- Synthesis of 2-Substituted Cyclobutanones by a Suzuki Reaction and Dephosphorylation Sequence
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We report a novel process for the preparation of 2-substituted cyclobutanones. Such a method relies on the cross-coupling reaction of bromocyclobutenyl diethyl phosphate with either boronic acids or organozinc reagents. Dephosphorylation of the prepared 2-substituted cyclobutenyl phosphates affords 2-substituted cyclobutanones. We observed that the course of the dephosphorylation reaction depends on the properties of the substituents found on the cyclobutene nucleus. The presence of groups capable of stabilizing the negative charge is necessary for ring opening of cyclobutanones. The scope of the reported process for the preparation of 2-substituted cyclobutanones has also been extended to the preparation of cyclobutenyl sulfides.
- Koudelka, Jakub,Tobrman, Tomá?
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p. 3260 - 3269
(2021/06/25)
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- Oxidative Ring Expansion of Cyclobutanols: Access to Functionalized 1,2-Dioxanes
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Cyclobutanols undergo an oxidative ring expansion with Co(acac)2 and triplet oxygen to give 1,2-dioxanols. The formation of an alkoxy radical drives the regioselective cleavage of the ring on the more substituted side before insertion of molecular oxygen. The reaction is particularly effective on secondary cyclobutanols but works also on certain tertiary alcohols. Further substitution with neutral nucleophiles under catalytic Lewis acid conditions led to original 1,2-dioxanes with a preferred 3,6-cis-configuration.
- Lapez, Mara-A Marta-N,Jamey, Nicolas,Pinet, Alexis,Figadeìre, Bruno,Ferri, Laurent
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p. 1626 - 1631
(2021/03/08)
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- Copper-Catalyzed Enantioselective Arylation via Radical-Mediated C-C Bond Cleavage: Synthesis of Chiral ω,ω-Diaryl Alkyl Nitriles
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The first example of copper-catalyzed ring-opening, enantioselective arylation of cyclic ketoxime esters to access ω,ω-diaryl alkyl nitriles has been developed in high yield (up to 92% yield) with excellent enantioselectivity (up to 91% ee). Side-arm bis(oxazoline) ligand plays a significant role in this asymmetric catalytic transformation, which provides an efficient route to construct diverse chiral ω,ω-diaryl alkyl nitriles. Synthetic utility has also been demonstrated in the further derivatization of the ω,ω-diaryl alkyl nitrile to the corresponding amide.
- Cui, Guo-Qing,Dai, Jing-Cheng,Li, Yan,Li, Yuan-Bo,Hu, Duo-Duo,Bian, Kang-Jie,Sheng, Jie,Wang, Xi-Sheng
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p. 7503 - 7507
(2021/10/02)
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- Visible-Light Photoredox-Catalyzed Dicarbofunctionalization of Styrenes with Oxime Esters and CO2: Multicomponent Reactions toward Cyanocarboxylic Acids and γ-Keto Acids
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A photoredox-catalyzed dicarbofunctionalization of styrenes with oxime esters and CO2 has been achieved. Notably, a series of four-, five-, or six-membered cyclic ketone oximes worked well to furnish a wide range of ε-, ζ-, and η-cyanocarboxylic acids in good yields. Furthermore, a series of γ-keto acids also could be obtained by employing acyclic ketone oxime esters as the carbonyl radical precursor. It provides convergent access to diverse biologically important cyanocarboxylic and γ-keto acids.
- Bai, Junxue,Li, Miao,Zhou, Cong,Sha, Yu,Cheng, Jiang,Sun, Jianwei,Sun, Song
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p. 9654 - 9658
(2021/12/14)
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- Metal-Free sp3 C-SCF3 Coupling Reactions between Cycloketone Oxime Esters and S-trifluoromethyl 4-Methylbenzenesulfonothioate
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A novel sp3 C-SCF3 coupling reaction between cycloketone oxime esters and S-trifluoromethyl 4-methylbenzenesulfonothioate was achieved. Ethanol was found to facilitate this transformation by trapping the sulfonyl cation. The metal-free and photocatalyst-free reaction conditions, as well as the broad substrate scope, make this a green protocol for the synthesis of SCF3-substituted nitriles.
