- Fritsch-Buttenberg-Wiechell rearrangement in the aliphatic series
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(Formula presented) Substituted vinylidene zinc carbenoids undergo a Fritsch-Buttenberg-Wiechell rearrangement. The migratory aptitude of the two groups R/R1 was studied by 13C labeling experiments and depends on the degree of substi
- Rezaei,Yamanoi,Chemla,Normant
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Read Online
- 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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- 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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- 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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- 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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- HOTf-Catalyzed, Solvent-Free Oxyarylation of Ynol Ethers and Thioethers
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A novel HOTf-catalyzed oxyarylation of ynol ethers and thioethers has been realized with aryl sulfoxides as the oxyarylating reagents, providing α-arylated esters or thioesters in good to excellent yields. Notably, all atoms of the starting materials were incorporated in the product (100% atom economy) and the reaction proceeded under very mild conditions. It was found that the reaction can be ran under air and that the best yields are obtained under solvent-free conditions.
- Hu, Liang,Gui, Qingwen,Chen, Xiang,Tan, Ze,Zhu, Gangguo
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p. 4861 - 4868
(2016/07/06)
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- Benzannulation of triynes to generate functionalized arenes by spontaneous incorporation of nucleophiles
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The thermal reaction of ester-tethered 1,3,8-triynes provides novel benzannulation products with concomitant incorporation of a nucleophile. Evidence suggests that this reaction proceeds via an allene-enyne intermediate generated by an Alder-ene reaction in the first step. Depending on the substituent of the alkyne moiety on the allene-enyne intermediate, the subsequent transformation can take one of two different paths, each leading to discrete aromatization products. The benzannulation of a silane-substituted 1,3,8-triynes provides arene products with a nucleophile incorporated onto the newly formed benzene core, whereas an aryl substituent leads to nucleophile trapping at the benzylic carbon atom connected to the aryl substituent. The formation of these two different products results from the involvement of two regioisomeric allene-enyne intermediates.
- Karmakar, Rajdip,Yun, Sang Young,Chen, Jiajia,Xia, Yuanzhi,Lee, Daesung
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supporting information
p. 6582 - 6586
(2015/06/02)
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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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- Nickel-catalyzed asymmetric reductive cross-coupling between vinyl and benzyl electrophiles
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A Ni-catalyzed asymmetric reductive cross-coupling between vinyl bromides and benzyl chlorides has been developed. This method provides direct access to enantioenriched products bearing aryl-substituted tertiary allylic stereogenic centers from simple, stable starting materials. A broad substrate scope is achieved under mild reaction conditions that preclude the pregeneration of organometallic reagents and the regioselectivity issues commonly associated with asymmetric allylic arylation.
- Cherney, Alan H.,Reisman, Sarah E.
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supporting information
p. 14365 - 14368
(2014/12/11)
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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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- 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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- CHBr3/TiCl4/Mg as an unusual nucleophilic CBr 2 carbenoid: Effective and chemoselective dibromomethylenation of aldehydes and ketones
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We report that instead of using CBr4, CHBr3 can serve as a highly nucleophilic dibromomethylene carbenoid in chemoselective carbonyl dibromomethylenation. Successful application of the dibromomethylenation to various carbonyl compoun
- Bhorge, Yeshwant Ramchandra,Chang, Cheng-Ta,Chang, Su-Haur,Yan, Tu-Hsin
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experimental part
p. 4805 - 4810
(2012/10/08)
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- Enyne chlorides: Substrates for copper-catalyzed asymmetric allylic alkylation
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A select few: Several prochiral enyne chlorides were employed as substrates in the title reaction using Grignard reagents as the alkylation reagents (see scheme; CuTC=copper(I) thiophenecarboxylate). Excellent 1,3 substitution regioselectivities and good to excellent enantioselectivities were obtained. The substrate scope is additionally extended to diene chlorides. Copyright
- Li, Hailing,Alexakis, Alexandre
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supporting information; experimental part
p. 1055 - 1058
(2012/04/05)
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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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- Amide-directed catalytic asymmetric hydroboration of trisubstituted alkenes
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(Chemical Equation Presented) Rhodium-catalyzed hydroborations of trisubstituted alkenes are generally slow and often suffer from competing alkene isomerization. In contrast, the trisubstituted alkene moieties contained within the framework of a β,γ-unsat
- Smith, Sean M.,Takacs, James M.
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supporting information; experimental part
p. 1740 - 1741
(2010/04/25)
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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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- Platinum-catalyzed nucleophilic addition of vinylsilanes at the β-position
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In the presence of catalytic amounts of PtCl2 and metal Iodides, β-substituted vlnylsllanes reacted with aldehydes at the β-position to give allyl silyl ethers. The Pt-catalyzed addition to aromatic aldehydes proceeded efficiently in the presence of Lil. The combined use of PtCl 2 and Mnl2 was found to be effective In addition to aliphatic aldehydes.
