Fused-s-triazino heterocycles. VII. 1,3,5,7,9b-Pentaazaphenalene and 1,3,4,6,8,9b-hexaazaphenalene

Cyclization of 2,6-diaminopyrazine to two new heterocyclic ring systems, 1,3,5,7,9b-pentaazaphenalene and 1,3,4,6,8,9b-hexaazaphenalene is reported.     

Structural and vibrational analyses of t,C,t,T,t,T,t-deca-1,3,5,7,9-pentaene

An analysis of the results of the fluorescence spectrum investigation of all-trans-deca-1,3,5,7,9-pentaene and t,C,t,T,t,T,t-deca-1,3,5,7,9-pentaene in an n-decane matrix [B.E. Kohler, V. Terpougov, J. Chem. Phys. 108 (1998) 9586–9593] has been performed using scaled quantum mechanical force field (SQM-FF) methodology at the HF/6-31G level. The measured vibronic wavenumbers were assigned taking into account the results of quantum-chemical predictions of the vibrational spectra for all-trans-deca-1,3,5,7,9-pentaene and t,C,t,T,t,T,t-deca-1,3,5,7,9-pentaene. Results from additional calculations at the MP2(FC)/aug-cc-pVDZ and B3LYP/6-311++G(d,p) levels are also reported.     

Corannulene and its penta-tert-butyl derivative co-crystallize 1:1 with pristine C60-fullerene

The first X-ray structural determinations of pristine fullerene C(60), cocrystallized 1:1 with corannulene and with its pentaalkyl-substituted derivative, 1,3,5,7,9-penta-tert-butyl-corannulene, have now been achieved.     

Multiethynyl corannulenes: synthesis, structure, and properties

Syntheses, crystal structures, ab initio density functional theory computations, and photophysical properties of 1,6-di-, 1,2,5,6-tetra-, and 1,3,5,7,9-pentaethynyl-substituted corannulenes (classes 3, 4, and 5, respectively) are reported. Classes 3 and 4 were prepared from the corresponding corannulenyl bromides and terminal alkynes in excellent yields (nine examples, with yields of 57-92%) using the Sonogarshira reaction. Class 5 was prepared from 1,3,5,7,9-pentacholorocorannulene and trimethylalkynylstannanes using a modification of Nolan's procedure (8 examples, with yields of 45-93%). The molecular packing in crystals of 1,6-diphenylethynyl-2,5-dimethylcorannulene (3-Ph2) displays a polar columnar structure with all of the molecule bowls oriented in the same direction. Similarly, 1,2,5,6-tetrakis(3,5-dimethylphenylethynyl)corannulene [4-Ar(c)5] and 1,3,5,7,9-pentakis(3,5-dimethylphenylethynyl)corannulene [5-Ar(c)5] form columnar structures, but the bowls are oriented in opposing directions. Additionally, the number of attached alkynyl arms is correlated with an increase in bowl depth of the corrannulene nucleus. Most of the aryl derivatives displayed high-quantum-efficiency solution luminescence and variable emission wavelengths that were dependent on the nature of the substitution.     

Embracing C(60) with multiarmed geodesic partners.

1,3,5,7,9-Pentakis(4-methoxyphenylthio)corannulene (3), 1,3,5,7,9-pentakis(2-naphthylthio)corannulene (4), and 1,3,6,8-tetrakis(4-methoxyphenylthio)corannulene (5b) have been synthesized by chlorination of corannulene with ICl in CH(2)Cl(2) at 25 degrees C and subsequent nucleophilic aromatic substitution with the appropriate sodium thiophenolate in DMEU at 25 degrees C. (1)H NMR titration studies demonstrate that these novel bowl-shaped hosts form 1:1 complexes with C(60) in toluene-d(8) solution with association constants of 454, 368, and 280 M(-1), respectively.     

The structure of enopeptins A and B, novel depsipeptide antibiotics

The structures of enopeptins A and B, novel depsipeptide antibiotics with 1,3,5,7,9-decapentaene-1,10-dicarboxylic acid and 2-amino-3-hydroxycyclopent-2-enone in a side chain, were determined by chemical and spectroscopic means.     

