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11.
van Eis MJ van Der Linde BS de Kanter FJ de Wolf WH Bickelhaupt F 《The Journal of organic chemistry》2000,65(14):4348-4354
In contrast to the terminal phosphinidene complex PhPW(CO)(5) (2), which adds to [5]metacyclophane (1) in a 1,4-fashion, dichlorocarbene preferentially adds in a 1,2-fashion to the formal "anti-Bredt" type double bond of the aromatic ring of 1 to afford the norcaradiene 11b, which immediately rearranges to the bridged cycloheptatriene 12b and further by a [1,5] sigmatropic chlorine migration to the isomeric 13b as the first observable product. More slowly, the latter isomerizes via a dissociative mechanism to give 15b. A computational study supports the notion that the [1,5] chlorine migration in the rearrangement 12b --> 13b, for which an activation barrier of 70.2 kJ mol(-)(1) was calculated, is essentially concerted with minor charge separation. In contrast, the analogous [1,5] chlorine migration in the flat model compound 7,7-dichlorocycloheptatriene (12a) displays features of a dissociative pathway. 相似文献
12.
S. Midura 《Aequationes Mathematicae》1968,1(1-2):77-84
Sans résumé 相似文献
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The asymmetric cyclopropanation of vinylphosphonate using (S)-dimethylsulfonium-(p-tolylsulfinyl)methylide was applied to obtain a dideuterated cyclopropyl sulfoxide. A three-step synthesis of enantiopure (+)-(1R)-1-amino-2,2-dideuteriocyclopropanephosphonic acid (+)-17-d2 was developed. 相似文献
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S. Midura 《Aequationes Mathematicae》1968,1(1-2):196-198
Ohne ZusammenfassungCf. pp. 77–84. 相似文献
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The X-ray crystal structure and properties of the [Mo(CN)2O(acetam)] · 2.5H2O {acetam = N-[1-(pyridin-2-yl)-ethylidene]diethanetriamine} complex are described. The complex was prepared by the in situ reaction of [Mo(CN)4O(H2O)]2–, 2-acetylpyridine and diethylenetriamine in aqueous solution. The complex is seven coordinated. The Mo atom having a distorted pentagonal bipyramid arrangement with a tetradentate 'half-unit' Schiff base and oxygen ligand in a plane. The properties of the salt, i.r., u.v.–vis. spectra and cyclic voltammetry measurements are described and compared with those of [Mo(CN)2O(diaceen)] · H2O {diaceen = N,N-bis[1-(pyridin-2-yl)ethylidene]ethane-1,2-diamine) having the same coordination number for the metal. 相似文献
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Oxidation of the α-alkylthio-substituted phosphonate carbanions was found to give the corresponding carbonyl compounds. A new synthesis of 1,4-dicarbonyl systems involving the oxygenation of phosphonate carbanions as a key step is described. Total synthesis of dihydrojasmone and allethrone and formal synthesis of methylenomycin B is reported. 相似文献
19.
Jerzy Krysiak Wanda H. Midura Wanda Wieczorek Lesław Sieroń Marian Mikołajczyk 《Tetrahedron: Asymmetry》2010,21(11-12):1486-1493
A new stereocontrolled synthesis of (+)-2-aminobicyclo[3.1.0]hexane-2.6-dicarboxylic acid (LY354740) 1, a potent and selective 2mGluR agonist, has been accomplished in four steps with an overall yield of 27% starting from the enantiopure (+)-(R)-2-(p-tolylsulfinyl)cyclopent-2-enone 3. The key steps include asymmetric cyclopropanation of 3 with (dimethylsulfuranylidene)acetate (EDSA) and removal of the chiral p-tolylsulfinyl auxiliary from the cycloadduct ent-4c upon treatment with iso-propylmagnesium chloride. The stereoselective hydantoin formation from the bicyclic ketone 6 formed (Bucherer–Bergs reaction) and subsequent hydrolysis completed the synthesis of 1. The same reaction sequence has been applied in the first synthesis of enantiopure (+)-2-amino-6-phosphonobicyclo[3.0.1]hexane-2-carboxylic acid 2, a structural 6-phosphono analogue of 1. The starting bicyclic ketophosphonates 9–11 have been obtained by asymmetric cyclopropanation of (?)-(S)-3 with phosphoryl sulfonium ylides, producing only two endo-isomers. The major endo-isomer (+)-11a containing the 6-diisopropoxyphosphoryl group has been converted in three steps into (+)-endo-2 in 46% overall yield. 相似文献
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