Enantioselective synthesis of 1,5-anti- and 1,5-syn-diols using a highly diastereoselective one-pot double allylboration reaction sequence
Enantioselective synthesis of 1,5-anti- and 1,5-syn-diols using a highly diastereoselective one-pot double allylboration reaction sequence
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DOI：
10.1021/ja028055j
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发表时间：
2002-11-20
影响因子：
15
通讯作者：
Roush, WR
中科院分区：
文献类型：
--
作者：
Flamme, EM;Roush, WR
1,2,5-二取代(E)-1,5-反-2-戊二烯醇1和(Z)-1,5-合-2-戊二烯醇2通过两种不同的醛分别与(E)-γ-（1,3,2-二恶aborinanyl）烯丙基]二异戊二苯硼烷(4)或(E)-γ-（4,4,5,5-四苯基-1,3,2-二恶aborinanyl）烯丙基]二异戊二苯硼烷（11）进行一罐偶联，实现了高度的非对映选择性和对映选择性合成。在所有情况下，得到的二醇1和二醇2的产率为63 ~ 95%，ee为89 ~ 96%，非对映选择性≥20:1。双官能团γ-硼基取代烯丙基硼烷试剂4和11是由烯丙烯3和10与二异戊二苯硼烷原位硼化反应生成的。该方法成功的关键是在导致5的烯基硼化步骤和相应的由11衍生的取代甲基硼酸盐中具有良好的立体控制性，取代甲基硼酸盐中间体在随后的烯基硼化反应中具有立体特异性，以及二醇助剂诱导取代基α在过渡态7和8中的赤道或轴向位置的能力。
Highly diastereo- and enantioselective syntheses of 1,5-disubstituted (E)-1,5-anti-pent-2-endiols1and (Z)-1,5-syn-pent-2-endiols2have been achieved via the one-pot coupling of two different aldehydes with either (E)-γ-(1,3,2-dioxaborinanyl)-allyl]diisopinocampheylborane (4) or (E)-γ-(4,4,5,5-tetraphenyl-1,3,2-dioxaborolanyl)allyl]diisopinocampheylborane (11), respectively. The indicated diols1and2are obtained in 63−95% yield with 89−96% ee and ≥20:1 diastereoselectivity in all cases. The bifunctional γ-boryl-substituted allylborane reagents4and11were generated in situ by the hydroboration of allenes3and10with diisopinocampheylborane. The keys to the success of this method are the excellent stereocontrol in the allylboration step leading to5and the corresponding substituted methallylboronate derived from11, the stereospecificity of the subsequent allylboration reaction of the substituted methallylboronate intermediates, and the ability of the diol auxiliary to induce equatorial or axial placement of the substituent α to boron in transition states7and8.