Article
Chemistry, Organic
Jiangkun Xiong, Maying Yan, Lvnan Jin, Weihong Song, Lei Xiao, Dong Xu, Chunyang Zhai, Douglas W. Stephan, Jing Guo
Summary: In this study, a new reaction method was reported for the synthesis of various organogermacycle compounds via a B(C6F5)(3) mediated domino hydrogermylation reaction of enones with dihydrogermanes. These germacyclic compounds were obtained in good to excellent yields under mild reaction conditions.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Betty A. Kustiana, Salma A. Elsherbeni, Thomas G. Linford-Wood, Rebecca L. Melen, Matthew N. Grayson, Louis C. Morrill
Summary: In this study, the B(C6F5)(3)-catalyzed E-selective isomerization of alkenes is reported. The transition-metal-free method is applicable to various accessible substrates, allowing the synthesis of synthetically useful products with versatile stereodefined internal alkenes. The reaction mechanism was investigated using synthetic and computational methods.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Qiaotian Wang, Wei Meng, Xiangqing Feng, Haifeng Du
Summary: A novel mode for the activation of N-heterocyclic carbene boranes was developed in this work by generating highly reactive zwitterion species. The B(C6F5)3-catalyzed hydroboration of a wide range of alkenes led to good to high yields of desired products with excellent regioselectivities in some cases. The study also proposed mechanisms involving B-H bond cleavage and electrophilic addition for further exploration in the future.
CHINESE JOURNAL OF CHEMISTRY
(2021)
Article
Chemistry, Applied
Jiaming Zhou, Jin Huang, Changhui Lu, Huanfeng Jiang, Liangbin Huang
Summary: A B(C6F5)(3)-catalyzed hydroarylation of terminal alkynes with various phenols at room temperature was developed, leading to the synthesis of 2-gem-vinylphenols with good regio-selectivity. The transformations exhibited a broad substrate scope with moderate yields, and mechanism studies suggested the activation of phenol by B(C6F5)(3) followed by protonation of the alkyne/Friedel-Crafts-type reaction.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Organic
Wen-Qin Yu, Jian-Hong Fan, Pu Chen, Bi-Quan Xiong, Jun Xie, Ke-Wen Tang, Yu Liu
Summary: This study describes the transition-metal-free alkylation/cyclization of activated alkenes using Hantzsch ester derivatives as effective alkyl reagents. A wide variety of valuable oxindoles can be constructed in a single step with excellent selectivity. The reaction proceeds via the formation of alkyl radical species followed by tandem addition/annulation of olefins under oxidative conditions. This protocol is expected to inspire the development of novel and efficient applications of Hantzsch esters in organic synthesis.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2022)
Article
Chemistry, Organic
Yinggao Meng, Manman Song, Yue Wang, Yuxin Wang, Er-Qing Li
Summary: A palladium-catalyzed asymmetric (4 + 3) cycloaddition was developed for the enantioselective synthesis of trifluoromethylated spirooxindoles. The reaction proceeded smoothly in a one-pot manner without the need for a Bronsted base, providing a cost-effective and efficient strategy for the construction of optically pure medium-sized rings.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Chemistry, Organic
Jibin Li, Zheng Liang, Yuzhi Ren, Jian Gao, Ding Du
Summary: A new class of functionalized gem-difluorocyclopropanes bearing acyl groups was synthesized via the N-heterocyclic carbene catalyzed difluorocyclopropanation of alkenes with aldehydes and CF2Br2. This reaction involves a cascade three-component radical relay/intramolecular cyclization process. The protocol features metal- and photocatalyst-free reaction conditions, readily accessible starting materials, good functional group tolerance, and easy scalability. Moreover, this strategy is appealing to pharmaceutical chemistry because it is potentially useful in constructing and modifying bioactive molecules via late-stage functionalization.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Chemistry, Applied
Xin Wu, Yue Wang, Ming-Xi Zhou, Zhang Chen, Xue Peng, Zhen Wang, Yao-Fu Zeng
Summary: A photo-induced metal-free radical hydroboration of various styrenes with NHC-borane has been developed, which can selectively provide mono- and di-alkylated boranes. This reaction exhibits mild conditions and good functional group compatibility.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Organic
Jun-Qi Zhang, Chunjiao Shen, Shihao Shuai, Ling Fang, Dandan Hu, Jiali Wang, Yu Zhou, Bukuo Ni, Hongjun Ren
Summary: A green and efficient approach for the difunctionalization of ynamides by merging the electrochemical and organoseleniumcatalyzed processes is described. This strategy features mild reaction conditions, broad functional group tolerance and high atom-economy, and requires no external chemical oxidant, providing a sustainable alternative for the synthesis of polysubstituted oxazoles.
