- Nickel-Catalyzed, Regio- and Enantioselective Benzylic Alkenylation of Olefins with Alkenyl Bromide
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A NiH-catalyzed migratory hydroalkenylation reaction of olefins with alkenyl bromides has been developed, affording benzylic alkenylation products with high yields and excellent chemoselectivity. The mild conditions of the reaction preclude olefinic products from undergoing further isomerization or subsequent alkenylation. Catalytic enantioselective hydroalkenylation of styrenes was achieved by using a chiral bisoxazoline ligand.
- Liu, Jiandong,Gong, Hegui,Zhu, Shaolin
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supporting information
p. 4060 - 4064
(2020/12/25)
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- Synthesis of 3,4-bis(Butylselanyl)selenophenes and 4-alkoxyselenophenes promoted by oxone
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We describe herein an alternative transition-metal-free procedure to access 3,4-bis(butylsela nyl)selenophenes and the so far unprecedented 3-(butylselanyl)-4-alkoxyselenophenes. The protocol involves the 5-endo-dig electrophilic cyclization of 1,3-diynes promoted by electrophilic organosele-nium species, generated in situ through the oxidative cleavage of the Se-Se bond of dibutyl diselenide using Oxone as a green oxidant. The selective formation of the title products was achieved by controlling the solvent identity and the amount of dibutyl diselenide. By using 4.0 equiv of dibutyl diselenide and acetonitrile as solvent at 80?C, four examples of 3,4-bis(butylselanyl)selenophenes were obtained in moderate to good yields (40–78%). When 3.0 equiv of dibutyl diselenide were used, in the presence of aliphatic alcohols as solvent/nucleophiles under reflux, 10 3-(butylselanyl)-4-alkoxyselenophenes were selectively obtained in low to good yields (15–80%).
- Hellwig, Paola S.,Guedes, Jonatan S.,Barcellos, Angelita M.,Perin, Gelson,Lenard?o, Eder J.
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supporting information
(2021/05/28)
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- Synthesis of Chiral Propargylamines, Chiral 1,2-Dihydronaphtho[2,1-b]furans and Naphtho[2,1-b]furans with C-Alkynyl N,N′-di-(tert-butoxycarbonyl)-aminals and β-Naphthols
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Chiral phosphoric acid-catalyzed couplings of C-alkynyl N,N′-di-(tert-butoxycarbonyl)-aminals with β-naphthols led to chiral propargylamines in moderate to high yields with high to excellent enantioselectivity, in which the reactions underwent sequential chiral phosphoric acid-catalyzed in situ formation of N-(tert-butoxycarbonyl)-imines (N-Boc-imines) from the aminals, and 1,2-addition of β-naphthols to the N-Boc-imines. Chiral 1,2-dihydronaphtho[2,1-b]furans and naphtho[2,1-b]furans were prepared with satisfactory results when 10 mol% AgOAc and 20 mol% 2,6-lutidine or 1.2 equiv. of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were added to the resulting chiral propargylamines solution, respectively.
- Man, Ningning,Li, Yuming,Jie, Jiyang,Li, Hongyun,Yang, Haijun,Zhao, Yufen,Fu, Hua
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supporting information
p. 12884 - 12889
(2021/07/28)
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- Selective Rhodium-Catalyzed Hydroformylation of Terminal Arylalkynes and Conjugated Enynes to (Poly)enals Enabled by a π-Acceptor Biphosphoramidite Ligand
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The hydroformylation of terminal arylalkynes and enynes offers a straightforward synthetic route to the valuable (poly)enals. However, the hydroformylation of terminal alkynes has remained a long-standing challenge. Herein, an efficient and selective Rh-catalyzed hydroformylation of terminal arylalkynes and conjugated enynes has been achieved by using a new stable biphosphoramidite ligand with strong π-acceptor capacity, which affords various important E-(poly)enals in good yields with excellent chemo- and regioselectivity at low temperatures and low syngas pressures.
- Zhao, Jiangui,Zheng, Xueli,Tao, Shaokun,Zhu, Yuxin,Yi, Jiwei,Tang, Songbai,Li, Ruixiang,Chen, Hua,Fu, Haiyan,Yuan, Maolin
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supporting information
p. 6067 - 6072
(2021/08/16)
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- Electrochemical Nozaki-Hiyama-Kishi Coupling: Scope, Applications, and Mechanism
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One of the most oft-employed methods for C-C bond formation involving the coupling of vinyl-halides with aldehydes catalyzed by Ni and Cr (Nozaki-Hiyama-Kishi, NHK) has been rendered more practical using an electroreductive manifold. Although early studies pointed to the feasibility of such a process, those precedents were never applied by others due to cumbersome setups and limited scope. Here we show that a carefully optimized electroreductive procedure can enable a more sustainable approach to NHK, even in an asymmetric fashion on highly complex medicinally relevant systems. The e-NHK can even enable non-canonical substrate classes, such as redox-active esters, to participate with low loadings of Cr when conventional chemical techniques fail. A combination of detailed kinetics, cyclic voltammetry, and in situ UV-vis spectroelectrochemistry of these processes illuminates the subtle features of this mechanistically intricate process.
- Baran, Phil S.,Blackmond, Donna G.,Gao, Yang,Hadt, Ryan G.,Hao, Wei,Hill, David E.,McNicholas, Brendon J.,Reisman, Sarah E.,Vantourout, Julien C.
