Cobalt-mediated oligomerization reactions of amino-substituted acetylene derivatives

Reactions of the aminoacetylenes Et₂N-CC-R (R = SiMe₃, SPh, PPh₂; 1a-c) with (η⁵-pentamethylcyclopentadienyl)bis(ethene)cobalt yield the corresponding (η⁵-pentamethylcyclopentadienyl)(η⁴-cyclobutadiene)cobalt complexes 2a-c. Treatment of 1-phenylthio-2-diethylaminoacetylene 1b with three equivalents of CpCo(CO)₂ leads to the 1,3-dicobalta-bicyclobutane derivative 3′b. The analogous compound 3′d and the trinuclear cobalt complex 4′d are obtained from the reaction of bis(diethylamino)acetylene (1d) with (η⁵-cyclopentadienyl)bis(ethene)cobalt. Treatment of 1d with excess Co₂(CO)₈ yielded unexpectedly a mixture of di- and tetranuclear cobalt-carbene complexes 7 and 8, most likely formed through interaction of oxygen. A designed route to 7 and 8 is found by reacting the tetraethyloxamide 6 with Co₂(CO)₈ and Co₄(CO)₁₂, respectively. The catalytic cyclotrimerization reaction of the aminothioacetylene derivative 1b with [CpCo(CO)₂] or [Co₂(CO)₈] leads to tris(phenylthio)-tris(diethylamino)benzene derivative 9. The new compounds have been characterized by NMR spectroscopy, mass spectrometry as well as by X-ray structure analyses for 3′d, 7 and 8. The molecular structure of 3′d in the crystal reveals the presence of a bicyclobutane framework with a Co-Co distance (2.36 Å) lying between a single and a double bond, whereas the former CC triple bond is completely ruptured (2.13 Å). The Co-C(carbene) distances in 7 and 8 are 1.93 and 1.95 Å, respectively.     

Photoaddition reactions of 1,4-diphenylbutadiyne with olefins

1,4-Diphenylbutadiyne(DPB) and several olefins such as 2,3-dimethyl-2-butene, 1,4-cyclohexadiene and dimethyl fumarate were irradiated with 300 nm UV light to obtain interesting cross-cycloaddition products.     

Photoaddition of thienocoumarin derivatives to DNA: stoichiometry and kinetics of binding

Photoreaction of the 6,9-dimethyl-4-methoxymethyl-2H-thieno[3,2-g]-1-benzopyran-2-one (compound I) and 4-acetoxymethyl-6,9-dimethyl-2H-thieno[3,2-g]-1-benzopyran-2-one (compound II) to DNA was studied. The quantitative evaluation of the photobound molecules was performed by means of inductively coupled plasma atomic emission spectrometry (ICP-AES), exploiting the presence of the sulphur atom inside the tricyclic chromophore. The concurrent estimation of the phosphorus atom, present exclusively in the macromolecule, allowed possible intercalation sites to be identified and their involvement in the photoaddition reaction to be determined. The development of a kinetic model made it possible to discriminate and evaluate the single kinetic events that constitute the overall photoaddition process of I and II to DNA.     

Photoaddition reactions of fluoroolefins with diols and cyclic ethers

Fluoroalkylation of aliphatic diols, tetrahydrofuran and 1,3-dioxolanes with perfluoroolefins under photochemical initiation was studied. The aim of the study was the preparation of fluoroalkylated diols as intermediates for special fluorinated monomers. Fluoroalkylation was only partly successful in the case of 1,4-butanediol and quite successful with tetrahydrofuran and 2,2-dimethyl-1,3-dioxolane. The fluoroalkyl diols obtained were converted to monomethacrylates that are amphiphilic monomers.     

Photoaddition reactions of benzene and related compounds with thiochromone 1,1-dioxide

The photoaddition reactions of benzene and some simple derivatives with thiochromone 1,1-dioxide have been examined in an attempt to correlate the pattern of photochemical behavior with data on ionization potentials.     

Photoaddition of N-ethylmaleimide to cumene

The photoaddition of N-ethylmaleimide (NEMI) to cumene is compared with that of benzene. The equilibrium constants of the CT-complexes were determined by means of ¹H-N.M.R. spectroscopy (K_benzene-NEMI = 0.035 kg mole^?1, K_cumene-NEMI = 0.049 kg mole). By irradiation with light of wavelength 254 nm the 2:1 adduct cumene-NEMI is formed. The structure was determined by ¹ H-N.M.R. and mass spectrometry. These data indicate that only one of the possible isomers is formed and that the free rotation of the isopropyl group is hindered in the adduct. Furthermore two isomeric 1 : 1 adducts could be detected and assigned to the 1 : 1 cycloaddition product and to cumyl-N-ethyl-succinimide.     

