- Trimethyl borate/magnesium halide complex-induced one-pot homologation reactions of isoquinoline with dialkyl-TMP-zincate
-
Novel one-pot homologation reactions of isoquinoline with lithium dialkyl-TMP-zincate?2MgBrCl/trimethyl borate are described. 1-Alkylisoquinolines (2, 3A, 4A, 5A, 6, and 7) and 1-alkyl-3,4- dihydroisoquinolines (3B, 4B, and 5B) are easily prepared under t
- Seo, Hye Ji,Namgoong, Sung Keon
-
-
Read Online
- Metal-Organic Layers for Synergistic Lewis Acid and Photoredox Catalysis
-
We report the design of a new multifunctional metal-organic layer (MOL), Hf12-Ir-OTf, comprising triflate (OTf)-capped Hf12 secondary building units (SBUs) and photosensitizing Ir(DBB)[dF(CF3)ppy]2+ [DBB-Ir-F, DBB = 4,4′-di(4-benzoato)-2,2′-bipyridine; dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridine] bridging ligands. Hf12-Ir-OTf effectively catalyzed dehydrogenative cross-couplings of heteroarenes with ethers, amines, and unactivated alkanes with turnover numbers of 930, 790, and 950, respectively. Hf12-Ir-OTf also competently catalyzed late-stage functionalization of bioactive and drug molecules such as caffeine, Fasudil, and Metyrapone. The superior catalytic performance of Hf12-Ir-OTf over a mixture of photoredox catalyst and stoichiometric amounts of Br?nsted acids or substoichiometric amounts (20 mol %) of Lewis acids is attributed to the close proximity (1.2 nm) between photoredox and Lewis acid catalysts in Hf12-Ir-OTf, which not only facilitates the reaction between the carbon radical and the activated heteroarene but also accelerates the electron transfer from the nitrogen radical intermediate to the Ir(IV) species in the catalytic cycle.
- Quan, Yangjian,Lan, Guangxu,Fan, Yingjie,Shi, Wenjie,You, Eric,Lin, Wenbin
-
-
Read Online
- Cyclotransformation of azinium salts into hydrogenated cyclic alkylamino ketones
-
A study was carried out on the nucleophilic cyclotransformation of pyrrolo[1,2-a]pyrazinium salts and isoquinolinium salts containing a methyl group in the α-position. A method for the preparation of alkylaminotetrahydroindolizinones and tetralones was pr
- Terenin,Ivanov
-
-
Read Online
- Minisci-Type Alkylation of N-Heteroarenes by N-(Acyloxy)phthalimide Esters Mediated by a Hantzsch Ester and Blue LED Light
-
A synthetic method that enables the Hantzsch ester-mediated Minisci-type C2-alkylation of quinolines, isoquinolines and pyridines by N-(acyloxy)phthalimide esters (NHPI) under blue LED (light emitting diode) light (456 nm) is described. Achieved under mild reaction conditions at room temperature, the metal-free synthetic protocol was shown to be applicable to primary, secondary and tertiary NHPIs to give the alkylated N-heterocyclic products in yields of 21–99%. On introducing a chiral phosphoric acid, an asymmetric version of the reaction was also realised and provided product enantiomeric excess (ee) values of 53–99%. The reaction mechanism was delineated to involve excitation of an electron-donor acceptor (EDA) complex, formed from weak electrostatic interactions between the Hantzsch ester and NHPI, which generates the posited radical species of the redox active ester that undergoes addition to the N-heterocycle.
- Li, Jiacheng,Siang Tan, Suan,Kyne, Sara Helen,Wai Hong Chan, Philip
-
p. 802 - 810
(2022/01/11)
-
- A Metal–Organic Framework as a Multiphoton Excitation Regulator for the Activation of Inert C(sp3)?H Bonds and Oxygen
-
The activation and oxidization of inert C(sp3)?H bonds into value-added chemicals affords attractively economic and ecological benefits as well as central challenge in modern chemistry. Inspired by the natural enzymatic transformation, herein,
- Cai, Junkai,Cai, Wei,Du, Zenggang,Duan, Chunying,He, Cheng,Ji, Guanfeng,Wei, Jianwei,Zhao, Liang
-
supporting information
(2021/11/27)
-
- Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C-C Cross-Couplings via H2Release
-
Designing molecular photocatalysts for potent photochemical reactivities ranks among the most challenging but rewarding endeavors in synthetic photochemistry. Herein, we document a quinoline-based organophotoredox catalyst, 2,4-bis(4-methoxyphenyl)quinoli
- Li, Jianbin,Huang, Chia-Yu,Han, Jing-Tan,Li, Chao-Jun
-
p. 14148 - 14158
(2021/11/27)
-
- A General Organocatalytic System for Electron Donor-Acceptor Complex Photoactivation and Its Use in Radical Processes
-
We report herein a modular class of organic catalysts that, acting as donors, can readily form photoactive electron donor-acceptor (EDA) complexes with a variety of radical precursors. Excitation with visible light generates open-shell intermediates under mild conditions, including nonstabilized carbon radicals and nitrogen-centered radicals. The modular nature of the commercially available xanthogenate and dithiocarbamate anion organocatalysts offers a versatile EDA complex catalytic platform for developing mechanistically distinct radical reactions, encompassing redox-neutral and net-reductive processes. Mechanistic investigations, by means of quantum yield determination, established that a closed catalytic cycle is operational for all of the developed radical processes, highlighting the ability of the organic catalysts to turn over and iteratively drive every catalytic cycle. We also demonstrate how the catalysts' stability and the method's high functional group tolerance could be advantageous for the direct radical functionalization of abundant functional groups, including aliphatic carboxylic acids and amines, and for applications in the late-stage elaboration of biorelevant compounds and enantioselective radical catalysis.