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supporting information
p. 9478 - 9488
(2021/07/19)
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- Pd-Catalyzed Indole Synthesis via C-H Activation and Bisamination Sequence with Diaziridinone
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This work describes an efficient Pd-catalyzed indole synthesis. A wide variety of indoles can be obtained in good yields from readily available vinyl bromides. The reaction likely proceeds through a sequential aryl C-H activation and bisamination of a resulting pallada(II)cycle with diaziridinone.
- Wang, Jianjun,Sun, Xiaofeng,Hu, Daguo,Shi, Yian
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supporting information
p. 7561 - 7565
(2021/10/02)
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- N -tert-butyl -2 -phenylindole derivative Preparation method and application
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The invention belongs to the technical field of organic synthesis, and particularly relates to N - tert-butyl -2 -phenyl indole derivatives as well as a preparation method and application thereof. The preparation method comprises the following steps: (Z)-1 - bromo -1 - phenyl -2 - styrene derivative, N, N - di-tert-butyl diazepinone, palladium catalyst, monophosphine ligand, hydrocarbon activator, base and first solvent, and N -tert-butyl -2 -aryl indole derivatives which can synthesize substituent type diversity, and the prepared N -tert-butyl -2 -aryl indole derivative can be used for preparing biologically active molecules N -2 .
- -
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Paragraph 0099-0103; 0110; 0113-0114; 0120; 0123-0124; ...
(2021/11/26)
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- Expedient Synthesis of Bridged Bicyclic Nitrogen Scaffolds via Orthogonal Tandem Catalysis
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Bridged nitrogen bicyclic skeletons have been accessed via unprecedented site- and diastereoselective orthogonal tandem catalysis from readily accessible reactants in a step economic manner. Directed Pd-catalyzed γ-C(sp3)-H olefination of aminocyclohexane with gem-dibromoalkenes, followed by a consecutive intramolecular Cu-catalyzed amidation of the 1-bromo-1-alkenylated product delivers the interesting normorphan skeleton. The tandem protocol can be applied on substituted aminocyclohexanes and aminoheterocycles, easily providing access to the corresponding substituted, aza- and oxa-analogues. The Cu catalyst of the Ullmann-Goldberg reaction additionally avoids off-cycle Pd catalyst scavenging by alkenylated reaction product. The picolinamide directing group stabilizes the enamine of the 7-alkylidenenormorphan, allowing further product post functionalizations. Without Cu catalyst, regio- and diastereoselective Pd-catalyzed γ-C(sp3)-H olefination is achieved.
- Bheemireddy, Narendraprasad Reddy,Biswas, Sovan,Evano, Gwilherm,Maes, Bert U. W.,Van Steijvoort, Ben F.,Waeterschoot, Marjo
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supporting information
p. 21988 - 21996
(2021/08/13)
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- The hydrodebromination of 1,1-dibromoalkenes via visible light catalysis
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Vinyl bromides are versatile synthetic intermediates and widely applied in organic synthesis and pharmaceuticals. Herein, a hydrodebromination reaction of 1,1-dibromoalkenes was established via visible light catalysis. A variety of structurally different vinyl bromides were obtained in moderate to excellent yields.
- Sun, Wencheng,Teng, Qiaoling,Cheng, Dongping,Li, Xiaonian,Xu, Xiaoliang
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supporting information
(2019/12/05)
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- Cs2CO3-Mediated Vicinal Thiosulfonylation of 1,1-Dibromo-1-Alkenes with Thiosulfonates: An Expedient Synthesis of (E)-1,2-Thiosulfonylethenes
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A new and highly efficient vicinal thiosulfonylation of 1,1-dibromo-1-alkenes with thiosulfonates in the presence of cesium carbonate has been developed. The metal-free diheterofunctionalization is an operationally simple to access a wide range of (E)-1,2-thiosulfonylethenes (α-aryl-β-thioarylvinyl sulfones) in moderate to high yields with high levels of stereoselectivities. Further, scalable reactions have been demonstrated for this transformation, thus illustrating its efficiency and practicality. (Figure presented.).
- Reddy, Raju Jannapu,Kumari, Arram Haritha,Kumar, Jangam Jagadesh,Nanubolu, Jagadeesh Babu
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supporting information
p. 1587 - 1591
(2019/02/16)
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- Pd-Catalyzed decarboxylative alkynylation of alkynyl carboxylic acids with arylsulfonyl hydrazides via a desulfinative process
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In the presence of a Pd(ii)/P-ligand catalytic system, decarboxylative alkynylation of alkynyl carboxylic acids and arylsulfonyl hydrazides by desulfinative coupling could provide aryl alkynes in satisfactory yields by either judiciously selecting palladium catalysts or modulating phosphine ligands under mild conditions. The reported coupling reactions are very practical as they do not require the protection of inert gas or oxygen and are tolerant to many functional groups.
