Unsymmetrical and symmetrical diphosphazane ligands derived from o-phenylene phosphorochloridite

Two new diphosphazane ligands, PrⁱN(PPh₂)(PO₂C₆H₄) ( 1 ) and PrⁱN{P(O₂C₆H₄)}₂ ( 3 ), have been synthesized and characterized by spectroscopic data. The structure of 1 has been confirmed by single crystal X-ray diffraction. Crystal data: Monoclinic, C2/c, Z = 16, a = 34.149(5) Å, b = 9.717(6) Å, c = 29.439(5) Å, β = 125.11(2)°, V = 7991 ų, R = 0.058, R_w = 0.061. This compound shows two different P–N bond lengths (1.654 (4) and 1.743(4) Å) and a P–N–P angle of 120.7(2)°. Variable temperature ³¹P NMR measurements for 1 and 3 throw light on the nature of the conformers present in solution.     

Synthesis and copolymerization of oligo(lactic acid) derived norbornene macromonomers with amino acid derived norbornene monomer: Formation of the 3D macroporous scaffold

Norbornene macromonomers 2 and 3 bearing 10‐ and 20‐mers of lactide were synthesized by ring‐opening polymerization of lactide using 5‐norbornene‐2, 3‐exo‐exo‐dimethanol as an initiator and DBU as a catalyst. Macromonomers 2 and 3 were copolymerized with amino acid derived norbornene monomer 1 , using the Grubbs 2nd generation ruthenium catalyst. The random and block copolymers with M_n's ranging from 28,000 to 180,000 were obtained almost quantitatively where the M_n's of the block copolymers were higher than those of the random ones. Three‐dimensional macroporous structure polymers with average pore size of 10 µm could be found in poly( 1 ) and the block co‐polymer of 1 and 2 or 1 and 3 at the high ratio of 1 . Meanwhile, poly( 2 ) and poly( 3 ) along with block and random copolymers with low ratio of 1 exhibit much larger pores in the range of 50–300 µm. The porosity increased with increase in the unit ratio of 1 . The compressive strength of the porous structure of poly( 2 ) and poly( 3 ) was improved by the copolymerization with 1 . © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1660–1670     

Cope rearrangements of diels-alder adducts containing norbornene and norbornenone systems

The product formed from cyclopentadiene and the cyclo-octatetraene dimer 5a has been shown to possess structure 6a, probably resulting from Cope rearrangement of an initial adduct 4a. The reaction of tetraphenylcyclopentadienone with 1 - methoxybuta - 1,3 - diene yields a mixture of the exo-adduct 14 and the rearranged endo-adduct 13 Rearrangement of the norbornenone derivative 27 gives the Cope product 29 Treatment of the 4,5-fused 2,3,4,5-tetrachlorocyclopent-2-enones 29,40 and 41 with powdered sodium hydroxide in tetrahydrofuran results in ring-cleaveage with the formation of 2,3,5-trichlorobuta-2,4-dienoic acid derivatives, 36, 43 and 44 respectively.     

Experimental study on synchrotron radiation photoionization of secondary organic aerosol derived from styrene ozonolysis

Secondary organic aerosol (SOA) produced by ozonolysis of styrene and other alkene compounds is a major part of fine particles in urban atmospheres. The atmospheric ozonolysis process of styrene is simulated in a smog chamber, and the formed SOA particles are detected on-line by a synchronous radiation vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) in this study. Through molecular ion peaks in the photonionization mass spectra of SOA and the corresponding photoionization efficiency curve, combined with off-line measurement verification of ultraviolet visible and infrared absorption spectra, it is determined that formaldehyde, formic acid, benzene, phenol, benzaldehyde, and benzoic acid are the main constituents of styrene SOA. These provide new information for studying the atmospheric ozonolysis oxidation mechanism of styrene. VUV-PIMS can get over complicated sample preparation procedures, secondary pollution, and other shortcomings of the off-line method and is a useful instrument to measure constituents and unveil the formation process of SOA particles.     

Unique emission from norbornene derived terpyridine--a selective chemodosimeter for G-type nerve agent surrogates

A new chemodosimeter for a G-type agent that exploits norbornene derived terpyridine (NDT)-lanthanide unique emission is reported. The unusual emission between terpyridine and norbornene motifs of NDT is attributed to the significant difference in the position of the HOMO and LUMO wave functions that prevents the non-radiative relaxation pathway. An interesting magenta emission from NDT along with Eu(III) is utilized as a new fluorometric chemodosimeter that selectively detects (by changing the observed magenta emission to blue) G-type agent surrogates. A detection limit of 40 ppb is obtained and the selectivity for reactive surrogates over a variety of other close chemical analogs is demonstrated.     

