Catalytic Asymmetric Rearrangement of α,α-Disubstituted α-Siloxy Aldehydes to Optically Active Acyloins Using Axially Chiral Organoaluminum Lewis Acids
作者:Takashi Ooi、Kohsuke Ohmatsu、Keiji Maruoka
DOI:10.1021/ja063051q
日期:2007.3.1
resulted in the smooth rearrangement to afford the corresponding α-siloxy ketone 2a (R = CH2Ph) in 96% isolated yield with 87% ee (S). The scope of this unprecedented stereoselective rearrangement has been investigated with representative substrates, in which impressive kinetic resolution of racemic, α,α-disubstituted α-siloxy aldehydes has also been achieved. These results clearly demonstrate the utility
基于立体化学定义的轴向手性有机铝路易斯酸 3 的设计,开发了 α,α-二烷基-α-甲硅烷氧基醛的催化不对称重排。例如,处理 (S,S)-4 (1.1 equiv)在室温下与甲苯中的 Me3Al 反应 30 分钟生成 (S,S)-3 (5 mol %),随后与 α-甲硅烷氧基醛 1a (R = CH2Ph) 在 -20 °C 反应 12 小时,得到平滑的重排得到相应的 α-甲硅烷氧基酮 2a (R = CH2Ph),分离产率为 96%,ee (S) 为 87%。这种前所未有的立体选择性重排的范围已经用代表性底物进行了研究,其中外消旋的 α,α-二取代 α-甲硅烷氧基醛的动力学分辨率也令人印象深刻。