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Many natural sounds have frequency spectra composed of integer multiples of a fundamental frequency. This property, known as harmonicity, plays an important role in auditory information processing. However, the extent to which harmonicity influences the processing of sound features beyond pitch is still unclear. This is interesting because harmonic sounds have lower information entropy than inharmonic sounds. According to predictive processing accounts of perception, this property could produce more salient neural responses due to the brain’s weighting of sensory signals according to their uncertainty. In the present study, we used electroencephalography to investigate brain responses to harmonic and inharmonic sounds commonly occurring in music: piano tones and hi-hat cymbal sounds. In a multi-feature oddball paradigm, we measured mismatch negativity (MMN) and P3a responses to timbre, intensity, and location deviants in listeners with and without congenital amusia—an impairment of pitch processing. As hypothesized, we observed larger amplitudes and earlier latencies (for both MMN and P3a) in harmonic compared to inharmonic sounds. These harmonicity effects were modulated by sound feature. Moreover, the difference in P3a latency between harmonic and inharmonic sounds was larger for controls than amusics. We propose an explanation of these results based on predictive coding and discuss the relationship between harmonicity, information entropy, and precision weighting of prediction errors.

5‐Chloro‐6‐nitroquinoxaline 2, made in six steps from 2,3‐dichloronitro‐benzene, reacts 1) with piperidine to give 6‐nitro‐5‐piperidinoquinoxaline as the only product; 2) with methoxide to give a 95:5 ratio of 5‐methoxy‐6‐nitro‐ and 5‐chloro‐6‐methoxy‐quinoxaline; 3) with p‐thiocresolate to give the disubstitution product without showing any monosubstitution product. Copyright © 1992 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim

Piperidine, cyclohexylamine, methoxide ion and para‐thiocresolate ion react with 2‐chloro‐3‐nitroquinoxaline 1 by selectively substituting the nitro group, in contrast to the behavior of most ortho‐chloronitroaromatics which loose halide when subjected to nucleophilic substitution reactions. This inversion is interpreted as being due to the lack of activation of the 2‐position by the nitro group in the 3‐position because of the low value of the π‐bond index between these two vertices. It is also suggested that the substitution by neutral reagents such as amines is strongly influenced by stabilizing interactions between the negatively charged nitro group and the ammonium moiety in the σ complex; this built‐in solvation may be responsible for inversions in the chemoselectivity between chloro and nitro nucleofugicities. Copyright © 1988 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim

6‐nitro‐, 2‐methyl‐6‐nitro‐ and 2,3‐dimethyl‐6‐nitroquinoxaline have been transformed into their N‐oxides by MCPBA in chloroform; the nitro group orients the oxygen atom preferentially to nitrogen atom N1, but the N4:N1 selectivity is diminished in the methylated derivatives. Under the action of POCl3 (the Meisenheimer reaction), the N‐oxides of the unmethylated compounds are transformed into chloro‐nitroquinoxalines having lost the N‐oxide oxygen atom. The orientation of the entering chloride ion is discussed on the basis of electronic effects induced by the N‐oxide and nitro groups, and it is suggested that the last step, the elimination of “HPO2Cl2” is a concerted process. Copyright © 1986 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim

Summary. New podands, based on 1,4,5,8‐tetra‐azaphenanthrene, have been synthesized from 2‐chloro‐1,4,5,8‐tetra‐azaphenanthrene 3; when the anchoring group is a nitrogen atom, the corresponding podands are, however, unstable. When reacted with Ru2+ in an ionizing solvent, podands tris(2‐(2‐(1,4,5,8‐tetra‐azaphenanthryloxy))ethyl)methane 4c and tri(2‐(2‐(1,4,5,8‐tetra‐azaphenanthryloxy))ethyl)trimesoate 9 give only polymeric complexes; in chloroform, complexation stops at bis‐chelation, giving two types of structures. The most intriguing is the twisted type (12, 13) where one of the chelating group has been inverted, giving rise to an unprecedented flattened Ru2+ octahedron. Copyright © 1989 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim

Reacting 2,2-dichlorododecanal with 1,2-diamino-4-nitrobenzene in dioxane in the presence of a base gives a 46% yield of 2-decyl-6-nitroquinoxaline, which after amination by hydroxylamine and reduction gave 5,6-diamino-2-decylquinoxaline. This diamine, again with 2,2-dichlorododecanal in dioxane and base, affords 2,6-didecyl- and 2,7-didecyl-1,4,5,8-tetraazaphenanthrene (2,7ddTAP); the latter ligand gives the hexane-soluble Ru(2,7ddTAP)3(PF6)2.

2-chloropyrimidine, 2-chloro- and 2-bromo-4,6-dimethylpyrimidines, 2-chloro- and 2-bromo-4,6-diphenylpyrimidines have been dimerized to the corresponding 2,2′-bipyrimidines in good yields by Tiecco's method using NiCl2, triphenylphosphine and zinc in DMF.

5‐Chloro‐6‐nitroquinoxaline 2, made in six steps from 2,3‐dichloronitro‐benzene, reacts 1) with piperidine to give 6‐nitro‐5‐piperidinoquinoxaline as the only product; 2) with methoxide to give a 95:5 ratio of 5‐methoxy‐6‐nitro‐ and 5‐chloro‐6‐methoxy‐quinoxaline; 3) with p‐thiocresolate to give the disubstitution product without showing any monosubstitution product. Copyright © 1992 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim

2-chloropyrimidine, 2-chloro- and 2-bromo-4,6-dimethylpyrimidines, 2-chloro- and 2-bromo-4,6-diphenylpyrimidines have been dimerized to the corresponding 2,2′-bipyrimidines in good yields by Tiecco's method using NiCl2, triphenylphosphine and zinc in DMF.

