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101.
Jaana M. H. Pakarinen Jaana Kolehmainen Sari Yrjölä Pirjo Vainiotalo 《Journal of mass spectrometry : JMS》2005,40(9):1237-1248
The electron ionization and methane chemical ionization mass spectra of some 2,2-disubstituted 1,3-dioxolanes, 1,3-dithiolanes and 1,3-oxathiolanes were studied. Especially, the effect of the length of the side chain in ring position 2 of these compounds and the ease of formation of possible lactone/thiolactone ion as a fragmentation product were examined. In addition, two 2,2-disubstituted 1,3-dioxanes were studied to see the effect of the bigger ring size. The formation of lactone ions was more favorable under methane chemical ionization than under electron ionization conditions. The structures of fragment ions and the ions generated from model compounds were carefully studied using both high- and low-energy collision-induced dissociation. Also ab initio molecular orbital calculations up to the HF/6–31G** level of theory for protonated 2-methyl-2-propanoic acid ethyl ester of 1,3-dioxolane, 1,3-oxathiolane and 1,3-dithiolane and for two isomeric bicyclic ions were carried out. The theoretical results obtained favor the formation of the lactone ion. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
102.
Paula Aulaskari Markku Ahlgrn Juha Rouvinen Pirjo Vainiotalo Esko Pohjala Jouko Vepslinen 《Journal of heterocyclic chemistry》1996,33(4):1345-1354
1-R-5-[(2-Nitro-2-phenyl)ethenyl]imidazoles (R = Bn, Me, H) 6a,b,c were synthesized by the Knoevenagel reaction of the corresponding aldehydes 4a,b,c with phenylnitromethane 5 . The E-isomers 6a,b,c were precipitated from the reaction mixture as crystalline compounds in 89, 81 and 60% yields, respectively. Traces of the Z-isomers 6a′b′,c′ were found in the reaction mixtures but could be obtained in a ratio of 4:3 from the E-form with UV irradiation. The E-forms were more stable and the Z-isomers changed again to the E-isomers in several weeks. 相似文献
103.
Jari Tamminen Erkki Kolehmainen Juha Linnanto Pirjo Vainiotalo Sami Vuorikoski Reijo Kauppinen 《Journal of inclusion phenomena and macrocyclic chemistry》2000,37(1-4):121-130
Lithocholic acid N-(2-aminoethyl)amide (1) and deoxycholic acid N-(2-aminoethyl)amide(2) have been prepared and characterized by1H, 13C and 15N NMR. The accurate molecular masses of 1 and 2 have been determined by ESI MS. The formation of the Cd2+-complexes (1+Cd and 2+Cd) in CD3OD solution have been detected by 1H,13C, 15N and 113Cd NMR. The 13C NMR chemical shift assignments of 1 and 2 and their Cd2+-complexes are based on DEPT-135 and z-GS 1H,13C HMQC experiments as well as comparison with the assignments of the related structures. The 15N NMR chemical shiftassignments of the ligands and theirCd2+-complexes are based on z-GS1H,15N HMBC experiments. 13C NMR chemical shift differences between 1and its 1:1 Cd2+-complex based on ab initiocalculations at Hartree-Fock SCI-PCM level using3-21G(d) basis set are in agreement with theexperimental shift changes observed onCd2+-complexation. 相似文献
104.
Szilvia Gedey Ferenc Fülp Pirjo Vainiotalo Peter A. M. De Witte Istvían Zupk 《Journal of heterocyclic chemistry》2003,40(6):951-956
Five sets of 27‐membered combinatorial libraries of alicyclic β‐lactams were prepared via liquid‐phase Ugi 4‐center 3‐component reactions (U‐4C‐3CR) utilizing 3 different cis β‐amino acids, 3 different isonitriles and 5×3 sets of aldehydes. Through combinations of the building blocks of one of these libraries, all of the possible sublibraries were also generated. A few azetidinone derivatives were synthesized individually by parallel synthesis. 相似文献
105.
Petri Huovinen 《Proceedings of the American Mathematical Society》2001,129(11):3345-3351
We construct an example of a purely 1-unrectifiable AD-regular set in the plane such that the limit
exists and is finite for almost every for some class of antisymmetric Calderón-Zygmund kernels. Moreover, the singular integral operators associated with these kernels are bounded in , where has a positive measure.
106.
Agakichiev G Appelshäuser H Baur R Bielcikova J Braun-Munzinger P Cherlin A Drees A Esumi SI Filimonov K Fraenkel Z Fuchs Ch Glässel P Hering G Huovinen P Lenkeit B Marín A Messer F Messer M Milosevic J Miśkowiec D Nix O Panebrattsev Y Petrácek V Pfeiffer A Rak J Ravinovich I Razin S Rehak P Sako H Saveljic N Schmitz W Shimansky S Socol E Specht HJ Stachel J Tilsner H Tserruya I Voigt C Voloshin S Weber C Wessels JP Wurm JP Yurevich V;CERES Collaboration 《Physical review letters》2004,92(3):032301
Elliptic flow and two-particle azimuthal correlations of charged hadrons and high-p(T) pions (p(T)>1 GeV/c) have been measured close to midrapidity in 158A GeV/c Pb+Au collisions by the CERES experiment. Elliptic flow (v(2)) rises linearly with p(T) to a value of about 10% at 2 GeV/c. Beyond p(T) approximately 1.5 GeV/c, the slope decreases considerably, possibly indicating a saturation of v(2) at high p(T). Two-pion azimuthal anisotropies for p(T)>1.2 GeV/c exceed the elliptic flow values by about 60% in midcentral collisions. These nonflow contributions are attributed to nearside and back-to-back jetlike correlations, the latter exhibiting centrality dependent broadening. 相似文献