- Miura, Katsukiyo,Inoue, Gen,Sasagawa, Hisashi,Kinoshita, Hidenori,Ichikawa, Junji,Hosomi, Akira
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supporting information; experimental part
p. 5066 - 5069
(2009/12/28)
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- Alkylidenesilacyclopropanes derived from allenes: Applications to the selective synthesis of triols and homoallylic alcohols
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Several alkylidenesilacyclopropanes were prepared by silver-mediated silylene transfer to allenes. Oxasilacyclopentanes derived from allenes were prepared with high regio- and diastereoselectivity by a two-step, one-flask silacyclopropanation/carbonyl ins
- Buchner, Kay M.,Clark, Timothy B.,Loy, Janice M.N.,Nguyen, Thong X.,Woerpel
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supporting information; experimental part
p. 2173 - 2175
(2009/10/24)
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- An atom-economic and selective ruthenium-catalyzed redox isomerization of propargylic alcohols. An efficient strategy for the synthesis of leukotrienes
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Catalytic ruthenium complexes in conjunction with an indium cocatalyst and Broensted acid isomerize primary and secondary propargylic alcohols in good yields to provide trans enals and enones exclusively. Readily available indenylbis(triphenylphosphine)ruthenium chloride, in the presence of indium triflate and camphorsulfonic acid, gives the best turnover numbers and reactivity with the broadest range of substrates. Deuterium labeling experiments suggest that the process occurs through propargylic hydride migration followed by protic cleavage of the resultant vinylruthenium intermediate. Application of this method to the synthesis of leukotriene B4 demonstrates its utility and extraordinary selectivity.
- Trost, Barry M.,Livingston, Robert C.
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supporting information; experimental part
p. 11970 - 11978
(2009/02/05)
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- Preparation of 2-trimethylsilylmethyl-1-alkene; cross-coupling and protodesilylation sequence from 1,1-dibromo-1-alkene
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A new method for the preparation of exomethylene type allylsilane is described. Selective mono-protodesilylation of 1-trimethylsilyl-2-trimethylsilylmethyl-2-alkenes 2 with PPTS afforded 2-trimethylsilylmethyl-1-alkenes 4 in excellent yields. Since the resulting allylsilanes 4 possess an exomethylene unit, the reactions of 4 with carbonyl compounds in the presence of Lewis acids gave the corresponding product 7 having an exomethylene unit in excellent yields.
- Uenishi, Jun'ichi,Iwamoto, Takuya,Ohmi, Masashi
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p. 1237 - 1240
(2007/10/03)
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- Tetraarylphosphonium salts as solubility-control groups: Phosphonium-supported triphenylphosphine and azodicarboxylate reagents
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(Chemical Equation Presented) Predictable solubilities! Reagents supported on a tetraarylphosphonium group have solubilities that can be predicted. The reagents and their by-products can be readily removed, recovered, and recycled after reaction by a precipitation/filtration sequence initiated by the addition of a low-polarity solvent, such as diethyl ether. Furthermore, the supported reagents are robust and exhibit reactivities similar to their parent compounds.
- Poupon, Jean-Christophe,Boezio, Alessandro A.,Charette, Andre B.
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p. 1415 - 1420
(2007/10/03)
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- Rh-catalyzed [4+2] annulation of 4-alkynals with isocyanates and its application to the parallel kinetic resolution of unfunctionalized 4-alkynals
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(Chemical Equation Presented) Enantioenriched 2-alkylideneglutarimides and cyclopentenones are prepared by parallel kinetic resolution of 3-substituted 4-alkynals with a cationic Rh′/(S)-segphos catalyst system. This is an attractive route to the above-me
- Tanaka, Ken,Hagiwara, Yuji,Hirano, Masao
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p. 2734 - 2737
(2007/10/03)
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- Enantioselective and regioselective nickel-catalyzed multicomponent coupling of chiral allenes, aromatic aldehydes, and silanes
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A detailed account of the development of a recently developed, nickel-catalyzed multicomponent coupling of chiral allenes, aromatic aldehydes, and silanes is described. The axial chirality of the allene is transferred completely to the product, a trisubstituted Z-allylic alcohol protected as a silyl ether. A very high preference for sp rather than sp2 coupling is observed, and differentially substituted allenes undergo highly site-selective coupling. These transformations represent the first enantioselective multi-component coupling processes of allenes.
- Ng, Sze-Sze,Jamison, Timothy F.
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p. 11405 - 11417
(2007/10/03)
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- Highly enantioselective and regioselective nickel-catalyzed coupling of allenes, aldehydes, and silanes
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A complex derived from Ni(cod)2 and NHC-IPr catalyzes a three-component coupling reaction involving allenes, aldehydes, and organosilanes and transfers the axial chirality of the allene to a stereogenic center in the product with very high fide
- Ng, Sze-Sze,Jamison, Timothy F.