Article
Chemistry, Organic
Lu Chen, Ya Li, Xiaoyan Bai, Dian Dong, Meiwei Pan, Ling Huang, Runqin Huang, Xiaotong Long, Yibiao Li
Summary: A novel method for the divergent and regioselective synthesis of (E)-2-bromo-1-phenylvinyl trifluoromethanesulfonates is proposed by using readily available alkynes, N-bromosuccinimide (NBS), and trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed by ruthenium(III) acetate [Ru(OAc)(3)]. This method provides a fundamental basis for the development of advanced functional compounds, including drugs and organic functional materials, as it can tolerate a wide range of functional groups. The potential value of this new reaction in organic synthesis is demonstrated by the use of alkynes derived from bioactive molecules such as l(-)-borneol.
Article
Chemistry, Multidisciplinary
Jiajun Wu, Satawat Tongdee, Marie Cordier, Christophe Darcel
Summary: This study presents a method for switching the selectivity of indole derivatives from C3-alkylation to N-alkylation using a catalyst. By using an iron complex and alcohols in trifluoroethanol, efficient N-alkylation of indole derivatives was achieved with high yields. The method also involves an oxidation step to convert the products into N-alkylated indoles.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Organic
Lei Gao, Zhi-Feng Wang, Lin-Wei Wang, Hai-Tao Tang, Zu-Yu Mo, Mu-Xue He
Summary: This study introduces a mild and efficient electrochemical selenium-catalyzed strategy for synthesizing polysubstituted aminophenols. The protocol has the striking features of high atom efficiency, transition metal-free and oxidant-free conditions. By merging electrochemical and organoselenium-catalyzed processes, the intramolecular rearrangement of N-aryloxyamides produces para-amination products at room temperature in a simple undivided cell.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Jie Li, Pei Zhao, Ruoling Li, Wen Yang, Wanxiang Zhao
Summary: An efficient rhodium-catalyzed beta-dehydroborylation of aldehyde-derived silyl enol ethers with bis(pinacolato)diboron is described, leading to a wide array of valuable functionalized beta-boryl silyl enolates with high efficiency and excellent stereoselectivity. The borylated products can be readily converted into diverse synthetically useful molecules through versatile carbon-boron bond transformations.
Article
Chemistry, Organic
Honglian Cui, Guangyang Xu, Jie Zhu, Jiangtao Sun
Summary: A new rhodium-catalyzed reaction has been developed using cyclopropenes as carbene precursors, enabling the synthesis of 2-alkylated 2-pyridone derivatives from 2-oxypyridines. This method offers broad substrate scope, mild reaction conditions and a reliable approach for the efficient synthesis of the desired compounds.
