Umpolung reactions of imines, especially the asymmetric reactions, have been extensively studied as they provide access to important chiral amines in an efficient manner. The reactions studied range from simple Michael reactions to several kinds of other reactions such as the aza-benzoin reaction, aza-Stetter reaction, addition with MBH carbonate, and Ir-catalysed allylation. Herein, we report the
Ir/PTC cooperatively catalyzed asymmetric umpolung allylation of α-imino ester enabled synthesis of α-quaternary amino acid derivatives bearing two vicinal stereocenters
作者:Yong-Liang Su、Yu-Hui Li、Yu-Gen Chen、Zhi-Yong Han
DOI:10.1039/c6cc09654a
日期:——
A novel Ir/PTC cooperatively catalyzed asymmetric umpolung addition of simple [small alpha]-imino esters is developed and it provides facile access to [small alpha]-quaternary amino acidderivatives bearing two vicinal stereocenters. Both the...
Enantiocontrol by assembled attractive interactions in copper-catalyzed asymmetric direct alkynylation of α-ketoesters with terminal alkynes: OH⋯O/sp<sup>3</sup>-CH⋯O two-point hydrogen bonding combined with dispersive attractions
作者:Martin C. Schwarzer、Akane Fujioka、Takaoki Ishii、Hirohisa Ohmiya、Seiji Mori、Masaya Sawamura
DOI:10.1039/c8sc00527c
日期:——
Copper-catalyzed asymmetric directalkynylation of α-ketoesters with terminal alkynes with chiral prolinol–phosphine ligands, most preferably (αR,2S)-1-(2-dicyclohexylphosphinobenzyl)-α-neopentyl-2-pyrrolidinemethanol, afforded various enantioenriched chiral propargylic tertiary alcohols. Quantum-chemical calculations using the BP86 density functional including Grimme's empirical dispersion correction
铜催化 α-酮酯与末端炔烃与手性脯氨醇-膦配体,最优选 (α R ,2 S )-1-(2-二环己基膦基苄基)-α-新戊基-2-吡咯烷甲醇的不对称直接炔基化,提供了各种对映体富集的手性炔丙基叔醇。使用 BP86 密度泛函(包括 Grimme 经验色散校正)的量子化学计算 [DF-BP86-D3(BJ)-PCM( t BuOH)/TZVPP//DF-BP86-D3(BJ)/SVP] 显示 OH⋯ 的出现手性配体和处于立体决定过渡态的酮酯的羰基之间的O/sp 3 -CH⋯O两点氢键。结合定向酮酯底物的氢键相互作用,手性配体(P-环己基)和有利过渡态的酮酯之间的色散吸引力,而不是不利过渡态的空间排斥,解释了不对称铜催化的对映选择性。
Development of a Practical Synthetic Method for<i>N</i>-<i>tert</i>-Butoxycarbonyl α-Ketimino Esters
作者:Takuya Hashimoto、Kumiko Yamamoto、Keiji Maruoka
DOI:10.1246/cl.2011.326
日期:2011.3.5
Despite the potential synthetic utility of N-Boc α-ketimino esters as prochiral ketimines to give chiral α-tertiary amines, there has been no general method to access these molecules in a practical fashion. We report herein a procedure for the one-step synthesis of N-Boc α-ketimino esters starting from the corresponding α-keto esters.
2-Oxo-Driven Coupling Reactions of 2-Oxo Aldehydes/2-Oxo Iminium Ions and Hydroperoxides at Room Temperature
作者:Shahnawaz Khan、Qazi Naveed Ahmed
DOI:10.1002/ejoc.201600795
日期:2016.11
2-oxo-group-promoted direct coupling reaction between 2-oxo aldehydes and hydroperoxides has been developed. The method has been used successfully for the generation of different 2-oxo esters and acids. This reaction harnesses the hydrogen-bonding-induced self-decomposition tendency of hydroperoxides; the intermediates produced by this process then attack the aldehyde or iminiumion to generate cross-coupled