2,3-Diphenyl-1,4,5,8,9,12-hexa-azatriphenylene 2 and 2,3,6,7-tetraphenyl-1,4,5, 8,9,12-hexa-azatriphenylene 3 can be synthesized by the direct condensation of hexa-aminobenzene with glyoxal and benzil. It is, however, not possible to make specifically one of the compounds, which is always accompanied by the parent compound 1 and the fully substituted hexaphenyl-hexaazatriphenylene 4 . It is nevertheless possible to optimize the yields of 2 and 3 by a careful choice of the experimental conditions.

1,4,5,8-Tetraazaphenanthrenemetal tetracarbonyl complexes (metal = Cr, Mo, W) have been synthesized. The CO force constants show that there is more backbonding in these complexes than in the analogous 1,10-phenanthroline complexes, because of the two additional electron-withdrawing nitrogen atoms. The M→ L CT transitions show a strong bathochromic shift relative to the corresponding o -phenanthroline complexes.

The 1H and 13C NMR spectra of 1,4‐diazaphenanthrene (benzol f quinoxaline) (1) and some of its derivatives have been fully assigned and most of the coupling constants have been measured. The compounds examined bear a piperidino or methoxy group at the 2‐ or 3‐position, or a chlorine atom at the 2‐, 3‐ or 9‐position. The spectra of the N‐1‐oxides of 1 and of 1,4,5,8‐tetraazaphenanthrene are also given. The syntheses are described. Copyright © 1987 John Wiley & Sons Ltd.

The yields of the direct amination of 6-nitroquinoxalines by hydroxylamine have been improved, opening thus a better access to 1,4,5,8-tetra-azaphenanthrenes.

The synthesis of 1,4,5,8,9,12-hexaazatriphenylene (HAT), a new ligand for low-valent transition metals, is described; it gives mono-, bis- and tris-chromium tetracarbonyl complexes. The CO stretching frequencies in (HAT)Cr(CO)4 show that HAT is a stronger electron acceptor than 1,10-phenanthroline.

Triethylamine accelerates the photodebromination of 5-bromopyrimidines, and much more so in methanol than in acetonitrile. The quantum yield in methanol is as high as 4, and additional data suggest that the amine-catalysed debromination is a photo-initiated free-radical chain reaction, the carrier being the .CH2OH radical; triethylamine acts as an electron donor in the initiation step and as a base catalyst in the chain reaction.

The yields of the direct amination of 6-nitroquinoxalines by hydroxylamine have been improved, opening thus a better access to 1,4,5,8-tetra-azaphenanthrenes.

Selective substitution of the nitro group is observed in the title reaction of the quinoxaline (I).

6‐nitro‐, 2‐methyl‐6‐nitro‐ and 2,3‐dimethyl‐6‐nitroquinoxaline have been transformed into their N‐oxides by MCPBA in chloroform; the nitro group orients the oxygen atom preferentially to nitrogen atom N1, but the N4:N1 selectivity is diminished in the methylated derivatives. Under the action of POCl3 (the Meisenheimer reaction), the N‐oxides of the unmethylated compounds are transformed into chloro‐nitroquinoxalines having lost the N‐oxide oxygen atom. The orientation of the entering chloride ion is discussed on the basis of electronic effects induced by the N‐oxide and nitro groups, and it is suggested that the last step, the elimination of “HPO2Cl2” is a concerted process. Copyright © 1986 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim

6,7-Dinitro-chinoxalin (II) reagiert mit Methylat zum erwarteten Austauschprodukt.(I), wahrend mit Ammoniak ein Gemisch aus (III) und (IV), mit Piperidin in Ethanol die Folgeprodukte (VI)-(VIII) in einer Gesamtausbeute von 90 - 95% erhalten werden.

The fluorescence spectra, quantum efficiencies and lifetimes of hexa-, hepta-, octa- and nona-helicene were observed in 1,4-dioxan solution. The fluorescence is assigned to the 1Lb state, which is obscured in the absorption spectra of the higher compounds.

The study of relative nucleofugicities of nitro and halogen in quinoxalines required the synthesis of the four 6-halo-7-nitroquinoxalines 2a-d. The fluoro-, chloro- and bromo-derivatives were made from the commercially available or readily accessible 1,2-diamino-4-halobenzenes, using the nitration of the corresponding p-toluenesulfonamides. This scheme failed in the case of the iodo compound because of extensive nitrodeiodination. The synthesis of 6-iodo-7-nitroquinoxaline was finally achieved from m-fluoroiodobenzene by taking advantage of the high reactivity of fluorine, compared to iodine, in 2,4-dinitrohalobenzenes. © 1987.

The excited state of the 1,4,5,8-tetra-azaphenanthrene complex, [Ru(TAP)3]2+, which unlike [Ru(phen)3]2+(phen = 1,10-phenanthroline) or [Ru(bipy)3]2+(bipy = 2,2′-bipyridyl) is strongly quenched upon binding to poly[d(G–C)], is found to be much more effective than either [Ru(phen)3]2+ or [Ru(bipy)3]2+ in causing cleavage of the DNA backbone.