- Molecular Solar Thermal Batteries through Combination of Magnetic Nanoparticle Catalysts and Tailored Norbornadiene Photoswitches
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Cobalt catalysts are immobilized on the surface of iron oxide nanoparticles for the preparation of highly active quasi-homogeneous catalysts toward an efficient release of photochemically stored energy in norbornadiene-based photoswitches. The facile sepa
- Lorenz, Patrick,Luchs, Tobias,Hirsch, Andreas
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supporting information
p. 4993 - 5002
(2021/02/26)
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- Copper-catalyzed domino synthesis of ynamines
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The hitherto unexploredN-alkynylation of electron-withdrawing or protecting group free N-heteroarenes such as indole, carbazole and pyrrole was developed usinggem-dibromoalkenes to synthesize ynamines under ligand-free copper-catalyzed domino conditions. The development methodology of ynamines was also applied in the synthesis of enynamines, multi-coupled bis-ynamines, tris-ynamines, and the natural product peyonine, demonstrating its broad synthetic scope and applications.
- Dasgupta, Priyabrata,Islam, Sk Shamim,Rao, Maddali L. N.
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supporting information
p. 7855 - 7860
(2021/09/28)
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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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- 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 .
- -
-
Paragraph 0162-0166
(2021/11/26)
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- Total Synthesis of Dictyodendrins A–F by the Gold-Catalyzed Cascade Cyclization of Conjugated Diyne with Pyrrole
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The total synthesis of dictyodendrins A–F was achieved by using the gold(I)-catalyzed annulation of a conjugated diyne with N-Boc-pyrrole for direct construction of the pyrrolo[2,3-c]carbazole scaffold. Late-stage functionalization of the resulting pyrrolo[2,3-c]carbazole to introduce various substituents provided divergent access to dictyodendrins. Some dictyodendrin analogues exhibited inhibitory activities toward CDK2/CycA2 and GSK3.
- Inuki, Shinsuke,Matsuda, Yuka,Matsuoka, Junpei,Miyamoto, Yoichi,Ohno, Hiroaki,Oishi, Shinya,Oka, Masahiro,Otani, Mayumi
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supporting information
(2020/07/13)
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- Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands
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A chiral phenol–NHC ligand enabled the copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters. The phenol moiety of the chiral NHC ligand played a critical role in producing the enantiomerically enriched products. The catalyst worked well for various (Z)-isomer substrates. Opposite enantiomers were obtained from (Z)- and (E)-isomers, with a higher enantiomeric excess from the (Z)-isomer.
- Mimura, Shohei,Mizushima, Sho,Sawamura, Masaya,Shimizu, Yohei
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supporting information
p. 537 - 543
(2020/05/14)
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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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- Thermal decarboxylative Nazarov cyclization of cyclic enol carbonates involving chirality transfer
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Decarboxylative Nazarov cyclization of chiral cyclic enol carbonates proceeded to afford chiral 2-cyclopentenones with excellent chirality transfer under thermal conditions without any catalyst. Interestingly, the thermal decarboxylative Nazarov cyclization furnished the desired product with better chirality transfer than the Lewis acid-catalyzed reaction.
- Kozuma, Akane,Komatsuki, Keiichi,Saito, Kodai,Yamada, Tohru
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supporting information
p. 60 - 63
(2019/12/12)
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- Iron-Catalyzed Reductive Vinylation of Tertiary Alkyl Oxalates with Activated Vinyl Halides
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We present herein a rare and efficient method for the creation of vinylated all carbon quaternary centers via Fe-catalyzed cross-electrophile coupling of vinyl halides with tertiary alkyl methyl oxalates. The reaction displays excellent functional group tolerance and broad substrate scope, which allows cascade radical cyclization and vinylation to afford complex bicyclic and spiral structural motifs. The reaction proceeds via tertiary alkyl radicals, and the putative vinyl-Br/Fe complexation appears to be crucial for activating the alkene and enabling a possibly concerted radical addition/C-Fe forming process.
