Article
Chemistry, Organic
Yu Guo, Ebrahim-Alkhalil M. A. Ahmed, Hongxin Liu, Xinhua Li, Juan Li, De-Kun Ma, Hong-Ping Xiao, Jun Jiang
Summary: The study describes a copper-catalyzed direct alkynylation reaction of tryptanthrins with terminal alkynes, resulting in the synthesis of 6-alkynyl-6-hydroxyindoloquinazolinone compounds in moderate to good yields under mild reaction conditions with varied functional group compatibility. The obtained adducts can be smoothly converted into versatile building blocks via hydrogenation, hydration, and further Sonogashira coupling transformations.
Article
Chemistry, Multidisciplinary
Long Hu, Martin C. Dietl, Chunyu Han, Matthias Rudolph, Frank Rominger, A. Stephen K. Hashmi
Summary: This study presents a dual catalytic cycle for the synthesis of 3-alkynyl benzofurans, merging C-H alkynylation of phenols and oxy-alkynylation of triple bonds using the redox property and carbophilic pi acidity of gold. Mechanistic studies suggest the involvement of a bimetallic gold-silver species. The one-pot protocol allows for a direct, simple, and regio-specific approach with excellent functional group tolerance, making it suitable for the late-stage incorporation of benzofurans.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Lara Lavrencic, Uttam Dhawa, Arthur Blumenstein, Xile Hu
Summary: Significant research efforts have been focused on the development of catalytic methods for lignocellulose depolymerization in the field of lignin biorefining. However, the conversion of obtained monomers into higher value-added products remains a key challenge in lignin valorization. In this study, copper-catalyzed reactions were utilized for benzylic functionalization of lignin-derived phenolics via the formation of hexafluoroisopropoxy-masked para-quinone methides (p-QMs). By controlling the rates of copper catalyst turnover and p-QM release, various unsaturated fragments suitable for further synthetic applications were successfully installed onto lignin-derived monomers.
Review
Biochemistry & Molecular Biology
Sergey V. V. Baykov, Anton A. A. Shetnev, Artem V. V. Semenov, Svetlana O. O. Baykova, Vadim P. P. Boyarskiy
Summary: This review discusses synthetic methods for obtaining 1,2,4-oxadiazole and their application in pharmaceutical preparation. The methods are divided into three groups, including two-stage protocols, one-pot synthesis, and oxidative cyclization. These methods have significant potential in drug design, allowing for the preparation of thermosensitive 1,2,4-oxadiazole and expanding the use of oxadiazole core as a linker in bioactive compound design.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Chemistry, Organic
Shunki Mamada, Narihito Ogawa
Summary: We developed a method for the alkynylation of allylic phosphates with acetylenes in the presence of copper and magnesium salts. The reaction showed regioselectivity to produce corresponding 1,4-enynes. The reaction also exhibited good tolerance towards functional groups. As an application, the synthesis of 1,4-enyne intermediate for 13R,19S,20S-trihydroxydocosapentaenoic acid was efficiently achieved.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Bowen Dou, Kang Wang, Jianbo Wang
Summary: In this paper, we report an efficient method for the synthesis of alkynylated furan derivatives using a Pd-catalyzed oxidative cross-coupling reaction between allenyl ketones and terminal alkynes. This novel synthesis demonstrates the generality of carbene-based cross coupling, and offers an operationally simple and wide substrate scope approach to access alkynylated furan derivatives with good functional group tolerance.
CHINESE JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Organic
Sabrina Giofre, Camilla Loro, Letizia Molteni, Carlo Castellano, Alessandro Contini, Donatella Nava, Gianluigi Broggini, Egle M. Beccalli
Summary: A useful aminohalogenation reaction for the cyclization of O-alkynyl carbamates under copper catalysis has been developed in this study. N-Halosuccinimides were used as the halogen source, leading to selective intramolecular C-N bond formation and the generation of haloalkylidene substituted heterocycles. The mechanism for the two alternative reaction pathways was investigated by modeling the corresponding transition states at the DFT level.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Yunhe Jin, Lifang Wang, Qingqing Zhang, Yongqiang Zhang, Qian Liao, Chunying Duan
Summary: This study demonstrates a practical iron-catalysed photoredox approach for C(sp(3))-H alkynylation of methane, ethane, and other light alkanes, producing valuable internal alkynes. The protocol offers advantages such as a concise and efficient system, good selectivity, mild conditions, wide application of the synthesised products, and low cost.
