Article
Chemistry, Multidisciplinary
Zhenzhong Li, Lorenz Roesler, Till Wissel, Hergen Breitzke, Torsten Gutmann, Gerd Buntkowsky
Summary: A novel immobilized chiral dirhodium catalyst has been prepared and shows high catalytic activity and significant enantioselectivity in asymmetric cyclopmpanation reaction. The catalyst can be readily recovered and reused.
JOURNAL OF CO2 UTILIZATION
(2021)
Article
Chemistry, Multidisciplinary
Chuntao Wang, Dong Zhu, Rui Wu, Shifa Zhu
Summary: This study reports a Rh2(II)-catalyzed asymmetric enyne cycloisomerization for the synthesis of chiral difluoromethylated cyclopropane derivatives, which can be easily transformed into highly functionalized difluoromethylated cyclopropanes with vicinal all-carbon quaternary stereocenters through ozonolysis. Mechanistic studies and X-ray crystallography of alkyne-dirhodium complexes suggest that cooperative weak hydrogen bondings between the substrates and the dirhodium catalyst may be crucial in this reaction.
Article
Chemistry, Multidisciplinary
Vincent Pirenne, Emma G. L. Robert, Jerome Waser
Summary: Efficient catalytic activation of donor-acceptor aminocyclopropanes lacking the commonly used diester acceptor was achieved in a (3 + 2) dearomative annulation with indoles, yielding cycloadducts in high yields and high diastereomeric ratios, leading to tricyclic indoline frameworks containing four stereogenic centers.
Article
Chemistry, Multidisciplinary
Shaotong Qiu, Xiang Gao, Shifa Zhu
Summary: A dirhodium-catalyzed asymmetric cycloisomerization reaction of azaenyne was successfully achieved through a cap-tether synergistic modulation strategy, leading to a variety of centrally chiral isoindazole derivatives. This strategy demonstrated high synthetic utility, with high yields and enantioselectivity achievable in the products.
Article
Chemistry, Organic
Jixin Pian, Qingqing Chen, Yujiao Luo, Zhifei Zhao, Jichang Liu, Lin He, Shi-Wu Li
Summary: An enantioselective cyclopropanation reaction of sulfoxonium ylides with beta,gamma-unsaturated ketoesters catalyzed by a chiral rhodium catalyst has been achieved, leading to the synthesis of various optically pure cyclopropanes.
Article
Chemistry, Organic
Zhili Liu, Lianfen Chen, Dong Zhu, Shifa Zhu
Summary: A highly efficient formal allylation of dihydronaphthotriazoles with alkenes under rhodium(II) catalysis is reported. Various allyl dihydronaphthalene derivatives were obtained with moderate to good yields and excellent chemoselectivity through rhodium(II) azavinyl carbenes. Notably, the allylic C(sp(2))-H activation occurs instead of the traditional C(sp(3))-H activation in the formal allylation process, and good to excellent enantioselectivities are achieved when monosubstituted alkenes are used.