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p. 7320 - 7321
(2007/10/03)
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- Alkene-Directed, Nickel-Catalyzed Alkyne Coupling Reactions
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In alkene-directed, nickel-catalyzed coupling reactions of 1,3-enynes with aldehydes and epoxides, the conjugated alkene dramatically enhances reactivity and uniformly directs regioselectivity, independent of the nature of the other alkyne substituent (ar
- Miller, Karen M.,Luanphaisarnnont, Torsak,Molinaro, Carmela,Jamison, Timothy F.
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p. 4130 - 4131
(2007/10/03)
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- A stereodivergent approach to amino acids, amino alcohols, or oxazolidinones of high enantiomeric purity
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(-)-Menthone, an inexpensive chiral auxiliary, was used to prepare both enantiomers of α-amino acids, amino alcohols, or oxazolidinones. The sequence includes the SN2′ displacement by a cuprate reagent and a Curtius rearrangement as key steps.
- Spino, Claude,Tremblay, Marie-Claude,Gobdout, Cedrickx
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p. 2801 - 2804
(2007/10/03)
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- Total synthesis of parvaquone and the serendipitous discovery of a novel chromium-mediated method for β-lactone formation
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During attempts to synthesise the 2-hydroxy-1,4-naphthoquinone, parvaquone, 1, a novel chromium-mediated method for the synthesis of functionalised β-lactones from propargyl alcohols has been discovered. Additionally, using both dry state and ultrasound conditions, the total synthesis of parvaquone (1) has been achieved; the most efficient techniques deliver this target compound in up to 46% overall yield over, as low as, two synthetic processes.
- Harrity, Joseph P. A.,Kerr, William J.,Middlemiss, David,Scott, James S.
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p. 219 - 227
(2007/10/03)
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- Reactions of 1,1-Dihaloalkenes with Triorganozincates: A Novel Method for the Preparation of Alkenylzinc Species Associated with Carbon-Carbon Bond Formation
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Lithium trialkylzincates react with 1,1-dibromoalkenes 1 and 1-bromo-1-chloroalkenes 2 at -85 deg C in THF to give 1-bromoalkenes 5 and 1-chloroalkenes 7, respectively, upon hydrolysis.The intermediate (1-haloalkenyl)zincates 4 and 6 are stable at low temperature but, when allowed to warm to 0 deg C, they undergo a 1,2-alkyl migration reaction to afford alkenylzinc species 10.A variety of alkylation products 11 are obtained by the hydrolysis of 10.In the presence of (Ph3P)2Pd (5 molpercent), alkenylzinc species 10 react smoothly with organic halides (AcCl, EtOCOCl, CH2=CH(Me)Br, PhBr) to yield the corresponding coupling products 13-16.
- Harada, Toshiro,Katsuhira, Takeshi,Hara, Daiji,Kotani, Yasuo,Maejima, Keiji,et al.
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p. 4897 - 4907
(2007/10/02)
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- Reactions with Phosphine Alkynenes, XL. A Sequence for the Preparation of Acetylenes Starting from Aldehydes
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Reaction of aldehydes 1 with CBr4/P(C6H5)3 gives rise to formation of 1,1-dibromoolefins 2 which are converted by treatment with butyllithium into the lithium acetylides 7.On the other side, aldehydes 5 are transformed by Wittig reaction into olefins 3 which are hydroborated to give trialkylboranes 9.Reaction of 7 + 9 followed by treatment with I2 yields acetylenes 11.
- Bestmann, Hans Juergen,Li, Kedong
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p. 828 - 831
(2007/10/02)
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- Reactions with Phosphinealkylenes, XXXIX. - New Methods for the Preparation of 1-Bromoacetylenes and Enynes
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1,1-Dibromoolefins 4 are obtained in good yield from the reaction of aldehydes 1 with triphenylphosphane (2) and carbon tetrabromide (3).Reaction of 4 with three moles of methylene(triphenyl)phosphorane (8) leads to the propargylidene(triphenyl)phosphoranes 11 which react with aldehydes to give the enynes 13.The ylides 11 can also prepared via the reaction of bromoacetylenes 7, which can be obtained from 4, with two moles of 8.This reaction sequence allows the synthesis of new retinoids with enyne structures from retinal.
- Bestmann, Hans Juergen,Frey, Herbert
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p. 2061 - 2071
(2007/10/02)
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- Alkylation of vinylidene chloride and vinylidene bromide
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Vinylidene chloride and vinylidene bromide are alkylated by reaction with alkylating agents such as selected olefins, tert-alkyl halides, and secondary or tertiary alcohols in a reaction medium comprising trifluoromethane-sulfonic acid. In specific embodiments, the reaction medium can additionally comprise water, methanol, and BF3.
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