Homogeneous catalysis. A transition metal based catalyst for the Mukaiyama crossed-aldol reaction and catalyst deactivation by electron transfer.
作者:William Odenkirk、John Whelan、B. Bosnich
DOI:10.1016/0040-4039(92)89017-7
日期:1992.9
The cationic complex [Ru(salen)(NO)H2O]SbF6 is intrinsically a powerful catalyst for the Mukaiyama crossed-aldol reaction at 25°C in nitromethane solutions and at very low catalyst loadings but, for some reactions, electron transferfrom the silylenolether to the ruthenium catalyst can occur which leads to catalyst deactivation.
In an improved catalytic process for preparing trialkylsilyl ethers from trialkylsilyl compounds and carbonyl group-containing compounds, the improvement consisting of using an organic or inorganic bifluoride (HF.sub.2.sup..crclbar.) as the catalyst.
Homogeneous catalysis. [TiCp2(CF3SO3)2] and [ZrCp2(CF3SO3)2THF], fast and efficient catalysts for the Mukaiyama cross-aldol reaction
作者:T.Keith Hollis、N.P. Robinson、B. Bosnich
DOI:10.1016/s0040-4039(00)79005-8
日期:1992.10
The catalysts [TiCp2(CF3SO3)2] and [ZrCP2(CF3SO3)2THF] are fast and efficient catalysts for the Mukaiyama cross-aldol reaction involving both ketones and aldehydes and the catalysis is promoted by binding of the carbonyl group to the metal after dissociation of triflato ligands.
Bis(hydroxyphenyloxazolinato)-titanium(IV) and -zirconium(IV) triflates as novel transition metal-based Lewis acids
作者:Pier Giorgio Cozzi、Carlo Floriani
DOI:10.1039/p19950002557
日期:——
The preparation of novel titanium, 3, and zirconium, 4, organometallic Lewis acids by treatment of the readily available [M(L)(2)(CI)(2)] complexes (M = Ti, Zr; L = hydroxyphenyl-4,5-dihydrooxazole) with AgOSO2CF3 are described. The new homogeneous organometallic Lewis acids, prepared in situ, are active in promoting aldol reactions, additions to imines and catalytic allylations. In addition, some examples of the use of 3 and 4 in other reactions (i. e. Mukaiyama-Michael reaction,addition of Me(3)SiCN, Diels-Alder, and hetero Diels-Alder reaction) are presented. Some mechanistic studies on the:aldol reaction and on the catalytic allylation have been performed in order to show some of the characteristics of the present Lewis acid system.
GONG, LEHI;STREITWIESER, ANDREW, J. ORG. CHEM., 55,(1990) N6, C. 6235-6236