Novel photochemical reaction of indole with naphthalene and phenanthrene in the solid state

Irradiation of mixed crystals of indole and naphthalene gave an addition product, 1-(1,4-dihydro-1-naphthyl)indole ( ), while irradiation in solution gave another product in addition to . Similar solid-state photoreaction of indole and phenanthrene gave .     

Photochemistry of 4H,7H-Benzo

The title compound 1 was synthesized starting from 1, 2-bis(2-hydroxyethyl)benzene (2). Irradiation (350 nm) of 1 in CH(3)CN affords the all-cis-dimer 6 in >90% yield. Irradiation (>390 nm) of 1 in the presence of tetrachloroethene leads selectively to the monocyclobuta adduct 8, which on subsequent irradiation is converted to a 4:1 mixture of biscyclobuta derivatives 9 and 10.     

2,5-环己二烯酮类的固相光化学(Ⅱ)

本文报道了2,4,6-三叔丁基-4-甲氧基-2,5-环己二烯酮的固相光化学反应,所得三种产物的比率随温度而变化,而液相光化学反应与温度无关。用带有NaNO₂滤色液的光照射该化合物,几乎得到100％的列米酮。在列米酮中加入少量萘的固相光化学反应所得产物的比率随萘量而变化。     

Reinvestigation in the photoreaction of 1-naphthalenecarbonitrile and furan

Photocycloaddition of furan to 1-naphthalenecarbonitrile (1) was reinvestigated. Irradiation of the mixture through Pyrex filter yielded endo-[4+4] adduct (2) and syn-[2+2] adduct (4). Considering the secondary orbital interaction in the singlet-state [4+4] photocycloaddition, the favorable formation of exo-[4+4] cyclodimer (3) over 2 followed by a facile Cope rearrangement was proposed for the formation of 4, and confirmed by a low temperature irradiation experiment.     

含氮杂环化合物的固相光化学

本文研究了含氮杂环化合物同尿嘧啶醛、芳香醛酮、稠环化合物的固相光化学反应, 得到与液相光化学反应不同的结果。合成了十九种新化合物, 它们的结构由IR, ^1H NMR, MS和元素分析确定。用光谱方法表征了混晶的性质。X射线粉未衍射和差热分析表明, 吲哚同萘, 咔唑同蒽的混晶, 形成了分子化合物。对反应机理进行了初步探讨。     

The Reaction of Indole with Propiolic Acid

The reaction of indole with propiolic acid ia 1 : 1 mole ratio gave an adduct (I) of 2 : 1 addition with decarboxylation. The reaction of indole with propiolic acid methyl ester gave a 2 : 1 adduct (II). Hydrolysis of adduct II yield the corresponding carboxylic acid (IV). Decarboxylation of IV also gave I. The mechanism of title reaction were fully studied.     

ENERGY TRANSFER IN PHENANTHRENE-DOPED NAPHTHALENE CRYSTALS

Abstract— Measurements at 77°K and room temperature are described on naphthalene crystals containing varying concentrations of phenanthrene. The lowest excited singlet and triplet states of phenanthrene iie between the singlet and triplet exciton bands of the host crystal. Triplet-triplet annihilation in the host was studied by absorbing radiation purely into the guest molecules; the absence of any phosphorescence or delayed naphthalene fluorescence allowed the radiationless processes out of the naphthalene triplet to be discussed. Singlet-singlet energy transfer was studied using radiation absorbed by the naphthalene. Two separate mechanisms of transfer were observed: (A) free exciton motion in the naphthalene band till encounter with a phenanthrene trap, the last step having an activation energy of 65 cm^-1, and (B) defect traps in the naphthalene transferring energy by a resonance mechanism to the phenanthrene; the average depth of the defect traps was calculated at 200 cm^-1.     

Photolysis of organopolysilanes. The reaction of photochemically generated methylphenylsilylene with conjugated dienes

Photolysis of 2-phenylheptamethyltrisilane (I) in the presence of acyclic and cyclic conjugated dienes has been investigated using both a high-pressure mercury lamp with a quartz filter and a low-pressure mercury lamp with a Vycor filter. Irradiation of I in the presence of 1,3-butadiene, isoprene or 2,3-dimethylbutadiene with a high-pressure mercury lamp gave a product arising from photochemical isomerization of a silacyclopropane derivative and a compound apparently formed by 1,4-silylene addition, along with a 1/1 “ene” adduct of the diene to a photo-rearranged intermediate containing the silicon—carbon double bond. Irradiation of I in the presence of the conjugated diene with a low-pressure mercury lamp, followed by treatment of the product with methanol, afforded a methoxysilane arising from methanolysis of the corresponding silacyclopropane, together with the isomerization product, silacyclopentene and rearranged addition product. Irradiation of I in the presence of cyclopentadiene with a high-pressure mercury lamp produced methylphenylsilylcyclopentadiene, while irradiation of a similar mixture with a low-pressure mercury lamp followed by treatment with methanol gave 4-(methoxymethylphenylsilyl)-1-cyclopentene. With 1,3-cyclooctadiene, the photochemically generated methylphenylsilylene afforded many types of addition product. Photolysis of I in the presence of 1,3-cyclohexadiene, however, afforded none of the silylene addition products.     

