An enantioselective one‐pot Michael/Michael/Henry/hemiacetalization reactionbetween α,β‐unsaturated aldehydes, α‐ketoamides, and nitroalkenes under mild conditions catalyzed by a diarylprolinol silyl ether has been developed. The sequential methodology provides a direct approach to a wide range of fully substituted chiral oxabicyclo[2.2.2]octanes with seven contiguous stereocenters in moderate to
已经开发了在二芳基脯氨醇甲硅烷基醚催化的温和条件下,α,β-不饱和醛,α-酮酰胺和硝基烯烃之间的对映选择性单锅Michael / Michael / Henry /半缩醛化反应。顺序方法学提供了一种直接方法,可处理多种具有七个连续立体中心的全取代手性氧杂双环[2.2.2]辛烷,中度至优异的收率(高达99%),高至极好的非对映选择性(高达> 25:1 dr)以及高到极好的对映选择性(高达99%ee)。
Expeditious, Metal-Free, Domino, Regioselective Synthesis of Highly Substituted 2-Carbonyl- and 2-Phosphorylfurans by Formal [3+2] Cycloaddition
the dual electrophilic properties of (2-chloro-2-nitroethenyl)benzenes in a one-pot, formal [3+2] cycloaddition. Using a base (DBU), the desired trisubstituted heterocycles were formed rapidly (10–30 min) in good to excellent yields (51–92 %), and this versatile, metal-free methodology was applied to the synthesis of 2-acyl- and 2-carboalkoxyfurans and furan-2-carboxamides. Additionally, by using 2-ketophosphonate
A syn-selective catalyticasymmetric 1,4-addition of α-ketoanilides to nitroalkenes is described. The homodinuclear Ni2-Schiff base 1b complex was suitable for the reaction, and products were obtained in 61−92% yield, 8.3:1 → 20:1 syn-selectivity, and 72−98% ee. Stereoselective transformation of the 1,4-adduct to a trisubstituted pyrrolidine was also performed.
between ambident electrophilic and 1,4‐bis‐nucleophilic 1,2‐ketoamides and 1,3‐bis‐electrophilic enals, leading to aza‐oxa‐bicyclo[3.2.1]octane. Then, the TiCl4/Et3SiH system ensures a chemoselectivecleavage of the C−N bond and affords the desired trisubstituted tetrahydropyran in good yield and with conservation of the precursors optical purity. This final synthetic operation includes two consecutive
据报道,快速合成对映体富集的2,3,4-三取代的四氢吡喃具有良好的收率和立体选择性。第一步是环境亲电子和1,4-双亲核1,2-酮酰胺和1,3-双亲电子烯醛之间的多米诺有机催化反应,形成氮杂-氧杂双环[3.2.1]辛烷。然后,TiCl 4 / Et 3 SiH系统确保C-N键的化学选择性裂解,并以高收率提供所需的三取代四氢吡喃,并保留了前体的光学纯度。该最终合成操作包括两个连续的氧碳鎓离子形成和还原。
Xu, Yingjie; Lu, Gang; Matsunaga, Shigeki, Angewandte Chemie - International Edition, 2009, vol. 48, p. 3353 - 3356