5-MePh)2PF-Pcy2) catalyzed the enantioselective arylation of silyl keteneacetals with iodoarenes in the presence of TlOAc to promote transmetalation of silyl keteneacetals. The highest enantioselectivities giving α-arylesters up to 91% ee were achieved when (E)-1-methoxy-1-(trimethylsiloxy)propene (E/Z = 88/12) was used for the silyl keteneacetal. The effect on enantioselection of a chiral ligand is discussed
在TlOAc存在下,钯/(4-MeO-3,5-MePh)2 PF-Pcy 2)催化硅烷基乙烯酮缩醛与碘芳烃的对映选择性芳基化,以促进硅烷基乙烯酮缩醛的金属转移。当将(E)-1-甲氧基-1-(三甲基甲硅烷氧基)丙烯(E / Z = 88/12)用于甲硅烷基烯酮缩醛时,可获得最高91%ee的α-芳基酯的最高对映选择性。基于钯/(4-MeO-3,5-MePh)2 PF-Pcy 2)配合物的X射线结构以及DFT在机械方面的计算研究结果,讨论了对手性配体对映体选择的影响催化循环。
Preparation and reactivity of the adducts of ketene alkylsilyl acetals with ethyl propiolate in the presence of titanium tetrachloride
作者:Alain Quendo、Syed Massarat Ali、Gerard Rousseau
DOI:10.1021/jo00051a039
日期:1992.12
The reaction of ketene alkylsilyl acetals with ethyl propiolate in the presence of TiCl4 led to intermediates whose reactivity was studied with electrophiles such as H2O, D2O, NBS, NCS, and PhSeCl to form glutaconate derivatives. Except in the case of the dimethylketene trimethylsilyl acetal, for which the reaction was stereospecific, with other ketene acetals the selectivity was lower. Similar results were observed in the reaction of these titanium intermediates with aldehydes and ketones. The results were interpretated as the formation of vinylic titanium intermediates (more stabilized in the case of the dimethylketene acetal) in equilibrium with the titanium allenolates.
Wenke, G.; Jacobsen, E. N.; Totten, G. E., Synthetic Communications, 1983, vol. 13, # 6, p. 449 - 458
作者:Wenke, G.、Jacobsen, E. N.、Totten, G. E.、Karydas, A. C.、Rhodes, Y. E.