Monodentate Non-<i>C</i><sub>2</sub>-symmetric Chiral <i>N</i>-Heterocyclic Carbene Complexes for Enantioselective Synthesis. Cu-Catalyzed Conjugate Additions of Aryl- and Alkenylsilylfluorides to Cyclic Enones
作者:Kang-sang Lee、Amir H. Hoveyda
DOI:10.1021/jo900589x
日期:2009.6.19
alkenyltetrafluorosilicate. Reactions proceed in the presence of 1.5 equiv of the aryl- or alkenylsilane reagents and 1.5 equiv of tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF). Desired products are isolated in 63−97% yield and 73.5:26.5−98.5:1.5 enantiomeric ratio (47%−97% ee). A major focus of the present studies is the design, evaluation, and development of new chiral imidazolinium salts and their
2-Methoxy-4-nitrobenzenediazonium Salt as a Practical Diazonium-Transfer Agent for Primary Arylamines via Tautomerism of 1,3-Diaryltriazenes: Deaminative Iodination and Arylation of Arylamines without Direct Diazotization
作者:Tomoyuki Saeki、Eun-Cheol Son、Kohei Tamao
DOI:10.1246/bcsj.78.1654
日期:2005.9
1,3-Diaryltriazenes, prepared from a 2-methoxy-4-nitrobenzenediazonium salt and primary arylamines, exist as “azo-transfer” tautomers in which the 2-methoxy-4-nitrophenyl group is present on the saturated nitrogen atom and forms a hydrogen bond between the 2-methoxy group and the N–H moiety. The synthetic utility of the diazonium salt as a practical diazonium-transfer agent for primary arylamines via tautomerism of the 1,3-diaryltriazenes has been demonstrated by the deaminative iodination and arylation of the arylamines without direct diazotization. The starting 2-methoxy-4-nitrophenylamine can be easily recovered after the reactions.
The palladium-catalyzedcross-couplingreaction of 1-aryltriazenes with aryl- and alkenyltrifluorosilanes occurs readily at room temperature to yield the corresponding biaryl and stilbene products in moderate to good yields. In contrast to the previous results for the reaction with areneboronic acids, in which an additional Lewis acid such as boron trifluoride is essential for the activation of the
Neutral pentacoordinate silicon complexes with SiO2FC skeleton: Synthesis, structural characterization and stereodynamical behavior
作者:Mikhail G. Voronkov、Ekaterina A. Grebneva、Alexander I. Albanov、Eleonora A. Zel'bst、Olga M. Trofimova、Alexander D. Vasil'ev、Nikolai F. Chernov、Elena N. Timofeeva
DOI:10.1016/j.jorganchem.2014.05.025
日期:2014.10
A series of new pentacoordinate intramolecular organosilicon complexes F(Ar)Si(OCH2CH2)(2)NMe (Ar = 4-MeC6H4 (1), 4-MeOC6H4 (2), 4-ClC6H4 (3), 2-BrC6H4 (4), 3-NO(2)C(6)H4 (5)) has been synthesized by transsilylation of aryltrifluorosilanes ArSiF3 by N-methyl-bis(2-trimethylsiloxyethyl)amine. Compounds 1-5 have been fully characterized by H-1, C-13, F-19, Si-29 NMR spectroscopy and X-ray diffraction analysis (for compound 3). Variable-temperature F-19 NMR studies of 5 indicate stereodynamic process of the ligand exchange with activation barrier Delta G(c)(not equal) of 13.1 kcal mol(-1). (C) 2014 Elsevier B.V. All rights reserved.