- Zhao, Xia,Tian, Miaomiao,Ji, Liangshuo,Liu, Junjie,Lu, Kui
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p. 863 - 866
(2020/02/04)
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- Radical-Cation Vinylcyclopropane Rearrangements by TiO2Photocatalysis
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Radical cation vinylcyclopropane rearrangements by TiO2 photocatalysis in lithium perchlorate/nitromethane solution are described. The reactions are triggered by oxidative single electron transfer, which is followed by immediate ring-opening of the cyclopropanes to generate distonic radical cations as unique reactive intermediates. This approach can also be applied to vinylcyclobutane, leading to the construction of six-membered rings. A stepwise mechanism via distonic radical cations is proposed based on preliminary mechanistic studies, which is supported by density functional theory calculations.
- Maeta, Naoya,Kamiya, Hidehiro,Okada, Yohei
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p. 6551 - 6566
(2020/07/14)
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- COMPOUNDS FOR THE TREATMENT OF PAIN
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Provided herein are compounds that are useful in the treatment of pain in a subject.
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- Enantioselective Radical Ring-Opening Cyanation of Oxime Esters by Dual Photoredox and Copper Catalysis
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Catalytic enantioselective chemical reactions involving highly reactive radical species remain largely unexplored. We report herein for the first time a novel enantioselective radical ring-opening cyanation of redox-active oxime esters by dual photoreodox
- Chen, Jun,Wang, Peng-Zi,Lu, Bin,Liang, Dong,Yu, Xiao-Ye,Xiao, Wen-Jing,Chen, Jia-Rong
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p. 9763 - 9768
(2019/11/29)
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- Visible light-induced palladium-catalyzed ring opening β-H elimination and addition of cyclobutanone oxime esters
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A palladium catalyst under visible light irradiation activates cyclobutanone oxime ester through single electron transfer to induce radical ring opening to generate hybrid cyanoalkyl Pd(i) radical species. Hybrid cyanoalkyl Pd(i) radical species can undergo either β-H elimination to deliver (E)-4-arylbut-3-enenitrile or undergo radical addition with silyl enol ether and enamide to generate δ-cyano ketones. A dual ligand system composed of two phosphine ligands is essential for the high reactivity.
- Xing, Wei-Long,Shang, Rui,Wang, Guang-Zu,Fu, Yao
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p. 14291 - 14294
(2019/12/02)
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- Photoinduced C—C Bond Cleavage and Oxidation of Cycloketoxime Esters
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A novel structural reorganization of cycloketoxime esters beyond the traditional Beckmann rearrangement process has been established to build cyano-containing ketones in the presence of photocatalyst. This novel transformation is remarkable with selective C—C bond cleavage and an oxidation process enabled by DMSO used as the solvent, oxidant, and oxygen source avoiding acid, base and toxic cyanide salts as the cyano source. Further applications in late-stage modification of complex and chiral molecules have also been reported.
- Zhao, Binlin,Tan, Hui,Chen, Cheng,Jiao, Ning,Shi, Zhuangzhi
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supporting information
p. 995 - 999
(2018/09/25)
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- Cu-Catalyzed Redox-Neutral Ring Cleavage of Cycloketone O-Acyl Oximes: Chemodivergent Access to Distal Oxygenated Nitriles
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A chemodivergent copper-catalyzed ring opening of cycloketone oximes via radical-mediated C-C bond cleavage under redox-neutral conditions is described. This method allows the divergent synthesis of γ- and δ-acyloxylated, alkoxylated, and hydroxylated nitriles while avoiding the use of toxic cyanide reagents. Moreover, these reactions proceed under very mild conditions with good functional group tolerance. Notably, ring-opening reactions of the less-strained substrate cyclopentanone oxime also proceeded well under the established conditions.
- Ai, Wenying,Liu, Yaqian,Wang, Qian,Lu, Zhonglin,Liu, Qiang
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p. 409 - 412
(2018/01/27)
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- An efficient synthesis of cyclopropyl silyl ketones
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The reaction of silylcyclopropyl bromides with dichloromethyl methyl ether in the presence of n-butyllithium is investigated. Under basic reaction conditions, the corresponding cyclopropylidene derivatives are exclusively obtained. The resulting cyclopropylidene compounds are subjected to protonolysis or trapping with electrophiles in a one-pot to give the cyclopropyl silyl ketone derivatives in good yields. Acidic treatment of derived cyclopropyl silyl ketone allows isomerization to give the thermodynamically favorable trans form exclusively.
