Iridium-catalyzed regio- and enantioselective allylation of ketone enolates
Iridium-catalyzed regio- and enantioselective allylation of ketone enolates
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DOI：
10.1021/ja0566275
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发表时间：
2005-12-14
影响因子：
15
通讯作者：
Hartwig, JF
中科院分区：
文献类型：
--
作者：
Graening, T;Hartwig, JF
本文报道了在金属环铱催化剂存在下，不稳定烯醇酮与不对称烯丙基碳酸酯的区域选择性和对映选择性α-烯丙基化反应，生成支链取代产物。产物，支链γ，δ-不饱和酮，由容易获得的甲硅烷基烯醇醚和非手性Boc保护的烯丙醇以高区域选择性和对映选择性（91 - 96%ee）获得。CsF和ZnF 2的组合被证明可以促进该反应并抑制二烯丙基化副产物的形成。此外，从简单的亚磷酰胺配体衍生的铱配合物被证明催化该反应具有优异的选择性，和光谱数据显示，环化的Ir预催化剂原位形成。该方法提供了合成重要的双官能化合物的对映选择性途径，所述双官能化合物通常是可获得的，但通过克莱森重排是外消旋形式。十个例子的芳香族，以及脂肪族，底物的反应报告。
The regio- and enantioselective α-allylation of unstabilized ketone enolates with unsymmetrical allylic carbonates to form the branched substitution products in the presence of metallacyclic iridium catalysts is reported. The products, branched γ,δ-unsaturated ketones, were obtained from readily available silyl enol ethers and achiral Boc-protected allylic alcohols in high regioselectivities and enantioselectivities (91−96% ee). The combination of CsF and ZnF2was shown to promote this reaction and suppress the formation of diallylation byproducts. In addition, iridium complexes derived from simple phosphoramidite ligands were shown to catalyze this reaction with excellent selectivities, and spectroscopic data show that a cyclometalated Ir precatalyst is formed in situ. This process provides an enantioselective access to synthetically important bifunctional compounds, which are generally accessible, but in racemic form, through Claisen rearrangements. Ten examples of the reactions of aromatic, as well as aliphatic, substrates are reported.