Article
Chemistry, Physical
Shrikant M. Khake, Naoto Chatani
Summary: The Rh(III)-catalyzed reaction of aniline derivatives containing a pyrimidine directing group with vinylsilanes leads to the formation of C3-substituted indoline derivatives via a highly regioselective C-H activation/alkene cyclization cascade. Mechanistic experiments suggest that C-H bond cleavage is not the rate-determining step, but rather the reaction proceeds through the formation of a six-membered rhodacycle as a key catalytic species via pyrimidine-directed electrophilic ortho-C-H rhodation.
Article
Chemistry, Multidisciplinary
Shuaishuai Song, Yunfei Lai, Zekun Tuo, Jianming Zhong, Wang Zhou
Summary: A rhodium(III)-catalyzed oxidative cyclization of chalcones with internal alkynes is reported, resulting in the formation of biologically important 3,3-disubstituted 1-indanones and reusable aromatic aldehydes. This transformation exhibits a unique (4+1) reaction mode, excellent regioselectivity, broad substrate scope, ability to construct quaternary carbon centers, and scalability. Steric hindrance from the substrate and ligand likely controls the chemoselectivity of this carbocyclization. Importantly, this discovery enables a practical two-step protocol to switch the overall reaction from a (3+2) to a (4+1) annulation of acetophenones with internal alkynes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Zhenjie Su, Shaozhong Wang
Summary: An atom-economical protocol utilizing Sc(OTf)3 as the catalyst has been developed to synthesize densely substituted 4acyl-2-quinolones. Mechanistic experimental studies suggest the involvement of coordinative interaction between Sc(OTf)3 and the substrate, formation of an oxetene intermediate, and an electrocyclic ring-opening of the oxetene.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
P. Andrew Evans, Molly J. Dushnicky, Dasol Cho, Jadab Majhi, Seulhui Choi, Bhavin Pipaliya, Phillip A. Inglesby, Mu-Hyun Baik
Summary: The research describes a method for constructing the tricyclic scaffold of tremulane sesquiterpene natural products, emphasizing the critical role of the stereoelectronic nature of the ligand in achieving stereocontrol. Various strategies were proposed to access the more stable diastereoisomer, but efforts to change the stereocontrol sense or epimerize the cycloadduct only led to modest improvements. Consequently, the synthetic utility of this strategy was highlighted through the development of concise and highly efficient syntheses of several natural products.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Physical
C. Rose Kennedy, Matthew Joannou, Janelle E. Steves, Jordan M. Hoyt, Carli B. Kovel, Paul J. Chirik
Summary: This study describes the selective intermolecular homodimerization and cross-cycloaddition of vinylsilanes with unbiased 1,3-dienes catalyzed by a pyridine-2,6-diimine (PDI) iron complex. The chemoselectivity of these reactions was found to be distinct from that of similar alpha-olefin reactions with 1,3-dienes. Mechanistic studies provided insights into substrate-controlled regioselectivity, and identified diamagnetic iron diene and paramagnetic iron olefin complexes as catalyst resting states. The relative rates of beta-H elimination and C-C reductive elimination were ultimately governed by the silyl substituents, dictating final product formation.
Article
Chemistry, Physical
Logan E. Vine, Ryan D. Reeves, Eleanor M. Landwehr, Israel Fernandez, Jennifer M. Schomaker
Summary: This study demonstrates predictable control over the mechanism of Pd-catalyzed allene cross-coupling/cyclization and cycloisomerization by targeted changes to the reaction conditions, resulting in the successful access to enantioenriched cyclopropanes and cyclopentenes. Furthermore, it shows a simple switch of the ligand on Pd can divert the reactivity of allenyl malonate from cross-coupling/cyclization to cycloisomerization.
Article
Chemistry, Multidisciplinary
Jung-Woo Park
Summary: This review focuses on cobalt catalyst systems in the hydrosilylation of alkynes, emphasizing ligand design and reaction pathways involving Co-H and/or Co-silyl species-mediated transformations to achieve Markovnikov/anti-Markovnikov hydrosilylations and new migratory transformations, showcasing their more environmentally friendly and economically beneficial features.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Nansalmaa Otog, Hayato Inoue, Doan Thi Thuy Trinh, Zolzaya Batgerel, Niklas Maximilian Langendorf, Ikuhide Fujisawa, Seiji Iwasa
Summary: The stereoselective synthesis of optically active cyclopropylsilanes was achieved in excellent yields and diastereo- and enantioselectivities with Ru(II)-Pheox catalysts. Among these catalysts, p-MeO-Ru(II)-Pheox was found to be the best for cyclopropanation reactions. The derivatives of cyclopropylsilanes could be transformed into beneficial building blocks for the synthesis of bioactive compounds.