- Chen, Haifeng,Gong, Hegui,Yao, Ken,Ye, Yang
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supporting information
(2020/03/13)
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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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- Nickel-Catalyzed Directed Hydroarylation of Alkynes with Boronic Acids
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A regio- and stereoselective nickel-catalyzed hydroarylation of alkynes using propargylic carbamates as directing groups has been developed. The reaction proceeds under mild reaction conditions using arylboronic acids in the absence of base. A range of heterocycles and functional groups are tolerated under the reaction conditions, providing high yields of trisubstituted alkenes with control of olefin geometry.
- Hanna, Luke E.,Konev, Mikhail O.,Jarvo, Elizabeth R.
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supporting information
p. 184 - 187
(2018/12/05)
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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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- Visible-Light-Promoted Oxo-Sulfonylation of Ynamides with Sulfonic Acids
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A visible-light-promoted oxo-sulfonylation of ynamides with sulfonic acids is reported, giving rise to a collection of functionalized α-sulfonylated amides in a straightforward manner. The reaction proceeds sequentially through a cascade of electrophilic addition and photoinduced sulfonyl radical-sustained skeleton rearrangement. The high atom economy, mild reaction conditions, and wide substrate scope comprised the merits of this synthetic transformation.
- Wang, Lu,Lu, Chengrong,Yue, Yanni,Feng, Chao
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supporting information
p. 3514 - 3517
(2019/05/16)
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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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- Enantioselective Oxy-Heck–Matsuda Arylations: Expeditious Synthesis of Dihydrobenzofuran Systems and Total Synthesis of the Neolignan (?)-Conocarpan
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This work discloses the first examples of an effective enantioselective oxy-Heck–Matsuda reaction using a variety of styrenic olefins to generate chiral dihydrobenzofurans. The reaction proceeds in moderate to good yields, with high trans diastereoselectivity (up to 20:1) in enantioselectivities up to 90:10 using the N,N-ligand pyrimidine-bisoxazoline (PyriBox). The oxy-Heck–Matsuda reactions were carried out under mild conditions and rather low catalyst loadings. The feasibility and practicality of the process is demonstrated by a concise total synthesis of the neolignan (?)-conocarpan. X-ray diffraction of an advanced brominated intermediate in the route to (?)-conocarpan has allowed the unequivocal assignment of the absolute stereochemistry of the oxy-Heck–Matsuda aryldihydrobenzofuran products. A rationale for the mechanism operating in these enantioselective oxy-Heck–Matsuda reactions is also presented. (Figure presented.).
- Silva, Allan R.,Polo, Ellen C.,Martins, Nelson C.,Correia, Carlos Roque D.
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p. 346 - 365
(2018/01/26)
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- Palladium-Catalyzed Hydride Addition/C-H Bond Activation Cascade: Cycloisomerization of 1,6-Diynes
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The use of ammonium halide salts as metal hydride precursors in a new Pd-catalyzed cycloisomerization of 1,6-diynes, which affords unexplored silylated 2-azafluorenes, is reported. This cascade process includes the addition of a Pd-hydride species to a π-system, intramolecular carbopalladation, and C(sp2)-H bond activation. A variety of functional groups are tolerated, and the synthetic utility of the resulting products has been demonstrated by a series of derivatizations.
- Rodríguez, José F.,Burton, Katherine I.,Franzoni, Ivan,Petrone, David A.,Scheipers, Ina,Lautens, Mark
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p. 6915 - 6919
(2018/11/21)
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- Rhodium-catalyzed enantioselective decarboxylative alkynylation of allenes with arylpropiolic acids
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A rhodium-catalyzed chemo-, regio-, and enantioselective intermolecular decarboxylative alkynylation of terminal allenes with arylpropiolic acids is reported. Employing a Rh(I)/(R)-Tol-BINAP catalytic system, branched allylic 1,4-enynes were obtained under mild conditions. The overall utility of this protocol is exemplified by a broad functional group compatibility.
