Article
Chemistry, Organic
Marco Corti, Marco Leusciatti, Mattia Moiola, Mariella Mella, Paolo Quadrelli
Summary: By mild oxidation of nitrile oxides with tertiary amine N-oxides, two new nitrosocarbonyl intermediates with carbohydrate-based chiral substituents were successfully synthesized and trapped, leading to hetero Diels-Alder cycloadducts and ene adducts from fair to excellent yields. The methodology shows promise in widening access to nitrosocarbonyls, versatile tools in organic synthesis, through easy conversion of aldoximes into hydroxymoyl halides.
SYNTHESIS-STUTTGART
(2021)
Article
Chemistry, Multidisciplinary
Wei Wen, Zhao-Pin Ai, Chang-Lin Yang, Chao-Xing Li, Zhu-Lian Wu, Tian Cai, Qi-Xiang Guo
Summary: This study presents a new catalytic asymmetric approach for the synthesis of chiral alpha-amino ketones using a chiral palladium-catalyzed arylation reaction. The method offers a straightforward and highly stereocontrolled approach for the synthesis of acyclic alpha-amino ketones.
Article
Chemistry, Multidisciplinary
Wenke Dong, Zhiyang Ye, Wanxiang Zhao
Summary: Catalytic asymmetric hydroboration of ketone-derived silyl enol ethers using cobalt catalyst has been reported, providing a convenient approach to access valuable enantiopure beta-hydroxy boronic esters. This method features mild reaction conditions, a broad substrate scope, and excellent enantioselectivities, making it potential to streamline the synthesis of complex molecules.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Paul Shaw, Storm J. Hassell-Hart, Gayle E. Douglas, Andrew G. Malcolm, Alan R. Kennedy, Gemma White, Laura C. Paterson, William J. Kerr
Summary: In this study, we applied silyl enol ether moieties as efficient alkene coupling partners within cobalt-mediated intramolecular Pauson-Khand reactions. This cyclization strategy delivers valuable oxygenated cyclopentenone products in high yields and allows for the incorporation of a variety of decorated structures.
Article
Chemistry, Organic
Debasish Ghosh, Aniruddha Ganguly, Saikat Khamarui
Summary: This study presents a novel approach for the expedited synthesis of valuable alpha-substituted ketones, using aliphatic amine catalysis to drive the oxidative C-O/C-N coupling reaction between alkynes and an appropriate nucleophile. The one-pot synthesis employs hypervalent iodine as both the oxidant and coupling agent. A fast, metal-free, and environmentally benign method is developed for synthesising alpha-acetoxyketones and alpha-imidoketones in an aqueous medium. To demonstrate the potential for larger-scale production, a gram-scale reaction is conducted. Moreover, this methodology has successfully enabled the direct synthesis of cathinone, a psychoactive drug. Overall, this work holds significant promise for the efficient and sustainable synthesis of alpha-substituted ketones and the potential development of novel biologically active compounds.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Alisa S. Sunagatullina, Andreas Hess, Alexander Kremsmair, Yifan Li, Yi-Hung Chen, Paul Knochel
Summary: We present a novel electrophilic amination method for primary, secondary, and tertiary alkyl, benzylic, and allylic zinc and magnesium organometallics using O-2,4,6-trimethylbenzoyl hydroxylamines (O-TBHAs) with yields ranging from 52-99%. These O-TBHAs exhibit excellent long-term stability and can be conveniently synthesized from various highly functionalized secondary amines through a three-step procedure. The amination reactions demonstrate remarkable chemoselectivity without the need for transition-metal catalysts, and are typically completed within 1-3 hours at 25 degrees Celsius. Furthermore, this electrophilic amination process enables the synthesis of enantioenriched tertiary amines (up to 88% ee) using optically enriched secondary alkylmagnesium reagents of the type s-AlkylMgCH(2)SiMe(3).
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Dekun Zhang, Ying-Bo Shao, Wansen Xie, Yunrong Chen, Wei Liu, Hanyang Bao, Faqian He, Xiao-Song Xue, Xiaoyu Yang
Summary: In this paper, a remote enantioselective desymmetrization protocol for asymmetric aromatic aminations of 9,10-dihydroacridines is disclosed. A new spirocyclic chiral phosphoric acid (CPA) catalyst is used to achieve this synthesis, leading to a wide range of chiral dihydroacridines with excellent enantioselectivities. This method is also applicable in the construction of stereogenic silicon center and kinetic resolution of unsymmetrical dihydroacridine derivatives. Density functional theory calculations elucidate the origin of the reactions' excellent regio- and enantioselectivity.
