Peri Positions Research Articles

(4-Ethoxybenzoyl)[8-(4-ethoxybenzoyl)-2,7-dimethoxynaphthalen-1-yl]methanone

The title mol­ecule, C30H28O6, possesses crystallographically imposed twofold symmetry, with two central C atoms in the naphthalene unit lying on the rotation axis along [001]. The 4-eth­oxy­benzoyl groups at the peri positions of the naphthalene ring system are disordered over two sets of sites with occupancies of 0.769 (4) and 0.231 (4). They are directed in opposite directions from the naphthalene plane (anti orientation). For the major component, the dihedral angle between the aroyl benzene ring and the naphthalene ring system is 75.62 (13)° [minor component 75.5 (4)°], and that between the aroyl benzene rings is 32.58 (15)°. In the crystal, mol­ecules are linked via C—H⋯O and C—H⋯π inter­actions, forming a three-dimensional network.

Tuning the Peri Effect for Enantioselectivity: Asymmetric Hydrogenation of Unfunctionalized Olefins with the BIPI Ligands

AbstractThe modular nature of the BIPI ligands allows for systematic optimization of each ligand region. The development of ligands optimized for asymmetric hydrogenation of the challenging unfunctionalized olefin substrate class is described. The naphthyl peri position, C‐8, has been identified as a critical stereocontrol element in the design of these ligands. Highly enantioselective ligands suitable for hydrogenation of tri‐ and tetrasubstituted olefins are detailed.

Noncovalent Interactions in Peri-Substituted Chalconium Acenaphthene and Naphthalene Salts: A Combined Experimental, Crystallographic, Computational, and Solid-State NMR Study

Twelve related monocation chalconium salts [{Nap(EPh)(E'Ph)Me}(+){CF(3)SO(3)}(-)] 2-4, [{Acenap(Br)(EPh)Me}{CF(3)SO(3)}(-)] 5-7, and [{Acenap(EPh)(E'Ph)Me}(+){CF(3)SO(3)}(-)] 8-13 have been prepared and structurally characterized. For their synthesis naphthalene compounds [Nap(EPh)(E'Ph)] (Nap = naphthalene-1,8-diyl; E/E' = S, Se, Te) N2-N4 and associated acenaphthene derivatives [Acenap(X)(EPh)]/[Acenap(EPh)(E'Ph)] (Acenap = acenaphthene-5,6-diyl; E/E' = S, Se, Te; X = Br) A5-A13 were independently treated with a single molar equivalent of methyl trifluoromethanesulfonate (MeOTf). In addition, reaction of bis-tellurium compound A10 with 2 equiv of MeOTf afforded the doubly methylated dication salt [{Acenap(TePhMe)(2)}(2+){(CF(3)SO(3))(2)}(2-)}] 14. The distortion of the rigid naphthalene and acenaphthene backbone away from ideal was investigated in each case and correlated in general with the steric bulk of the interacting atoms located at the proximal peri positions. Naturally, introduction of the ethane linker in acenaphthene compounds increased the splay of the bay region compared with equivalent naphthalene derivatives resulting in greater peri distances. The conformation of the aromatic rings and subsequent location of p-type lone pairs has a significant impact on the geometry of the peri region, with anomalies in peri separations correlated to the ability of the frontier orbitals to take part in attractive or repulsive interactions. In all but one of the monocations a quasi-linear three-body C(Me)-E···Z (E = Te, Se, S; Z = Br/E) fragment provides an attractive component for the E···Z interaction. Density functional studies confirmed these interactions and suggested the onset of formation of three-center, four-electron bonding under appropriate geometric conditions, becoming more prevalent as heavier congeners are introduced along the series. The increasingly large J values for Se-Se, Te-Se, and Te-Te coupling observed in the (77)Se and (125)Te NMR spectra for 1, 3, 4, 9, 10, and 13 give further evidence for the existence of a weakly attractive through-space interaction.

