92268-71-8Relevant academic research and scientific papers
Homogeneous catalysis. Transition metal based lewis acid catalysts
Hollis, T. Keith,Odenkirk, William,Robinson,Whelan, John,Bosnich
, p. 5415 - 5430 (2007/10/02)
Transition metal based Lewis acids provide catalysts for the Diels-Alder and Mukaiyama reactions. These catalysts must possess an electron deficient axophilic metal center and a labile coordination position. Unlike traditional Lewis acids, those derived from transition metals can function in the presence of water and have well defined structures. It is shown how a normally electron rich ruthenium atom can be converted to a Lewis acid by incorporation of electron withdrawing ligands and ligands with hard donor atoms. This ruthenium complex, [Ru(salen)(NO)(H2O)]+, is an efficient catalyst for the Diels-Alder reaction, but in the Mukaiyama reaction, it tends to be reduced and thereby deactivated by the silyl enol ether. It is shown that the complex [TiCp*2(H2O)2]2+ (Cp* is pentamethylcyclopentadienyl) is an efficient catalyst for the Diels-Alder reaction even when water is present. Similarly, the triflato complexes [TiCp2(CF3 SO3)2] and [ZrCp2(CF3SO3)2] (Cp is cyclopentadienyl) are efficient catalysts for both the Diels-Alder and Mukaiyama reactions. All of these catalysts are effective at very low loadings of ≈ 1 mol%. Catalysis has been shown to occur via substrate-catalyst adducts and moreover these adducts are formed rapidly and reversibly as required for efficient catalysis.
Homogeneous catalysis. A transition metal based catalyst for the Mukaiyama crossed-aldol reaction and catalyst deactivation by electron transfer
Odenkirk, William,Whelan, John,Bosnich
, p. 5729 - 5732 (2007/10/02)
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 transfer
NOVEL SYNTHESIS OF β-SILOXY ESTERS BY CONDENSATION OF CARBONYLS AND TRIMETHYLSILANE WITH α,β-UNSATURATED ESTERS CATALYZED BY RhCl3
Revis, Anthony,Hilty, Terrence K.
, p. 4809 - 4812 (2007/10/02)
A novel one pot reaction of α,β-unsaturated esters with carbonyls and trimethylsilane gave good yields of β-siloxy esters.This RhCl3 catalyzed method improves upon the two step reaction of silyl ketene acetals with carbonyls.