Article
Chemistry, Organic
Cidan Lv, Xiangxiang Meng, Min Wang, Yan Zhang, Changwei Hu, Chan Kyung Kim, Zhishan Su
Summary: The mechanism and stereoselectivity of an asymmetric cyclopropanation reaction between 3-alkenyl-oxindole and sulfoxonium ylide catalyzed by a chiral N,N'-dioxide-Mg(II) complex were explored. The presence of N-protecting groups in the isatin enhanced the reactivity of the reactants, while steric effects of substituents in the chiral ligand played a crucial role in the selectivity of the reaction.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Vincent George, Burkhard Konig
Summary: Prompted by the interest in strained hydrocarbons as drug candidates, a simple and efficient photochemical method was developed to obtain (spiro)cyclopropanes from stable tosylhydrazones and electron poor olefins. The two-step one-pot transformation involves the (3+2)-cycloaddition of donor-donor diazo compounds, followed by nitrogen extrusion of the &UDelta;1-pyrazoline intermediates. Notably, intermediary spiro-heterocycles were isolated using kinetic analysis.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Vincent George, Burkhard Koenig
Summary: Prompted by the increasing interest in strained hydrocarbons as potential drug candidates, the researchers developed a simple and efficient photochemical protocol for the synthesis of (spiro)cyclopropanes from stable tosylhydrazones and electron-poor olefins. This protocol involves a two-step one-pot transformation using donor-donor diazo compounds and subsequent nitrogen extrusion of the intermediate UΔ1-pyrazoline. Notably, kinetic analysis allowed for the isolation of intermediate spiro-heterocycles.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Eric S. Yang, Emma Combey, Jose M. Goicoechea
Summary: This article reports a series of group 9 pyridine-diimine complexes M((PDI)-P-Dipp)X and [M((PDI)-P-Dipp)L](+) (M = Co, Rh; (PDI)-P-Dipp = 1,1'-(pyridine-2,6-diyl)bis(N-(2,6-diisopropylphenyl)ethan-1-imine); X = CP-, CCH-; L = CO, tBuNC) with strong-field ligands, including the cyaphide ion (C=P). A comparative study of the group 9 PDI cyaphide complexes Co((PDI)-P-Dipp)(CP) and Rh((PDI)-P-Dipp)(CP), as well as the N-heterocyclic carbene (NHC) gold(I) cyaphide complex Au(IDipp)(CP) (IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), reveals the s donor and p acceptor properties of the kC-cyaphido ligand, and suggests a position for this ion in the spectrochemical series.
Article
Chemistry, Physical
Thomas P. P. Fay, David T. T. Limmer
Summary: In this paper, a physically motivated framework is proposed to describe spin-selective recombination processes in chiral systems. Spin-selective reaction operators for recombination reactions of donor-bridge-acceptor molecules are derived based on chirality and spin-orbit coupling. It is found that spin polarization selectivity only arises in hopping-mediated electron transfer. The framework presented here can be extended to describe spin-selective recombination processes in more complex systems.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Organic
Guihua Nie, Xuan Huang, Zhongyao Wang, Dingwu Pan, Junmin Zhang, Yonggui Robin Chi
Summary: A carbene-catalyzed formal umpolung reaction of donor-acceptor cyclopropanes has been revealed, where the electrophilic carbon attached to the donor group of the cyclopropane aldehyde is inverted to a nucleophilic reaction center. Subsequent reaction with isatins via a formal [3 + 2] process forms lactones with multiple functional groups and excellent enantio- and diastereoselectivities.
ORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Organic
Zhao-Zhao Zhou, Xiao-Feng Zhai, Shu-Liang Zhang, Ke-Jian Xia, Haixin Ding, Xian-Rong Song, Wan-Fa Tian, Yong-Min Liang, Qiang Xiao
Summary: A highly selective alkylation method using nickel-mediated radical cross-electrophile coupling reaction was developed for trisubstituted allenes with alkyl N-hydroxyphthalimide (NHP) esters. This method provides mild conditions, broad substrate scope, and a direct approach for the introduction of primary alkyl groups. Preliminary mechanistic studies indicate that the reaction proceeds through radical-radical coupling process.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Chemistry, Multidisciplinary
Jing Li, Martin J. Lear, Yujiro Hayashi
Summary: A new transition metal-free synthesis method for cyclopropanes has been achieved, which tolerates various aryl systems, as well as sulfide or alkene functionality, to yield cis-aryl/cyano cyclopropanes bearing congested tetrasubstituted quaternary carbons.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Organic
Xin Ji, Zhikun Zhang, Yuzhu Wang, Yazhe Han, Huiling Peng, Fangzhu Li, Lu Liu
Summary: A HFIP-promoted Wolff rearrangement reaction has been developed for the synthesis of various alpha,alpha-disubstituted carboxylic acid derivatives in good to excellent yields. The activation of alpha-diazoketone using HFIP under mild conditions is achieved via hydrogen bonding between the hydroxyl and carbonyl groups.
ORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Multidisciplinary
Ryan C. Cammarota, Wenbin Liu, John Bacsa, Huw M. L. Davies, Matthew S. Sigman
Summary: Leveraging congested catalyst scaffolds is a key strategy for altering substrate site-selectivity in C-H functionalization reactions. In this study, a new set of descriptors (SMART) was developed to quantify reactive site spatial constraints for a library of dirhodium catalysts and predict site-selectivity for C-H functionalization reactions. The study also developed global site-selectivity models to assess the roles of steric congestion and dirhodium-carbene electrophilicity in controlling the site of C-H functionalization.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Organic
Robert W. Kubiak, William F. Tracy, Joshua S. Alford, Huw M. L. Davies
Summary: This paper describes a rhodium-catalyzed enantioselective synthesis of 1-phenoxy-cyclopropane-1-carbaldehydes by intermolecular cyclopropanation of terminal alkenes followed by imine hydrolysis. The reaction proceeds via rhodium-stabilized donor/acceptor carbene intermediates, and the study demonstrates compatibility of a heteroatom donor group with enantioselective transformation.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Yannick T. Boni, Ryan C. Cammarota, Kuangbiao Liao, Matthew S. Sigman, Huw M. L. Davies
Summary: In this work, C-H functionalization of silyl ethers via carbene-induced C-H insertion has been achieved, providing an efficient synthetic disconnection strategy. The use of different catalyst preferences has enabled site- and stereoselective functionalization at different positions relative to the siloxy group. Additionally, a machine learning model has been developed to predict the major product, aiding in the application of these methods to new substrates.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Physical
Jack C. Sharland, David Dunstan, Dyuti Majumdar, Jinhai Gao, Kian Tan, Hasnain A. Malik, Huw M. L. Davies
Summary: In the presence of HFIP, nucleophilic and reactive reagents are prevented from interacting with a rhodium carbene, allowing for efficient asymmetric cyclopropanation with high yield and stereoselectivity on a variety of compounds. A high-throughput screen was conducted to expand the scope of the reaction and develop complementary catalytic systems, leading to the enantioselective functionalization of complex molecules including API and natural products.
Article
Chemistry, Physical
Zhi Ren, Djamaladdin G. Musaev, Huw M. L. Davies
Summary: Computational studies on the dirhodium(tetracarboxylate)-catalyzed C-H functionalization reveal that the enantioselectivity and site-selectivity of this reaction are controlled by the ratio of conformers of both the diazo compound and the dirhodium carbene intermediates and two distinct steps of the reaction. The findings provide important insights into the mechanism and factors influencing the selectivity of this catalytic reaction.
Article
Chemistry, Multidisciplinary
Ming Bao, Xiongda Xie, Jingjing Huang, Michael P. Doyle, Zhi Ren, Haibo Yue, Xinfang Xu
Summary: In this study, an Ag/Au-catalyzed cascade reaction of alkyne embedded diazoketones with indoles has been reported. Mechanistic studies indicate that the reaction involves a [4+2] cycloaddition followed by a retro-Michael addition/carbene N-H insertion process with gold catalysis, and a dearomatization/rearomatization sequence with silver catalysis, leading to the selective construction of N-doped polycyclic aromatic hydrocarbons (PAHs) with diverse structures and functional groups.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Yannick T. Boni, Janakiram Vaitla, Huw M. L. Davies
Summary: Rhodium(II) catalyst-controlled site- and stereo-selective carbene insertion into the allylic C(sp3)-H bond of allyl boronates is achieved. The chiral catalyst Rh2(S-TPPTTL)4 exhibits high fidelity and asymmetric induction, enabling diastereoselective and enantioselective C-C bond formation without interference from the allyl boronate functionality. The resulting functionalized allyl boronates are amenable to stereo-selective allylations, leading to products with control of stereochemistry at four contiguous stereogenic centers.
Article
Chemistry, Physical
Korkit Korvorapun, Yannick T. Boni, Thomas C. Maier, Armin Bauer, Thomas Licher, John E. Macor, Volker Derdau, Huw M. L. Davies
Summary: Rhodium-catalyzed C-H insertion by donor/acceptor carbenes is a useful transformation in organic synthesis, but the site-selectivity of the C-H transformation on the target molecule is often a major issue. Chiral rhodium carbene intermediates can achieve site-selective C-H functionalizations of challenging substrates such as N-aryl and N-heteroaryl piperidines, leading to the formation of highly stereoselective C-2 products. Additionally, N-aryl morpholines and piperazines can selectively react at the alpha position to the N-aryl group.