Angular Benzoperylenetetracarboxylic Bisimides

Benzoperylene derivatives with two angularly attached dicarboxylic imide rings, which were prepared by the Diels-Alder-reaction, exhibit strong fluorescence and their free peri positions allow either control of the UV/Vis spectra through their substituents or form anchor positions for the attachment of functional units. The angular chromophore 3 may be used both for fluorescent labeling such as for primary amines or enzymes or as building blocks for more complex assemblies where they may act as energy donors for FRET or electron acceptors in PET such as for photovoltaic solar cells.

Rhodium(III)-Catalyzed Oxidative Olefination of N-(Naphthalen-1-yl)amides

Rhodium(III)-catalyzed oxidative coupling of N-(naphthalen-1-yl)amides with acrylates and styrene was achieved through selective C–H bond activation at the peri position. This reaction proceeded smoothly to give the direct olefination product or the corresponding olefination–cyclization product. High functional-group tolerance was observed

ChemInform Abstract: Rh(III)‐Catalyzed Oxidative Olefination of N‐(1‐Naphthyl)sulfonamides Using Activated and Unactivated Alkenes.

AbstractActivated olefins react to afford five‐membered azacycles [cf.

Rh(III)-Catalyzed Oxidative Olefination of N-(1-Naphthyl)sulfonamides Using Activated and Unactivated Alkenes

Rhodium(III)-catalyzed oxidative olefination of N-(1-naphthyl)sulfonamides has been achieved at the peri position. Three categories of olefins have been successfully applied. Activated olefins reacted to afford five-membered azacycles as a result of oxidative olefination-hydroamination. Unactivated olefins reacted to give the olefination product. 2-fold oxidative C-C and C-N coupling was achieved for allylbenzenes.

Cyclopalladation of indole-3-carboxaldehyde aroylhydrazones

Reactions of PdCl 2, LiCl, indole-3-carboxaldehyde 4- R-benzoylhydrazones (H 2L n ; n = 1, 2, 3 and 4 for R = H, Cl, OMe and NMe 2, respectively) and CH 3COONa·3H 2O in 1:2:1:1 mol ratio in methanol produce the cyclopalladated species of general formula [Pd(HL n )Cl] in 65–85% yields. The complexes have been characterized with the help of elemental analysis and spectroscopic (infrared, electronic and NMR) measurements. The proton NMR spectra of the complexes suggest palladation at the peri position of the indole moiety in (HL n ) −. Molecular structure of a representative complex determined by X-ray crystallography confirms the peri-palladation and formation of a distorted CNOCl square-plane around the metal centre by the tridentate (HL n ) − and the chloride.

The human carcinogen aristolochic acid i is activated to form DNA adducts by human NAD(P)H:quinone oxidoreductase without the contribution of acetyltransferases or sulfotransferases

Ingestion of aristolochic acid (AA) is associated with development of urothelial tumors linked with AA nephropathy and is implicated in the development of Balkan endemic nephropathy-associated urothelial tumors. We investigated the efficiency of human NAD(P)H:quinone oxidoreductase (NQO1) to activate aristolochic acid I (AAI) and used in silico docking, using soft-soft (flexible) docking procedure, to study the interactions of AAI with the active site of human NQO1. AAI binds to the active site of NQO1 indicating that the binding orientation allows for direct hydride transfer (i.e., two electron reductions) to the nitro group of AAI. NQO1 activated AAI, generating DNA adduct patterns reproducing those found in urothelial tissues from humans exposed to AA. Because reduced aromatic nitro-compounds are often further activated by sulfotransferases (SULTs) or N,O-acetlytransferases (NATs), their roles in AAI activation were investigated. Our results indicate that phase II reactions do not play a major role in AAI bioactivation; neither native enzymes present in human hepatic or renal cytosols nor human SULT1A1, -1A2, -1A3, -1E, or -2A nor NAT1 or NAT2 further enhanced DNA adduct formation by AAI. Instead under the in vitro conditions used, DNA adducts arise by enzymatic reduction of AAI through the formation of a cyclic hydroxamic acid (N-hydroxyaristolactam I) favored by the carboxy group in peri position to the nitro group without additional conjugation. These results emphasize the major importance of NQO1 in the metabolic activation of AAI and provide the first evidence that initial nitroreduction is the rate limiting step in AAI activation.

