不对称氢化是制备单一对映体化合物的最有效方法之一。然而,在具有多个不饱和键的底物中相对惰性的不饱和基团的化学和对映选择性氢化仍然是一个挑战。我们在此报告了共轭烯炔的高度化学和对映选择性氢化同时保持炔键完整的协议。机理研究表明,Co II 配合物的锌还原产生的伴随的 Zn 2+在启动合理的 Co I /Co III催化循环中起着关键作用。这种方法可以高效生成手性炔丙胺(高达 99.9 % ee 和 2000 S/C)和进一步有用的化学转化。
不对称氢化是制备单一对映体化合物的最有效方法之一。然而,在具有多个不饱和键的底物中相对惰性的不饱和基团的化学和对映选择性氢化仍然是一个挑战。我们在此报告了共轭烯炔的高度化学和对映选择性氢化同时保持炔键完整的协议。机理研究表明,Co II 配合物的锌还原产生的伴随的 Zn 2+在启动合理的 Co I /Co III催化循环中起着关键作用。这种方法可以高效生成手性炔丙胺(高达 99.9 % ee 和 2000 S/C)和进一步有用的化学转化。
afford a class of valuable 4H-benzo[d][1,3]dioxin-4-ones with a 2-site quaternary carbon structure in up to 92% yield by secondary amine-catalyzed dual Michael cascade reactions under mild reaction conditions. The α,β-unsaturated ketone as the key intermediate in the cascade process was successfully separated and characterized. As a result, a new reaction route for ynone species is demonstrated, which
水杨酸和取代的炔酮被用作底物,以提供一类有价值的4 H-苯并[ d ] [1,3]二恶英-4-酮,其具有2位季碳结构,仲胺-收率最高可达92%。在温和的反应条件下催化双重Michael级联反应。成功地分离和表征了α,β-不饱和酮作为级联过程中的关键中间体。结果,证明了一种用于炔酮的新反应路线,这与现有的艾伦胺活化模型完全不同。
Enantio- and Diastereoselective Double Mannich Reaction between Ketones and Imines Catalyzed by Zn-ProPhenol
作者:Barry M. Trost、Elumalai Gnanamani
DOI:10.1021/acs.orglett.0c00318
日期:2020.2.21
Herein we present a Zn-ProPhenol-catalyzed double Mannich reaction between ynones and imines that generates 1,3-diamines in excellent yield as well as diastereo- and enantioselectivity (>99.5% ee). With 2.2 equiv of a single imine electrophile, we obtain pseudo-symmetrical diamines whereas, with two different imine partners, we obtain unsymmetrically substituted 1,3-diamines with three contiguous stereocenters
Alkynylketones were obtained in good yield from reaction of 3-(N-isopropylamino)-1-arylbut-2-en-1-ones with chlorotrimethylsilane. On the other hand, t-butyldimethylchlorosilane leads to gamma-silylated enaminones. Compounds arising from silicon attack at the oxygen atom are never observed. Evidences of the mechanistic pathway of the reaction are reported.