- Iron-Catalyzed Regioselective Alkenylboration of Olefins
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The first examples of an iron-catalyzed three-component synthesis of homoallylic boronates from regioselective union of bis(pinacolato)diboron, an alkenyl halide (bromide, chloride or fluoride), and an olefin are disclosed. Products that bear tertiary or quaternary carbon centers could be generated in up to 87 % yield as single regioisomers with complete retention of the olefin stereochemistry. With cyclopropylidene-containing substrates, ring cleavage leading to trisubstituted E-alkenylboronates were selectively obtained. Mechanistic studies revealed reaction attributes that are distinct from previously reported alkene carboboration pathways.
- Yu, Xiaolong,Zheng, Hongling,Zhao, Haonan,Lee, Boon Chong,Koh, Ming Joo
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supporting information
p. 2104 - 2109
(2020/11/30)
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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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- 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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- A Radical-Initiated Fragmentary Rearrangement Cascade of Ene-Ynamides to [1,2]-Annulated Indoles via Site-Selective Cyclization
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Straightforward access to [1,2]-annulated indoles, key substructures in natural products, is highly desirable yet challenging. Herein, a radical triggered fragmentary cyclization cascade reaction of ene-ynamides is presented, providing a rapid access into [1,2]-annulated indoles by an intermolecular radical addition, intramolecular cyclization, desulfonylative aryl migration, and site-selective C(sp2)-N cyclization sequence. DFT calculations support oxidation of N-centered radical species to cations prior to the C-N bond formation, followed by an unusual aza-Nazarov cyclization.
- Li, Sifan,Wang, Yu,Wu, Zibo,Shi, Weiliang,Lei, Yibo,Davies, Paul W.,Shu, Wei
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p. 7209 - 7214
(2021/09/14)
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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 0173-0177
(2021/11/26)
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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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- 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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- 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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- 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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- Efficient Access to Chiral β-Borylated Carboxylic Esters via Rh-Catalyzed Hydrogenation
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Rh/bisphosphine?thiourea ligand (ZhaoPhos)-catalyzed asymmetric hydrogenation of (Z)-β-substituted-β-boryl-α,β-unsaturated esters was successfully developed, furnishing a variety of chiral β-borylated carboxylic esters with high yields and excellent enantioselectivities (up to 99% yield and >99% ee). The gram-scale asymmetric hydrogenation was performed efficiently in the presence of only 0.05 mol% (S/C=2 000) catalyst loading with full conversion, 99% yield and 99% ee. Moreover, the hydrogenation product was easily converted to other versatile synthetic intermediates, such as methyl (S)-3-hydroxy-3-phenylpropanoate and methyl (S)-3-(furan-2-yl)-3-phenylpropanoate. (Figure presented.).
- Liu, Gang,Li, Anqi,Qin, Xueyuan,Han, Zhengyu,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 2844 - 2848
(2019/04/26)
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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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- 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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- Rh-Catalyzed Asymmetric Hydrogenation of β-Substituted-β-thio-α,β-unsaturated Esters: Expeditious Access to Chiral Organic Sulfides
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Rh/bifunctional bisphosphine-thiourea ligand (ZhaoPhos)-catalyzed asymmetric hydorgenation of both (Z)- and (E)-isomers of β-substituted-β-thio-α,β-unsaturated esters was successfully developed. This new asymmetric catalytic methodology provided highly efficient access to two enantiomers of chiral organic sulfides ethyl β-substituted-β-thio-propanoates with excellent results (up to 99% yield and >99% ee for (Z)-substrates, up to 99% yield and 98% ee for (E)-substrates, TON up to 5000), which are important intermediates in organic synthesis.
- Liu, Gang,Han, Zhengyu,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 5636 - 5639
(2018/09/12)
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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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- Ni-catalyzed reductive coupling of α-halocarbonyl derivatives with vinyl bromides
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This work describes the vinylation of α-halo carbonyl compounds with vinyl bromides under Ni-catalyzed reductive coupling conditions. While aryl-conjugated vinyl bromides entail pyridine as the sole labile ligand, the alkyl-substituted vinyl bromides require both bipyridine and pyridine as the co-ligands.
- Qiu, Canbin,Yao, Ken,Zhang, Xinghua,Gong, Hegui
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supporting information
p. 11332 - 11335
(2016/12/18)
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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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- 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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- 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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- 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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- 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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- 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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- 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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- Formation of quaternary stereogenic centers by copper-catalyzed asymmetric conjugate addition reactions of alkenylaluminums to trisubstituted enones
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Alkenylaluminums undergo asymmetric copper-catalyzed conjugate addition (ACA) to β-substituted enones allowing the formation of stereogenic all-carbon quaternary centers. Phosphinamine-copper complexes proved to be particularly active and selective compared with phosphoramidite ligands. After extensive optimization, high enantioselectivities (up to 96 % ee) were obtained for the addition of alkenylalanes to β-substituted enones. Two strategies for the generation of the requisite alkenylaluminums were explored allowing for the introduction of aryl- and alkyl-substituted alkenyl nucleophiles. Moreover, alkyl-substituted phosphinamine (SimplePhos) ligands were identified for the first time as highly efficient ligands for the Cu-catalyzed ACA. Chiral synthesis made easy: The copper-catalyzed conjugate addition of alkenylaluminum reagents to 3-substituted cyclic enones allows for the formation of all-carbon chiral quaternary centers (see scheme; CuTC=copper(I) thiophene-2-carboxylate). Chiral phosphinamine (SimplePhos) ligands were found to be highly efficient for this transformation.