微环境影响下的乙酰基香豆素与吲哚的固相光反应

本文研究了乙酰基香豆素及其衍生物与吲哚的混晶在微环境影响下的固相光反应，并用固体紫外光谱、固体荧光光谱和X-射线粉末衍射技术考察了混晶的特征。实验结果表明，3-乙酰基香豆素及其7-乙酰氧基、7-苯甲酰氧基、5,6-苯并和6-溴衍生物与吲哚的固相光反应分别得到1:2缩合产物1～5，而6-硝基衍生物与吲哚的固相光反应却得到开环脱羰加成产物6。通过IR、MS、^1H NMR和元素分析结果确定了这六个新产物的结构。固体光谱的测试结果表明，取代乙酰基香豆素与吲哚间混晶的形成，分子间存在相互作用，使分子所处的微环境条件发生了变化。     

Solid-state photochemistry of the mixed crystals between benzoquinones and polymethylbenzenes

Nine mixed crystals combined 1,4-benzoquinone (1), 2,5-xyloquinone (2) and duroquinone (3) with durene (a), pentamethylbenzene (b) and hexamethylbezene (c) were prepared by a melting-resolidifying process and characterized by powder X-ray diffractometry, DSC and IR. Only the mixed crystal of 3 and a formed a 2:1 novel molecular crystal (4); other eight mixed crystals were simple polycrystalline mixtures of the two components. Irradiation of the molecular crystal 4 (3/a) and the mixed crystals 1/a, 1/b and 3/b caused intermolecular hydrogen abstraction to give hydroquinones and in some cases adducts. Product selectivities in the solid state were different from those in solution. Correlation between the crystal structure and the reactivity of 4 is discussed.     

Photochemical and Acid-Catalyzed Rearrangements of 4-Carbomethoxy-4-methyl-3-(trimethylsilyl)-2,5-cyclohexadien-1-one

The synthesis of 4-carbomethoxy-4-methyl-3-(trimethylsilyl)-2,5-cyclohexadien-1-one (1) in 60% overall yield from benzaldehyde is described. Irradiation (366 nm) of 1 in benzene solution gave products of type A photorearrangement; e.g., diastereomers of the 4-(trimethylsilyl)- and 5-(trimethylsilyl)bicyclo[3.1.0]hex-3-en-2-ones 8 and 9. Bicyclohexenones 9a and 9b could not be isolated, but underwent acid-catalyzed protiodesilylative rearrangements on attempted chromatography (silica gel) to give a 1:1 mixture of (E)- and (Z)-4-(carbomethoxymethylmethylene)cyclopent-2-en-1-ones 12 and 13. Irradiation (366 nm) of either 12 or 13 resulted in photoisomerization to a photostationary state that was also a 1:1 mixture. Irradiation of 8a or 8b gave equivalent mixtures of phenols 14 and 15 by way of the type B oxyallyl zwitterion 17. The available experimental evidence suggests that both 9a and 9b undergo regiospecific photorearrangement to phenol 16 with no trace of 3-methyl-4-carbomethoxyphenol (19), the product of ipso substitution of the Me(3)Si group at C(4). Phenol 15 was isolated in 65% yield from the photoreaction of 1 in benzene with 20 equiv of CF(3)CO(2)H. The acid-catalyzed rearrangement of 1 to 3-carbomethoxy-4-methylphenol (21) occurs in 91% yield by way of CO(2)Me group rearrangement to C(3) to give the Me(3)Si-stabilized carbocation 23.     

Regioselective photocycloaddition of pyridine derivatives to electron-rich alkenes

Irradiation of a benzene solution of 3-cyano-2,6-dimethoxypyridine in the presence of ethyl vinyl ether (EVE) gave 1:1 photoadducts, 3-cyano-5-ethoxy-2,8-dimethoxy-4,5-dihydroazocine, in good yields, whose structure was established by X-ray single-crystal analysis. The photoadduct was produced via cycloaddition between the C3-C4 position of the pyridine derivatives and an alkene chromophore. On the other hand, 3-cyano-2,6-dimethoxy-4-methylpyridine cycloadds to EVE at the C2-C3 position of the pyridine ring upon irradiation. The difference is explained on the basis of the steric effect.     