- De Pedro Beato, Eduardo,Melchiorre, Paolo,Spinnato, Davide,Zhou, Wei
-
supporting information
p. 12304 - 12314
(2021/08/20)
-
- An ultrastable olefin-linked covalent organic framework for photocatalytic decarboxylative alkylations under highly acidic conditions
-
The application of two-dimensional covalent organic frameworks (2D-COFs) as photoredox catalysts offers sustainable alternatives for visible-light-driven organic transformations. However, under highly complicated organic reaction conditions, maintaining their basic structure and photoactivity is always neglected, which impedes their potential in more organic reaction types and industrial use. Herein, we describe a visible-light-driven decarboxylative alkylation of heterocycles catalysed by an olefin-linked covalent organic framework (2D-COF-2) instead of the commonly used precious metal complexes and organic dyes. A wide range of alkylated heterocycles were selectively and efficiently synthesized under heterogeneous reaction conditions. Relying on the ultrastability of olefin linkage, 2D-COF-2 maintained its basic structure and photoactivity under highly acidic conditions. Moreover, its streamlining industrial potential was demonstrated in recycling experiments, functionalization of bioactive molecules and scale-up reactions.
- Bu, Xiubin,Tian, Miao,Wang, Yichen,Wang, Yichun,Yang, Xiaobo
-
p. 4272 - 4279
(2021/06/30)
-
- Direct functionalization of quinoxalin-2(1H)-one with alkanes: C(sp2)-H/C(sp3)-H cross coupling in transition metal-free mode
-
Considering the significance of pharmaceutically important heterocycles, efficient and highly versatile protocols for the functionalization of diverse heterocycles with easily accessible feedstock are crucial. Here, we have reported selective alkylation of quinoxalin-2(1H)-one with a broad class of hydrocarbons having different C(sp3)-H bonds with varying bond strengths using di-tert-butyl peroxide (DTBP) as an alkoxyl radical mediator for hydrogen atom transfer (HAT). This dehydrogenative coupling approach utilizes feedstock chemicals such as cycloalkanes, cyclic ethers and alkyl arenes as coupling partners. This protocol exhibits good functional group compatibility and selectivity regarding both heterocycles and unactivated alkanes. Moreover, this methodology allows functionalization of relatively strong C-H bonds of adamantane and exclusive selectivity towards 3° C(sp3)-H bonds is observed. We also illustrate the applicability of this C(sp2)-H/C(sp3)-H cross-coupling for practical access to bioactive pharmaceuticals.
- Dagar, Neha,Raha Roy, Sudipta,Singh, Swati
-
p. 5383 - 5394
(2021/06/28)
-
- Photo-Induced Cross-Dehydrogenative Alkylation of Heteroarenes with Alkanes under Aerobic Conditions
-
We report a Minisci-type cross-dehydrogenative alkylation in an aerobic atmosphere using abundant and inexpensive cerium chloride as a photocatalyst and air as an oxidant. This photoreaction exhibits excellent tolerance to functional groups and is suitabl
- Xu, Jun,Cai, Heng,Shen, Jiabin,Shen, Chao,Wu, Jie,Zhang, Pengfei,Liu, Xiaogang
-
p. 17816 - 17832
(2021/12/17)
-
- Modular Synthesis of Carbazole-Substituted Phthalimides as Potential Photocatalysts
-
The modular synthesis of carbazole functionalized phthalimides (PIs) and their applicability as catalyst in selected photocatalytic transformations are reported. The developed synthetic approach provides high variability of phthalimide considering that the synthesis of the phthalimide core can be easily performed. Starting from fluorophthalic acid anhydrides, the corresponding fluorophthalimides were prepared with various amines, and the fluoro function ensured the introduction of carbazoles into the phthalimide framework through aromatic nucleophilic substitution. Besides the synthetic developments, some of the carbazolyl phthalimides were tested in four different photocatalytic transformations, which showed attractive and comparable activity to the known 4-CzIPN and noble metal complexes.
