ROM polymerization-capture-release strategy for the chromatography-free synthesis of novel unsymmetrical porphyrazines

[reaction: see text] Crossover-Linstead macrocyclization reactions of two norbornenyl-tagged diaminomaleonitriles with dipropylmaleonitrile gave access to crude mixtures of porphyrazines containing diamino-hexapropyl-porphyrazine magnesium complexes. The mixtures were subjected to ring-opening metathesis polymerization to yield the insoluble diaminoporphyrazine-functionalized polymers. Acid-mediated cleavage from the polymer backbone followed by acylation of the resultant sensitive macrocyclic diamines gave monoacetyl-, monotrifluoroacetyl-, and ditrifluoroacetyl-substituted porphyrazinediamines. Conversion of these amido-porphyrazines to the corresponding zinc macrocycles and studies of their electronic absorption and emission spectra, electrochemistry, and photophysics are described.     

Base-catalyzed synthesis of bicyclic 4-aminopyrimidines from the reaction of dinitriles with mononitriles

A convenient method for the synthesis of bicyclic 4-aminopyrimidines is described, involving the reaction of dinitriles with mononitriles in the presence of catalytic potassium tert-butoxide. These reactions proceed via the Thorpe-Ziegler cyclization of the dinitrile to form an intermediate β-cyanoenamine, which then undergoes annulation with the mononitrile in situ.     

Enzymic hydrolysis of prochiral dinitriles

A series of prochiral 3-hydroxyglutaronitrile derivatives 1–5 has been enzymically hydrolysed to the corresponding nitrile-carboxylic acids 1b–5b with enantiomeric excesses ranging from 22–84%. In all cases the products were of the (S)-configuration.     

Photoprocesses of chloro-substituted p-benzoquinones

The photochemistry of chloro-(ClBQ), dichloro-(2,5- and 2,6-Cl 2BQ), and trichloro-1,4-benzoquinone (Cl 3BQ) was studied in aqueous solution and/or in mixtures with acetonitrile. Final products are the corresponding hydroquinones (QH 2s) and 2-hydroxy-1,4-benzoquinones (QOHs). Three transients were detected by UV-vis absorption spectroscopy. The triplet state appears within the 20 ns 248 nm pulse and is converted within 0.1-1 micros into a photohydrate (HI aq). HI aq which is spectroscopically and kinetically separated from the triplet state decays within 5 ms, whereas the anion of the hydroxyquinone (QO (-)) grows in at ca. 500 nm in the 0.1-1 s time range. The proton formation and decay kinetics within 0.1-10 micros were observed by transient conductivity in the course of the reaction of the triplet state with water en route to HI aq at pH 4-9. Formation of QO (-) results in a permanent conductance. The efficient photoconversion of Cl n BQs at low concentrations (<0.2 mM) into QH 2s and HOQs is due to a redox reaction of Q with rearranged HI aq. The quantum yield of photoconversion at lambda irr = 254 nm is 0.8-1.2 for ClBQ or Cl 2BQs in aqueous acetonitrile and smaller (0.4) for Cl 3BQ. The yield of semiquinone radical ( (*)QH/Q (*-)) of Cl n BQs ( n = 1-4) in acetonitrile-water (1:1) is low (<20%) at low substrate concentration but is significantly increased upon addition of an H-atom donor, for example, 2-propanol. Other mechanisms involving (*)QH/Q (*-) radicals, such as quenching of the triplet state at enhanced Cl n BQ concentrations and H-atom abstraction from an organic solvent in mixtures with water, have also to be considered.     

Supramolecular squares of porphyrazines

The design, self-assembly, and characterization of discrete arrays of porphyrazine (Pz) squares are presented to illustrate the supramolecular chemistry of these macrocycles, and to highlight that these arrays have physical chemical properties that are different from similar arrays of porphyrinic systems.     

二腈的区域和对映选择性生物水解反应: 腈水合酶与二腈分子 作用模式初探

在Rhodococcussp.AJ270细胞的催化作用下,内消旋的内式和外式双环[2.2.1]-庚烯-2,3-二腈和双环[2.2.2]-5-辛烯-2,3-二腈水解生成相应的二酸或酸酐,而外消旋的反式双环[2.2.1]-5-庚烯-2,3-二腈和双环[2.2.2]-5-辛烯-2,3-二腈则发生区域选择性和立体选择性的水解反应生成光活性的氰基酰胺和氰基羧酸。讨论了腈水合酶与二腈的作用模式。     

Angle-resolved photoelectron spectroscopy of the chloro-substituted methanes

The angular distribution parameter, β, was determined for the valence orbitals (IP ′ 21.2 eV) of CCl₄, CHCl₃, CH₂Cl₂, and CH₃Cl in the 10–30 eV photon energy range using dispersed polarized synchrotron radiation. The energy dependence of β in the photoelectron energy range of 2 to 10 eV for the non-bonding chlorine n(Cl) orbitals of these molecules was found to be similar for all n(Cl) orbitals investigated. The energy dependence of β for the σ orbitals in these molecules was similar to that observed previously for other σ orbitals. The experimental CCl₄ results were compared with theoretical CCl₄ results obtained using the Xα multiple scattering formalism. Theory predicts the existence of two strong shape resonances in each of the valence orbitals of CCl₄. The overall agreement between experiment and theory is evaluated along with the experimental evidence concerning the verification of the predicted shape resonances.     