Article
Chemistry, Organic
Shogo Nakamura, Soshi Nishino, Koji Hirano
Summary: A copper-catalyzed regioselective hydroamination method was developed to synthesize alpha-aminophosphonates from alpha,beta-unsaturated phosphonates, which are of interest in medicinal chemistry. The use of an umpolung, electrophilic amination strategy with a hydroxylamine derivative is key to achieving the desired regioselectivity, as compared to the conventional nucleophilic hydroamination conditions with the parent amine. The article also discusses the asymmetric synthesis using a chiral bisphosphine ligand and its application in a related silylamination reaction.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Xin Fu, Yu Hao, He-Yuan Bai, Abing Duan, Shu-Yu Zhang
Summary: The cobalt-catalyzed regio- and enantioselective gamma-amination of beta,gamma-unsaturated N-acylpyrazoles has been achieved, delivering the corresponding products with good regio- and enantioselectivity. DFT calculations were used to explain the selectivity of this gamma-amination, and the chiral products were easily converted into chiral gamma-amino acid derivatives.
Review
Chemistry, Organic
Wu Wenqian, Chen Chunxia, Peng Jinsong, Li Zhanyu
Summary: This article classifies and summarizes different methods for the synthesis of α-amino carbonyl derivatives, providing new insights for the synthesis of diverse compounds in this class.
CHINESE JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Chenhao Zhang, Anthony Z. Gao, Xin Nie, Chen-Xi Ye, Sergei I. Ivlev, Shuming Chen, Eric Meggers
Summary: This study demonstrates the catalytic deracemization of ketones with alpha-stereocenters in a single reaction through photoredox deprotonation and enantioselective protonation. By utilizing a photoredox catalyst and a tertiary amine, nonracemic carbonyl compounds with up to 97% enantiomeric excess can be obtained. This light-driven strategy provides a blueprint for deracemizations of common carbonyl compounds.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Soshi Nishino, Masahiro Miura, Koji Hirano
Summary: This study established a copper-catalysed hydroamination method for the regio- and stereoselective synthesis of alpha-amino acids from acrylates using hydrosilanes and hydroxylamines. Regioselectivity control was achieved by utilizing hydroxylamine as an electrophilic amination reagent. The use of CsOPiv base and DTBM-dppbz ligand facilitated the challenging C-N bond formation at the alpha position, while the chiral ligands Xyl-BINAP and DTBM-SEGPHOS controlled the stereochemistry at the beta-position. Additionally, the chiral auxiliary (-)-8-phenylmenthol induced stereoselectivity at the alpha-position to produce optically active unnatural alpha-amino acids with adjacent stereocentres.
Article
Chemistry, Organic
Yujiro Hayashi, Yutaro Hatano, Naoki Mori
Summary: An asymmetric Michael reaction of malononitrile and alpha,beta-unsaturated aldehydes catalyzed by a diarylprolinol silyl ether was developed. The Michael products were obtained in good yields and with excellent enantioselectivities without the formation of overreaction products. The malononitrile moiety can be transformed into an alkoxy or amino carbonyl moiety by oxidative transformation, allowing the synthesis of alpha-chiral esters or amides with all-carbon quaternary centers and excellent enantioselectivities.
Article
Chemistry, Multidisciplinary
Soshi Nishino, Yuji Nishii, Koji Hirano
Summary: A copper-catalyzed reaction has been developed for the regio- and diastereoselective borylamination of alpha,beta-unsaturated esters with B(2)pin(2) and hydroxylamines. The reaction delivers acyclic beta-boryl-alpha-amino acid derivatives with high anti-diastereoselectivity, which is difficult to achieve using established methods. Furthermore, the use of a chiral phosphoramidite ligand allows for the enantioselective synthesis of optically active beta-borylated alpha-amino acids. The resulting products can be further transformed into beta-functionalized alpha-amino acids, which are of great interest in medicinal chemistry.
Article
Chemistry, Organic
Maxime Bouquin, Florian Jaroschik, Marc Taillefer
Summary: A ligand and base-free copper catalyzed synthetic method for the efficient alpha-arylation of aromatic ketones is described in this study. Ketone-derived silyl enol ethers were used to avoid strong bases in the reaction, providing intermolecular C-C coupling with good functional group tolerance and requiring low catalyst loading.
TETRAHEDRON LETTERS
(2021)