- F?ldesi, Tamás,Gonda, Zsombor,Nagy, Bálint,Novák, Zoltán
-
supporting information
(2021/11/22)
-
- C-H alkylation of heteroarenes with alkyl oxalates by molecular photoelectrocatalysis
-
An oxidant- and metal-free photoelectrocatalytic C-H alkylation reaction of heteroarenes with alkyl oxalates has been developed. Several classes of heteroaromatics, such as quinolines, isoquinolines, pyridines, and phenanthridines, can be alkylated with t
- Xu, Fan,Lai, Xiao-Li,Xu, Hai-Chao
-
p. 369 - 372
(2020/12/07)
-
- Alkyl Carbazates for Electrochemical Deoxygenative Functionalization of Heteroarenes
-
The C?O bond cleavage for activation of alcohols is synthetically useful and practically challenging. This work describes carbazate as a new type of electrochemically activated alkylating agent derived from ubiquitous alcohols for direct functionalization of heteroarenes under mild electrolytic conditions. The simple undivided cell at low oxidative potentials with carbon/platinum electrode set-ups offers excellent substrate tolerance, affording a variety of primary, secondary and tertiary alkyl-decorated heterocycles in good chemical yields. Furthermore, the mechanism for this electrochemical deoxyalkylation reaction has been investigated.
- Gao, Yongyuan,Wu, Zhengguang,Yu, Lei,Wang, Yi,Pan, Yi
-
supporting information
p. 10859 - 10863
(2020/05/04)
-
- Cross-Dehydrogenative Coupling of Strong C(sp3)-H with N-Heteroarenes through Visible-Light-Induced Energy Transfer
-
The sustainable cross-dehydrogenative coupling of strong C(sp3)-H with N-heteroarenes has been developed using an efficient organic photocatalyst. It features atomic- and step-economy, and acid-free conditions. Mechanism studies suggest a previous elusive
- An, Guanghui,Li, Guangming,Tian, Chao,Tian, Haitao,Yang, Hui
-
supporting information
p. 7709 - 7715
(2020/10/09)
-
- Method for catalyzing decarboxylation of active carboxylic ester to introduce nitrogen heterocycle through photo-induced non-metal
-
The invention provides a method for catalyzing decarboxylation of active carboxylic ester to introduce a nitrogen heterocycle through a photo-induced non-metal. According to the method, the decarboxylation of the active carboxylic ester is realized throug
- -
-
Paragraph 0055; 0056; 0057; 0058; 0059; 0194; 0196; 0197
(2019/01/23)
-
- Ni-Catalyzed Reductive Liebeskind-Srogl Alkylation of Heterocycles
-
Herein we present a Ni-catalyzed alkylation of C-SMe with alkyl bromides for the decoration of heterocyclic frameworks. The protocol, reminiscent to the Liebeskind-Srogl coupling, makes use of simple C(sp2)-SMe to be engaged in a reductive coupling. The reaction is suitable for a preponderance of highly valuable heterocyclic motifs. In addition to cyclic bromides, noncyclic alkyl bromides are well accommodated with exquisite levels of retention over isomerization. The protocol is scalable and permits orthogonal couplings in the presence of other functionalization handles.
- Ma, Yuanhong,Cammarata, Jose,Cornella, Josep
-
supporting information
p. 1918 - 1922
(2019/02/14)
-
- Visible-Light-Induced Copper-Catalyzed Decarboxylative Coupling of Redox-Active Esters with N-Heteroarenes
-
Herein we report a protocol for visible-light-induced copper-catalyzed decarboxylative coupling reactions between N-heteroarenes and redox-active esters. Various N-hydroxyphthalimide esters reacted with isoquinoline, quinoline, pyridine, pyrimidine, quina
- Lyu, Xue-Li,Huang, Shi-Sheng,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
-
p. 5728 - 5732
(2019/08/01)
-
- Catalyst-free electrochemical decarboxylative cross-coupling of: N -hydroxyphthalimide esters and N-heteroarenes towards C(sp3)-C(sp2) bond formation
-
Cheap and widely available carboxylic acids are a class of ideal substrates to construct valuable compounds. As a candidate of decarboxylative reactions, the acid-based neutral N-hydroxyphthalimide ester undergoes a reductive decarboxylative process rather than a common oxidative decarboxylative process, which is a potential transformation mode for new reactions. In this work, we developed an electrochemical C(sp3)-C(sp2) coupling of N-hydroxyphthalimide esters and N-heteroarenes without any catalysts. Remarkably, this electrochemical protocol can not only be directly realised by carboxylic acids in a one-pot fashion, but also be scaled up using a continuous-flow reactor.