Some acetylene derivatives of indoline

Conclusions A method was developed for the synthesis of 1-methyl-5-ethynylindoline and its derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1169–1170, May, 1976.     

Photoaddition of Iodoform to P-Chlorostyrene and Indene

A new type of triiodo compounds synthesized by irradiation of p-chlorostyrene or indene with iodoform in the inert solvent is reported.     

Photoaddition of N-substituted piperazines to C60: an efficient approach to the synthesis of water-soluble fullerene derivatives

An oxidative radical photoaddition of mono N-substituted piperazines to [60]fullerene was systematically investigated. Reactions of C60 with piperazines bearing bulky electron-withdrawing groups (2-pyridyl, 2-pyrimidinyl) were found to be the most selective and yielded C60(amine)4O as major products along with small amounts of C60(amine)2. In contrast, interactions of fullerene with N-methylpiperazine and N-(tert-butoxycarbonyl)piperazine were found to have low selectivity due to different side reactions. Tetraaminofullerene derivative C60(N-(2-pyridyl)piperazine)4O was found to react readily with organic and inorganic acids to yield highly water-soluble salts (solubility approximately 150 mg mL(-1)). In contrast, C60(N-(2-pyrimidinyl)piperazine)4O undergoes hydrolysis under the same conditions and results in a complex mixture of compounds with an average composition of C60(N-(2-pyrimidinyl)piperazine)2(OH)2O. Radical photoaddition of N-(2-pyridyl)piperazine to fullerene derivatives can be used as a facile route for their transformation into water-soluble compounds. Two model fullerene cycloadducts (a methanofullerene and a pyrrolidinofullerene) were easily converted into mixtures of regioisomers of A=C60(N-(2-pyridyl)piperazine)4O (A=cyclic addend) that give highly water-soluble salts under acid treatment.     

Laser induced polymerization of acetylene derivatives

He-Cd laser induced polymerization of aryl-propargylamines such as phenyl- and diphenylpropargylamines were studied. The polymerization of these monomers was shown to be realized only in presence of acceptor of electrons. Polymer formation process is based on the formation of an intermediate compound and its following polymerization by the radical reaction of C≡C bond. Photochemical and photophysical processes leading to the formation of intermediate compound were investigated. The polymers obtained were characterized by IR-, ESR-, NMR-spectroscopy. The conjugated double bond system formation is the main characteristic of these polymers. Some polymer properties were studied.     

Quantum-chemical investigation of the mechanisms of nucleophilic addition reactions to acetylene

The interactions between an acetylene molecule and lithium hydrosulfide in the dissociated and undissociated states have been calculated in the framework of the semiempirical MNDO method. It has been established that acetylene can easily form molecular complexes with lithium hydrosulfide, which are stable toward all the possible types of nonradical dissociation. A comparison with the previously considered reaction between C₂H₂ and LiOH shows that in the case of LiSH, the activation barriers to the isomerization of the complex C₂H₂·LiSH to vinyl mercaptans are considerably lower.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1792–1796, August, 1989.     

An unusual acetylene–allene rearrangement in iodomethylates of cotarnine acetylene derivatives

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Photoaddition reactions of 1,2-diketones with silyl ketene acetals. formation of beta-hydroxy-gamma-ketoesters

Photochemical reactions taking place between 1,2-diketones and silyl ketene acetals and their excited state reaction mechanisms have been explored. Irradiation of benzene, acetone, or acetonitrile solutions containing 1,2-diketones and silyl ketene acetals is observed to promote formation of 1,4-dioxenes, resulting from [4 + 2]-cycloaddition, oxetanes, arising by Paterno-Buchi processes, and beta-hydroxy-gamma-ketoesters, generated by SET-promoted Claisen-type condensation. These competitive pathways leading from the excited states of the 1,2-diketones to these products are influenced by solvent polarity and the nature of the silyl ketene acetal and 1,2-diketone. The Claisen-type condensation process, following an SET desilylation pathway and predominating when the photoreactions are carried out in the polar solvent acetonitrile, represents an efficient method to prepare a variety of diversely substituted beta-hydoxy-gamma-ketoesters.     

Synthesis of acetylene derivatives of diphenylolpropane ethers

Syntheses are reported for monomers and oligomers of dipropyl and di(propen-1-yl) (cis,cis and cis, trans isomers) ethers of 2-(4 -hydroxy-3, 5 -diethynylphenyl)- 2-(4-hydroxyphenyl)propane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1668–1670, July, 1991.