ORGANIC CHEMISTRY FRONTIERS
(2022)
Article
Chemistry, Organic
Manish K. Gupta, Chinmay K. Jena, Nagendra K. Sharma
Summary: The paper describes the synthesis of N-alkyl-3-methenyl chiral isoindolinone derivatives from aryl amides of l-amino acids and non-activated alkene via Pd-catalyzed C(sp(2))-H olefination. The amino acid residue acts as a directing group for olefination at the aryl ring and cyclization occurs at the amide NH. This methodology could be useful in transforming standard amino acids into respective chiral isoindolinone derivatives.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Zhi-Yuan Zhao, Ming Cui, Elisabeth Irran, Martin Oestreich
Summary: This study successfully achieved highly enantioselective silylation of 3-substituted 2H-azirines using a copper-catalyzed reaction with a silyl boronic ester as a latent silicon nucleophile. The resulting C-silylated, unprotected (N-H) aziridines were obtained in high yields and with excellent enantioselectivities, and they can be further converted into valuable compounds without significant loss of enantiomeric excess.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Yi Peng, Martin Oestreich
Summary: Opening the ring of cyclic amines by selectively breaking the carbon-nitrogen bond greatly expands the range of available nitrogen-containing structures. However, methods that can directly open secondary amines are limited. This study presents an efficient reductive ring opening of cyclic amines using PhSiH3 under B(C6F5)(3) catalysis, allowing for the transformation of unstrained cyclic amines into acyclic amines in a simple one-step process. Experimental evidence supports a stepwise mechanism involving silylammonium ions and reductive cleavage of carbon-nitrogen bonds.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Avijit Roy, Haopeng Gao, Hendrik F. T. Klare, Martin Oestreich
Summary: The electrophilic silylium ions were used to investigate the intramolecular Friedel-Crafts-type cyclization of aryl tethered 1,1-difluoroalkenes. The preference for electrophilic silylation of the carbon-carbon double bond over vinylic C(sp(2))-F bonds activation initiates the reaction. Subsequent cyclization and hydrodefluorination of the resulting C(sp(3))-F bonds produce the final product in moderate to good yields. Unlike previous reports, the reaction proceeds with perfluorinated tetraphenylborate counteranion under ambient conditions without the need for a carborate counteranion associated with the silylium ion intermediates.
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Organic
Lucie Finck, Sarah Dabrowski, Martin Oestreich
Summary: A denitrogenative palladium-catalyzed C(sp(2))-C(sp(2)) cross coupling reaction of aryl-substituted diazenes capped with a trimethylsilyl group and functionalized aryl bromides is described. The use of a PEPPSITM catalyst in the presence of NaOt-Bu enables the activation of the N-aryl-N'-silyldiazene pronucleophile, leading to the loss of dinitrogen and subsequent coupling with the in-situ-formed aryl nucleophile. This methodology provides access to biaryl compounds with various substituents.
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Multidisciplinary
Benedikt Wolff, Zheng-Wang Qu, Stefan Grimme, Martin Oestreich
Summary: This study presents a method for the enantioselective reduction of simple carbenium ions using cyclohexadienes with a hydridic C-H bond at an asymmetrically substituted carbon atom. Chiral cyclohexadienes are used as dihydrogen surrogates for the transfer hydrogenation of alkenes (styrenes). The reaction mechanism involves the initiation by trityl cation and a delicate intermolecular capture of a carbenium-ion intermediate by the chiral hydride source, resulting in good enantiomeric ratios of the reduction products.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Min Zhu, Hua-Jie Jiang, Illia Sharanov, Elisabeth Irran, Martin Oestreich
Summary: A desymmetrizing silylation of aromatic diols is achieved by using List's counteranion directed silylation technique for asymmetric silyl ether formation of phenol derivatives. The enantioselective discrimination of achiral 1,1'-biaryl-2,6-diols is enabled by a silylium-ion-like silicon electrophile generated from an allylic silane paired with an imidodiphosphorimidate (IDPi). The enantioselectivity of the desymmetrization is further improved by a downstream kinetic resolution, converting the monosilylated minor enantiomer into the corresponding bissilylated diol.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Review
Chemistry, Multidisciplinary
Benedikt Wolff, Martin Oestreich
Summary: This Review summarizes the approaches taken to achieve the stereoselective addition of nucleophiles to these fleeting intermediates, including recent advances where non-covalent interactions and chiral counterions are employed to discriminate either side of a trigonal-planar carbenium ion bearing three different substituents.