Ring Transformation of Unsaturated N-Bridgehead Fused Pyrimidin-4(3H)-ones: Role of Repulsive Electrostatic Nonbonded Interaction

Thermal ring transformation ability of unsaturated N-bridgehead fused pyrimidin-4(3H)-ones A is governed by both the steric and the electrostatic interactions between the oxygen of the carbonyl group and the substituent in the peri position.

Comparative density functional theory study on the relative gas phase enthalpies and free energies of formation for the mono- through hepta-halogenated (X=F, Cl, Br) anthraquinones

Gas phase standard state (298.15 K, 1 atmosphere) relative enthalpies and free energies of formation were calculated for all mono- through hepta-halogenated (X=F, Cl, Br) anthraquinone congeners using the B3LYP, BHandHLYP, M062X, PBE0, and B97D density functionals with the 6-311++G(d,p) basis set. All levels of theory yielded similar results with strong intra- and inter-method correlations for both the relative enthalpy and free energy values and the corresponding thermodynamic stability rank. Within each homolog group, the most thermodynamically stable isomers are those which maximize substitution at the lateral positions (2, 3, 7, and 8) versus the less stabilizing peri positions (1, 4, 6, and 9), while also minimizing destabilizing adjacent substitution patterns (1/2, 2/3, 3/4, 6/7, 7/8, and 8/9). These trends are consistent regardless of halogen substituent or theoretical method employed, and are analogous to those predicted for other classes of halogenated ortho-diaryl systems with single connecting atoms.

Comparative density functional theory study on the relative gas phase enthalpies and free energies of formation for the mono- through hepta-halogenated (X=F, Cl, Br) anthraquinones

AbstractGas phase standard state (298.15 K, 1 atmosphere) relative enthalpies and free energies of formation were calculated for all mono- through hepta-halogenated (X=F, Cl, Br) anthraquinone congeners using the B3LYP, BHandHLYP, M062X, PBE0, and B97D density functionals with the 6-311++G(d,p) basis set. All levels of theory yielded similar results with strong intra- and inter-method correlations for both the relative enthalpy and free energy values and the corresponding thermodynamic stability rank. Within each homolog group, the most thermodynamically stable isomers are those which maximize substitution at the lateral positions (2, 3, 7, and 8) versus the less stabilizing peri positions (1, 4, 6, and 9), while also minimizing destabilizing adjacent substitution patterns (1/2, 2/3, 3/4, 6/7, 7/8, and 8/9). These trends are consistent regardless of halogen substituent or theoretical method employed, and are analogous to those predicted for other classes of halogenated ortho-diaryl systems with single connecting atoms.

Sterically Crowded peri‐Substituted Naphthalene Phosphines and their PV Derivatives

Three sterically crowded peri-substituted naphthalene phosphines, Nap[PPh(2)][ER] (Nap=naphthalene-1,8-diyl; ER=SEt, SPh, SePh) 1-3, which contain phosphorus and chalcogen functional groups at the peri positions have been prepared. Each phosphine reacts to form a complete series of P(V) chalcogenides Nap[P(E')(Ph(2))(ER)] (E'=O, S, Se). The novel compounds were fully characterised by using X-ray crystallography and multinuclear NMR spectroscopy, IR spectroscopy and MS. X-ray data for 1, 2, nO, nS, nSe (n=1-3) are compared. Eleven molecular structures have been analysed by naphthalene ring torsions, peri-atom displacement, splay angle magnitude, X...E interactions, aromatic ring orientations and quasi-linear arrangements. An increase in the congestion of the peri region following the introduction of heavy chalcogen atoms is accompanied by a general increase in naphthalene distortion. P...E distances increase for molecules that contain bulkier atoms at the peri positions and also when larger chalcogen atoms are bound to phosphorus. The chalcogenides adopt similar conformations that contain a quasi-linear E...P-C fragment, except for 3O, which displays a twist-axial-twist conformation resulting in the formation of a linear O...Se-C alignment. Ab initio MO calculations performed on 2O, 3O, 3S and 3Se reveal Wiberg bond index values of 0.02 to 0.04, which indicates only minor non-bonded interactions; however, calculations on radical cations of 3O, 3S and 3Se reveal increased values (0.14-0.19).