Article
Chemistry, Multidisciplinary
Lixin Liang, Shiqiang Zhou, Wei Zhang, Rongbiao Tong
Summary: Two complementary approaches were developed for the catalytic asymmetric alkynylation of 3,4-dihydro-beta-carbolinium ions with up to 96 % yield and 99 % ee. The utility of chiral C1-alkynyl TH beta Cs was demonstrated through the total synthesis of seven indole alkaloids.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Chen Li, Bin Chen, Xiaodong Ma, Xueling Mo, Guozhu Zhang
Summary: A catalytic asymmetric alkylation of azoles with secondary 1-arylalkyl bromides through direct C-H functionalization was reported. The reaction, under blue-light photoexcitation, showed good reactivity and high stereoselectivity, providing an efficient strategy for the construction of chiral alkyl azoles at low temperature. The reactions are compatible with a wide range of azoles.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Xiangwen Kong, Fang Yu, Shengtong Niu, Fan Gong, Shuang Yang, Jinggong Liu, Benlong Luo, Xinqiang Fang
Summary: Copper-catalyzed divergent annulation reactions between alpha-diketones and alkynyl alpha-diketones have been successfully achieved, enabling the synthesis of highly functionalized and biologically important cis-hexahydro-2H-cyclopenta[b]furan and 2-hydroxydihydrofuran-3(2H)-one products. The use of earth-abundant copper catalyst, mild conditions, and shortened synthetic routes contribute to the reduction of waste production. The substituents of the nucleophilic alpha-diketones play a crucial role in determining the reaction pathways.
CHINESE CHEMICAL LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Akash Kaithal, Himadri Sekhar Sasmal, Subhabrata Dutta, Felix Schafer, Lisa Schlichter, Frank Glorius
Summary: This study reports a catalytic approach to synthesizing cis-selective saturated carbo-and heterocyclic germanium compounds with a 3D framework through the hydrogenation of readily accessible aromatic germanes with a 2D framework. Nishimura's catalyst exhibited the best hydrogenation reactivity, achieving an isolated yield of up to 96%. The synthesized products showed versatile applications in coupling reactions and demonstrated orthogonal reactivity with boranes or silanes, acquiring a three-dimensional structure with high stability.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Organic
Babita Yadav, Arvind Kumar Yadav, Vishnu Prabhakar Srivastava, Santosh K. Srivastava
Summary: A convenient and efficient method for the synthesis of 2-amino-1,3,4-oxadiazoles from N-acyl thiosemicarbazides using aerobic visible light photoredox catalysis is reported. This protocol demonstrates the first example of oxidative cyclodesulfurization of N-acyl thiosemicarbazides using visible light and air as inexpensive, readily available, non-toxic, and sustainable reagents.
TETRAHEDRON LETTERS
(2023)
Article
Chemistry, Organic
Mikkel B. Buendia, Jan-Georges J. Balin, Mette E. Andersen, Zhong Lian, Soren Kramer
Summary: A simple method for copper-catalyzed benzylic C-H alkynylation using alkynylboronic esters as nucleophilic coupling partners is reported. The catalytic system is readily available and reactions occur under mild conditions. Different substrates and alkynylboronic ester nucleophiles were evaluated, and enantioselective C-H alkynylations were also demonstrated in three examples.