- Chang, Sheng,Liu, Ying,Yin, Shu Zhu,Dong, Lin Lin,Wang, Jian Feng
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supporting information
p. 5357 - 5362
(2019/04/04)
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- Synthesis of Chiral β-Borylated Carboxylic Esters via Nickel-Catalyzed Asymmetric Hydrogenation
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The highly efficient Ni-catalyzed asymmetric hydrogenation of β-boronic ester substituted-α,β-unsaturated carboxylic esters was successfully developed using (S,S)-Ph-BPE as the ligand. A series of chiral β-borylated carboxylic esters were obtained with high yields (94%-99% yields) and excellent enantioselectivities (89%-99% ee). The gram-scale asymmetric hydrogenation with a low catalyst loading (0.25 mol %) and synthetic transformation of hydrogenation product demonstrated the great synthetic utility of this methodology.
- Han, Zhengyu,Liu, Gang,Zhang, Xianghe,Li, Anqi,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 3923 - 3926
(2019/06/14)
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- Catalytic Enantioselective Synthesis of 1,4-Keto-Alkenylboronate Esters and 1,4-Dicarbonyls
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A catalytic enantioselective method for the synthesis of 1,4-keto-alkenylboronate esters by a rhodium-catalyzed conjugate addition pathway is disclosed. A variety of novel, bench-stable alkenyl gem-diboronate esters are synthesized. These easily accessible reagents react smoothly with a collection of cyclic α,β-unsaturated ketones, generating a new C?C bond and stereocenter. Products are isolated in up to 99 % yield with greater than 20:1 E/Z and greater than 99:1 e.r. Mechanistic studies show the site-selectivity of transmetalation and reactivity is ligand dependent. The utility of the approach is highlighted by gram-scale synthesis of enantioenriched cyclic 1,4-diketones, and stereoselective transformations of the products by hydrogenation, allylation, and isomerization.
- Liang, Michael Z.,Meek, Simon J.
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supporting information
p. 14234 - 14239
(2019/08/30)
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- Construction of Phenanthrenes and Chrysenes from β-Bromovinylarenes via Aryne Diels-Alder Reaction/Aromatization
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A highly efficient transition-metal-free general method for the synthesis of polycyclic aromatic hydrocarbons like phenanthrenes and chrysenes (and tetraphene) from β-bromovinylarenes and arynes has been developed. The reactions proceed via an aryne Diels-Alder (ADA) reaction, followed by a facile aromatization. This is the first report on direct construction of chrysenes (and tetraphene) using the ADA approach. Unlike the literature method which is limited to only 9/10-substituted derivatives, this method gives access to a wide variety of functionalized phenanthrenes.
- Singh, Vikram,Verma, Ram Subhawan,Khatana, Anil K.,Tiwari, Bhoopendra
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supporting information
p. 14161 - 14167
(2019/10/28)
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- Visible Light-Catalyzed Decarboxylative Alkynylation of Arenediazonium Salts with Alkynyl Carboxylic Acids: Direct Access to Aryl Alkynes by Organic Photoredox Catalysis
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A convenient method mediated by photoredox catalysis is developed for the direct construction of aryl alkynes. Readily available aromatic diazonium salts have been utilized as the aryl radical source to couple alkynyl carboxylic acids to feature the decarboxylative arylation. A wide range of substrates are amenable to this protocol with broad functional group tolerance, and diversely-functionalized aryl alkynes could be synthesized under mild, neutral and transition metal-free reaction conditions using visible light irradiation. Alongside synthetic sustainability associated with the photocatalytic and transition metal-free operation, another key point of this method is that the organic dye catalyst acts as an excited-state reductant, thus establishing the quenching cycle for radical addition and decarboxylative elimination. (Figure presented.).
- Yang, Liangfeng,Li, Haifeng,Du, Yijun,Cheng, Kai,Qi, Chenze
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p. 5030 - 5041
(2019/11/03)
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- Stereoselective Synthesis of Vinylboronates by Rh-Catalyzed Borylation of Stereoisomeric Mixtures
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The stereoselective preparation of vinylboronates via rhodium-catalyzed borylation of E/Z mixtures of vinyl actetates is described, and this method was also extended to synthesis of vinyldiboronates. These transformations feature high functional group compatibility and mild reaction conditions. Control experiments support a mechanism that involved a Rh-catalyzed borylation-isomerization sequence. The isomerization of (Z)-vinylboronates to (E)-isomers was also demonstrated.
- Li, Shenhuan,Li, Jie,Xia, Tianlai,Zhao, Wanxiang
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p. 462 - 468
(2019/03/28)
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- Dual nickel- and photoredox-catalyzed reductive cross-coupling of aryl vinyl halides and unactivated tertiary alkyl bromides
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A novel reductive cross-coupling of aryl vinyl halides and unactivated tertiary alkyl bromides has been realized via photoredox/nickel dual catalysis to produce vinyl arene derivatives bearing all-carbon quaternary centers with excellent E-selectivity. A stoichiometric metal reductant could be avoided by employing commercially available N,N,N′,N′-tetramethylethylenediamine (TMEDA) as the terminal reductant.
- Yu, Weijie,Chen, Long,Tao, Jiasi,Wang, Tao,Fu, Junkai
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supporting information
p. 5918 - 5921
(2019/05/27)
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- Direct Access to Aryl Bis(trifluoromethyl)carbinols from Aryl Bromides or Fluorosulfates: Palladium-Catalyzed Carbonylation
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A palladium-catalyzed carbonylative approach for the direct conversion of (hetero)aryl bromides into their α,α-bis(trifluoromethyl)carbinols is described, and it employs only stoichiometric amounts of carbon monoxide and trifluoromethyltrimethylsilane. In addition, aryl fluorosulfates proved highly compatible with these reaction conditions. The method is tolerant of a diverse set of functional groups, and it is adaptable to late-stage carbon-isotope labeling.