Direct electrospray tandem mass spectrometry of the unstable hydroperoxy bishemiacetal product derived from cholesterol ozonolysis

Cholesterol is the most abundant neutral lipid in the epithelial lining fluid of the lower airways of the lung also known as pulmonary surfactant and a potential target for reaction with ambient ozone when inspired into the human lung. The isolated double bond of cholesterol has been shown to be susceptible to attack by ozone, but the major reaction product from cholesterol ozonolysis had been remarkably difficult to structurally characterize. Recently, NMR and X-ray crystallography have been used to suggest the formation of a hydroperoxy, hydroxy hemiacetal product, using various derivatives and models of cholesterol to stabilize this chemically reactive product. Electrospray ionization mass spectrometry was used to study the somewhat unstable ozonolysis product of cholesterol which was found to display unique ionization and fragmentation properties when collisionally activated. The electron-deficient carbon atoms of this highly oxygenated product permitted covalent attachment of an acetate anion during negative ion electrospray ionization, leading to the formation of abundant adduct ions at m/z 511. Surprisingly, positive ions were not readily formed. Collision induced dissociation of the adduct anion yielded a major ion at m/z 477, corresponding to the loss of hydrogen peroxide. The most abundant fragment ion following collisional activation was observed at m/z 93, resulting from a complex rearrangement subsequent to the attack of the hydroperoxide anion on the carbon center of the acetate adduct. Based on the interpretation of the tandem mass spectral data, the major cholesterol ozonization product was characterized as a hydroperoxy, hydroxy hemiacetal derivative, which was consistent with the NMR and X-ray crystallographic studies which were carried out on the more stable methyl ether derivative.     

Nonplanarity of π systems. An ab initio study of norbornene and norbornadiene

The geometry of norbornene $\text{1}$ and norbornadiene $\text{2}$ fully optimized by ab initio calculations reveals the nonplanarity of the π system(s). The exo addition of electrophiles on norbornene systems is analyzed in this context.     

Synthesis of heterocyclic systems with carbohydrate fragment

The reactions of levoglucosenone with amides of several -nitrocarboxylic acids and acetoacetic acid result in tetra hydropyridones fused with a carbohydrate fragment. In the case of acetoacetic acid amides, mixtures of keto and enol tautomers were obtained. The stereochemistry of cyclization is discussed in detail.For Communication 1, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 409–414, February, 1996.     

糖骨架手性配体合成及应用于不对称催化反应研究进展

获得对映异构体纯的手性化合物在药物、农用化学品、香料等领域愈来愈引起了科学界和工业界的广泛关注.不对称催化反应作为获得光学纯化合物的一种有效手段,由于其手性增殖的突出优势而特别引人注目.不对称催化一般通过含有手性配体     

Synthesis of heterocyclic systems with a carbohydrate fragment

Levoglucosenone reacts with α-aminoazoles to yield azolo[1,5-a]pyrimidine systems fused with a carbohydrate fragment. The reaction oocurs much more smoothly than in the case of other α,β-unsaturated ketones. The reactions of levoglucosenone with β-dicarbonyl compounds (dimedone, barbituric acid) in the presence of a base results in the pyran ring closure, which has never been observed earlier in reactions of β-dicarbonyl compounds with α,β-unsaturated ketones under the conditions of basic catalysis. The structures of products were established by IR and NMR spectroscopy. For Part 3, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 553–558, March, 1997.     

Synthesis of heterocyclic systems with a carbohydrate fragment

The reactions of levoglucosenone with urea, thiourea andN-cyano- andN-nitroguanidines result in pyrimidine systems fused with a carbohydrate fragment. In all cases, the cyclization occurs stereospecifically. The structures of different products of conversion of levoglucosenone were established on the basis of NMR and X-ray diffraction data.     

