Catalytic asymmetric rearrangement of α,α-disubstituted α-siloxy aldehydes to optically active acyloins using axially chiral organoaluminum lewis acids
Catalytic asymmetric rearrangement of α,α-disubstituted α-siloxy aldehydes to optically active acyloins using axially chiral organoaluminum lewis acids
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DOI：
10.1021/ja063051q
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发表时间：
2007-03-07
影响因子：
15
通讯作者：
Maruoka, Keiji
中科院分区：
文献类型：
--
作者：
Ooi, Takashi;Ohmatsu, Kohsuke;Maruoka, Keiji
基于立体化学定义的轴向手性有机铝路易斯酸3的设计，发展了α，α-二烷基-α-硅氧基醛的催化不对称重排反应。例如，(S，S)-4(1.1当量)与Me3Al在甲苯中于室温下反应30min，生成(S，S)-3(5mol%)，然后在-20℃下与α-硅氧基醛1a(R=CH2Ph)反应12h，得到相应的α-硅氧基酮2a(R=CH2Ph)，产率为96%，产率为87%(S)。这一史无前例的立体选择性重排的范围已经用有代表性的底物进行了研究，其中外消旋，α，α-二取代的α-硅氧基醛的动力学拆分也取得了令人印象深刻的结果。这些结果清楚地证明了本方法在催化对映体选择性合成各种不对称方法所不容易获得的酰基和叔羟基醛方面的有效性。
A catalytic asymmetric rearrangement of, alpha,alpha-dialkyl-alpha-siloxy aldehydes has been developed based on the design of a stereochemically defined, axially chiral organoaluminum Lewis acid 3. For instance, treatment of (S,S)-4 (1.1 equiv) with Me3Al in toluene at room temperature for 30 min generated (S,S)-3 (5 mol %), and subsequent reaction with alpha-siloxy aldehyde 1a (R = CH2Ph) at -20 degrees C for 12 h resulted in the smooth rearrangement to afford the corresponding alpha-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, alpha,alpha-disubstituted alpha-siloxy aldehydes has also been achieved. These results clearly demonstrate the utility of the present approach for the catalytic enantioselective synthesis of various acyloins and tertiary hydroxy aldehydes not readily accessible by the previously known asymmetric methodologies.