Article
Chemistry, Multidisciplinary
Andreas C. Hans, Patrick M. Becker, Johanna Haussmann, Simon Suhr, Daniel M. Wanner, Vera Lederer, Felix Willig, Wolfgang Frey, Biprajit Sarkar, Johannes Kaestner, Rene Peters
Summary: This article discloses a catalyst type that enables highly efficient direct 1,4-additions. The catalyst is a zwitterionic entity, with acetate binding to negatively charged Cu-II and serving as a counterion for benzimidazolium. All three functionalities are involved in the catalytic activation. The productivity of maleimides increased by a factor greater than 300 compared to the literature (TONs up to 6700). High stereoselectivity and productivity were achieved for a wide range of other Michael acceptors as well. The polyfunctional catalyst, accessible in only 4 steps from N-Ph-benzimidazole with an overall yield of 96%, remained robust during catalysis, allowing for multiple reuse with nearly constant efficiency. Mechanistic studies, particularly using DFT, provided a detailed understanding of how the catalyst operates. The benzimidazolium unit stabilizes the coordinated enolate nucleophile and prevents the dissociation of acetate/acetic acid from the catalyst.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Kento Asai, Koji Hirano, Masahiro Miura
Summary: A new method for the palladium-catalyzed benzylic silylation of diarylmethyl carbonates with silylboranes has been developed. The reaction proceeds smoothly even without external base, and high yields of benzylic silanes are obtained. The obtained silanes can work as nucleophiles and react with carbon electrophiles to deliver benzylic C-C cross-coupled products.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Review
Chemistry, Multidisciplinary
Koji Hirano
Summary: The development of new C-N bond forming strategies is crucial due to the importance of nitrogen atom in bioactive molecules and functional materials. This account presents the nitrogen-umpolung-enabled copper-catalyzed highly selective amination protocols developed by the author's research group. The application of these methods to the synthesis of alkyl-amines with rich functionality is demonstrated.
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN
(2023)
Article
Chemistry, Multidisciplinary
Rikuto Tanaka, Shiho Ochiai, Asumi Sakai, Yoshinosuke Usuki, Bubwoong Kang, Tetsuro Shinada, Tetsuya Satoh
Summary: The C-H alkenylation of N-acetylcarbazoles using a cationic Cp*Rh(III) catalyst at the C1-position results in the formation of 1-alkenylcarbazoles. Further alkenylation is achieved with the use of a cationic (CpRh)-Rh-E(III) catalyst, leading to the formation of 1,8-dialkenylcarbazoles. The direct alkenylation procedure, combined with easy removal of the acetyl directing group, provides a straightforward synthetic route to 1- and/or 8-alkenyl-N-H-carbazole derivatives. One of the 1-alkenyl-N-H-carbazoles obtained in this study exhibits solvatochromism.
CHEMISTRY-AN ASIAN JOURNAL
(2023)
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, Inorganic & Nuclear
Yuji Nishii, Masahiro Miura
Summary: Sulfur-containing functional groups have recently gained attention as useful directing groups for the direct catalytic C-H transformation of aromatic and heteroaromatic compounds. In this study, we summarize our recent work on site-selective substitution using thioether directing groups under either Cp*Rh(III) or Cp*Ir(III) catalysis. The thioether groups can be easily removed and transformed to other functional groups. These reactions appear to be important in pharmaceutical and materials chemistry.
PHOSPHORUS SULFUR AND SILICON AND THE RELATED ELEMENTS
(2023)
Article
Chemistry, Organic
Soshi Nishino, Koji Hirano
Summary: A copper-catalyzed regio- and diastereoselective borylacylation reaction has been developed to synthesize β'-boryl-β-ketoesters with high anti-diastereoselectivity. The reaction can also be extended to borylcarbamoylation, and enantioselective variants have been achieved using chiral phosphoramidite-ligated copper complexes.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Review
Chemistry, Physical
Yuji Nishii, Masahiro Miura
Summary: Dibenzo-fused five-membered heteroaromatic compounds, such as dibenzofuran, carbazole, and dibenzothiophene, are important structural units in various polycyclic heteroaromatic compounds. The intramolecular C-H/C-H biaryl coupling of diaryl (thio)ethers and amines based on palladium(II) catalysis under oxidative conditions is an effective method for their construction. This mini-review briefly summarizes representative examples of constructing structurally intriguing pi-extended polycyclic heteroaromatics through catalytic coupling reactions.