ISRAEL JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Organic
Honghua Zuo, Hendrik F. T. Klare, Martin Oestreich
Summary: A catalytic silylium-ion-promoted intramolecular alkyne carbosilylation reaction is reported, involving electrophilic activation of the C-C triple bond by a silylium ion and maintenance of the catalytic cycle through protodesilylation of an allylsilane reagent. The reaction exhibits exclusive 7-endo-dig selectivity and results in fully substituted vinylsilane derivatives of silylated benzocycloheptenes. Control experiments demonstrate that the catalytically active silylium ion can be regenerated by protodesilylation of the vinylsilane product.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Weichen Huang, Yongxiang Zheng, Sebastian Keess, Gary A. Molander
Summary: Over the past decade, the bicycle[1.1.1]pentane (BCP) motifs have been proven to be valuable bioisosteres of para-disubstituted benzenes in pharmaceuticals. However, the limited approaches and complex syntheses of BCP building blocks are hindering early discovery research in medicinal chemistry. In this study, a modular strategy for preparing functionalized BCP alkylamines was developed, which includes a general method for introducing fluoroalkyl groups to BCP scaffolds using readily available fluoroalkyl sulfinate salts. Furthermore, this strategy can also be extended to incorporate sulfones and thioethers into the BCP core using S-centered radicals. Overall, this multicomponent strategy allows for rapid construction of BCP-type bioisosteres for drug discovery applications.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Organic
Daniel Broesamlen, Martin Oestreich
Summary: A newly developed hept-4-yl-substituted Pybox ligand enables a nickel-catalyzed enantio- and regioconvergent alkylation of regioisomeric mixtures of racemic germylated allylic electrophiles with alkyl nucleophiles, yielding various chiral gamma-germyl alpha-alkyl allylic building blocks with excellent yields and enantioselectivities. The regioconvergence is attributed to the steering effect of the bulky germyl group. The resulting vinyl germanes can be easily halodegermylated without racemization of the allylic stereocenter, providing synthetically valuable gamma-stereogenic vinyl halides.
Article
Chemistry, Organic
Daniel Bro''samlen, Martin Oestreich
Summary: A Ni-H-catalyzed hydroalkylation of vinylsilanes and -germanes as well as allylsilanes with unactivated alkyl iodides is described. In contrast to reactions with styrene or vinyl boronate esters, the addition across the C-C double bond exhibits anti-Markovnikov selectivity, yielding the linear regioisomer. Mechanistic control experiments confirm a radical mechanism, and a competition experiment demonstrates the chemoselectivity favoring the vinyl group over the allyl group.
Article
Chemistry, Organic
Peng-Wei Long, Tao He, Hendrik F. T. Klare, Martin Oestreich
Summary: This Account summarizes the fascinating chemistry of cyclopropyl-stabilized silylium ions, which can be readily obtained from vinyl-cyclopropanes (VCPs). Depending on the nucleophilic partner, these reactive intermediates undergo direct ring opening or ring expansion, leading to the formation of nonclassical alkene-stabilized silylium ions. The latter can also be obtained by gold and proton electrophiles from silicon compounds containing unsaturated C-C bonds. These reaction cascades can be terminated by the formation of C-H or C-C as well as Si-O bonds, revealing the versatility of these complex reactions.
Article
Chemistry, Physical
Min Zhu, Martin Oestreich
Summary: A group-selective monosilylation of silanediols using List's counteranion-directed silylation methodology is described. The enantioselectivity is achieved by generating a silylium-ion-like silicon electrophile from an allylic silane paired with an imidodiphosphorimidate (IDPi), enabling discrimination of the two hydroxy groups attached to the prochiral silicon atom. Furthermore, the enantioselectivity is improved by a subsequent kinetic resolution, resulting in silicon-stereogenic disiloxanes with high enantiocontrol.
Article
Chemistry, Multidisciplinary
Yuanjiu Xiao, Lei Tang, Tong-Tong Xu, Jiang-Yi-Hui Sheng, Zhongyan Zhou, Lei Yue, Guoqiang Wang, Martin Oestreich, Jian-Jun Feng
Summary: A boron Lewis acid-catalyzed intermolecular carboacyloxylation of ynamides with esters is reported, which provides a direct and efficient way to access fully substituted acyclic enol esters. The reaction shows high regio- and Z/E selectivity and is compatible with readily available allylic carbonates. This strategy allows the construction of acyclic beta,beta-disubstituted enol carbonates of amides and can be applied to the synthesis of enantioenriched alpha-quaternary amides.
Review
Chemistry, Organic
Lucie Finck, Martin Oestreich
Summary: This perspective provides an overview of the underexplored chemistry of diazenes and highlights their potential in synthetic transformations. The stability and reactivity of diazenes have been enhanced by using silicon protection. The generation of aryl, diazenyl, and alkyl anionic intermediates under catalytic conditions opens up new synthetic approaches as alternatives to existing methodologies.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
