Highly enantioselective alk-2-enylation of aldehydes through an allyl-transfer reaction
Highly enantioselective alk-2-enylation of aldehydes through an allyl-transfer reaction
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DOI：
10.1002/anie.200390327
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发表时间：
2003-01-01
影响因子：
16.6
通讯作者：
Kataoka, K
中科院分区：
文献类型：
--
作者：
Nokami, J;Nomiyama, K;Kataoka, K
高对映体纯的高烯丙醇已经通过使用烯丙基有机金属试剂（MCH2CH^CH2; M=金属）和化学计量量的手性助剂[3]或催化量的手性促进剂来制备。[4]此外，在手性助剂或催化剂的存在下，与g-取代的有机金属试剂4的烯丙基化反应提供g加合物5非对映和对映选择性。[5]该C12 C-键形成反应对于在柔性烃链中构建邻位立体中心特别有用[Eq.然而，据我们所知，还没有报道醛的不对称烷-2-烯基化反应（例如巴豆基化）得到4-取代的高烯丙醇6（加合物）[Eq.（3）]。这是因为通过烷-2-烯基金属试剂4进行的烯丙基化反应无一例外地通过六元环状过渡态进行烯丙基转座，仅得到g加合物5。[6]美国
Highly enantiopure homoallylic alcohols have been prepared by using allylic organometallic reagents (MCH2CH¼CH2; M= metal) and a stoichiometric amount of a chiral auxiliary [3] or a catalytic amount of a chiral promoter.[4] Furthermore, allylation reactions with g-substituted organometallic reagents 4 in the presence of a chiral auxiliary or catalyst afford the g adduct 5 diastereo-and enantioselectively.[5] This CÀC-bond-formation reaction is particularly useful for the construction of vicinal stereogenic centers in a flexible hydrocarbon chain [Eq.(2)].However, to the best of our knowledge, no asymmetric alk-2-enylation reaction (eg crotylation) of aldehydes to give 4-substituted homoallylic alcohols 6 (a adduct) has yet been reported [Eq.(3)]. This is because the allylation reactions by alk-2-enyl metal reagents 4 proceed, without exception, with allylic transposition via a six-membered cyclic transition state, affording exclusively the g adduct 5.[6]