- Grugel, Christian P.,Breit, Bernhard
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supporting information
p. 1066 - 1069
(2018/02/23)
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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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- Direct Cross-Coupling of Allylic C(sp3)?H Bonds with Aryl- and Vinylbromides by Combined Nickel and Visible-Light Catalysis
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An efficient protocol for the direct allylic C(sp3)?H bond activation of unactivated tri- and tetrasubstituted alkenes and their functionalization with aryl- and vinylbromides by nickel and visible-light photocatalysis has been developed. The method allows C(sp2)?C(sp3) formation under mild reaction conditions with good functional-group tolerance and excellent regioselectivity.
- Huang, Long,Rueping, Magnus
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supporting information
p. 10333 - 10337
(2018/07/31)
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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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- Total Synthesis of Dictyodendrins by the Gold-Catalyzed Cascade Cyclization of Conjugated Diynes with Pyrroles
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In total and formal syntheses of dictyodendrins B, C, E, and F, the key step involved the direct construction of the pyrrolo[2,3-c]carbazole core by the gold-catalyzed annulation of a conjugated diyne with a pyrrole to form three bonds and two aromatic rings. The subsequent introduction of substituents at the C1 (Suzuki–Miyaura coupling), C2 (addition to an aldehyde), N3 (alkylation), and C5 positions (Ullman coupling) provided divergent access to dictyodendrins.
- Matsuoka, Junpei,Matsuda, Yuka,Kawada, Yuiki,Oishi, Shinya,Ohno, Hiroaki
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supporting information
p. 7444 - 7448
(2017/06/13)
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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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- Synthesis of ent-[3]-Ladderanol: Development and Application of Intramolecular Chirality Transfer [2+2] Cycloadditions of Allenic Ketones and Alkenes
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An enantioselective synthesis of ent-[3]-ladderanol is presented. The ladderanes are an interesting class of molecules for their unique structure of fused cyclobutane rings as well as their perceived biological function of organism protection. The route h
- Line, Nathan J.,Witherspoon, Brittany P.,Hancock, Erin N.,Brown, M. Kevin
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supporting information
p. 14392 - 14395
(2017/10/24)
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- Enantioselective Palladium-Catalyzed Oxidative Cascade Cyclization of Aliphatic Alkenyl Amides
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The catalyst system of Pd(TFA)2/(S,S)-diPh-pyrox is reported to promote the highly efficient enantioselective oxidative cascade cyclization of alkene-tethered aliphatic acrylamides under mild aerobic conditions. A series of pyrrolizidine derivatives have been synthesized in good yield and excellent enantioselectivity. Deuterium-labeling experiments have revealed that the reaction proceeded through an anti-aminopalladation (anti-AP) pathway with high selectivity. The transition states for the anti-AP step have been calculated to account for the observed enantioselectivity.
- Du, Wei,Gu, Qiangshuai,Li, Yang,Lin, Zhenyang,Yang, Dan
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supporting information
p. 316 - 319
(2017/04/21)
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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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- Palladium-catalyzed tandem C-H functionalization/cyclization strategy for the synthesis of 5-hydroxybenzofuran derivatives
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A palladium-catalyzed benzoquinone C-H functionalization/ cyclization strategy with terminal alkynes was employed for the synthesis of some biologically relevant 2, 3-disubstituted 5-hydroxybenzofuran derivatives. The benzoquinone acts as a reactant as well as an oxidant. During the process, an additional alkyne functionality can be introduced at the C3 position of the benzofuran. Base, ligand, and external oxidant are not required in this protocol.
- Ichake, Sachin S.,Konala, Ashok,Kavala, Veerababurao,Kuo, Chun-Wei,Yao, Ching-Fa
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supporting information
p. 54 - 57
(2017/11/28)
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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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- Synthesis of Ketones and Esters from Heteroatom-Functionalized Alkenes by Cobalt-Mediated Hydrogen Atom Transfer
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Cobalt bis(acetylacetonate) is shown to mediate hydrogen atom transfer to a broad range of functionalized alkenes; in situ oxidation of the resulting alkylradical intermediates, followed by hydrolysis, provides expedient access to ketones and esters. By modification of the alcohol solvent, different alkyl ester products may be obtained. The method is compatible with a number of functional groups including alkenyl halides, sulfides, triflates, and phosphonates and provides a mild and practical alternative to the Tamao-Fleming oxidation of vinylsilanes and the Arndt-Eistert homologation.
