Tandem intramolecular silylformylation and silicon-assisted cross-coupling reactions.: Synthesis of geometrically defined α,β-unsaturated aldehydes
Tandem intramolecular silylformylation and silicon-assisted cross-coupling reactions.: Synthesis of geometrically defined α,β-unsaturated aldehydes
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DOI：
10.1021/jo034064e
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发表时间：
2003-06-27
影响因子：
3.6
通讯作者：
Kobayashi, T
中科院分区：
文献类型：
--
作者：
Denmark, SE;Kobayashi, T
报道了钯和铜催化的环硅醚与芳基碘的交叉偶联反应。在一氧化碳气氛中，高炔丙基硅醚2通过分子内硅甲酰化反应容易地合成了硅醚3。环硅醚3在[(烯丙基)PdCl](2)、CuI、氢硅烷和KF-2H(2)O存在下，在DMF中于室温下与不同的芳基碘化合物7反应，高产率地得到了α，β-不饱和醛偶联产物8。在这一过程中对铜的需求表明，从硅到铜的转金属作用是该机制中的重要一步。虽然硅氧烷3和产物8在碱性条件下不稳定，但KF-2H(2)O提供了对硅的反应活性和还原碱度的适当平衡。需要在[(烯丙基)PdCl](2)中加氢硅烷才能将钯(II)还原为活性钯(0)形式。
The palladium- and copper-catalyzed cross-coupling reactions of cyclic silyl ethers with aryl iodides are reported. Silyl ethers 3 were readily prepared by intramolecular silylformylation of homopropargyl silyl ethers 2 under a carbon monoxide atmosphere. The reaction of cyclic silyl ethers 3 with various aryl iodides 7 in the presence of [(allyl)PdCl](2), CuI, a hydrosilane, and KF-2H(2)O in DMF at room temperature provided the alpha,beta-unsaturated aldehyde coupling products 8 in high yields. The need for copper in this process suggested that transmetalation from silicon to copper is an important step in the mechanism. Although siloxane 3 and the product 8 are not stable under basic conditions, KF-2H(2)O provided the appropriate balance of reactivity toward silicon and reduced basicity. The addition of a hydrosilane to [(allyl)PdCl](2) was needed to reduce the palladium(II) to the active palladium(0) form.