Article
Chemistry, Organic
Wei Liu, Donglei Wang, Dekun Zhang, Xiaoyu Yang
Summary: Optically active amines are crucial in bioactive natural products, pharmaceuticals, chiral catalysts, and ligands. The development of nonenzymatic asymmetric catalytic approaches for the kinetic resolution and desymmetrization of amines in the past two decades has been systematically summarized.
Article
Chemistry, Multidisciplinary
Benjamin Poelloth, Mukund P. Sibi, Hendrik Zipse
Summary: The factors responsible for the kinetic resolution of alcohols by chiral pyridine derivatives have been elucidated through accurate competitive linear regression analysis. Increasing the size of the aromatic side chain accelerates the reaction rate of the major enantiomer, leading to the design of a new catalyst with increased steric bulk for higher enantioselectivity values. Experimental and theoretical results suggest that the enhancement of enantioselectivity is achieved by accelerating the transformation of the major enantiomer through attractive non-covalent interactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Yongkai Pan, Donglei Wang, Yunrong Chen, DeKun Zhang, Wei Liu, Xiaoyu Yang
Summary: The kinetic resolution of alpha-tertiary propargylic amines was successfully achieved through asymmetric remote aminations of anilines with azodicarboxylates enabled by chiral phosphoric acid catalysis. A broad range of substituents at the alpha-position were well tolerated, with high kinetic resolution performances. Additionally, excellent stereoselectivity was demonstrated for alpha-tertiary amines bearing an alpha-CN group under the same reaction conditions. The successful transformations of the chiral amination products and the recovered propargylic amines showcased the power of this method in asymmetric synthesis of alpha-tertiary amines and their derivatives.
Article
Chemistry, Multidisciplinary
Jose A. Carmona, Patricia Rodriguez-Salamanca, Rosario Fernandez, Jose M. Lassaletta, Valentin Hornillos
Summary: An atroposelective Ir-catalyzed dynamic kinetic resolution (DKR) of 2-(quinolin-8-yl)benzaldehydes/1-naphthaldehydes is achieved by transfer hydrogenative coupling of allyl acetate. The reaction leads to the installation of central and axial chirality, with high diastereoselectivities and excellent enantioselectivities when ortho-cyclometalated iridium-DM-BINAP is used as the catalyst. The racemization of the substrates is facilitated through a designed transient Lewis acid-base interaction between the quinoline nitrogen atom and the aldehyde carbonyl group.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Review
Chemistry, Organic
Helene Pellissier
Summary: Organocatalytic dynamic kinetic resolution (DKR) has emerged as a promising field in the past two decades, allowing efficient separation of chiral compounds. This review aims to provide an update on organocatalytic DKRs since 2016.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Pratibha Chand-Thakuri, Indunil Alahakoon, Daniel Liu, Mohit Kapoor, John F. Kennedy, Kenneth W. Jenkins, Allison M. Rabon, Michael C. Young
Summary: Free or unfunctionalized benzylamines are commonly used in C-H activation in the presence of palladium salts. However, subsequent functionalization of the dimeric cyclometalates can be challenging. This study demonstrates a protocol for ortho-C-H chlorination and bromination of unprotected benzylamines, as well as a unique acetoxylation/-cyclization utilizing fluorine-based oxidants and the nucleophilicity of the free primary amine directing group.
SYNTHESIS-STUTTGART
(2022)
Article
Chemistry, Organic
Ken Okuno, Yasuaki Furuya, Seiji Shirakawa
Summary: The kinetic resolution of racemic compounds is a reliable method to prepare chiral molecules in highly optically enriched forms. However, the kinetic resolution of racemic carboxylic acids has not been well developed. Esterification and lactonization promoted by chiral organocatalysts have been found to be effective methods for the kinetic resolution of chiral carboxylic acids.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Jan Seliger, Martin Oestreich
Summary: A novel approach for the dynamic kinetic resolution of benzylic alcohols was reported, achieving enantioselective silylation of racemic alcohol mixtures in high yields by merging different catalytic processes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Tairin Kawasaki, Tomohiro Tosaki, Naoki Ishida, Masahiro Murakami
Summary: An alternative method has been developed for obtaining aryl esters from aliphatic primary alcohols and phenols using visible light irradiation at ambient temperature. The reaction does not require any oxidant or hydrogen acceptor, and successfully esterifies primary alcohols with various functional groups with phenols. The produced esters can be used as precursors for various carbonyl compounds.