Article
Chemistry, Organic
Farzaneh Saeedifard, Yasir Naeem, Yannick T. Boni, Yi-Chien Chang, Junxiang Zhang, Yadong Zhang, Bernard Kippelen, Stephen Barlow, Huw M. L. Davies, Seth R. Marder
Summary: Hole-transport materials based on triarylamine derivatives have critical applications in organic electronics. This study demonstrates a method using Rh-carbenoid chemistry to incorporate carboxylic esters and norbornene functional groups into triarylamine materials. The resulting materials exhibit similar properties to those synthesized by conventional means and offer the potential for diverse hole-transport materials with different functional groups.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Sebastian Fischer, Terrence-Thang H. Nguyen, Andreas Ratzenboeck, Huw M. L. Davies, Oliver Reiser
Summary: A stereoselective, solvent- and metal-free method for endocyclic C-C bond cleavage of monocyclopropanated cyclopentadienes mediated by strong acids has been developed. It leads to the formation of highly functionalized six-membered carbocycles with high stereocontrol. The critical step involves the formation of a cyclopropyl carbocation that undergoes endocyclic ring opening through an SN2'-type attack of various nucleophiles. Subsequent synthetic transformations demonstrate the versatility of the resulting cyclohexenes for the synthesis of compounds with nonconventional substitution patterns.
Article
Chemistry, Organic
Ziyi Chen, Qinyan Cai, Yannick T. Boni, Wenbin Liu, Jiantao Fu, Huw M. L. Davies
Summary: The rhodium-catalyzed enantioselective C-H functionalization of unactivated C-H bonds by donor/acceptor carbene-induced C-H insertion can be extended to substrates containing nitrogen functionality. The rhodium-stabilized donor/acceptor carbenes are generated by rhodium-catalyzed decomposition of aryldiazoacetates. The phthalimido group is the optimal nitrogen protecting group. C-H functionalization at the most sterically accessible site can be achieved using Rh-2(S-2-Cl-5-BrTPCP)(4) as catalyst, while Rh-2(S-TPPTTL)(4) is the most effective catalyst for functionalization at tertiary C-H bonds and for the desymmetrization of N-phthalimidocyclohexane.
Article
Chemistry, Organic
Maizie Lee, Huw M. L. Davies
Summary: The rhodium-catalyzed C-H functionalization of cyclohexadiene derivatives with diaryldiazomethanes, followed by oxidation with DDQ, allows for the synthesis of triarylmethanes. Two chiral dirhodium tetracarboxylates, Rh-2(S-PTAD)(4) and Rh-2(S-TPPTTL)(4), were identified as the optimal chiral catalysts for this transformation. This method demonstrates the ability of diaryldiazomethanes to perform intermolecular C-H insertion with high enantioselectivity and good yields. The broad substrate scope includes various aryl and heteroaryl substituents, including benzofuran and pyridine heterocycles.
Correction
Chemistry, Organic
Sebastian Fischer, Terrence-Thang H. Nguyen, Andreas Ratzenboeck, Huw M. L. Davies, Oliver Reiser
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
Farzaneh Saeedifard, Yasir Naeem, Yannick T. Boni, Yi-Chien Chang, Junxiang Zhang, Yadong Zhang, Bernard Kippelen, Stephen Barlow, Huw M. L. Davies, Seth R. Marder
Summary: Hole-transport materials (HTMs) based on triarylamine derivatives are important in organic electronic applications. This study presents a method to incorporate carboxylic esters and norbornene functional groups into sp2 C-H bonds of triarylamine materials using Rh-carbenoid chemistry. The resulting materials exhibit similar properties to those synthesized by conventional means and offer a straightforward approach to diverse HTMs with different functional groups.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