- Liu, Yichang,Xue, Liwei,Shi, Biyin,Bu, Faxiang,Wang, Dan,Lu, Lijun,Shi, Renyi,Lei, Aiwen
-
p. 14922 - 14925
(2019/12/24)
-
- Photocatalytic decarboxylative alkylations mediated by triphenylphosphine and sodium iodide
-
Most photoredox catalysts in current use are precious metal complexes or synthetically elaborate organic dyes, the cost of which can impede their application for large-scale industrial processes. We found that a combination of triphenylphosphine and sodium iodide under 456-nanometer irradiation by blue light–emitting diodes can catalyze the alkylation of silyl enol ethers by decarboxylative coupling with redox-active esters in the absence of transition metals. Deaminative alkylation using Katritzky’s N-alkylpyridinium salts and trifluoromethylation using Togni’s reagent are also demonstrated. Moreover, the phosphine/iodide-based photoredox system catalyzes Minisci-type alkylation of N-heterocycles and can operate in tandem with chiral phosphoric acids to achieve high enantioselectivity in this reaction.
- Fu, Ming-Chen,Shang, Rui,Zhao, Bin,Wang, Bing,Fu, Yao
-
p. 1429 - 1434
(2019/04/30)
-
- Radical C?H Acylation of Nitrogen Heterocycles Induced by an Aerobic Oxidation of Aldehydes
-
An aerobic radical approach for the synthesis of unsymmetrical heteroaryl ketones is described herein. The reaction involves cross-dehydrogenative coupling between aldehydes and heteroaromatic bases with molecular oxygen (O2). The key aspect of the method is the generation of reactive acyl radical via homolytic activation of aldehyde C?H bond using O2 as the sole oxidant. The reaction has a good substrate scope with respect to aldehydes and functionalized nitrogen heterocycles. Based on our mechanistic studies, a radical chain pathway is suggested for the reaction. A synthetic application of the method is demonstrated in the formal synthesis of natural alkaloid (±) angustureine.
- Paul, Subhasis,Bhakat, Manotosh,Guin, Joyram
-
supporting information
p. 3154 - 3160
(2019/08/30)
-
- Visible-light-induced C(sp3)-H oxidative arylation with heteroarenes
-
Considering the ubiquitous C(sp3)-H and the important value of alkylated heteroarenes, developing a universal method for C(sp3)-H arylation with heteroarenes is significant. Herein, we proposed a method where Selectfluor can promote
- Liang, Xing-An,Niu, Linbin,Wang, Shengchun,Liu, Jiamei,Lei, Aiwen
-
supporting information
p. 2441 - 2444
(2019/03/26)
-
- Introduction of Heteroaromatic Bases onto Cycloalkanes with BPO
-
Heteroaromatic bases, such as lepidine, phenanthridine, isoquinoline, etc., were treated with cycloalkanes, such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, etc., under warming conditions with benzoyl peroxide (BPO) to form heteroaromatic bases bearing cycloalkyl groups in good yields. Here, the inert C(sp3)-H bond of cycloalkanes could be functionalized to C(sp3)-heteroaromatic bases via an oxidative radical reaction pathway under transition-metal-free conditions.
- Zhou, Luan,Togo, Hideo
-
p. 1627 - 1634
(2019/02/19)
-
- Direct Arylation of Unactivated Alkanes with Heteroarenes by Visible-Light Catalysis
-
The functionalization of aliphatic C-H bonds is both a major challenge and a desirable goal in organic synthesis. Here, we describe the successful arylation of unactivated alkanes with heteroarenes by using iridium polypyridyl complexes as the photocatalyst and persulfate as the HAT catalyst precursor under visible-light irradiation. This reaction features good functional group tolerance and broad scope with regard to both alkane and heteroarene substrates (37 examples), which allows direct access to alkyl-substituted N-heteroarenes, a key structural motif in natural products and bioactive molecules.
- Huang, Cheng,Wang, Jing-Hao,Qiao, Jia,Fan, Xiu-Wei,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
-
p. 12904 - 12912
(2019/09/09)
-
- Visible Light-Promoted Aliphatic C-H Arylation Using Selectfluor as a Hydrogen Atom Transfer Reagent
-
A mild, practical method for direct arylation of unactivated C(sp3)-H bonds with heteroarenes has been achieved via photochemistry. Selectfluor is used as a hydrogen atom transfer reagent under visible light irradiation. A diverse range of chem
- Zhao, Hong,Jin, Jian
-
supporting information
p. 6179 - 6184
(2019/09/06)
-
- Diacetyl as a "traceless" visible light photosensitizer in metal-free cross-dehydrogenative coupling reactions
-
Minisci alkylation is of prime importance for its applicability in functionalizing diverse heteroarenes, which are core structures in many bioactive compounds. In alkyl radical generation processes, precious metal catalysts, high temperatures and excessive oxidants are generally involved, which lead to sustainability and safety concerns. Herein we report a new strategy using diacetyl (2,3-butanedione) as an abundant, visible light-sensitive and "traceless" hydrogen atom abstractor to achieve metal-free cross-dehydrogenative Minisci alkylation under mild conditions. Mechanistic studies supported hydrogen atom transfer (HAT) between an activated C(sp3)-H substrate and diacetyl. Moreover, with the assistance of di-tert-butyl peroxide (DTBP), the scope of the reaction could be extended to strong aliphatic C-H bonds via diacetyl-mediated energy transfer. The robustness of this strategy was demonstrated by functionalizing complex molecules such as quinine, fasudil, nicotine, menthol and alanine derivatives.