- Ma, Xiaoshen,Herzon, Seth B.
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p. 8673 - 8695
(2016/10/17)
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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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- Direct Metal-Free Entry to Aminocyclobutenes or Aminocyclobutenols from Ynamides: Synthetic Applications
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The [2+2] cycloaddition of ynamides with the highly polarized reagent Tf2C=CH2has been developed to regioselectively afford bis(triflyl)aminocyclobutenes in the absence of catalyst under mild conditions. Incidentally, with the ynamides bearing electron-rich aromatic rings at the C-terminal, an interesting reactivity switch was observed; a cyclization/hydroxylation sequence yielded 2-amino-3-(triflyl)cyclobut-2-enols. Aminocyclobutene construction with addition of alcohols resulted in the formation of aminocyclobutenyl ethers through a cyclization/hydroalkoxylation process. Moreover, the utility of functionalized aminocyclobutenes as precursors for further elaboration was demonstrated with the preparation of α-amino-β,γ-unsaturated ketones and 3-(triflyl)buta-1,3-dien-2-amines through 4 π-electrocyclic ring opening.
- Alcaide, Benito,Almendros, Pedro,Lázaro-Milla, Carlos
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supporting information
p. 8998 - 9005
(2016/07/06)
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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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- 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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- 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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- Dual gold catalysis: A novel synthesis of bicyclic and tricyclic pyrroles from n -propargyl ynamides
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Various N-propargyl ynamides were converted to bicylic and tricyclic pyrroles by the use of a cationic dual-activation gold catalyst. This reaction starts with the nucleophilic addition of a gold acetylide onto an ynamide triple bond at the ?2-position of the nitrogen atom. Thus, gold vinylidene is formed, and then a second cyclization takes place. The formation of the gold vinylidene is indicated by the evidence that not only aryl ynamides but also alkyl ynamides undergo C-H activation in these reactions.
- Tokimizu, Yusuke,Wieteck, Marcel,Rudolph, Matthias,Oishi, Shinya,Fujii, Nobutaka,Hashmi, A. Stephen K.,Ohno, Hiroaki
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supporting information
p. 604 - 607
(2015/03/05)
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- Anionic sigmatropic-electrocyclic-chugaev cascades: Accessing 12-aryl-5-(methylthiocarbonylthio)tetracenes and a related anthra[2,3-b]thiophene
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1,4-Diols resulting from the double addition of ArCCLi (Ar = Ph, substituted phenyl, 2-thienyl) to ortho-C6H4(CHO)2 undergo cascades to tetracenes on simple admixture of LiHDMS, CS2 and MeI. Acene formation proceeds by [3,3]-sigmatropic rearrangement of xanthate anions followed by 6π electrocyclisations. The reactions are terminated by E2 or anionic Chugaev-type eliminations. Structural packing motifs and electronic properties are reported for the tetracenes.
- Burroughs, Laurence,Ritchie, John,Ngwenya, Mkhethwa,Khan, Dilfaraz,Lewis, William,Woodward, Simon
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supporting information
p. 273 - 279
(2015/06/23)
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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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- Synthesis of benzannulated heterocycles by twofold Suzuki-Miyaura couplings of cyclic diarylborinic acids
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Two-fold Suzuki-Miyaura cross-couplings of cyclic diarylborinic acids are described. This novel annulation method enables the synthesis of benzo-fused heterocycles from dihaloarenes or gem-dibromoolefins.
- Dimitrijevic, Elena,Cusimano, Madeline,Taylor, Mark S.
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supporting information
p. 1391 - 1394
(2014/03/21)
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- Copper-catalyzed N-alkynylations of sulfoximines with bromoacetylenes
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N-Alkynylated sulfoximines have been obtained by copper-catalyzed cross-coupling reactions starting from NH-sulfoximines and bromoacetylenes in moderate to good yields. The reaction conditions are mild, and the substrate scope is wide.
