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
For the first time the room-temperature rhodium-catalyzedasymmetric1,4-addition of potassium aryltrifluoroborates to α,β-unsaturated substrates is described. Thanks to the use of a chiral diene as ligand for rhodium and triethylamine as base, to facilitate transmetalation of the boron species, high yields and enantioselectivities were generally achieved. Moreover, the use of such tetravalent boron