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81.
82.
83.
Louis Cazaux Christiane Vidal Maurice Pasdeloup 《Magnetic resonance in chemistry : MRC》1983,21(3):190-195
Two 1,4-benzodiazepinones of psychopharmacological interest, pinazepam (2) and prazepam (3), were studied in solution by 13C and 1H NMR. 1H variable-temperature experiments showed that the seven-membered ring exists in a simple pseudo-boat form at room temperature, but the energy barrier is higher in 3 (ΔG405°c = 82.8 kJ mol?1) than in diazepam (1). Moreover, upon addition of LSR, the boat conformation is retained in the lanthanide ion-substrate complex, as with 1 in the solid state. Using a concentration-dependent shift technique and a computer-assisted LIS method, the conformations of the N-branched side-chain were investigated. Two preferred orientations were found for the propargyl group of 2, while three unequally populated conformations of the cyclopropyl moiety of 3 are distributed preferentially in the sterically unhindered space around the complex. 相似文献
84.
Guinot C Malvy DJ Latreille J Ezzedine K Galan P Tenenhaus M Ambroisine L Hercberg S Tschachler E 《Photochemistry and photobiology》2005,81(4):934-940
Phototype classifications were initially developed in an attempt to predict the skin reactions of patients to phototherapy and are now widely used to advise individuals with regard to sun protection. A transversal study was conducted on the SU.VI.MAX cohort to estimate the frequency of sun-reactive skin features in a large, general adult population-based sample, and to describe the associations between these features. The data were collected 3 years after the beginning of the SU.VI.MAX nutritional intervention study on 4912 volunteers (2868 women aged 35-60 years and 2044 men aged 45-60 years). A multiple correspondence analysis was performed to study the associations between the features. The results showed that these features correspond to a one-dimensional phenomenon, which allowed us to establish a score to summarize skin sensitivity to sun exposure. Furthermore, we found a link between gender and phototype using the Césarini classification (phototype > or = IV: 37% of women, 47% of men). The analysis of the relationship with sun-reactive skin features and the score revealed the same trend. Phenotypic evaluation appears to be a good estimator of skin sensitivity to sun exposure for clinical screening or for use in research, and is easy to collect at a lower cost. Moreover, the sun sensitivity difference between gender should be considered in education about photoprotection. 相似文献
85.
Dietrich-Buchecker C Colasson B Jouvenot D Sauvage JP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(15):4374-4386
The synthesis of two multisite ligands containing four and five 1,10-phenanthroline (phen) chelates in line, respectively, is presented. The connectors are 1,3-phenylene linkers. The two ligands were prepared following multistep procedures, the two key reactions being the Suzuki coupling reaction between aromatic nuclei and the nucleophilic addition of aryllithium derivatives onto a phen fragment. The coordination chemistry of both ligands with Li+ ions was very clean and selective, whereas their reaction with copper(I) led to intractable mixtures of insoluble complexes. The tetraphen and the pentaphen compounds afforded almost quantitatively the four- and five-lithium double-stranded helical complexes, respectively. The helical systems are probably highly wound, as indicated by NMR measurements. The pronounced strain of the 5-Li+ complex is reflected by the easy loss of a lithium cation, as shown by electrospray mass spectrometry. 相似文献
86.
Dihydroxyacetone in amino acid catalyzed Mannich-type reactions 总被引:3,自引:0,他引:3
87.
Janina?Karolak-WojciechowskaEmail author Andrzej?Fruziński Sandrine?Alibert-Franco Christiane?Santelli-Rouvier Jacques?Barbe 《Journal of chemical crystallography》2005,35(7):551-554
As a part of studies on MDR reversal agents, structure of the 9,10-dihydro-11,12-bis[(1,3,3-trimethylureido)methyl]-9,10-ethanoanthracene dihydrate is reported. Crystal data: C26H34N4O2 × 2 H2O; mol. mass 470.60; monoclinic; space group: C2/c, a = 15.7492(6) Å; b = 7.2245(3) Å; c = 24.3442(10) Å; β = 106.795(2)∘; V = 2651.73(22) Å3; z = 4; dx = 1.179 mg/m3; μ = 0.64 mm−1; F(000) = 1016; final R = 0.061 for 2501 reflections [I > 4 σ (I)]. Only half of the molecule is unique. The two nonplanar rings from the independent part of 9,10-dihydro-9,10-ethanoanthracene adopt a boat conformation. Crystallographic data demonstrate the “syn-syn” conformation of urea substituents in the molecule. In the crystal, water molecules are linked to the main species by H-bonds: O3′⋅sH12w—O1—H11w⋅sO3′(1.5 − x, 0.5 − y, 1 − z). 相似文献
88.
89.
Jacques Streith Arnaud Boiron Jean-Louis Paillaud Elsa-Maria Rodriguez-Perez Christiane Strehler Thophile Tschamber Margareta Zehnder 《Helvetica chimica acta》1995,78(1):61-72
Asymmetric methylation and phenylation of the chiral pyridinium salt 7 , as well as methylation of chiral pyridinium salt 18 , with Grignard reagents occurred in good yield and with good-to-excellent diastereoselectivities (Schemes 2 and 3, resp.). These results are best explained by assuming chelate control to govern the asymmetric alkylation/arylation process. The minimum-energy conformations of the out-of-plane twisted pyridinium salts 7 and 18 , as determined by the ‘Molecular Simulations Cerius-Dreiding II’ program, are in good agreement with the postulated asymmetric chelate-control mechanism. 相似文献
90.
Farmer and Hale [3] prove that every copolar space fully embedded in a finite projective space PG(n, q), with q>, is the copolar space arising from a symplectic polarity. We show that this result is still valid in arbitrary projective spaces; this provides a different and shorter proof of [3] in the finite case. 相似文献