Vis‐sensitive photopolymer containing vinyl ether compound and pyrromethene dye

A visible light(vis)‐sensitive photoresist based on the concept of chemical amplification was developed utilizing poly(p‐hydroxystyrene) (PHS), 2,2‐bis[4‐(2‐(vinyloxy)‐ethoxy)phenyl]propane (BPA‐DEVE) as a crosslinking agent, N‐trifluoromethylsulfonyloxy‐1,8‐naphthalimide (NIT) as a photoacid generator (PAG) and pyrromethene dyes such as 1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRH) and 2,8‐diethyl‐1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRE) and 3,3′‐carbonylbis(7,7′‐diethylaminocoumarin) (KCD). On irradiation with an argon ion laser, the photopolymer comprising PRH and PRE exhibited a high sensitivity of 65 and 46 mJ cm^?2, respectively. It is suggested that the sensitization mechanism of the pyrromethene dye/PAG system involves singlet electron transfer. The sensitivity of the photoresist increased with the decreasing molecular weight of PHS because of the high dissolution rate. Copyright © 2002 John Wiley & Sons, Ltd.     

Mass spectra of polymeric thioformaldehydes (CH2S)3, (CH2S)4, (CH2S)5 and (CH2S)x

The mass spectral fragmentations of various thioformaldehydes, 1,3,5-trithiacyclohexane, 1,3,5,7-tetrathiacyclooctane, 1,3,5,7,9-pentathiacyclodecane and a polymeric form (CH₂S)_x have been examined. The principal features of the spectra are reported. The fragmentation occurred by fracture of the ring in the cyclic compounds with or without rearrangement.     

Synthesis and Study of Equilenin Derivatives and Modified Analogs

Modified equilenin analogs were synthesized with a view to examine the relation between the structure and biological properties of steroid estrogens. The ¹H and ¹³C NMR signals of six estra-1,3,5,7,9-pentaenes were completely assigned using homo- and heteronuclear correlation NMR spectroscopy. The structure of equilenin methyl ester was determined by X-ray analysis. Among the synthesized steroids, compounds were found which exhibit hypocholesterinemic activity with no uterotropic and hypertriglyceridemic effects.     

Synthese neuer schwefel- und selen-haltiger ‘Donor-Akzeptor-stabilisierter’ Molekülsysteme mit zentraler bicyclo[4.4.1]undeca-4,6,8,10-tetraen-2,3-diyliden- oder Bicyclo[4.4.1]undeca-3,6,8,10-tetraen-2,5-diyliden-Gruppe

Synthesis of New Sulfur- and Selenium-Containing ‘Donor-Acceptor-Stabilized’ Systems with Central Bicyclo-[4.4.1]undeca-4,6,8,10-tetraene-2,3-diylidene- or Bicyclo[4.4.1]undeca-3,6,8,10-tetraene-2,5-diylidene Groups Syntheses of starting materials 3 – 55 and 8 and of the S- and containing 1,6-methano[10]annulene (=1,6-methanobicyclo[4.4.1]undeca-1,3,5,7,9-pentaene) derivatives 12, 13, 15 and 16 are described.     

On the self-condensation of aminoguanidine leading to 1,1,4,10,10-pentaamino-2,3,5,6,8,9-hexaazadeca-1,3,5,7,9-pentaene (structure elucidation through X-ray powder diffraction)

Chemical and spectroscopic (UV; ¹H, ¹³C, ¹⁵N NMR; HRMS) studies determined the structure of 1,1,4,10,10-pentaamino-2,3,5,6,8,9-hexaazadeca-1,3,5,7,9-pentaene for the red-violet compound, which was obtained by treating aminoguanidine hydrochloride with KOH. X-ray powder diffraction and lattice-constrained PBC-DFT optimization confirmed this structure and defined a linear all-trans configuration.     

The synthesis of higher cyclomethylalkylsilazanes

The ammonolysis of dichloro(isobutyl)methylsilane and dichloro(methyl)(nonyl)silane forms triisobutyltrimethylcyclotrisilazane, tetraisobutyltetramethylcyclotetrasilazane, and trimethyltrinonylcyclotrisilazane. The coammonolysis of dichloro(isobutyl)(methyl)silane with trichloro(nonyl)silane gave a cyclic compound with free amino groups-3,7-diamino-1,1,5,5-tetraisobutyl-1,1,5,5-tetramethyl-3, 7-dinonylcyclotetrasilazane- and the coammonolysis of dichloro(isobutyl) (methyl)silane with trichloro-(isobutyl)silane yielded bicyclic products-1,3,5,7-tetraisobutyl-1,5-dimethylbicyclotetrasilazane and 1,3,5,7,9pentaisobutyl-1,5,7-trimethylbicyclopentasilazane.     

