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。
Phosphine-Catalyzed α-Umpolung–Aldol Reaction for the Synthesis of Benzo[<i>b</i>]azapin-3-ones
作者:Kui Zhang、Lingchao Cai、Sooji Hong、Ohyun Kwon
DOI:10.1021/acs.orglett.9b01749
日期:2019.7.5
serves as a conduit for the construction of benzo[b]azepin-3-ones in good to excellent yields under mild conditions. The resulting 2-benzylidene moieties are formed exclusively in the E-configuration. Mechanistically, this unusual annulation occurs through a phosphine-catalyzed α-umpolung addition, followed by an aldol reaction. One of the benzo[b]azepin-3-one products was converted to the core structure
报道了一种新型膦催化的 2-磺酰胺苯甲醛和炔酮之间的分子间环化。该方法可作为在温和条件下以良好至优异的产率构建苯并[ b ]氮杂-3-酮的渠道。所得的2-亚苄基部分仅以E-构型形成。从机制上讲,这种不寻常的环化是通过膦催化的 α-umpolung 加成,然后是羟醛反应发生的。其中一种苯并[ b ]氮杂卓-3-酮产品被转化为3-氨基-[ a ]苯并氮杂卓-2-一-1-链烷酸的核心结构,其中许多充当血管紧张素转换酶抑制剂。
Phosphane-Catalyzed [3+3] Annulation of C,N-Cyclic Azomethine Imines with Ynones: A Practical Method for Tricyclic Dinitrogen-Fused Heterocycles
A phosphane‐catalyzed [3+3] annulation of azomethineimines with ynones has been developed. Under mild reaction conditions, the reaction proceeds smoothly to afford tricyclic dinitrogen‐fused heterocyclic compounds in moderate to excellent yields with moderate to excellent stereoselectivies. Using a chiral phosphine as the catalyst, the reaction could work to give the cycloadduct in moderate yield
Bisphosphine catalyzed sequential [3 + 2] cycloaddition and Michael addition of ynones with benzylidenepyrazolones <i>via</i> dual α′,α′-C(sp<sup>3</sup>)–H bifunctionalization to construct cyclopentanone-fused spiro-pyrazolones
作者:Jiayong Zhang、Zhiwei Miao
DOI:10.1039/c8ob02675k
日期:——
A bisphosphine-catalyzed sequential [3 + 2] cycloaddition and Michael addition reaction of ynones with benzylidenepyrazolones has been developed. Under the catalysis of DPPB [1,4-bis(diphenylphosphino)butane], the reaction proceeded smoothly to give spiro-[cyclopentanone] pyrazolone derivatives in moderate to good yields with good diastereoselectivities via sequential dual α′,α′-C(sp3)–H bifunctionalization
A green and efficient iridium-catalyzed asymmetric transfer hydrogenation of alkynyl ketones to chiral propargylic alcohols has been developed. By using sodium formate and ethanol as hydrogensources, a series of alkynyl ketones were hydrogenated by chiral spiro iridium catalyst (S)-1b to provide optically active chiral propargylic alcohols with up to 98% ee under base-free conditions. This protocol