- Domino, Katrine,Veryser, Cedrick,Wahlqvist, Benjamin A.,Gaardbo, Cecilie,Neumann, Karoline T.,Daasbjerg, Kim,De Borggraeve, Wim M.,Skrydstrup, Troels
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supporting information
p. 6858 - 6862
(2018/05/08)
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- Silver-catalyzed Double Decarboxylative Radical Alkynylation/Annulation of Arylpropiolic Acids with α-keto Acids: Access to Ynones and Flavones under Mild Conditions
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Ynones are privileged building blocks in various organic syntheses of heterocyclic derivatives due to their multifunctional nature, and flavones are an important class of natural products with a wide range of biological activities. We describe the catalytic double decarboxylative alkynylation of arylpropiolic acids with α-keto acids. With Ag(I)/persulfate as the catalysis system, the valuable ynones bearing various substituents could be easily obtained. The introduction of hydroxyl substituent on ortho-site of α-keto acids make this strategy further applicable to the construction of flavone derivatives via heteroannulation in moderate to good yields with a similar silver-catalyzed system. The reactions proceed under relatively mild reaction conditions and tolerate a wide variety of functional groups. Control experiments indicated that both the reactions undergo radical processes. (Figure presented.).
- Meng, Mengting,Wang, Guofang,Yang, Liangfeng,Cheng, Kai,Qi, Chenze
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supporting information
p. 1218 - 1231
(2018/02/16)
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- Enantiodivergent Synthesis of Allenes by Point-to-Axial Chirality Transfer
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An enantiodivergent method for the synthesis of multiply substituted allenes is described. Highly enantioenriched, point-chiral boronic esters were synthesized by homologation of α-seleno alkenyl boronic esters with lithiated carbamates and eliminated to form axially chiral allene products. By employing either oxidative or alkylative conditions, both syn and anti elimination could be achieved with complete stereospecificity. The process enables the synthesis of either M or P allenes from a single isomer of a point-chiral precursor and can be employed for the enantioselective assembly of di-, tri-, and tetrasubstituted allenes.
- Armstrong, Roly J.,Nandakumar, Meganathan,Dias, Rafael M. P.,Noble, Adam,Myers, Eddie L.,Aggarwal, Varinder K.
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supporting information
p. 8203 - 8208
(2018/06/06)
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- Nickel(ii)-catalyzed tandem C(sp2)-H bond activation and annulation of arenes with gem-dibromoalkenes
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A nickel(ii)/silver(i)-catalyzed tandem C(sp2)-H activation and intramolecular annulation of arenes with dibromoalkenes has been successfully achieved, which offers an efficient approach to the 3-methyleneisoindolin-1-one scaffold. Attractive features of this system include its low cost, ease of operation, and its ability to access a wide range of isoindolinones.
- Shi, Yun,Li, Meng-Sheng,Zhang, Fangdong,Chen, Baohua
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p. 28668 - 28675
(2018/08/29)
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- Synthesis of o-Allyloxy(ethynyl)benzene Derivatives by Cu-Catalyzed Suzuki–Miyaura-Type Reaction and Their Transformations into Heterocyclic Compounds
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We have found that Suzuki–Miyaura-type reactions of o-allyloxy(bromoethynyl)benzenes with arylboronic acids using a hydrazone/Cu catalyst system proceeded smoothly in iPrOH under mild conditions to afford the corresponding o-allyloxy(arylethynyl)benzene derivatives in good yields without decomposition of the allyloxy group. We have further demonstrated that annulation and enyne metathesis of the o-allyloxy(arylethynyl)benzene derivatives using transition-metal catalysts led to various heterocyclic compounds.
- Watanabe, Kohei,Mino, Takashi,Ishikawa, Eri,Okano, Miyu,Ikematsu, Tatsuya,Yoshida, Yasushi,Sakamoto, Masami,Sato, Kazuki,Yoshida, Kazuhiro
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supporting information
p. 2359 - 2368
(2017/05/01)
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- Nickel-Catalyzed Reductive Cross-Coupling of Vinyl Bromides with Unactivated Alkyl Halides
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The use of pyridine as the sole ligand for the reductive vinylation of unactivated secondary alkyl halides under Ni-catalyzed conditions has been developed. Both alkyl- and aryl-substituted vinyl bromides are suitable, in which alkyl-decorated α-alkenyl bromides resulted in the α-products in good results.
- Gu, Jun,Qiu, Canbin,Lu, Wenbin,Qian, Qun,Lin, Kunhua,Gong, Hegui
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supporting information
p. 1867 - 1873
(2017/04/06)
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- Synthesis of Highly Substituted Polyenes by Palladium-Catalyzed Cross–Couplings of Sterically Encumbered Alkenyl Bromides and N-Tosylhydrazones
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A new method for the synthesis of polysubstituted conjugated dienes is described, through the palladium-catalyzed cross-coupling between N-tosylhydrazones and alkenyl bromides. The reaction proceeds efficiently when a combination of a highly substituted bromoalkene and a hydrazone derived from a ketone are employed, pointing to the convenience of a sterically encumbered environment. This unprecedented process allows for the stereocontrolled preparation of highly substituted dienes and polyenes. (Figure presented.).