- Huang, Chia-Yu,Li, Jianbin,Liu, Wenbo,Li, Chao-Jun
-
p. 5018 - 5024
(2019/06/05)
-
- A visible light-driven minisci-type reaction with N-hydroxyphthalimide esters
-
A visible light-promoted protocol for the redox-neutral coupling of N-hydroxyphthalimide esters with different N-heterocyclic compounds is described. The reaction proceeds through an alkyl radical intermediate generated by reductive decarboxylation of N-hydroxyphthalimide esters. In contrast to the original Minisci protocol, polyalkylation can largely be avoided. Mechanistic investigations revealed a radical chain mechanism which in some cases can proceed even if no photocatalyst is added. This valuable and functional group-tolerant reaction produces substituted heterocycles in moderate to excellent yield. The use of inexpensive starting materials and LEDs as the light source are key features of this C–C bond formation.
- Kammer, Lisa Marie,Rahman, Aliyaah,Opatz, Till
-
-
- Organocatalyzed, Visible-Light Photoredox-Mediated, One-Pot Minisci Reaction Using Carboxylic Acids via N-(Acyloxy)phthalimides
-
An improved, one-pot Minisci reaction has been developed using visible light, an organic photocatalyst, and carboxylic acids as radical precursors via the intermediacy of in situ-generated N-(acyloxy)phthalimides. The conditions employed are mild, demonstrate a high degree of functional group tolerance, and do not require a large excess of the carboxylic acid reactant. As a result, this reaction can be applied to drug-like scaffolds and molecules with sensitive functional groups, enabling late-stage functionalization, which is of high interest to medicinal chemistry.
- Sherwood, Trevor C.,Li, Ning,Yazdani, Aliza N.,Dhar, T. G. Murali
-
p. 3000 - 3012
(2018/03/09)
-
- A Fully Automated Continuous-Flow Platform for Fluorescence Quenching Studies and Stern–Volmer Analysis
-
Herein, we report the first fully automated continuous-flow platform for fluorescence quenching studies and Stern–Volmer analysis. All the components of the platform were automated and controlled by a self-written Python script. A user-friendly software allows even inexperienced operators to perform automated screening of novel quenchers or Stern–Volmer analysis, thus accelerating and facilitating both reaction discovery and mechanistic studies. The operational simplicity of our system affords a time and labor reduction over batch methods while increasing the accuracy and reproducibility of the data produced. Finally, the applicability of our platform is elucidated through relevant case studies.
- Kuijpers, Koen P. L.,Bottecchia, Cecilia,Cambié, Dario,Drummen, Koen,K?nig, Niels J.,No?l, Timothy
-
supporting information
p. 11278 - 11282
(2018/08/11)
-
- Visible Light-Mediated Direct Decarboxylative C-H Functionalization of Heteroarenes
-
The direct visible light-mediated C-H alkylation of heteroarenes using aliphatic carboxylic acids is reported. This mild method proceeds at low catalyst loadings (0.5 mol %) and has a high functional group tolerance and a broad substrate scope. Notably, f
- Garza-Sanchez, R. Aleyda,Tlahuext-Aca, Adrian,Tavakoli, Ghazal,Glorius, Frank
-
p. 4057 - 4061
(2017/06/19)
-
- Deaminative Strategy for the Visible-Light-Mediated Generation of Alkyl Radicals
-
A deaminative strategy for the visible-light-mediated generation of alkyl radicals from redox-activated primary amine precursors is described. Abundant and inexpensive primary amine feedstocks, including amino acids, were converted in a single step into redox-active pyridinium salts and subsequently into alkyl radicals by reaction with an excited-state photocatalyst. The broad synthetic potential of this protocol was demonstrated by the alkylation of a number of heteroarenes under mild conditions.
- Klauck, Felix J. R.,James, Michael J.,Glorius, Frank
-
p. 12336 - 12339
(2017/09/06)
-
- Method for solvent accelerated selective dehydrogenation of tetrahydroisoquinoline type compound
-
The invention discloses a method for synthesizing 1-substituted-3,4-dihydroisoquinoline through the solvent accelerated selective partial dehydrogenation of a 1-substituted-1,2,3,4-tetrahydroisoquinoline compound. For a simple and easily obtained cyclic amine type compound such as a tetrahydroisoquinoline compound, a corresponding imine compound can be obtained through selective dehydrogenation; the conversion ratio of the cyclic amine type compound is higher; further, the proportion of a partially dehydrogenated product to a fully dehydrogenated product is more than 20 to 1. The method is simple and convenient to operate, is practical, easy and feasible, and is mild in reaction condition; the actual cost is greatly reduced. In addition, a method for synthesizing 3,4-dihydroisoquinoline through the direct dehydrogenation of tetrahydroisoquinoline has the advantages of atom economy and environmental friendliness.