Concave polyarenes with sulfide-linked flaps and tentacles: new electron-rich hosts for fullerenes

Pentakis(1,4-benzodithiino)corannulene (6) in CS2 formed the strongest 1:1 complexes with C60 and C70 of any corannulene derivative yet reported. The 1,3,5,7,9-pentakis(propylthio)corannulene (4b) formed weaker 1:1 complexes with C60 and C70 in CS2, whereas the decakis(propylthio)corannulene (5b) and unsubstituted corannulene (1) showed no evidence for complexation with either C60 or C70 in CS2.     

X-ray and density functional theory structural study of 1,3,5,7,9-penta-tert-butylcorannulene, C40H50

The first X-ray structural characterization of an alkyl-substituted corannulene, namely, 1,3,5,7,9-penta-tert-butylcorannulene (C40H50), has been accomplished. The addition of bulky tert-butyl groups to the corannulene core flattens the bowl and affects the solid-state packing. The presence of two enantiomers, in addition to positional disorder of the C40H50 bowls in the solid-state structure, has prevented the acquisition of accurate geometric parameters of this open geodesic polyarene. Therefore, DFT calculations have been used to describe its molecular geometry and to access bond lengths, bond angles, and a bowl depth.     

Stereoselective Synthesis of Substituted 1,3,5,7,9-Decapentaenes

Conjugated 1,3,5,7,9-decapentaene is an important structural unit in various of natural products such as phytoene, aurenin, vitamin At and A2[1]. It has been shown that conjugated polyenes are potentially useful compounds for non-linear optical materials. In the meantime the study of well-defined molecules has advanced into a strong field on its own right, because of the promising electronic and optical properties of these compounds[2]. It also attracts the interests of physical chemists as a calculation model[3] during the past decades. In the literature, there are only a few general strategies for the stereocontrolled construction of the decapentaene unit. This is mainly due to the instability and the facile (E)-(Z) isomerization of pentaene system. Synthetic methods for the construction of conjugated decapentaenes relied on the Wittig olefination[4], the Heck coupling reaction[5], the mixed crossed aldol condensation between conjugated esters and aldehydes[6], opening reaction of fulvalene complexes[7]. In our previous studies[8] on stereoseletive synthesis of polyene, we reported that conjugated trienes and enediynes could be prepared by our modified Ramberg-Backlund reaction from corresponding diallylic sulfones and dipropagylic sulfones. This synthetic method was applied to the synthesis of natural products containing a conjugated triene unit such as Galbanolenes. Reported here are our finding that bis-dienylic sulfones when submitted our Ramberg-Backlund conditions, provide decapentaenes in good yield. We use this synthetic method to synthesize 1,3,5,7,9-dec apentaene.     

Cascade Transformations of Trifluoromethanesulfonamide in Reaction with Formaldehyde

Trifluoromethanesulfonamide reacts with paraformaldehyde in acid medium to give both open-chain and cyclic condensation products: bis(trifluoromethylsulfonylamino)methane, N, N-bis(trifluoromethylsulfonylaminomethyl)trifluoromethanesulfonamide, 5-(trifluoromethylsulfonyl)dihydro-1,3,5-dioxazine, 3,5-bis(trifluoromethylsulfonyl)tetrahydro-1,3,5-oxadiazine, 1,3,5-tris(trifluoromethylsulfonyl)hexahydro-1,3,5-triazine, 5,7-bis(trifluoromethylsulfonyl)-1,3,5,7-dioxadiazocane, and 5,7,9-tris(trifluoromethylsulfonyl)-1,3,5,7,9-dioxatriazecane. Amidoalkylation of acetonitrile in the system trifluoromethanesulfonamide-paraformaldehyde-phosphoric acid leads to formation of N-(trifluoromethylsulfonylaminomethyl)acetamide.     