- Paraja, Miguel,Barroso, Raquel,Cabal, M. Paz,Valdés, Carlos
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supporting information
p. 1058 - 1062
(2017/03/27)
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- [Cu]-catalyzed direct coupling of dibromoalkenes: Synthesis of symmetrical 1,3-diynes and triazoles
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An efficient [Cu]-catalyzed homocoupling of 1,1-dibromoalk-1-enes is described for the synthesis of symmetrical 1,3-diyines. The method showed good substrate scope and amenable to aryl and heteroaryl systems. Significantly, the strategy was also successfully applied to the sequential one-pot synthesis of triazoles.
- Mahendar, Lodi,Ramulu, Bokka Venkat,Satyanarayana, Gedu
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p. 1151 - 1158
(2017/06/13)
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- Na2S-mediated synthesis of terminal alkynes from: Gem -dibromoalkenes
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The Na2S-mediated facile synthesis of terminal alkynes from gem-dibromoalkenes, at 20/40 °C under open flask conditions has been developed. Various precursors derived from heteroaromatic/aromatic/aliphatic aldehydes were found compatible. The reaction is proposed to proceed through the Fritsch-Buttenberg-Wiechell (FBW) rearrangement involving the corresponding vinyl carbene. Using mild reaction conditions with inexpensive Na2S·9H2O under air atmosphere has significant advantages over earlier routes.
- Singh, Radhey M.,Nandini, Durgesh,Bharadwaj, Kishor Chandra,Gupta, Tanu,Singh, Raj Pal
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supporting information
p. 9979 - 9982
(2017/12/26)
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- Microwave-Assisted Dibromoolefination of Aromatic and Heteroaromatic Aldehydes and Ketones
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Microwave (MW) irradiation was successfully employed to convert aromatic and heteroaromatic aldehydes and ketones efficiently to the corresponding dibromoolefins. Exemplified by the successful dibromoolefination of traditionally inert pyridyl-flanked carbonyls, MW activation significantly broadens the scope of this valuable transformation, although some limitations especially with electron-rich aromatic ketone derivatives remain.
- Nauroozi, Djawed,Bruhn, Clemens,Fürmeier, Sven,Holzhauer, J?rn-Uwe,Faust, Rüdiger
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supporting information
p. 615 - 619
(2016/04/19)
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- Direct Alkynylation of 3H-Imidazo[4,5-b]pyridines Using gem-Dibromoalkenes as Alkynes Source
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C2 direct alkynylation of 3H-imidazo[4,5-b]pyridine derivatives is explored for the first time. Stable and readily available 1,1-dibromo-1-alkenes, electrophilic alkyne precursors, are used as coupling partners. The simple reaction conditions include an inexpensive copper catalyst (CuBr·SMe2 or Cu(OAc)2), a phosphine ligand (DPEphos) and a base (LiOtBu) in 1,4-dioxane at 120 °C. This C-H alkynylation method revealed to be compatible with a variety of substitutions on both coupling partners: heteroarenes and gem-dibromoalkenes. This protocol allows the straightforward synthesis of various 2-alkynyl-3H-imidazo[4,5-b]pyridines, a valuable scaffold in drug design.
- Aziz, Jessy,Baladi, Tom,Piguel, Sandrine
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p. 4122 - 4133
(2016/06/09)
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- 1,1-Dibromoalkenes as versatile reagents to a transition metal-free and stereoselective synthesis of (E)-1-bromo-1-selenoalkenes and ketene selenoacetals
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We describe here a metal-free and selective method for the synthesis of (E)-1-bromo-1-seleno alkenes and ketene selenoacetals by a stoichiometric and temperature-controlled reaction. These protocols employ a diverse array of 1,1-dibromoalkenes and different diaryl diselenides to afford the corresponding products in good yields and in a short reaction time.
- Webber, Rodrigo,Peglow, Thiago J.,Nobre, Patrick C.,Barcellos, Angelita M.,Roehrs, Juliano A.,Schumacher, Ricardo F.,Perin, Gelson
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supporting information
p. 4128 - 4132
(2016/08/24)
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- Preparation of Vinyl Arenes by Nickel-Catalyzed Reductive Coupling of Aryl Halides with Vinyl Bromides
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This work emphasizes the synthesis of substituted vinyl arenes by reductive coupling of aryl halides with vinyl bromides under mild and easy-to-operate nickel-catalyzed reaction conditions. A broad range of aryl halides, including heteroaromatics, and vinyl bromides were employed to yielding products in moderate to excellent yields with high functional-group tolerance. The nickel-catalytic system displays good chemoselectivity between the two C(sp2)-halide coupling partners, thus demonstrating a mechanistic pathway distinct from other stepwise protocols.
