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71.
Functionalized aryl fluorides were regioselectively prepared by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 2-fluoro-3-silyloxy-2-en-1-ones. 相似文献
72.
Schmidt A Michalik D Rotzoll S Ullah E Fischer C Reinke H Görls H Langer P 《Organic & biomolecular chemistry》2008,6(15):2804-2814
Densely functionalized azoxabicyclo[3.3.1]nonanones were prepared by regio- and diastereoselective condensation of 1,1-bis(silyloxy)ketene acetals with isoquinolinium and quinolinium salts and subsequent regioselective and stereospecific iodolactonization. 相似文献
73.
1-Trimethylsiloxyalkyl-bis(trimethylsilyl)silanes ( 5 ), obtained by a base induced isomerization of easily accessable 1-hydroxyalkyl-tris(trimethylsilyl)silanes ( 1 ) were hydrolized to give 1-hydroxyalkyl-bis(trimethylsilyl)silanes ( 6 ), which in presence of sodium hydride underwent a further 1,3-Si,O-trimethylsilyl migration resulting in the formation of 1-trimethylsiloxyalkyl-disilanes Me3SiSiH2–C(OSiMe3)R1R2 ( 7 ). Under acidic conditions, the alkoxysilanes 5 isomerized in a Me3Si/OSiMe3 exchange under formation of the 1-trimethylsilylalkyldisiloxanes 10 , which were hydrolyzed affording the silanols 11 . Chlorination of the H-silanes 5 with CCl4 gave the chlorosilanes 12 , which underwent rapid thermal isomerizations to give via the 1-chloroalkyldisiloxanes 13 the 1-trimethylsilylalkyl-chlorodisiloxanes 15 . Hydrolysis of 12 or 15 , resp., finally afforded the 1-trimethylsilylalkyl-silanediols 18 . Possible mechanisms of the various isomerization processes are discussed. The structures of the products described were elucidated by full spectral analyses. For 18 a the results of an X-ray structural analysis are given. 相似文献
74.
Crystal Structure of a Lithiumsilylamidebutanide Colorless single crystals of {Li6[Me2(H)Si—N—Si(H)—(CHMe2)2]2[n‐C4H9]4} ( 1 ) were obtained from a solution of Me2(H)SiN(Li)Si(H)(CHMe2)2 and n‐C4H9Li in n‐hexane. The X‐ray analysis showed that the core of 1 is a distorted octahedron of lithium atoms with ten long and with two short LiÄLi distances. Four of the eight triangular Li3 faces are capped by an n‐butyl group. The nitrogen atoms of the amide groups are situated about opposite edges of adjacent unoccupied Li3 faces. (Si)H····Li interactions exist between the hydridic H atom of each Me2(H)Si group and one Li atom. 相似文献
75.
First X-ray Crystallographic Characterized Cs+ ‘‘in cavity”︁”︁ Complex of a Twenty-one Membered Coronand: (Maleonitrile-Dithio[21]crown-7)caesium Hexachloroantimonate A new maleonitrile-crown dithioether, the maleonitrile-dithio[21]crown-7 (mn–21 S2O5), was synthesized by high dilution cyclization of (Z)-1,2-disodium-1,2-dicyanoethene-1,2-dithiolate ( 1 ) with 1,17-dichloro-3,6,9,12,15-pentaoxaheptadecane ( 2 ) in ethanol/water mixtures. Mn–21 S2O5 forms with CsSbCl6 in MeCN/MeNO2 a 1 : 1 complex [Cs(mn–21 S2O5)]SbCl6. X-ray crystal analysis revealed that the complex cation [Cs(mn–21 S2O5)]+ is an ‘‘in cavity”︁”︁ complex in which the Cs+ ion is coordinated by seven donor atoms (five O and two S atoms). This is the first X-ray crystallographic evidence of Cs+ coordination by seven donors in a hole of a twenty-one membered coronand. 相似文献
76.
Stefan Büttner Ibrar Hussain Mathias Lubbe Helmut Reinke Peter Langer 《Tetrahedron》2009,65(10):2124-603
A variety of functionalized 5-aryl-3-(trifluoromethyl)phenols were prepared by the first TiCl4-mediated [3+3] cyclocondensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 3-aryl-3-trimethylsilyloxy-1-trifluoromethyl-2-en-1-ones. 相似文献
77.
E. Salkowski M. Jastrowitz und O. Reinke 《Fresenius' Journal of Analytical Chemistry》1892,31(1):724-725
Ohne Zusammenfassung 相似文献
78.
Reinke AA Ung PM Quintero JJ Carlson HA Gestwicki JE 《Journal of the American Chemical Society》2010,132(50):17655-17657
Alzheimer's disease (AD) is characterized by the self-assembly of amyloid beta (Aβ) peptides. Recent models implicate some of the earliest Aβ oligomers, such as trimers and tetramers, in disease. However, the roles of these structures remain uncertain, in part, because selective probes of their formation are not available. Toward that goal, we generated bivalent versions of the known Aβ ligand, the pentapeptide KLVFF. We found that compounds containing sufficiently long linkers (~19 to 24 ?) recognized primarily Aβ trimers and tetramers, with little binding to either monomer or higher order structures. These compounds might be useful probes for early Aβ oligomers. 相似文献
79.
34 compounds containing the SO2-N-C-N-moiety are investigated by means of infrared spectroscopy and differential scanning calorimetry to study problems of polymorphic species. There are arguments for different crystalline solids of 16 sulphonyl derivatives. The phenomenon of polymorphism can be discussed both in terms of different hydrogen bonding and conformational effects. Although two tautomers are thinkable for the compounds being investigated the sulphonylimino structure is assumed to yield the most stable state. 相似文献
80.
The cyclization of dilithiated nitriles with epibromohydrin afforded 2-cyano-1-(hydroxymethyl)cyclopropanes. 2-Cyanomethylidene-(4-hydroxymethyl)thiazolidines were prepared by one-pot cyclization of dilithiated nitriles with isothiocyanates and epibromohydrin. 相似文献