Dichlorocyclopropanation of chloro-substituted vinyl phenyl ethers

Conclusions The reaction of chloro-substituted vinyl phenyl ethers with dichlorocarbene generated by the thermolysis of phenyl(trichloromethyl)mercury leads to the corresponding gem-dichlorocyclopropyl derivatives while the reaction of cis--chlorovinyl phenyl ether with chloroform and alkali under phase transfer catalysis conditions gives -trichloromethyl--chloroethyl phenyl ether.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 222–224, January, 1985.     

Mass spectra of chloro-substituted benzophenones

The mass spectra of all three monochloro-, seven of the dichloro- and two of the trichloro-substituted benzophenones are reported. The major fragments in the spectra are due to α-fission to oxonium ions followed by the well-known subsequent fragmentations. The ring bearing the greater number of chlorine atoms appears to cleave more readily, with 2-chloro substituents enhancing this tendency. There is evidence for the formation of the biphenylene ion in all monochloro and all dichloro compounds studied and for the formation of the chloro biphenylene ion in both trichloro compounds studied. In the case of 2,2′-, 2,4- and 3,4-dichlorobenzophenones evidence exists for hydrogen transfer between rings.     

Electronic structure of chloro-substituted pyrimidines

The electron-density distribution in the molecules of six chloro-substituted pyrimidines was calculated by the MO LCAO method within the Hoffmann and Pariser-Parr-Pople approximations. The reactivities and transmission of the effect of substituents in these compounds are discussed. The charges and orders of the bonds in the excited states of the chloropyrimidines were calculated with allowance for the interaction of the configurations. An interpretation of their electronic spectra is given.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1409–1413, October, 1973.The authors thank V. M. Cherkasov for his constant interest in this research.     

Excited state behaviour of pentahelicene dinitriles

The excited singlet and triplet states 2,13-dicyano[5]helicene (1) and two para-dicyno[5]helicenes containing one and two methyl groups (2 and 3, respectively) were studied in solvents of different polarity as a function of temperature. Fluorescence quenching by electron donors such as triethyl amine indicated photoinduced electron transfer. In the absence of additives triplet states were observed by flash photolysis. The triplet lifetime at room temperature was rather short (<1 μs) and the decay limited by intramolecular processes, e.g. charge transfer in the cases of 2 or 3. Luminescence of singlet molecular oxygen, O₂(¹Δ_g), was observed with moderate and low quantum yield for 1 and 3, respectively. For 1–3, the triplet lifetime increases by six orders of magnitude on going to −196°C. Two subsequently formed triplet states were observed for 3 at lower temperatures. The effects of temperature and solvent polarity on the quantum yields of fluorescence and phosphorescence and the spectroscopic and kinetic triplet absorption properties were examined. The influence of substituents on the deactivation pathways of excited pentahelicenes are discussed.     

D-A-D type dinitriles with vapor-dependent luminescence in the solid state

D-A-D (Donor-Acceptor-Donor) type dinitriles linked by a styryl or phenylethynyl group have been prepared. These groups were introduced to increase the flexibility and the size of the π-conjugation in the chromophores. Both compounds showed strong emission in the solid state, AIE (aggregation-induced emission) behavior, and mechanochromism. The fluorescence color of ground powder changed by organic solvent vapor (vapochromism). Especially, the emission color of the styryl dinitrile after exposures depends on the solvent, while that of the phenylethynyl dinitrile is the same after exposure to different solvents. These results were explained by single crystal and powder XRD measurements, which revealed that the flexible styryl linker leads to a loose crystal packing, resulting in a dinitrile with multi-state microcrystalline structures. This methodology based on the flexible linker allows for the detection of small organic molecules without transition metals.     

Amination of chloro-substituted heteroarenes with adamantane-containing amines

Russian Chemical Bulletin - Amination of 3,6-dichloropyridazine, chloropyrazine, 2,3and 2,6-dichloropyrazines, 2-chloroquinoxaline, 1-chloroand 1,3-dichloroisoquinolines with various...     

Reaction of novolac resin with aromatic dinitriles

Cross-linking of Novolac resin with aromatic dinitriles in the presence of aluminum chloride was studied.     

Unsaturated four-membered N-heterocycles: From synthesis to applications

The ubiquity of strained motifs in drug discovery has recently witnessed a large regain of interest, as such scaffold can be used to modulate the properties of drug candidates. Unsaturated N-containing four-membered heterocycles present unique opportunities to access functionalized azetidines, which play an essential role in pharmacological studies. Even though those unsaturated patterns have been much less reported than the corresponding saturated versions, the consequent impact that those structures could have on molecular design with implementation of strained modules deserves to be summarized. In this review, synthetic accesses to substituted azetes, 1-azetines and 2-azetines are depicted, as well as their involvement in further transformations.     

Acid-base interactions of benzo-annelated porphyrazines in proton-donor media

Acid-base interactions of benzo-annelated trifluoromethylphenylporphyrazines in media based on acetic and trifluoroacetic acids were studied. The quantitative characteristics of the equilibria between acid-base species were obtained. Variation of the porphyrazine structure leads to changes not only in the macroring basicity, but also in the structure and order of formation of acidic species depending on the nature of the proton-donor medium.     

Highly efficient one-pot synthesis of D-ring chloro-substituted neocryptolepines via a condensation—Pd-catalyzed intramolecular direct arylation strategy

D-ring chloro-substituted neocryptolepines have been synthesized in excellent yield starting from 3-bromo-2-chloro-1-methylquinolinium triflate via a one-pot condensation—Pd-catalyzed intramolecular direct arylation strategy involving chloroanilines. The 3-bromo-2-chloro-1-methylquinolinium triflate was obtained via methylation of commercial 3-bromo-2-chloroquinoline with methyl triflate.