<i>N</i>,<i>N′</i>-Dioxide/Nickel(II)-Catalyzed Asymmetric Inverse-Electron-Demand Hetero-Diels-Alder Reaction of β,γ-Unsaturated α-Ketoesters with Enecarbamates
作者:Yuhang Zhou、Yin Zhu、Lili Lin、Yulong Zhang、Jianfeng Zheng、Xiaohua Liu、Xiaoming Feng
DOI:10.1002/chem.201403764
日期:2014.12.8
have been developed to catalyze the inverse‐electron‐demand hetero‐Diels–Alder reaction of β,γ‐unsaturated α‐ketoesters with acyclic enecarbamates. After detailed screening of the reaction parameters, mild optimized reaction conditions were established, affording 3,4‐dihydro‐2H‐pyranamines in up to 99 % yield, 99 % ee and more than 95:5 d.r. The catalytic system was also efficient for β‐substituted acyclic
N,N'-二氧化物/镍(II)络合物的开发可催化β,γ-不饱和α-酮酸酯与无环烯氨基甲酸酯的反电子需求异Diels-Alder反应。在详细筛选反应参数之后,建立了温和的优化反应条件,以高达99%的收率,99%ee和95:5 dr以上的产率提供了3,4-二氢-2 H-吡喃胺。 β-取代的无环烯氨基甲酸酯,提供更具挑战性的2,3,4-三取代的3,4-二氢-2 H-吡喃胺具有三个连续的立体生成中心,具有优异的收率,非对映选择性和对映选择性。该反应可按比例放大至克级,而对映选择性或收率均不降低。基于这些实验和先前的报道,提出了一种可能的过渡态。