Electrocyclic rearrangement of pentamethylcyclooctapyrimidine-2,4-diones: reaction pathway into a 9,11-diazapentacyclo-[6.4.0.0(1,3).0(2,5).0(4,8)]dodecane system and a 9,11-diazapentacyclo [6.4.0.0(1,3).0(2,6).0(4,8)]dodecane system

Photolysis of 6-chloro-1,3-dimethyluracil and mesitylene in the presence of trifluoroacetic acid (TFA) at low temperature gave 1,3,5,7,9- and 1,3,6,8,10-pentamethylcyclooctapyrimidine-2,4-diones (1b, 1c). Sequential photoreaction of the former (1b) resulted in the formation of 9,11-diazapentacyclo[6.4.0.0(1,3).0(2,5).0(4,8)]dodecane-2,4-dione (2b) by way of 9-exo-methylene derivative (7b) and cyclobutaquinazoline (8b). On the other hand, UV-irradiation of 1c led to the bond shift isomer (5c) whose photolysis in the presence of TFA gave rise to the formation of the [6.4.0.0(1,3).0(2,6).0(4,8)]dodecane isomer (3c).     

(4-溴甲基双环[4.4.1]-1,3,5,7,9-十一碳五烯基-3-)甲醇环氧化反应机理的理论研究

A reaction mechanism of epoxidation reaction of the 4-(bromomethyl)bicyclo4.4.1undeca-1,3,5,7,9-pentaen-3-ylmethanol has been studied by using the density functional theory(DFT) method at B3LYP level with 6 31G* basis set. The geometric structures of reactant, product and transition state have been optimized. The transition state is found by the QST2 method and characterized by the vibration frequency analysis. The intrinsic reaction coordinate(IRC) for this reaction is traced and confirms the reaction mechanism. The changes and the nature of related chemical bonds along the IRC path have been analyzed by the theory of electronic charge density. The result shows that the elimination reaction and ring closing reaction are synergistic, and the hydrogen in the elimination reaction derives from hydroxyl. In addition, the activation energy of the reaction is 139.2 kJ/mol.     

Bidirectional Hiyama–Denmark Cross-Coupling Reactions of Bissilyldeca-1,3,5,7,9-pentaenes for the Synthesis of Symmetrical and Non-Symmetrical Carotenoids

The construction of the carotenoid skeleton by Pd-catalyzed Csp²−Csp² cross-coupling reactions of symmetrical and non-symmetrical 1,10-bissilyldeca-1,3,5,7,9-pentaenes and the corresponding complementary alkenyl iodides has been developed. Reaction conditions for these bidirectional and orthogonal Hiyama–Denmark cross-coupling reactions of bisfunctionalized pentaenes are mild and the carotenoid products preserve the stereochemical information of the corresponding oligoene partners. The carotenoids synthesized in this manner include β,β-carotene and (3R,3′R)-zeaxanthin (symmetrical) as well as 9-cis-β,β-carotene, 7,8-dihydro-β,β-carotene and β-cryptoxanthin (non-symmetrical).     

Funktionelle Siloxane und Cyclotetrasiloxane – Kristallstruktur eines Cycloboratrisiloxans

Functional Siloxanes and Cyclotetrasiloxanes – Molecular Structure of a Cycloboratrisiloxane Lithium salts of di-tert-butyl-fluorosilanol and -silandiol react with fluorosilanes to give 1,3-di- ( 1 , 2 ), 1,3,5-tri- ( 3 , 4 ), and 1,3,5,7,9-pentasiloxanes ( 5 ). Reactions of the dilithium salt of the silandiol with SiF₄ and CH₃SiF₃ lead to the formation of fluorofunctional cyclo-1,3,5,7-tetrasiloxanes ( 6 , 7 ). The cyclotetra-siloxane 8 is obtained by thermal LiF elimination from 1,1-difluoro-1,3-disiloxane-3-ol ( 2 ). The eight-membered ring systems 9 and 10 are formed in the reaction of dilithiated 1,3,5-trisiloxane-1,5-diol with SiF₄ ( 9 ) and BF₃ ( 10 ). The crystal structure of the cyclo-1-bora-3,5,7-trisiloxane 10 is reported and discussed.