Palladium- and Platinum-Catalyzed Addition of Aldehydes and Imines with Allylstannanes. Chemoselective Allylation of Imines in the Presence of Aldehydes
Pd(II) or Pt(II) complexes (10 mol %) either at room temperature or at reflux, giving the corresponding homoallylic alcohols 3 in high to good yields. Among the catalysts examined, PtCl2(PPh3)2 gave the best result. No only allyltribitylstannane but also methallyl- and crotyltributylstannane could be utilized in this transition metal catalyzed reaction. Detailed mechanistic studies of the Pd(II)-catalyzed
palladium(0) complex has been prepared from γ-chloropropyltriethoxysilane via immobilization on fumed silica, followed by reacting with potassium diphenylarsenide and palladium chloride, and then the reduction with hydrazine hydrate. The palladium(0) complex has been found to catalyze the allylation of aldehydes via the formation of π-allylpalladiumcomplexes, using allylic chlorides as allylating
The reaction of allylic stannanes 1 with aldehydes 2(or a ketone) takes place in the presence of catalytic amounts of PdCl2(PPh3)2 or PtCl2(PPh3)2 to give the corresponding homoallyl alcohols 3 in good to high yields.
Preparation of Allyltin Reagents Grafted on Solid Support: Clean and Easily Recyclable Reagents for Allylation of Aldehydes
作者:Jean-Mathieu Chrétien、Françoise Zammattio、Delphine Gauthier、Erwan Le Grognec、Michaël Paris、Jean-Paul Quintard
DOI:10.1002/chem.200501595
日期:2006.9.6
The preparation of polymer-supported allyltin reagents was shown to be possible for both unfunctionalized and functionalized allyl units. These reagents were treated with aldehydes in the presence of cerium(III) or indium(III) salts to afford high yields of homoallylic alcohols, practically uncontaminated with organotin residues (less than 5 ppm). Some mechanism aspects are briefly discussed and the
Lewis acids are crucial in chemistry, with applications in pharmaceuticals, agrochemicals, and materials science. In main-group chemistry, they offer alternatives to transition metals, prompting our study of halogenated boronicacid esters (BAEs). Although BAEs are well-known, their catalytic potential has been overlooked. Our investigation found their Lewis acidity superior to that of boron trifluoride