Bronsted acid-assisted chiral Lewis acid (BLA) was highly effective as a chiral catalyst for the enantioselective Diels−Alder reaction of both α-substituted and α-unsubstituted α,β-enals with various dienes. Hydroxy groups in opticallyactive binaphthol derivatives and boron reagents with electron-withdrawing substituents were used as Bronsted acids and Lewis acids, respectively. Intramolecular Bronsted
布朗斯台德酸辅助的手性路易斯酸 (BLA) 作为手性催化剂非常有效,可用于 α-取代和 α-未取代的 α,β-烯醛与各种二烯的对映选择性 Diels-Alder 反应。光学活性联萘酚衍生物中的羟基和具有吸电子取代基的硼试剂分别用作布朗斯台德酸和路易斯酸。手性 BLA 催化剂中的分子内布朗斯台德酸在加速 Diels-Alder 反应速率和产生高水平的对映选择性方面发挥了重要作用。特别是,由于手性 BLA 催化剂中羟基芳基在过渡态组装中的分子内氢键相互作用和有吸引力的 π-π 供体-受体相互作用,实现了优异的对映选择性。
Asymmetric hydrogenation of imines with chiral alkene-derived boron Lewis acids
作者:Xiaoqin Liu、Ting Liu、Wei Meng、Haifeng Du
DOI:10.1039/c8ob02446d
日期:——
With the aim of developing easily accessible chiral Lewis acids for asymmetrichydrogenation, a variety of binaphthyl-based chiral alkenes were prepared in one step from the corresponding diols. Using the in situ generated chiral boron Lewis acids through the hydroboration of chiral alkenes with Piers’ borane, metal-free asymmetrichydrogenations of imines were realized to furnish the desired amine
Enantioselective Direct Aza Hetero-Diels−Alder Reaction Catalyzed by Chiral Brønsted Acids
作者:Hua Liu、Lin-Feng Cun、Ai-Qiao Mi、Yao-Zhong Jiang、Liu-Zhu Gong
DOI:10.1021/ol062499t
日期:2006.12.1
The first chiral Bronsted acid-catalyzed asymmetric direct aza hetero-Diels-Alder reaction has been described. The phosphoric acids, prepared from binol and H-8-binol derivatives, have shown catalytic ability for the reaction of cyclohexenone with N-PMP-benzaldimine. A chiral phosphoric acid, derived from 3,3-di(4-chloropheneyl)-H-8-binol, exhibited superior enantioselectivity, affording fairly good yields and enantioselectivities for the reaction of a range of aromatic aldimines with cyclohexenone.
Synthesis of Novel Chiral Phosphoric Acid-Bearing Two Acidic Phenolic Hydroxyl Groups and its Catalytic Evaluation for Enantioselective Friedel-Crafts Alkylation of Indoles and Enones
A novel chiral phosphoric acid catalyst bearing two acidic phenolic hydroxyl groups was synthesized. Its catalytic activity as a chiral Brøsted acid has been examined in the enantioselective Friedel‐Crafts alkylation of indoles and enones as a model reaction. In comparison with the other chiral phosphoric acid catalysts, the reaction catalyzed by the novel chiral catalyst afforded the desired 3‐substituted