Article
Chemistry, Organic
Kazutoshi Nishimura, Shibo Xu, Yuji Nishii, Koji Hirano
Summary: A metal-free, phosphenium-dication-mediated sequential C-P and C-C bond forming reaction has been developed for the concise synthesis of (di)benzophosphole derivatives from readily available and simple arylalkynes and phosphinic acids. The application of this protocol to multiple cyclization reactions and fully intermolecular three-component coupling-type reactions is also described.
Article
Chemistry, Organic
Ayumi Inami, Yuji Nishii, Koji Hirano, Masahiro Miura
Summary: In this study, a new synthetic method was developed using vinyl selenone as a surrogate for phenylacetylene in the Rh-catalyzed annulative coupling reaction. This method successfully produced 3,4-nonsubstituted isoquinoline compounds. The reaction conditions were mild and the vinyl selenone could be recovered and recycled.
Article
Chemistry, Organic
Soshi Nishino, Yuji Nishii, Koji Hirano
Summary: A copper-catalyzed stereoselective 1,4-acylboration reaction between B(2)pin(2) and pivalic anhydride with a,b-unsaturated esters has been developed, yielding (E)-allylboronates with two distinct oxygenated functional groups at the gamma positions, a challenging transformation to achieve using other methods. The chemoselective post functionalizations of Bpin and pivalate moieties in the product are also demonstrated.
Article
Chemistry, Organic
Ayako Nishida, Yasuhito Inai, Yoshinosuke Usuki, Tetsuya Satoh
Summary: The dehydrogenative cyclization of 9-anthracenecarboxylic acids and 2-substituted 1-naphthoic acids catalyzed by rhodium(III) leads to the formation of fused lactones through peri C-H bond cleavages. These aromatic carboxylic acids also undergo dehydrogenative coupling with styrenes and successive Wacker-type cyclization under palladium catalysis to construct 3-benzylidenebenzo[de]isochromen-1-one frameworks.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Atsushi Matsumura, Yoshinosuke Usuki, Tetsuya Satoh
Summary: The sp(3) C-H acetoxylation at the beta-position of alpha,alpha-disubstituted alpha-amino acids can be smoothly achieved under palladium catalysis using PhI(OAc)(2) as the reagent. This reaction provides an easy synthetic route to non-natural beta-acetoxy-alpha-amino acids. The reaction of alpha-aminocyclopropanecarboxylic acid selectively generates an acyclic gamma-acetoxy-alpha,beta-unsaturated amino acid through ring-opening.
CHEMISTRY-SWITZERLAND
(2023)
Article
Chemistry, Multidisciplinary
Shotaro Nakamura, Kohei Okubo, Yuji Nishii, Koji Hirano, Norimitsu Tohnai, Masahiro Miura
Summary: This study synthesized bent-type bisbenzofuropyrazine derivatives with good solubilities and investigated their physical and optical properties. The materials exhibited different luminescence properties depending on their crystal packing structures and concentration-dependent vapochromic luminescence. These findings have potential implications for sensing systems.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Yoshinosuke Usuki, Yuka Tanaka, Miyu Morii, Tetsuya Satoh
Summary: Antimycins are well-known antifungal metabolites produced by Streptomyces bacteria. Neoantimycin and its analogues, featuring a 15-membered tetraester ring, have shown effectiveness as regulators of the oncogenic proteins GRP78/BiP and K-Ras. Isoneoantimycin, isolated as a minor metabolite during neoantimycin fermentation, is the first reported antibiotic in the antimycin family without the macrolide core. This study focuses on the total synthesis and stereochemical assignment of isoneoantimycin for structure-activity studies on neoantimycins, successfully achieving synthesis of the target molecule with the same stereochemistry as natural isoneoantimycin.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)