- Liu, Jiandong,Ren, Qinghua,Zhang, Xinghua,Gong, Hegui
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supporting information
p. 15544 - 15548
(2016/12/09)
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- One-pot sequential alkynylation and cycloaddition: Regioselective construction and biological evaluation of novel benzoxazole-triazole derivatives
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Individually, benzoxazole and triazole moieties are of significant biological interest owing to their importance in drugs and pharmaceuticals. To assess their combined biological impact when woven into one molecule, we designed a novel, regioselective, multicomponent, one-pot (MCOP) approach for the construction of benzoxazole-linked triazoles. The synthesis has been achieved in two sequential steps involving copper-catalyzed alkynylation of benzoxazole followed by a 1,3-dipolar cycloaddition reaction. By combination of these two bioactive units into one core, a series of new benzoxazole-triazole scaffolds has been synthesized and subjected to in vitro antibacterial and anticancer evaluation. Tests against clinical isolates of Staphylococcus aureus and Escherichia coli showed potent Gram-negative activity for compounds 4{1,1,1}, 4{1,1,4}, and 4{1,2,1}. The cytotoxicity of the synthesized library was determined against three cancer cell lines: HeLa, SKBr3, and Hep G2. Compound 4{2,2,2} showed significant cytotoxicity against all the cell lines. These preliminary bioassay evaluations strongly suggest the promise and scope of these novel molecules as therapeutic agents in medical science.
- Srivastava, Ananya,Aggarwal, Leena,Jain, Nidhi
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- Addition of selenium(II) bromide to arylalkynylamides - a route to hypervalent T-shaped 10-Se-3 systems
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Abstract A route for the generation of hypervalent T-shaped 10-Se-3 systems is described involving an interaction between in situ prepared selenium(II) bromide and an aryl alkynyl amide derivative. The existence of hypervalent selenium in both the solid and solution states has been supported by X-ray analysis and 77Se NMR data.
- Paegle, Edgars,Belyakov, Sergey,Kirsch, Gilbert,Arsenyan, Pavel
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supporting information
p. 4554 - 4557
(2015/06/30)
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- Combining silver- and organocatalysis: An enantioselective sequential catalytic approach towards pyrano-annulated pyrazoles
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A one-pot asymmetric Michael addition/hydroalkoxylation sequence, catalyzed by a sequential catalytic system consisting of a squaramide and a silver salt, provides a new series of chiral pyrano-annulated pyrazole derivatives in excellent yields (up to 95%) and high enantioselectivities (up to 97% ee).
- Hack, Daniel,Chauhan, Pankaj,Deckers, Kristina,Mizutani, Yusuke,Raabe, Gerhard,Enders, Dieter
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supporting information
p. 2266 - 2269
(2015/02/05)
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- Practical Synthesis of Polysubstituted Haloimidazoles from 1,1-Dibromoalkenes and Amidines
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The copper-catalyzed cycloamination reaction of 1,1-dibromoalkenes with amidines affords a diverse set of polysubstituted haloimidazole derivatives. By using this strategy, high regio- and chemoselectivity has been achieved, using 4,7-diphenyl-1,10-phenanthroline as ligand without the addition of expensive catalysts to provide moderate to good yields. The copper-catalyzed cycloamination reaction of 1,1-dibromoalkenes with amidines affords a diverse set of polysubstituted haloimidazole derivatives. Moderate to good yields with high regio- and chemoselectivities were achieved by using 4,7-diphenyl-1,10-phenanthroline as ligand without the addition of expensive catalyst.
- Li, Yibiao,Cheng, Liang,Shao, Yan,Jiang, Shaohua,Cai, Jialing,Qing, Ning
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supporting information
p. 4325 - 4329
(2015/07/27)
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- N-Substitution dependent stereoselectivity switch in palladium catalyzed hydroalkynylation of ynamides: A regio and stereoselective synthesis of ynenamides
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A highly general palladium catalysed regioselective hydroalkynylation of ynamides for versatile enamide building blocks with an alkyne tether is achieved with an N-substitution dependent stereoselectivity switch under very mild reaction conditions.
- Dwivedi, Vikas,Hari Babu, Madala,Kant, Ruchir,Sridhar Reddy, Maddi
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supporting information
p. 14996 - 14999
(2015/10/12)
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- A Convenient Stereoselective Reduction of Gem-Dibromides with a Combination of Dimethyl Phosphite and Potassium Carbonate
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An efficient and highly stereoselective reduction of a gem-dibromocyclopropane to the corresponding monobromocyclopropane under mild reaction conditions was developed using a combination of dimethyl phosphite and potassium carbonate. This reaction provided a simple and practical way for the synthesis of the valuable monobromocyclopropanes and β-monobromoalkenes.
- Zhao, Yalei,Chen, Tieqiao,Wang, Xiang-Bo,Han, Li-Biao
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p. 1820 - 1827
(2015/12/12)
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- Gold-catalyzed 1,2-iminonitronation of electron-deficient alkynes with nitrosoarenes to afford α-imidoyl nitrones
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Gold-catalyzed 1,2-iminonitronation of propiolate derivatives with nitrosoarenes to give α-imidoyl nitrones is described; this new reaction is applicable to diverse propiolate derivatives and nitrosoarenes.
- Singh, Rahulkumar Rajmani,Liu, Rai-Shung
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supporting information
p. 15864 - 15866
(2015/01/08)
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- Palladium(0)-catalyzed cross-coupling of 1,1-diboronates with vinyl bromides and 1,1-dibromoalkenes
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Palladium-catalyzed cross-coupling reactions of 1,1-diboronates with vinyl bromides and dibromoalkenes were found to afford 1,4-dienes and allenes, respectively. These reactions utilize the high reactivities of both 1,1-diboronates and allylboron intermediates generated in the initial coupling.