- -
-
Paragraph 0039; 0040; 0041; 0042; 0043
(2017/07/22)
-
- Versatile cross-dehydrogenative coupling of heteroaromatics and hydrogen donors via decatungstate photocatalysis
-
A facile sunlight-induced derivatization of heteroaromatics via photocatalyzed C-H functionalization in amides, ethers, alkanes and aldehydes is described. Tetrabutylammonium decatungstate (TBADT) was used as the photocatalyst and allowed to carry out the
- Quattrini, Matteo C.,Fujii, Saki,Yamada, Keiichi,Fukuyama, Takahide,Ravelli, Davide,Fagnoni, Maurizio,Ryu, Ilhyong
-
supporting information
p. 2335 - 2338
(2017/02/23)
-
- Palladium carbon catalyzed selective partial dehydrogenation method of tetrahydroisoquinoline
-
The invention relates to a method for synthesis of 1-substituted-3, 4-dihydroisoquinoline by palladium carbon catalyzed selective partial dehydrogenation of a 1-substituted-1, 2, 3, 4-tetrahydroisoquinoline compound. The reaction temperature is 0-80DEG C. For easily available cyclic amine compounds like tetrahydroisoquinoline, a corresponding imine compound can be obtained through selective dehydrogenation, the conversion rate is up to 99%, and the proportion of a partial dehydrogenation product and a complete dehydrogenation product is greater than 20:1. The method provided by the invention has simple and practical operation, the raw materials and catalyst are cheap and easily available, the reaction conditions are mild, and the catalyst can be recycled, thus greatly reducing the actual cost. In addition, the method for synthesis of 3, 4-dihydroisoquinoline through direct dehydrogenation of tetrahydroisoquinoline has the advantages of atom economy and environmental friendliness.
- -
-
Paragraph 0044-0047; 0050
(2017/02/09)
-
- Transition metal-free Minisci reaction promoted by NCS, and TBHP: Acylation of heteroarenes
-
A method for acylation for heteroarenes under metal-free conditions has been described using NCS as an additive and TBHP as an oxidant. This method has been successfully employed in acylation of a variety of aldehyde with heteroarenes. The application of the method has been illustrated in synthesizing isoquinoline derived natural products. This strategy provides an efficient, mild and inexpensive method for acylation of heteroarenes.
- Siddaraju, Yogesh,Prabhu, Kandikere Ramaiah
-
supporting information
p. 959 - 967
(2016/02/03)
-
- Direct alkylation of heteroarenes with unactivated bromoalkanes using photoredox gold catalysis
-
Although visible light photoredox catalysis has emerged as a powerful tool for the construction of C-C bonds, common catalysts and/or their photoexcited states suffer from low redox potentials, limiting their applicability to alkyl radical generation from substrates with activated carbon-halogen bonds. Radicals derived from these activated compounds, being highly electrophilic or stabilized, do not undergo efficient addition to heteroarenes. Herein we describe the photocatalytic generation of nucleophilic alkyl radicals from unactivated bromoalkanes as part of a universal and efficient cross-coupling strategy for the direct alkylation of heteroarenes using a dimeric gold(i) photoredox catalyst, [Au2(bis(diphenylphosphino)methane)2]Cl2. The method proves to be efficient for alkylation of arenes under mild conditions in the absence of directing groups.
- McCallum,Barriault
-
p. 4754 - 4758
(2016/07/06)
-
- Dioxygen-Mediated Decarbonylative C-H Alkylation of Heteroaromatic Bases with Aldehydes
-
An operationally simple and economical method for the direct alkylation of heteroaromatic bases employing readily available aldehydes as alkyl radical precursors and molecular oxygen as a reagent is presented. This simple transformation demonstrates a broad substrate scope with respect to aldehydes and nitrogen heterocycles, enabling the introduction of several medicinally important yet challenging alkyl moieties, such as ethyl, isopropyl, tert-butyl, and cyclohexyl to the different classes of heterocyclic bases in good to excellent yields. A simple method for the direct alkylation of heteroaromatic bases with aldehydes as inexpensive alkyl radical precursors and molecular oxygen as a reagent is presented. This transformation demonstrates a broad substrate scope with respect to aldehydes and nitrogen heterocycles, enabling the introduction of various alkyl moieties to heterocyclic bases (>40 examples) in good to excellent yields.