Synthetic and Structural Studies of 1,8‐Chalcogen Naphthalene Derivatives

Four novel 1,8-disubstituted naphthalene derivatives 4-7 that contain chalcogen atoms occupying the peri positions have been prepared and fully characterised by using X-ray crystallography, multinuclear NMR spectroscopy, IR spectroscopy and MS. Molecular distortion due to noncovalent substituent interactions was studied as a function of the bulk of the interacting chalcogen atoms and the size and nature of the alkyl group attached to them. X-ray data for 4-7 was compared to the series of known 1,8-bis(phenylchalcogeno)naphthalenes 1-3, which were themselves prepared from novel synthetic routes. A general increase in the E...E' distance was observed for molecules containing bulkier atoms at the peri positions. The decreased S...S distance from phenyl-1 and ethyl-4 analogues is ascribed to a weaker chalcogen lone pair-lone pair repulsion acting in the ethyl analogue due to the presence of two equatorial S(naphthyl) ring conformations. Two novel peri-substituted naphthalene sulfoxides of 1, Nap(O=SPh)(SPh) 8 and Nap(O=SPh)(2) 9, which contain different valence states of sulfur, were prepared and fully characterised by using X-ray crystallography and multinuclear NMR spectroscopy, IR spectroscopy and MS. Molecular structures were analysed by using naphthalene ring torsions, peri-atom displacement, splay angle magnitude, S...S interactions, aromatic ring orientations and quasi-linear O=S...S arrangements. The axial S(naphthyl) rings in 8 and 9 are unfavourable for S...S contacts due to stronger chalcogen lone pair-lone pair repulsion. Although quasi-linear O=S...S alignments suggest attractive interaction is conceivable, analysis of the B3LYP wavefunctions affords no evidence for direct bonding interactions between the S atoms.

Peri-Amino ketones of the acenaphthene and acenaphthylene series

peri-Amino-substituted methyl and aryl ketones of the acenaphthene and acenaphthylene series were subjected to protonation and acylation at the nitrogen atom, dehydrogenation, and reactions with aldehydes. Conformations of substituents in the peri positions and probability for their participation in intra- and intermolecular transformations were determined on the basis of spectral data and quantum-chemical calculations.

Synthetic and Structural Studies of 1-Halo-8-(alkylchalcogeno)naphthalene Derivatives

A series of eight 1-halo-8-(alkylchalcogeno)naphthalene derivatives (1-8; halogen=Br, I; alkylchalcogen=SEt, SPh, SePh, TePh) containing a halogen and a chalcogen atom occupying the peri positions have been prepared and fully characterised by using X-ray crystallography, multinuclear NMR spectroscopy, IR spectroscopy and MS. Naphthalene distortion due to non-covalent substituent interactions was studied as a function of the bulk of the interacting chalcogen atoms and the size and nature of the alkyl group attached to them. X-ray data for 1, 2, 4 and 5-8 were compared. Molecular structures were analysed in terms of naphthalene ring torsions, peri-atom displacement, splay angle magnitude, X...E interactions, aromatic ring orientations and quasi-linear X...E-C arrangements. A general increase in the X...E distance was observed for molecules that contain bulkier atoms at the peri positions. The I...S distance of 4 is comparable with the I...Te distance of 8, and is ascribed to a stronger lone pair-lone pair repulsion due to the presence of an axial S(naphthyl) ring conformation. Density functional theory (B3LYP) calculations performed on 5-8 revealed Wiberg bond index values of 0.05-0.08, which indicate minor interactions taking place between the non-bonded atoms in these compounds.