- Li, Huan,Zhang, Zhikun,Shangguan, Xianghang,Huang, Shan,Chen, Jun,Zhang, Yan,Wang, Jianbo
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supporting information
p. 11921 - 11925
(2015/01/09)
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- Synthesis of dibromoolefins via a tandem ozonolysis-dibromoolefination reaction
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In this Letter we outline the synthesis of a variety of dibromoolefins (DBOs) from a series of alkenes by coupling an oxidative cleavage and a reaction with a phosphorous ylide. This approach strategically avoids isolation of reactive aldehyde intermediates and presents one of the few examples coupling carbon-carbon bond formation with ozonolysis.
- Brown, Brenna Arlyce,Veinot, Jonathan G.C.
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supporting information
p. 792 - 795
(2013/02/25)
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- Nickel(II)-magnesium-catalyzed cross-coupling of 1,1-dibromo-1-alkenes with diphenylphosphine oxide: One-pot synthesis of (E)-1-alkenylphosphine oxides or bisphosphine oxides
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A novel nickel(II)-magnesium-mediated cross-coupling of diphenylphosphine oxide with a variety of 1,1-dibromo-1-alkenes has been developed, which provides a powerful and general methodology for the stereoselective synthesis of various (E)-1-alkenylphosphine oxides or bisphosphine oxides, with operational simplicity of the procedure, good to high yields and broad substrate applicability. Mechanistic studies reveal that the reaction might involve a Hirao reduction, cross-coupling and Michael addition. Copyright
- Liu, Liu,Wang, Yulei,Zeng, Zhiping,Xu, Pengxiang,Gao, Yuxing,Yin, Yingwu,Zhao, Yufen
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supporting information
p. 659 - 666
(2013/04/10)
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- An efficient one-pot synthesis of 3,5-diaryl-4-bromopyrazoles by 1,3-dipolar cycloaddition of in situ generated diazo compounds and 1-bromoalk-1-ynes
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A simple, highly efficient, one-pot synthesis of 3,5-di-aryl-4- bromopyrazoles via 1,3-dipolar cycloaddition of diazo compounds and alkynyl bromides has been developed. The diazo compounds and alkynyl bromides were generated in situ from tosylhydrazones and gem-dibromoalkenes, respectively. When ketone-derived hydrazones were used, 3,5-diaryl-4-bromo-3H-pyrazoles were obtained and the isomerization products 3,5-diaryl-4-bromo-1H-pyrazoles were formed when using aldehyde-derived hydrazones. The reaction system exhibited high regioselectivity and good functional group tolerance. Both electron-rich and electron-deficient-substituents on the aromatic ring of the hydrazones or the gem-dibromoalkenes gave desired products in moderate to good yields (67-86%). Georg Thieme Verlag Stuttgart - New York.
- Sha, Qiang,Wei, Yunyang
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supporting information
p. 413 - 420
(2013/03/14)
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- Copper-mediated C-H activation of 1,3,4-oxadiazoles with 1,1-dibromo-1-alkenes using PEG-400 as a solvent medium: Distinct approach for the alkynylation of 1,3,4-oxadiazoles
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The direct C-H alkynylation of 1,3,4-oxadiazoles with 1,1-dibromo-1-alkenes has been accomplished by using a combination of CuBr/LiOtBu in PEG-400 (a green solvent) at 80 °C. The products were formed in high yields (73-86%) in 2 h. No additional ligand or volatile solvent was required and the conversion was ecofriendly. The direct C-H alkynylation of 1,3,4-oxadiazoles with 1,1-dibromo-1-alkenes has been accomplished by using a combination of CuBr/LiOtBu in PEG-400 (a green solvent) at 80 °C. The products were formed in high yields (73-86%) in 2 h. No additional ligand or volatile solvent was required and the conversion was ecofriendly. Copyright
- Reddy, Gandolla Chinna,Balasubramanyam, Penagaluri,Salvanna,Das, Biswanath
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supporting information; experimental part
p. 471 - 474
(2012/03/08)
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- Pd-Catalyzed C-3 functionalization of indolizines via C-H bond cleavage
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New transition metal-catalyzed methods for the arylation of indolizines by the direct cleavage of C-H bonds have been developed. A wide range of aryltrifluoroborate salts react with indolizines in the presence of Pd(OAc) 2 catalyst and AgOAc oxidant to give the arylated indolizines in high yields. Both electron-donating and electron-withdrawing groups perform smoothly while bromide and chlorine substituents are tolerated. In addition, the indolizines display similar reactivities in the Pd-catalyzed reaction with 3-phenylpropiolic acid to afford the corresponding C-3 alkynylated indolizines. These methods allow the direct functionalization of indolizines in one step.
- Zhao, Baoli
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supporting information; experimental part
p. 7108 - 7119
(2012/09/25)
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- Synthesis of 1,2-disubstituted acetylenes via copper-catalyzed Suzuki coupling of organoboronic acids with 1,1-dibromo-1-alkenes
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An efficient synthesis of 1,2-disubstituted acetylenes has been described. Reactions of organoboronic acids with 1,1-dibromo-1-alkenes in the presence of a catalytic amount of CuI (10 mol %), 8-hydroxyquinoline (10 mol %), and using potassium phosphate as base in C2H5OH afforded the desired 1,2-disubstituted acetylenes in good to excellent yields. It is important to note that the formation of 1,3-diynes, which are derived from the homocoupling of 1,1-dibromo-1-alkenes, can be almost completely suppressed under these optimized conditions.