- Chen, Xiao Yun,Wang, Long,Frings, Marcus,Bolm, Carsten
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supporting information
p. 3796 - 3799
(2014/08/05)
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- Chiral propargylic cations as intermediates in SN1-type reactions: Substitution pattern, nuclear magnetic resonance studies, and origin of the diastereoselectivity
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Nine propargylic acetates, bearing a stereogenic center (-C*HXR 2) adjacent to the electrophilic carbon atom, were prepared and subjected to SN1-type substitution reactions with various silyl nucleophiles employing bismuth trifluoromethanesulfonate [Bi(OTf)3] as the Lewis acid. The diastereoselectivity of the reactions was high when the alkyl group R2 was tertiary (tert-butyl), irrespective of the substituent X. Products were formed consistently with a diastereomeric ratio larger than 95:5 in favor of the anti-diastereoisomer. If the alkyl substitutent R2 was secondary, the diastereoselectivity decreased to 80:20. The reaction was shown to proceed stereoconvergently, and the relative product configuration was elucidated. The reaction outcome is explained by invoking a chiral propargylic cation as an intermediate, which is preferentially attacked by the nucleophile from one of its two diastereotopic faces. Density functional theory (DFT) calculations suggest a preferred conformation in which the group R2 is almost perpendicular to the plane defined by the three substituents at the cationic center, with the nucleophile approaching the electrophilic center opposite to R2. Transition states calculated for the reaction of allyltrimethylsilane with two representative cations support this hypothesis. Tertiary propargylic cations with a stereogenic center (-C* HXR2) in the α position were generated by ionization of the respective alcohol precursors with FSO3H in SO2ClF at -80 C. Nuclear magnetic resonance (NMR) spectra were obtained for five cations, and the chemical shifts could be unambiguously assigned. The preferred conformation of the cations as extracted from nuclear Overhauser experiments is in line with the preferred conformation responsible for the reaction of the secondary propargylic cations.
- Nitsch, Dominik,Huber, Stefan M.,Poethig, Alexander,Narayanan, Arjun,Olah, George A.,Prakash, G. K. Surya,Bach, Thorsten
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supporting information
p. 2851 - 2857
(2014/03/21)
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- Rhodium(I)-catalyzed carbonylative arylation of alkynes with arylboronic acids using formaldehyde as a carbonyl source
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The rhodium(I)-catalyzed reaction of alkynes with arylboronic acids in the presence of formaldehyde resulted in a carbon monoxide gas-free carbonylative arylation to yield α,β-enones. The simultaneous loading of phosphine-ligated and phosphine-free rhodium(I) complexes is required for efficient catalysis, which catalyze the abstraction of a carbonyl moiety from formaldehyde (decarbonylation) and its subsequent introduction into the substrate (carbonylation), respectively. Georg Thieme Verlag Stuttgart New York.
- Wang, Chuang,Morimoto, Tsumoru,Kanashiro, Hiroyuki,Tanimoto, Hiroki,Nishiyama, Yasuhiro,Kakiuchi, Kiyomi,Artok, Levent
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supporting information
p. 1155 - 1159
(2014/05/20)
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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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- 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 catalyzed decarboxylative alkynylation of quaternary α-cyano acetate salts
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Cu-catalyzed decarboxylative alkynylation of quaternary α-cyano acetate salts with alkynyl bromides and alkynyl chlorides is described. This new reaction can be used for preparing functionalized butynenitrile derivatives.
- Feng, Yi-Si,Xu, Zhong-Qiu,Mao, Long,Zhang, Feng-Feng,Xu, Hua-Jian
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supporting information
p. 1472 - 1475
(2013/06/27)
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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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- HISTONE DEACETYLASE INHIBITORS
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The disclosure provides compounds of formula I and methods for preparation thereof. The compounds act as inhibitor of histone deacetylase.
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Page/Page column 11
(2012/05/04)
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