Synthesis of heterocyclic systems with a carbohydrate fragment

Levoglucosenone, the ,ß-unsaturated ketone obtained by the pyrolysis of cellulose, reacts with NH-azoles in the presence of bases. In this process not only normal Michael adducts are formed, but in some cases their hydrates (gem-diols) are also formed. In all cases the addition proceeds stereospecifically and with good yields. 3-Nitro-s-triazole, 3-nitro- and 4-nitropyrazoles, 3-methyl-4-nitropyrazole, 5-nitrotetrazole, 4,5-dicarbomethoxy-v-triazole, 3,4-dinitropyrazole, 3(5)-methylpyrazole, pyrazole, and imidazole have been studied in this reaction. All of the adducts are characterized by NMR- and IR-spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1135–1140, June, 1994.     

Pd(II)-catalyzed vinylic polymerization of norbornene and copolymerization with norbornene and copolymerization with norbornene carboxylic acid esters

The vinylic polymerization of norbornene and its copolymerization with norbornene carboxylic acid methyl esters were investigated. Norbornene was polymerized by us using di-μ-chloro-bis-(6-methoxybicyclo[2.2.1]hept-2-ene-endo-5σ,2π)-palladium(II) as catalyst. The polymerization time can be decreased by a factor of 100000 by activation of the catalyst with methylaluminoxane (MAO). With this palladium catalyst activated by MAO, 140 t of norbornene can be polymerized per mol palladium per h. This catalyst system was much more active than [Pd(CH₃CN)₄](BF₄)₂ ( I ). The polymerization of norbornene by (6-methoxybicyclo[2.2.1]hept-2-ene-endo-5σ,2π)-palladium(II) tetrafluoroborate was also possible but it was not as fast as the polymerization by Pd catalysts activated with MAO. We were also able to obtain copolymers of norbornene and 5-norbornene-2-carboxylic acid methyl ester (exo/endo = 1/4 or 2/3) containing between 15 and 20 mol-% ester units. The copolymerization of norbornene and 2-methyl-5-norbornene-2-carboxylic acid methyl ester (exo/endo = 7/3) was faster than the copolymerization mentioned before. In contrast the homopolymerization of 2-methyl-5-norbornene-2-carboxylic acid methyl ester was 10 times slower than that of 5-norbornene-2-carboxylic acid methyl ester (exo/endo = 1/4).     

Unsymmetrical Ni(II)-imidoylamidine complexes derived from a novel oxime-mediated single-pot reaction of nitriles

The neutral bisimidoylamidine (or 1,3,5-triazapentadiene) Ni(II) complexes [Ni{HN=C(R)N=C(C(6)H(4)CO)N}(2)] {R=Me, Et, nPr, iPr, (CH(2))(3)Cl}, bearing an iminoisoindolinone moiety, have been generated by a novel 2-propanone oxime-mediated single-pot reaction of phthalonitrile and nickel(II) acetate in solution of the corresponding alkylnitrile (RCN). Single-crystal X-ray diffraction analyses indicate a square-planar geometry of the imidoylamidine core. The synthesised compounds represent rare specimens of genuine unsymmetrical imidoylamidine complexes as well as their first examples generated from nitriles in a single-pot reaction.     

Hypervirial analysis of enclosed quantum mechanical systems. III. Unsymmetrical boundary conditions

New theoretical developments based upon hypervirial analysis of enclosed systems are given. Systems which obey unsymmetrical boundary conditions are analyzed. Several results which were given by the authors in two previous communications are generalized.     

Products of the ozonolysis of isoabienol

The ozonization of abienol in ethyl acetate in the presence of pyridine or in methanol followed by the reduction of the peroxides by methyl sulfide has given ambreinolide. On reduction of the peroxide products of the ozonolysis of isoabienol in methanol with potassium tetrahydroborate, the main reaction product was 15,16-bisnorlabdane-8,13,14-triol. Dimethyl sulfide first caused the rearrangement of the peroxide products of ozonization with the cleavage of the ordinary C-13-C-14 carbon bond, and then their reduction.Institute of Chemistry, Academy of Sciences of the Moldavian SSR, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 50–53, January–February, 1991.     

Novel approach towards one pot stereospecific synthesis of carbohydrate derived substituted imidazolines

A simple synthetic approach has been developed towards one pot synthesis of 2-imidazolines under mild acidic conditions from N-acetyl glucosamine via reductive amination followed by dehydrative cyclization. Synthetic studies were explored in detail with different amines and sugar derivatives. While the conversion was good, the corresponding substituted imidazolines were obtained in moderate yields.