- Paul, Subhasis,Guin, Joyram
-
supporting information
p. 17618 - 17622
(2015/12/05)
-
- Highly selective partial dehydrogenation of tetrahydroisoquinolines using modified Pd/C
-
A highly selective procedure has been developed for the partial dehydrogenation of 1-substituted-1,2,3,4-tetrahydroisoquinolines over K3PO4·3H2O-modified Pd/C catalyst. This new method provides facile, atom-economical and environmentally friendly access to 1-substituted-3,4-dihydroisoquinolines without the need for stoichiometric amounts of harmful oxidants. The use of standard Pd/C as a catalyst for this process gave poor chemoselectivity. Pleasingly, the use of a K3PO4·3H2O-modified Pd/C catalyst promoted the partial dehydrogenation of 1-substituted-1,2,3,4-tetrahydroisoquinolines with excellent chemoselectivity by suppressing further dehydroaromatization. Furthermore, conducting the reaction under an atmosphere of oxygen led to further improvements in the chemoselectivity of the dehydrogenation, with the ratio of imine to isoquinoline reaching up to 32/1. The heterogenous Pd/C catalyst could also be recycled and reused at least three times with excellent conversion and chemoselectivity, demonstrating the significantly practical potential of this methodology.
- Ji, Yue,Chen, Mu-Wang,Shi, Lei,Zhou, Yong-Gui
-
-
- Ligand-Free Copper-Catalyzed Negishi Coupling of Alkyl-, Aryl-, and Alkynylzinc Reagents with Heteroaryl Iodides
-
Reported herein is an unprecedented ligand-free copper-catalyzed cross-coupling of alkyl-, aryl-, and alkynylzinc reagents with heteroaryl iodides. The reaction proceeds at room temperature for the coupling of primary, secondary, and tertiary alkylzinc reagents with heteroaryl iodides without rearrangement. An elevated temperature (100 C) is required for aryl-heteroaryl and alkynyl-heteroaryl couplings.
- Thapa, Surendra,Kafle, Arjun,Gurung, Santosh K.,Montoya, Adam,Riedel, Patrick,Giri, Ramesh
-
supporting information
p. 8236 - 8240
(2015/07/07)
-
- Metal-Free Oxidative Decarbonylative Coupling of Aliphatic Aldehydes with Azaarenes: Successful Minisci-Type Alkylation of Various Heterocycles
-
A metal-free oxidative decarbonylative coupling of aliphatic aldehydes with various electron-deficient heterocycles has been developed. This reaction is supposed to be realized via a Minisci-type mechanism, based on the substrate scope, regioselectivity and radical trapping experiments. The ready availability of aliphatic aldehydes, metal-free conditions and broad substrate scope should make this method attractive for the late-stage alkylation of bioactive heterocycles.
- Tang, Ren-Jin,Kang, Lei,Yang, Luo
-
supporting information
p. 2055 - 2060
(2015/06/23)
-
- Benzoyl peroxide promoted radical ortho-alkylation of nitrogen heteroaromatics with simple alkanes and alcohols
-
A catalytic amount of benzoyl peroxide (BPO)-initiated cross-dehydrogenative coupling reaction of N-iminopyridine ylides with simple alkanes and alcohols leads to the corresponding 2-alkylpyridines with high regioselectivity in moderate to good yields without an additional reduction step to remove the activated group. A catalytic amount of benzoyl peroxide (BPO)-initiated cross-dehydrogenative coupling reaction of N-iminopyridine ylides with simple alkanes and alcohols has been developed. The strategy allowed convenient access to various 2-alkylpyridines in moderate to good yields without an additional reduction step to remove the activated group.
- Fang, Lei,Chen, Liangshun,Yu, Jianjun,Wang, Limin
-
p. 1910 - 1914
(2015/03/18)
-
- Cross-dehydrogenative coupling of α-C(sp3)-H of ethers/alkanes with C(sp2)-H of heteroarenes under metal-free conditions
-
Here we have developed an effective metal-free dehydrogenative coupling method wherein α-oxyalkyl and alkyl radicals were generated from various ethers and alkanes to undergo coupling with a variety of electron-deficient heteroarenes such as un/substitute
- Ambala, Srinivas,Thatikonda, Thanusha,Sharma, Shweta,Munagala, Gurunadham,Yempalla, Kushalava Reddy,Vishwakarma, Ram A.,Singh, Parvinder Pal
-
p. 11341 - 11350
(2015/11/27)
-
- Acceptorless dehydrogenation of nitrogen heterocycles with a versatile iridium catalyst
-
Gas up: A cyclometalated iridium complex is found to catalyze the dehydrogenation of various benzofused N-heterocycles, thus releasing H 2. Driven by as low as 0.1 mol % catalyst, the reaction affords quinolines, indoles, quinoxalines, isoquinolines, and β-carbolines in high yields. Copyright
- Wu, Jianjun,Talwar, Dinesh,Johnston, Steven,Yan, Ming,Xiao, Jianliang
-
supporting information
p. 6983 - 6987
(2013/07/26)
-
- Direct selective oxidative cross-coupling of simple alkanes with heteroarenes
-
A dream reaction: An efficient and practical method for the oxidative cross-coupling of heteroaromatic compounds and simple alkanes has been developed. The desired products are smoothly and regioselectively formed under mild reaction conditions at ambient temperature in a hypervalent-iodine-mediated transformation. The method allows for preferential transformation of stronger C sp 3-H bonds in the presence of weaker C sp 3-H bonds under metal-free conditions.