Article
Chemistry, Multidisciplinary
Mengyao Tang, Huanchao Gu, Shunlong He, Subramani Rajkumar, Xiaoyu Yang
Summary: An efficient protocol for kinetic resolution of tertiary alcohols has been developed via unprecedented asymmetric enamide-imine tautomerism process enabled by chiral phosphoric acid catalysis. This method is particularly effective for a series of 1,1-dialkyl substituted allyl alcohols, producing chiral tertiary alcohols that are difficult to access through other asymmetric methods. Facile and versatile transformations of the chiral products demonstrate the value of this kinetic resolution method.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Jian Zhang, Mingyang Song, Weijun Tang, Dong Xue, Jianliang Xiao, Huaming Sun, Chao Wang
Summary: Converting racemic compounds to enantioenriched products is a common method in accessing chiral molecules. In this study, a kinetic resolution method is used to transform racemic allylic alcohols into chiral compounds, with good yields and stereoselectivities.
Article
Chemistry, Physical
Ming-Sheng Xie, Ning Li, Yin Tian, Xiao-Xia Wu, Yun Deng, Gui-Rong Qu, Hai-Ming Guo
Summary: A study reported the use of bifunctional chiral PPY N-oxides as catalysts for dynamic kinetic resolution of racemic carboxylic esters, achieving high yields and enantioselectivity for the synthesis of chiral alpha-aryl alpha-alkyl carboxylic esters. Mechanistic studies revealed the crucial role of oxygen atoms in PPY N-oxides during the reaction process.
Article
Chemistry, Physical
Patricia Rodriguez-Salamanca, Gonzalo de Gonzalo, Jose A. Carmona, Joaquin Lopez-Serrano, Javier Iglesias-Siguenza, Rosario Fernandez, Jose M. Lassaletta, Valentin Hornillos
Summary: This article describes a highly enantioselective biocatalytic dynamic kinetic resolution (DKR) for configurationally labile N-arylindole aldehydes. The DKR is achieved through atroposelective bioreduction of the carbonyl group using commercial ketoreductases (KREDs), resulting in axially chiral N-arylindole aminoalcohols with excellent conversions and optical purities. The strategy relies on the racemization of the stereogenic axis facilitated by a transient Lewis pair interaction between NMe2 and the aldehyde groups. This protocol offers a broad substrate scope under mild conditions.
Article
Chemistry, Multidisciplinary
Zheng Tan, Long Chen, Lingyu Li, Yuzhen Li, Yao Luo, Fei Wang, Shunxi Dong, Xiaoming Feng
Summary: In this study, a practical and efficient synthesis of a-methylene-?-butyrolactones was developed using chiral N,N'-dioxide/Al-III complex as the catalyst. The key success of this transformation was the kinetic resolution of allylboration intermediate via asymmetric lactonization. Taking advantage of this method, a catalytic asymmetric total synthesis of eupomatilones 2, 5, and 6 was accomplished.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Jihoon Moon, Takusho Kin, Karin Mizuno, Shuji Akai, Kyohei Kanomata
Summary: This study presents a chemoenzymatic dynamic kinetic resolution (DKR) of racemic sec-alcohols using immobilized lipase and aqueous sulfuric acid as catalysts for kinetic resolution and racemization, respectively. The use of nanoparticle-stabilized phase separation in a Pickering emulsion allowed the use of these incompatible catalysts in a single vessel. The racemization reaction in the aqueous sulfuric acid solution effectively suppressed side reactions, resulting in high yields and optical purities.