Hydrogen bonding interactions between indole and benzenoid-pi-bases

The NH-pi interactions of indole with benzene, naphthalene, phenanthrene, toluene, m-xylene, and mesitilene, in carbon tetrachloride solutions, have been studied by Fourier transform infrared spectroscopy. The experiments, carried out on the NH stretching band of indole, prove the formation of 1:1 complexes in which the NH bond of indole is engaged. The NH frequency shifts are independent of the number of rings in the base, but they progressively increase as the electron density is enhanced by methylation. The association constants increase with the increase of both, the number of rings and the methyl groups on the base. At higher base concentrations, further shifts on the free NH and associated bands indicate the formation of 1:2 complexes, which suggest hybride NH-pi and van der Waals interactions between one indole ring and two benzene acceptor molecules.     

Resolution of 13 polycyclic aromatic hydrocarbons by constant-wavelength synchronous spectrofluorometry.

A method capable of determining 13 PAHs (acenaphthene, anthracene, benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, dibenzo[ah]anthracene, fluoranthene, fluorene, indene[1,2,3-cd]pyrene, phenanthrene and pyrene) in a mixture of 16 EPA PAHs by second derivative synchronous spectrofluorometry in the constant wavelength mode was developed. It has not been possible to determine the following PAHs in the mixture: acenaphthylene, benzo[ghi]perylene and naphthalene. The approach studied allows the sensitive, rapid and inexpensive identification and quantitation of 13 PAHs in a solution of hexane. The detection limits are <1 microg L(-1) (except for chrysene and phenanthrene).     

An efficient acceptor of 1-hydroxy(or alkoxy)alkyl radicals – ketene dithioacetal S,S-dioxide –

Irradiation of a ketene dithioacetal S,S-dioxide (2) in alcohols or ethers containing benzophenone gave an adduct which was formed by addition of 1-hydroxy- or 1-alkoxyalkyl radicals to 2 followed by hydrogen transfer.     

A Novel Photochemical Reaction of 4-Bromo-3-methyl-1- phenyl-4,5-dihydro-pyrazol-5-one

UV-Irradiation of 4-bromo-3-methyl-l-phenyl-4,5-dihydro-pyrazol-5-one (1) in the presence of various aromatic hydrocarbons gave different types of photoproducts depending on the nature of the hydrocarbons via an electron-transfer mechanism. In the presence of naphthalene or phenanthrene a photochemical homocoupling reaction of 1 occurred to form 2 or 2 and 3, respectively.     

The sulfonation of aromatic and heteroaromatic polycyclic compounds

Relative reactivities of a series of polycyclic carbo- and heteroaromatic compounds to sulfonation by sulfur trioxide in nitrobenzene are measured and discussed. The results show the following reactivity in decreasing order: indole, carbazole, pyrene, perylene, naphthalene, phenanthrene, benzene, benzothiophene, and dibenzothiophene.     

Photochemical studies of thymine in ice

Abstract— Solutions containing various concentrations of thymine have been irradiated (254 nm) at — 196°, and the corresponding absorbance changes at 315 nm due to thymine-thymine adduct formation have been followed as a function of dose. The maximum yield of the adduct is about 3–2 per cent. Additional irradiation leads to a reduction in the yield of adduct and to an increase in the yield of the proposed trimer, which shows a sigmoid dose response curve. Not more than 10 per cent of the thymine is converted to trimer. Irradiation of the trimer in solution converts it into adduct plus thymine. Fluorescence due to the adduct does not appear directly after irradiation at — 196°, but comes about upon annealing at elevated temperatures (T > - 80°).     

Diastereospecific photocyclization of a isopropylbenzophenone derivative in crystals and the morphological changes

Reaction of crystals of 2,4,6-triisopropylbenzophenone derivative with the (S)-phenylethylamide group caused diastereospecific Norrish type II photocyclization by UV irradiation to give (R,S)-cyclobutenol as a sole product. In contrast, the solution photolysis gave an almost 1:1 mixture of (R,S)- and (S,S)-cyclobutenol. The specific diastereodifferentiation in the crystalline state is attributed to the smooth transformation with minimum molecular motion due to the very similar molecular shapes as well as the 2-fold helical arrangements between the reactant crystal and the product (R,S)-cyclobutenol crystal. UV irradiation of the bulk crystals led to cracking and breaking into small fragments. In contrast, the microcrystals maintained the single-crystalline morphology in the course of photocyclization, suggesting the single-crystal-to-single-crystal transformation.     

The photochemical [4+4] cyclodimerization of 2-pyrazinone in the solid state

Irradiation of 1-methyl-5,6-diphenyl-2-pyrazinone (Ia) in the solid state gave the [4+4] anti dimer (II) in 100% yield, while (Ia) in a solution phase was inert upon irradiation.