(2,7-Dimethoxynaphthalene-1,8-diyl)bis(4-fluorobenzoyl)dimethanone

The title compound, C26H18F2O4, is a naphthalene derivative in which the two aroyl groups at the 1- and 8-positions (peri positions) are anti to each other. There is an appreciable difference in the dihedral angles between the naphthalene ring system and the two benzene rings [66.88 (7)° and 88.09 (6)°]. In the crystal, weak C—H⋯O inter­actions involving one of the carbonyl groups and an aromatic C—H group ortho to the F atom seem to stabilize the packing of the mol­ecules.

Are the silyl group hydrogens in peri-substituted-9-silyltriptycenes engaged in blue-shifting hydrogen bonds?

In three 9-silyltriptycenes bearing chlorine, bromine and the methyl group in one of the peri positions, the silyl group suffers extreme hindrance of its reorientational motion. Owing to this, separate signals of the individual silyl group protons could be observed in NMR spectra at relatively high temperatures. For each compound, the measured values of J couplings of these protons to the 29Si nucleus are strongly diversified, especially when a halogen atom occurs in the peri position. These differences can be qualitatively interpreted in terms of electron density transfers from the peri substituent, causing the individual Si-H bonds to differentiate. The stereoelectronic picture revealed by natural bond orbital analysis fits the pattern normally interpreted as that of the blue-shifting hydrogen bond. However, an essential similarity of the stereoelectronic effects for both the halogen and methyl substituents raises a serious question about the applicability of that concept to the present case.

Ab initio and TDDFT study of the structural and spectroscopic properties of buckybowls: Corannulene and two methylcorannulenes

Optimization of the C 60 fullerene fragment, corannulene, by HF and DFT methods at 6-31++G ∗∗ and 6-311+G(2d,p) levels confirms its curved (bowl shaped) structure. The calculated charge density distribution and bond orders support the assumption [W.E. Barth, R.G. Lawton, J. Am. Chem. Soc. 88 (1966) 380] that the corannulene structure is a polar resonance hybrid involving two concentric rings with (4 n + 2)π-electrons. Geometry optimization also reveals that methylation at peri positions causes flattening of the bowl, in conformity with a previous general analysis [Seiders et al., J. Am. Chem. Soc. 123 (2001) 517] and the dipole moment vector along the C 5-axis of corannulene is more and more tilted towards the methyl groups with increasing extent of methylation. The UV–vis spectra of corannulene, methyl- and 2,3-dimethyl corannulene in CHCl 3 were calculated by time dependent density functional theory under the polarizable continuum model and the results are in agreement with the experimentally observed red shift on progressive methyl substitution. The theoretically calculated IR and NMR spectra of corannulene and its two methyl derivatives agree well with reported experimental data. 13C NMR shift calculation explicitly shows the presence of three sets of C-atoms in corannulene. The C H vibrational modes have been classified group theoretically and their calculated frequencies agree well with experimental data.

Synthesis of 1H-benzo[de]cinnolines from nitronaphthalenes

Lacy et al. previously reported on the synthesis of 1H-benzo[de]cinnolines II (1,2-diazaphenalenes) via cyclization of 1-acetyl-, 1-benzoyl[1], and 1-formyl8-hydroxynaphthalenes [2] by the action of hydrazine hydrate. The present communication describes the synthesis of the same compounds from more accessible 1-formyl-, 1-acetyl-, and 1-benzoyl-8-nitronaphthalenes Ia–Ic [3]. Heating of compounds I with excess hydrazine hydrate in boiling ethanol gave the corresponding 1H-benzo[de]cinnolines IIa–IIc in 62–87% yield. Presumably, the reaction involved nucleophilic attack by hydrazine on the carbonyl carbon atom, followed by intramolecular replacement of the nitro group in the peri position. 3-H), 7.28 d (1H, 4-H, J4, 5 = 7.4 Hz), 8.16 br.s (1H, NH). Found, %: C 78.71; H 4.72; N 16.57. C11H8N2. Calculated, %: C 78.55; H 4.79; N 16.66.