- Liu, Jidan,Dai, Fenglin,Yang, Zhiyong,Wang, Sizhuo,Xie, Kai,Wang, Anwei,Chen, Xiang,Tan, Ze
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supporting information
p. 5678 - 5683
(2015/04/15)
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- One-pot synthesis of telluroketene acetals and haloketene acetals using sp2 geminated hetero organobismetallic intermediates
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A novel one-pot synthesis of 1,1-dihalo-1-alkenes and 1,1-bis(butyltelluro) -1-alkenes was developed from hydrozirconation of alkynylzinc bromide with Cp2Zr(H)Cl and subsequent capture of the Zn/Zr 1,1-heterodimetallo-1- alkene intermediates wi
- Guerrero Jr., Palimécio G.,De Oliveira, Paulo R.,Baroni, Adriano C.M.,Marques, Francisco A.,Labes, Ricardo,Dabdoub, Miguel J.
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experimental part
p. 1582 - 1586
(2012/04/10)
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- An efficient, overall [4+1] cycloadditon of 1,3-dienes and nitrene precursors
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Intermolecular cycloadditions of conjugated dienes and nitrene precursors usually produce aziridines. A generally useful method was lacking to directly provide the [4+1] cycloadducts, 3-pyrrolines. We have realized this transformation by using an uniquely active catalyst, copper(II) 1,1,1,5,5,5-hexafluoroacetylacetonate ([Cu(hfacac)2]). The method is applicable to a wide array of dienes with good yields. When 1,4-disubsituted dienes are used as substrates, good-to-excellent cis or trans selectivity can be obtained. Interestingly, the cis or trans preference depends on the nature of the substituents, rather than diene geometry. Mechanistic studies reveal that the [4+1] cycloaddition proceeds through diene aziridination and subsequent ring expansion. Among common copper catalysts, only [Cu(hfacac)2] can efficiently catalyze both steps, which explains the unique efficiency of the catalyst.
- Wu, Qiong,Hu, Jian,Ren, Xinfeng,Zhou, Jianrong
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supporting information; experimental part
p. 11553 - 11558
(2011/11/29)
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- Convenient synthesis of 2-aryl-1-haloindolizines from pyridinium salts and 2-aryl-1,1-dihaloalk-1-enes
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2-Aryl-1-haloindolizines were synthesized from pyridinium salts and 2-aryl-1,1-dihaloalk-1-enes using a DBU/THF system. 2-Aryl-1,1-dihaloalk-1-enes containing electron-withdrawing or -donating groups were efficiently converted into the corresponding 2-aryl-1-haloindolizines in moderate to excellent yields. Georg Thieme Verlag Stuttgart.
- Yang, Yiwen,Kuang, Chunxiang,Jin, Hui,Yang, Qing
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supporting information; experimental part
p. 3447 - 3452
(2011/12/04)
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- Tandem suzuki-miyaura cross-coupling/dehydrobromination of 1,1-dibromoalkenes to alkynes with a cyclobutene-1,2-diylbis(imidazolium) salt as catalyst precursor
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A cyclobutene-1,2-bis(imidazolium) salt proved to be an efficient catalyst precursor for one-pot tandem Suzuki-Miyaura/dehydrobromination reactions for the synthesis of alkynes starting from 1,1-dibromoalkenes and palladium(II) acetate, aryl boronic acids, and potassium tert-butoxide in toluene. Starting materials were prepared from aldehydes under Corey-Fuchs conditions. Georg Thieme Verlag Stuttgart New York.
- Rahimi, Alireza,Schmidt, Andreas
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experimental part
p. 2621 - 2625
(2010/09/10)
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- Pd-catalyzed domino synthesis of internal alkynes using triarylbismuths as multicoupling organometallic nucleophiles
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Figure presented The domino coupling reaction of 1,1-dibromo-1-alkenes with triarylbismuth nucleophiles has been demonstrated to furnish disubstituted alkynes directly under catalytic palladium conditions. The couplings of triarylbismuths as multicoupling nucleophiles with 3 equiv of 1,1-dibromo-1-alkenes are very fast, affording high yields of alkynes in a short reaction time. Thus, an efficient domino process has been accomplished using 1,1-dibromo-1-alkenes as surrogates for internal alkyne synthesis in couplings with triarylbismuths in a one-pot operation.
- Rao, Maddali L. N.,Jadhav, Deepak N.,Dasgupta, Priyabrata
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supporting information; experimental part
p. 2048 - 2051
(2010/07/03)
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- 1,1-dibromo-1-alkenes as valuable partners in the copper-catalyzed direct alkynylation of azoles
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The copper-catalyzed direct alkynylation of azoles with 1,1-dibromo-1-alkenes as electrophiles is described. These easily accessible substrates are a useful addition to the field of direct alkynylations in an efficient and functional group tolerant reaction to provide a straightforward entry to diverse alkynyl heterocycles.
- Pacheco Berciano, Beatriz,Lebrequier, Sabrina,Besselievre, Francois,Piguel, Sandrine
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supporting information; experimental part
p. 4038 - 4041
(2010/11/16)
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