Article
Chemistry, Organic
Takeshi Nanjo, Hikari Sada, Taisei Nagaya, Yuri Maruo, Yoshiji Takemoto
Summary: In this study, a cationic rhodium catalyst and methyl trifluoroborate salt were used to achieve the stereoselective formation of beta,beta-disubstituted dehydroamino acids (ΔAAs) in peptides. This method allowed the direct installation of an alkyl group on a beta-monosubstituted ΔAA in the peptide chain, leading to the successful synthesis of both isomers of dehydroisoleucine, which is an important yet usually inaccessible ΔAA.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Simin Wang, Qiao Zhang, Junbo Niu, Xiaobing Guo, Tao Xiong, Qian Zhang
Summary: A copper-catalyzed asymmetric hydroallylation reaction was developed for the transformation of readily available vinylsilanes with allylic phosphates in the presence of hydrosilane. The reactions can be conducted under mild conditions and provide chiral organosilanes with good to excellent enantiocontrol.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Kolimi Sayyad Basha, Rengarajan Balamurugan
Summary: Gold-catalyzed intermolecular hydroarylation using arylboronic acid as the reactant was reported. This carboxylic acid-directed arylation showed high regioselectivity, leading to the formation of α-aryl acrylic acids at the less electrophilic carbon in good yields. This method provides a convenient route to NSAID precursors.
Article
Chemistry, Physical
Shrikant M. Khake, Ken Yamazaki, Yusuke Ano, Naoto Chatani
Summary: This study reports a branch-selective C-H alkenylation method using an iridium catalyst with alkenes, suitable for aniline derivatives containing a pyrimidine-directing group, offering a broad substrate scope and tolerating various functional groups. The origin of branch selectivity was investigated using density functional theory calculations.
Article
Chemistry, Physical
Ignacio Medina-Mercado, Abraham Colin-Molina, Jose Enrique Barquera-Lozada, Braulio Rodriguez-Molina, Susana Porcel
Summary: In this study, arylative carbocyclization of alkynes catalyzed by gold was achieved using aryldiazonium tetrafluoroborates in a protocol free of photosensitizers and irradiation. Ascorbic acid acted as a radical initiator to generate aryl radicals that were added to Au(I) to form Au(III). The process resulted in the transformation of arylpropargyl ethers into valuable 3,4-diaryl-2H-chromenes in a regio- and stereoselective manner, with the added discovery of polymorphism in the synthesized compounds.
Article
Multidisciplinary Sciences
Liang Ling, Chenyang Hu, Linhong Long, Xue Zhang, Lixing Zhao, Liu Leo Liu, Hui Chen, Meiming Luo, Xiaoming Zeng
Summary: The hydrogenation of alkynes allows for the synthesis of olefins, which have various industrial applications. Achieving stereochemical control in this reaction has been a challenge. This study reports on a chromium-catalyzed method for selectively synthesizing E- and Z-olefins via the hydrogenation of alkynes, controlled by two carbene ligands.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Inorganic & Nuclear
Joshua K. Sailer, Jack C. Sharland, John Bacsa, Caleb F. Harris, John F. Berry, Djamaladdin G. Musaev, Huw M. L. Davies
Summary: A series of chiral bowl-shaped diruthenium(II,III) tetracarboxylate catalysts were prepared for asymmetric cyclopropanation reactions. These diruthenium catalysts self-assembled to form C(4)-symmetric bowl-shaped structures, similar to their dirhodium counterparts. The best catalyst, Ru-2(S-TPPTTL)(4)& BULL;BArF, achieved up to 94% ee in the cyclopropanation of various substrates. In contrast, the copper and cobalt congeners produced catalysts with little to no asymmetric induction. Computational studies revealed that the carbene complexes of the dicopper and dicobalt systems were prone to losing carboxylate ligands, which are essential for the bowl-shaped structure critical for asymmetric induction.
Article
Chemistry, Organic
Fuying Zhu, Yamei Lin
Summary: In this study, a low-metal iron-supported catalyst (Fe20/NC-Mg) was reported for the efficient synthesis of quinoxaline compounds, using water as a solvent and without additional bases. The synergistic effect of FeNx site and Mg (OH)2 nanorods in the catalyst played a key role in achieving high yields (82-91%) in 16 examples. The gram-level synthesis and reusability of the catalysts after four cycles demonstrated its industrial application potential.
Article
Chemistry, Organic
Mikhail Kozlov, Alexey Tyurin, Andrey Dmitrenok, Vyacheslav Rusak, Aleksander Fedorov, Igor Zavarzin, Yulia Volkova
Summary: This study presents a novel and practical synthesis method for phosphorus-substituted 1,3,4-thiadiazolines using phosphorylthioformic acid hydrazides and ketones. The protocol demonstrates operational simplicity, availability of reagents, and tolerance towards different functional groups.
Article
Chemistry, Organic
Jisna Jose, Thomas Mathew
Summary: 2-Cyclopentenone and its derivatives are highly esteemed synthetic intermediates with exceptional utility in organic synthesis. They are favored structural motifs in numerous pharmaceutical drugs and natural products, highlighting their significance. The review discusses the various methods used to synthesize cyclopentenones from 2016 to 2023.