Article
Chemistry, Multidisciplinary
Eduardo Da Concepcion, Israel Fernandez, Jose L. Mascarenas, Fernando Lopez
Summary: This study demonstrates that low-valent cobalt complexes equipped with chiral ligands can efficiently promote highly enantioselective (3+2) cycloadditions, resulting in good yields and excellent enantiomeric ratios. A mechanistic discussion based on experimental and computational data suggests the involvement of Co-I/Co-III catalytic cycles in this process.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Ling Li, Xiu-Shuai Chen, Xiang-Ping Hu
Summary: In this study, an intramolecular Cu-catalyzed asymmetric propargylic [4 + 2] cycloaddition reaction was achieved using a chiral tridentate N-ligand as the catalyst, leading to chiral tetrahydroisoindolo[2,1-a]quinoxalines with high yields and good to excellent enantioselectivities. The reaction is efficient, simple, and has a broad substrate scope, providing a powerful and concise strategy for the stereoselective synthesis of optically active polycyclic heterocycle frameworks.
Article
Chemistry, Organic
Guo-Ke Zhang, Shu-Fang Wu, Chen Zhong, Yu-Qi Liu, Da-Hua Wang, Yu-Chen Zhang, Feng Shi
Summary: A copper-catalyzed alpha,beta-regioselective (2+4) cycloaddition of propargylic esters with o-hydroxyphenyl substituted secondary phosphine oxides (SPOs) was established, which afforded phosphorus-containing six-membered heterocycles in high yields. This reaction not only represents the first alpha,beta-regioselective (2+n) cycloaddition of propargylic esters via the intermediates of copper-allenylidenes, but also represents the first application of o-hydroxyphenyl substituted SPOs as 1,4-dinucleophiles in (2+4) cycloadditions.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Yu-Hao Wang, Zhen-Ni Zhao, Subarna Jyoti Kalita, Yi-Yong Huang
Summary: Novel annulations have been developed via ketene intermediates using allenyl imide and alkynoates with good leaving groups in a tandem conjugate addition-elimination reaction (SN2' type) promoted by nucleophilic phosphine catalysts. By utilizing thioamides as 1S,3N-bis-nucleophiles, [3+3] and [3+2] annulations yield 1,3-thiazin-4-ones and 5-alkenyl thiazolones in high yields, respectively, with proposed reaction mechanisms based on deuterium labeling experiments and density functional theory calculations.
Article
Chemistry, Multidisciplinary
Tsukasa Tawatari, Ritsuki Kato, Riku Kudo, Kiyosei Takasu, Hiroshi Takikawa
Summary: In this study, we report on the intramolecular (3+2) cycloaddition reactions between ynamides and benzyne. These reactions involve the formation of two bonds and are facilitated by using benzyne precursors containing a chlorosilyl group. The intermediate indolium ylide in these reactions exhibits both nucleophilic and electrophilic properties at its C2 atom.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Yulin Han, Anni Qin, Qian Zhang, Xue Zhang, Hui Qian, Shengming Ma
Summary: The Rh-catalyzed reaction allows for the efficient synthesis of cis-fused bicyclic products with excellent selectivity and tolerance towards synthetically useful functional groups. The proposed mechanism involves the rapid racemization of the allene moiety in the starting materials.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Yaxin Zeng, Ying Xia
Summary: The direct synthesis of gem-difluorinated carbocyclic molecules has long been a challenge in organic chemistry. Here, a Rh-catalyzed [3+2] cycloaddition reaction between gem-difluorinated cyclopropanes and internal olefins has been developed, providing an efficient method to synthesize gem-difluorinated cyclopentanes with good functional group compatibility, excellent regioselectivity, and good diastereoselectivity. The resulting products can also be further transformed into various mono-fluorinated cyclopentenes and cyclopentanes, demonstrating the potential of this reaction as a strategy for synthesizing other gem-difluorinated carbocyclic molecules.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
John M. Halford-McGuff, Alexandra M. Z. Slawin, Allan J. B. Watson
Summary: This article presents a predictive model for the reactivity and turnover of the Rh-catalyzed [2 + 2 + 2] cycloaddition of diynes and alkynes. Contrary to the proposed electronic model, this model suggests that the reaction is predominantly driven by steric effects, and turnover is proportional to alkyne steric parameters. The model allows for the prediction of catalyst loading, turnover, and reaction yield based on the assessment of the alkyne's steric parameter.
