Brønsted Acid-Catalyzed, Highly Enantioselective Addition of Enamides to In Situ<i>-</i>Generated<i>ortho</i>-Quinone Methides: A Domino Approach to Complex Acetamidotetrahydroxanthenes
作者:Satyajit Saha、Christoph Schneider
DOI:10.1002/chem.201406044
日期:2015.2.2
The highly enantioselective conjugate addition of enamides and enecarbamates to in situ‐generated ortho‐quinone methides, upon subsequent N,O‐acetalization, gives rise to acetamido‐substituted tetrahydroxanthenes with generally excellent enantio‐ and diastereoselectivities. A chiral BINOL‐based phosphoric acid catalyst controls the enantioselectivity of the carbon–carbon bond‐forming event. The products
Asymmetric Transfer Hydrogenation of <i>o</i>-Hydroxyphenyl Ketones: Utilizing Directing Effects That Optimize the Asymmetric Synthesis of Challenging Alcohols
作者:Ye Zheng、Guy J. Clarkson、Martin Wills
DOI:10.1021/acs.orglett.0c01213
日期:2020.5.1
A systematic range of o-hydroxyphenyl ketones were reduced under asymmetrictransferhydrogenation conditions using the C3-tethered catalyst 2. Two directing effects, i.e., an o-hydroxyphenyl coupled to a bulky aromatic on the opposite side of the ketone substrate, combine in a matched manner to deliver reduction products with very high enantiomeric excess.
Organocatalytic Enantioselective Synthesis of Chiral Diarylmethylamines from Racemic Alcohols
作者:Min Chen、Yaodong Han、Dengke Ma、Yong Wang、Zengwei Lai、Jianwei Sun
DOI:10.1002/cjoc.201800135
日期:2018.7
An organocatalytic approach for direct conversion of racemic diarylmethanols to valuable chiral diarylmethylamines is described. Different from the previously reported elegant “borrowing hydrogen” approach, the present process employs a distinct complementary formal SN1 strategy. This approach enjoys excellent enantioselectivity, mild conditions, broad scope, and easy product derivatization. Mechanistically
描述了将外消旋二芳基甲醇直接转化为有价值的手性二芳基甲胺的有机催化方法。与先前报道的优雅的“借用氢”方法不同,本方法采用了独特的互补形式S N 1策略。这种方法具有出色的对映选择性,温和的条件,广泛的范围以及容易的产品衍生化。从机理上讲,对照实验还提供了对某些显着特征的重要见解,例如底物动力学拆分和可逆性以及邻羟基在底物中的关键作用。
Enantioselective Addition of Thiols to ortho-Quinone Methides Catalyzed by Chiral Phosphoric Acids
作者:Jianwei Sun、Zengwei Lai
DOI:10.1055/s-0035-1560546
日期:——
The first Bronsted acidcatalyzed enantioselective addition of thiols to the in situ generated ortho-quinone methides (o-QMs) is described. Complementary to the chiral amine catalyzed approach, the present reaction employs a chiral phosphoric acid as the catalyst. The readily available o-hydroxybenzyl alcohols serve as the atom-economical precursors of o-QMs to react with tritylthiol with moderate
A base-promoted cascade reaction of α,β-unsaturated <i>N</i>-tosylhydrazones with <i>o</i>-hydroxybenzyl alcohols: highly regioselective synthesis of <i>N-sec</i>-alkylpyrazoles
作者:Lian-Mei Chen、Juan Zhao、An-Jie Xia、Xiao-Qiang Guo、Ya Gan、Chuang Zhou、Zai-Jun Yang、Jun Yang、Tai-Ran Kang
DOI:10.1039/c9ob01780a
日期:——
N-sec-alkylpyrazoles through a base-promoted cascade cyclization/Michael addition reaction of α,β-unsaturated N-tosylhydrazones with ortho-hydroxybenzyl alcohols has been developed. The desired products containing di- or triaryl groups at the same carbon atom were afforded in good to excellent yields with excellent regioselectivities (>20 : 1). Moreover, a three-component reaction of ortho-hydroxybenzyl alcohols, α