- Antonchick, Andrey P.,Burgmann, Lars
-
supporting information
p. 3267 - 3271
(2013/04/10)
-
- Iron-catalyzed heterocycle and arene deprotonative alkylation
-
Figure Presented. A method for iron-catalyzed deprotonative alkylation of arene C-H bonds by alkyl iodides and bromides has been developed. In the presence of an amide base, both primary and secondary alkyl halides can be coupled with furans, thiophenes, pyridine derivatives, and some electron-withdrawing-group containing arenes.
- Tran, Ly Dieu,Daugulis, Olafs
-
supporting information; experimental part
p. 4277 - 4279
(2010/11/04)
-
- A novel radical reaction of alkyl xantates useful for the selective substitution of heteroaromatic bases
-
Cyclohexyl radical is generated from cyclohexyldithiocarbonate and benzoyl peroxide. The radical source is used for the alkylation of heteroaromatic bases.
- Coppa, Fausta,Fontaria, Francesca,Minisci, Francesco,Pianese, Giuseppe,Tortoreto, Paola,Zhao, Lihua
-
p. 687 - 690
(2007/10/02)
-
- New General Processes of Homolytic Alkylation of Heteroaromatic Bases by t-BuOOH or (t-BuO)2 and Alkyl Iodides
-
New general, selective processes of homolytic alkylation of protonated heteroaromatic bases have been developed using alkyl iodides and t-BuOOH or (t-BuO)2 as sources of alkyl radicals.Both processes are based on the generation of methyl radical from the peroxides, and on iodine abstraction from the alkyl iodide by the methyl radical.The selective processes are the result of combined enthalpic and polar effects.The enthalpic factor governs the equilibrium of iodine abstraction, whereas the polar effect governs the reactivity of the alkyl radicals with the protonated heteroaromatic ring.A redox chain is operative with t-BuOOH and an unusual free-radical chain process is involved with (t-BuO)2.Both chains are particularly effective because of the electron-transfer oxidation of the pyridyl radical intermediate, the ionization potential of which (5.4-6.0 eV) is close to that of lithium (5.39 eV) or sodium (5.14 eV).
- Fontana, Francesca,Minisci, Francesco,Barbosa, Maria Claudia Nogueira,Vismara, Elena
-
p. 995 - 999
(2007/10/02)
-
- Polar Effects in Free-Radical Reactions. Rate Constants in Phenylation and New Methods of Selective Alkylation of Heteroaromatic Bases
-
The rate constants for the addition of the phenyl radical to protonated and unprotonated 4-substituted pyridines have been determined by competition with chlorine abstraction from CCl4.The constants range from 2 * 105 to 6 * 106 M-1 s-1 depending on the substituent and on the degree of protonation.The phenyl radical shows a clear-cut nucleophilic character.On the basis of these rate constants, the use of phenyl radical from diazonium salt or benzoyl peroxide to generate alkyl radicals by iodine or hydrogen abstraction has been developed as a general procedure for the alkylation of heteroaromatic bases.This reaction is characterized by high yields and selectivities.
- Minisci, Francesco,Vismara, Elena,Fontana, Francesca,Morini, Giampiero,Serravalle, Marco,Giordano, Claudio
-
p. 4411 - 4416
(2007/10/02)
-
- A NEW GENERAL METHOD OF HOMOLYTIC ALKYLATION OF PROTONATED HETEROAROMATIC BASES
-
Alkyl iodides and benzoyl peroxides provide a new general method of homolytic alkylation of protonated heteroaromatic bases.Yields are good and the substitution is selective in the positions ortho and para to the heteroatom.
- Castaldi, Graziano,Minisci, Francesko,Tortelli, Vito,Vismara, Elena
-
p. 3897 - 3900
(2007/10/02)
-
- REDUCTION OF 1-ISOQUINOLYL-DIMETHYLMETHANOL AND 1-(1-ISOQUINOLYL)CYCLOHEXANOL
-
Reduction of alcohols Ia and IIa with zinc and formic acid afforded 1-isopropylisoquinoline (Ib) and 1-cyclohexylisoquinoline (IIb), respectively, reduction with sodium in 1-butanol led to the 1,2,3,4-tetrahydroisoquinoline derivatives III, IV and Va and electrolytical reduction gave 1-isopropyl-1.2.3.4-tetrahydroisoquinoline (Vd) and the 1-cyclohexyl derivative Ve, respectively.
- Ferles, Miloslav,Sputova, Michaela,Tegza, Marian
-
p. 262 - 265
(2007/10/02)
-