- Mueller, Daniel,Alexakis, Alexandre
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supporting information
p. 15226 - 15239
(2013/11/06)
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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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- Copper-catalyzed asymmetric 1,4-addition of alkenyl alanes to N-substituted-2-3-dehydro-4-piperidones
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Readily available vinyl alanes are used in the Cu-catalyzed asymmetric conjugate addition reaction to N-substituted-2-3-dehydro-4-piperidones. The enhanced reactivity of recently developed and easily prepared phosphine amine ligands in combination with inexpensive Cu(II)naphtenate (CuNp) allows the introduction of a great variety of alkenyl, alkyl, and aryl aluminums in high enantioselectivity.
- Mueller, Daniel,Alexakis, Alexandre
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supporting information; experimental part
p. 1842 - 1845
(2012/06/18)
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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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- 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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- Structure-activity relationship study of a novel necroptosis inhibitor, necrostatin-7
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Necroptosis is a regulated caspase-independent cell death mechanism characterized by morphological features resembling non-regulated necrosis. Necrotatin-7 (Nec-7), a novel potent small-molecule inhibitor of necroptosis, is structurally distinct from previously described necrostatins (Nec-1, Nec-3, Nec-4 and Nec-5). Here, we describe a series of structural modifications and the structure-activity relationship (SAR) of the Nec-7 series for inhibiting necroptosis.
- Zheng, Weihong,Degterev, Alexei,Hsu, Emily,Yuan, Junying,Yuan, Chengye
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scheme or table
p. 4932 - 4935
(2009/05/26)
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- Stereospecific approach to α,β-disubstituted nitroalkenes via coupling of α-bromonitroalkenes with boronic acids and terminal acetylenes
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(Z)-α-Bromo-β-substituted nitroethylenes undergo facile Suzuki coupling with aryl, heteroaryl, and vinylboronic acids in the presence of Pd(PPh3)4 as catalyst to afford (E)-α,β-disubstituted nitroethylenes in high yield (up to 95%) and complete specificity. Similar coupling of α-bromonitroethylenes with terminal acetylenes (Sonogashira coupling) provides a novel route to (E)-nitroenynes. These Pd-catalyzed coupling methods offer a convenient and stereospecific entry into a diverse array of synthetically and biologically useful α,β-disubstituted nitroethylenes.
- Ganesh, Madhu,Namboothiri, Irishi N.N.
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p. 11973 - 11983
(2008/03/13)
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- Aminoacetamide acyl guanidines as beta-secretase inhibitors
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There is provided a series of substituted acyl guanidines of Formula (Ik) or a stereoisomer; or a pharmaceutically acceptable salt thereof, wherein R2, R3, R4, R5, R25, R26 and R27 as defined herein, their pharmaceutical compositions and methods of use. These compounds inhibit the processing of amyloid precursor protein (APP) by β-secretase and, more specifically, inhibit the production of Aβ-peptide. The present disclosure is directed to compounds useful in the treatment of neurological disorders related to β-amyloid production, such as Alzheimer's disease and other conditions affected by anti-amyloid activity.
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Page/Page column 28
(2008/06/13)
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- A novel synthesis of β,β-dibromostyrenes
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A new simple and efficient transformation of aromatic aldehydes to β,β-dibromostyrenes and arylbromoacetylenes is described. The olefination procedure was conducted under mild conditions and in good yields.
- Shastin,Korotchenko,Nenajdenko,Balenkova
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p. 2081 - 2084
(2007/10/03)
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- Synthesis and Characterization of Side-Chain Liquid Crystalline Polymethacrylates Containing Fluorinated Diphenyldiacetylene Side-Groups
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The synthesis of four side-chai liquid crystalline polymethacrylates containing either 4-alkanyloxy-4'-fluorodiphenydiacetylenes or 4-alkanyloxy-3',4'-difluorodiphenyldiacetylenes side groups is presented.The phase behavior of both monomeric and polymeric
- Lu, Y.-H.,Tsay, K.-T.,Hsu, C.-S.,Chang, H.-L.
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- Synthesis and Physical Properties of Asymmetric Diphenyldiacetylenic Liquid Crystals
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Fifty-six asymmetric diphenyl-diacetylene liquid crystal homologs including dialkyl, alkyl-alkoxy, cyano-alkyl, chloro-alkyl, fluoro-alkyl, difluoro-alkyl, lateral chloro-substituted fluoro-alkyl (or alkoxy), lateral fluoro-substituted asymmetric dialkyl, and vinyl-alkyl are synthesized and their physical properties evaluated.Among these asymmetric diphenyl-diacetylene liquid crystals, many dialkyl homologs exhibit low melting point, wide nematic range, and low heat of fusion.They are ideal host candidates for formulating eutectic mixtures.The polar groups make important contributions to the phase transition temperature, dielectric anisotropy, refractive indices and viscosity.Detailed effects depend on the position of the substitution.These new liquid-crystals compounds and mixtures are particularly useful for electro-optic modulation of infrared radiation. - Keywords: Diphenyl-diacetylenes, eutectic mixtures, electro-optic modulation, physical properties
- Meng, H.-H. B.,Dalton, L. R.,Wu, S.-T.
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p. 303 - 314
(2007/10/02)
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