Article
Chemistry, Organic
Eduardo Da Concepcion, Carlos Lazaro-Milla, Israel Fernandez, Jose L. Mascarenas, Fernando Lopez
Summary: This study investigates the application of cobalt(I) catalysts with bisphosphine ligands for promoting intramolecular cycloadditions of enynylidenecyclopropanes. The method successfully synthesizes 5,7,5-fused tricyclic systems with high yields and complete diastereo- and chemoselectivity. Interestingly, the scope and mechanism of this reaction differ from previously reported annulations using rhodium and palladium catalysts.
Article
Chemistry, Organic
Chen-Long Li, Yusheng Yang, Yi Zhou, Zhi-Xiang Yu
Summary: A formal [3+3+1] reaction was developed through gold(I)-catalyzed enyne cycloisomerization and rhodium(I)-catalyzed [6+1] reaction to synthesize aza-6/7 bicyclic compounds, hexahydrocyclohepta[c]pyridinones. DFT calculations revealed four steps involved in the [6+1] cycloaddition reaction of vinylspiropentanes and CO.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Daisuke Yokose, Yuki Nagashima, Suzuka Kinoshita, Juntaro Nogami, Ken Tanaka
Summary: Axially chiral styrene-carboxylic esters and stilbenedicarboxylic esters were synthesized with high yields and excellent enantioselectivity using chelation-controlled cycloaddition reactions. The five-membered chelate coordinating to rhodium showed higher reactivity in the reactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Braja Gopal Das, Sadhna Shah, Arko Das, Vinod K. Singh
Summary: The first stereoselective propargylic dearomatization of 2-naphthol derivatives was achieved using a chiral Cu-II-L10 complex, leading to the formation of products with a contiguous all-carbon quaternary-tertiary stereocenter and a terminal alkyne functionality. Both reactions demonstrated excellent chemodivergent reactivity and yielded the desired products with high chemo- and stereoselectivities.
Article
Chemistry, Multidisciplinary
Qi Cui, Zi-You Tian, Zhi-Xiang Yu
Summary: The unexpected three-component [4+2+1] reaction between two vinylallenes and CO was discovered to give highly functionalized tropone derivatives under mild conditions, where one vinylallene acts as a C-4 synthon, the other vinylallene as a C-2 synthon, and CO as a C-1 synthon.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
Ryota Abe, Yuki Nagashima, Jin Tanaka, Ken Tanaka
Summary: The development of an operationally simple method for diversity-oriented fluoranthene synthesis is important in the field of organic synthesis due to the presence of the fluoranthene skeleton in natural products and fluorescent materials. In this study, substituted fluoranthenes and azafluoranthenes were synthesized at room temperature through a cationic Rh(I)/H8-BINAP complex-catalyzed [2 + 2 + 2] cycloaddition reaction using 1,8-dialkynylnaphthalenes. Both theoretical and experimental studies revealed that noncovalent interactions between the phenyl groups on the substrates and ligand stabilize the transition states, facilitating the sterically demanding reactions.
Article
Chemistry, Physical
Ryota Abe, Yuki Nagashima, Jin Tanaka, Ken Tanaka
Summary: Developing a simple method for synthesizing diverse fluoranthene skeletons is crucial in organic synthesis. Existing methods have limitations in reaction conditions and substrate applicability. This study presents a room temperature synthesis of substituted fluoranthenes and azafluoranthenes using cationic Rh(I)/H-8-BINAP complex-catalyzed cycloaddition. The reactions were stabilized by the H-8-BINAP ligand, and noncovalent interactions between phenyl groups on the substrates and ligand accelerated the reaction.
Article
Chemistry, Organic
Geeta Devi Yadav, Pooja Chaudhary, Balaram Pani, Surendra Singh
Summary: Chiral transition metal complexes with privileged ligands are efficient catalysts for various asymmetric organic transformations. Transition metal complexes of C1-symmetric pyrrolidine-based ligands have been widely used in asymmetric organic reactions. However, a comprehensive review article on the transition metal complexes of chiral C1-symmetric pyrrolidine-based ligands derived from (L)-proline has not been published.
TETRAHEDRON LETTERS
(2024)
