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51.
Anhydrides as acylating agents in the enzymatic resolution of an intermediate of (-)-Paroxetine 总被引:2,自引:0,他引:2
de Gonzalo G Brieva R Sánchez VM Bayod M Gotor V 《The Journal of organic chemistry》2003,68(8):3333-3336
A new chemoenzymatic method for the preparation of an intermediate of (-)-Paroxetine is reported. Cyclic anhydrides are used as acylating agents in the lipase-catalyzed esterification of trans-4-(4'-fluorophenyl)-3-hydroxymethyl-N-phenyloxycarbonylpiperidine in organic solvents. The best enantioselectivities are obtained with two different lipases from Candida antarctica. These two lipases show opposite stereochemical preference in these processes, so that both enantiomers can be obtained in their optically pure forms. The (3S,4R) isomer is an intermediate for the synthesis of (-)-Paroxetine. 相似文献
52.
Givaja G Blake AJ Wilson C Schröder M Love JB 《Chemical communications (Cambridge, England)》2003,(19):2508-2509
The complexation of palladium(II) by a unique family of [2+2] diiminodipyrromethane macrocycles yields compounds that adopt structures reminiscent of Pac-Man porphyrins. 相似文献
53.
We performed a high resolution imaging of a coiled coil filament used in tungsten lamps, a standard reference source in spectroscopy. The radiometric results using two-wavelength thermometry indicate that its configuration also introduces cavity effects and non-uniformity of filament temperature distribution, with the average temperature calculated to be 2869 K. Considering the tungsten source as an extended body, significant temperature variations of up to +19 K are found above its nominal 2850 K value. 相似文献
54.
55.
Jesús Gonzalo Pérez 《Geometriae Dedicata》2008,132(1):105-119
A simple dynamical condition is given for line fields within a contact structure, which is satisfied exactly by those line
fields which are common kernels of contact circles. Some convexity properties are established which are useful in the study
of contact circles up to homotopy. A necessary condition for extending a contact form to a contact circle is given. Based
on work of Lisca–Matić and Honda, concrete examples are given which show that the condition is not just homotopic but a geometric
one. The paper ends with an open question.
Dedicated to Fernando Varela, for many reasons. 相似文献
56.
G de Gonzalo R Brieva V M Sánchez M Bayod V Gotor 《The Journal of organic chemistry》2001,66(26):8947-8953
Two Candida antarctica lipases catalyze the enantioselective acylation of N-substituted trans-4-(4'-fluorophenyl)-3-hydroxymethylpiperidines in organic solvents. These two lipases show opposite stereochemical preference in these processes. Both enantiomers can be obtained in their optically pure forms. The (3S,4R) isomer, is an intermediate for the synthesis of (-)-Paroxetine. 相似文献
57.
58.
Rafael de la Madrid Gaston Garcia-Calderon Juan Gonzalo Muga 《Czechoslovak Journal of Physics》2005,55(9):1141-1150
The goal of this contribution is to discuss various resonance expansions that have been proposed in the literature.
Presented at the 3rd International Workshop “Pseudo-Hermitian Hamiltonians in Quantum Physics”, Istanbul, Turkey, June 20–22,
2005. 相似文献
59.
A two-step synthesis of 3-heteroaryl indoles has been developed. The first step of the sequence involves a Friedel-Crafts alkylation of indoles with 1,4-diaryl-2-buten-1,4-diones to give the corresponding indoles bearing a 1,4-dicarbonyl moiety. The reaction is catalyzed by InCl3 and takes place with good yields. Cyclization of the diones under different Paal-Knorr conditions allows to prepare indoles substituted at the C3 position with 3-furanyl, 3-pyrrolyl- and 3-thienyl moieties. 相似文献
60.
Gonzalo Angulo Dr. Jakob Grilj Eric Vauthey Prof. Luis Serrano‐Andrés Prof. Òscar Rubio‐Pons Dr. Patrice Jacques Prof. 《Chemphyschem》2010,11(2):480-488
The experimental ultrafast photophysics of thioxanthone in several aprotic organic solvents at room temperature is presented, measured using femtosecond transient absorption together with high‐level ab initio CASPT2 calculations of the singlet‐ and triplet‐state manifolds in the gas phase, including computed state minima and conical intersections, transition energies, oscillator strengths, and spin–orbit coupling terms. The initially populated singlet ππ* state is shown to decay through internal conversion and intersystem crossing processes via intermediate nπ* singlet and triplet states, respectively. Two easily accessible conical intersections explain the favorable internal conversion rates and low fluorescence quantum yields in nonpolar media. The presence of a singlet–triplet crossing near the singlet ππ* minimum and the large spin–orbit coupling terms also rationalize the high intersystem crossing rates. A phenomenological kinetic scheme is proposed that accounts for the decrease in internal conversion and intersystem crossing (i.e. the very large experimental crescendo of the fluorescence quantum yield) with the increase of solvent polarity. 相似文献