with other experimental data [1] [2] – that the dimethylphosphino substituent is electron-attracting. This effect is thought to be due mainly to P ← C_π delocalization, which is analogous to the Si? C_π interaction in trimethylsilyl-substituted π-systems [3]. The ESR. spectrum previously [4] ascribed to I^? is shown to arise from a secondary radical. The formation and structure of this radical are briefly discussed.     

ESR Spectra of radicals produced by reduction of pyridine and pyrazine

Radicals produced by reaction of e^?_aq with pyridine, pyrazine, and pyrazinedicarboxylic acid have been studied by electron spin resonance using the in situ radiolysis steady-state ESR technique. The radical anions initially produced have been found to undergo rapid protonation on nitrogen to form pyridinyl and pyrazinyl radicals. The NH proton of pyridinyl radical does not dissociate even at pH 13.7. The radical from pyrazine has been observed only in the doubly protonated positively charged form in acid and neutral solutions, but no spectrum was observed in alkaline media. With 2,3-pyrazinedicarboxylic acid the doubly protonated radical has been observed at pH 4–8 and the singly protonated one at pH 11–12. The pK for this dissociation is 9.2. The hyperfine constants of the pyridinyl radical are compared with those obtained from INDO molecular orbital calculations.     

Synthesis of new fluorinated 1,5-benzoxazepine derivatives

A simple approach to the fluorinated 1,5-benzoxazepine ring system is described. By reacting commercially accessible aminophenols 1 and the trifluoroacetylvinyl ether 2, high yields of enaminones 3 were obtained. Functionalization of methyl group of compounds 3 gave rise to dieneamines 4 that were cyclized in acidic environment to benzoxazepine derivatives 5.     

Synthesis of novel fluorinated 4-aminoquinoline derivatives

New 4-aminoquinolines having a -CF₂CH-(heteroaryl)-OH moiety are obtained in moderate yields from the electrochemical catalyzed reaction of the corresponding 4-amino-3-chlorodifluoroacetyl-2-methoxyquinoline in the presence of heteroaryl aldehydes. A one-pot intramolecular zinc mediated aromatic nucleophilic substitution also gave access to novel difluorinated 5-aminodihydropyrano[2,3-b]quinolin-4-ones.     

Synthesis and spectroscopic study of complexes of antimony pentachloride with some benzonitrile derivatives

The complexes SbCl₅ · L (L = 2,3 and 4-chlorobenzonitriles and 2,3 and 4-aminobenzonitriles) have been isolated and investigated by conductivity and IR and Raman spectral measurement. From the IR spectra it is inferred that in all complexes, coordination of the ligands to the Sb takes place through the nitrogen atom of the nitrile group. In addition, the spectral data are in full accord with a molecular adduct of local C_4v symmetry for the SbCl₅N moiety.