- Honda, Mitsunori,Nakae, Kenta,Nishizawa, Toshiaki,Suda, Mitsuhiro,Kunimoto, Ko-Ki,Segi, Masahito
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scheme or table
p. 9500 - 9508
(2012/01/02)
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- Iron salt, a cheap, highly efficient and environment-friendly metal catalyst for Se-Se bond cleavage and the further reaction with methylenecyclopropanes under mild conditions
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FeCl3 was found to be a good catalyst in Se-Se bond cleavage. Further electrophilic additions to methylenecyclopropanes provide a convenient access to diphenylselenylcyclobutanes. Comparing with other Lewis acids, FeCl3 is much cheaper and the reaction conditions are milde and more tolerance to air and moisture.
- Yu, Lei,Ren, Lingfeng,Yi, Rong,Wu, Yulan,Chen, Tian,Guo, Rong
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supporting information; experimental part
p. 2228 - 2233
(2011/06/22)
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- Catalytic and regioselective ring expansion of arylcyclobutanones with trimethylsilyldiazomethane. Ligand-dependent entry to β-ketosilane or enolsilane adducts
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Divergent reactivity is uncovered in the homologation of arylcyclobutanones with trimethylsilyldiazomethane. With Sc(OTf)3 as catalyst, enolsilanes are obtained with a high preference for methylene migration. By contrast, Sc(hfac)3 g
- Dabrowski, Jennifer A.,Moebius, David C.,Wommack, Andrew J.,Kornahrens, Anne F.,Kingsbury, Jason S.
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supporting information; experimental part
p. 3598 - 3601
(2010/11/04)
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- Lewis acid catalyzed reaction of methylenecyclopropanes with 1,2-diphenyldiselane or 1,2-di-p-tolyldisulfane
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(Chemical Equation Presented) Catalyzed by Lewis acid, 1,2-diphenyldiselane or 1,2-di-p-tolyldisulfane could add to methylenecyclopropanes smoothly. Compared with the reported free radical additions, the results were quite different. A four-membered carbon ring was constructed to give cyclobutane-1,1-diylbis(phenylselane) derivatives or cyclobutane-1,1-diylbis(p- tolylsulfane) derivatives as products, which are useful intermediates in organic synthesis.
- Yu, Lei,Meng, Jundong,Xia, Ling,Guo, Rong
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supporting information; experimental part
p. 5087 - 5089
(2009/10/17)
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- A Novel Route to Geminal Dibromocyclobutanes: Syntheses of 2-Substituted Cyclobutanone Acetals and Their Reaction with Boron Tribromide
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Nine 2-substituted cyclobutanone acetals, in addition to the parent cyclobutanone acetal, were synthesized from their corresponding cyclobutanones and subsequently treated with boron tribromide. The substituents were either alkyl chains or a phenyl and a
- Nordvik, Tore,Brinker, Udo H.
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p. 9394 - 9399
(2007/10/03)
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- First synthesis of (1S,2S)- and (1R,2R)-1-amino-2-isopropylcyclobutanecarboxylic acids by asymmetric Strecker reaction from 2-substituted cyclobutanones
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An efficient and easy one-pot reaction from readily available racemic 2-substituted cyclobutanones gave, by means of asymmetric Strecker synthesis in the presence of an amine chiral auxiliary, two major aminonitriles with excellent diastereoselectivity. After separation, the major cis-aminonitriles were hydrolysed and hydrogenolysed to lead for the first time to pure non-racemic (+)-1-amino-2-isopropylcyclobutanecarboxylic acid (ACBC) and its antipode.
- Truong, Molika,Lecornue, Frederic,Fadel, Antoine
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p. 1063 - 1072
(2007/10/03)
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- Convenient preparation of 2-substituted cyclobutanones from esters of 2-alkoxyalkanoic acids
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Esters of 2-alkoxyalkanoic acids react with ethylmagnesium bromide in the presence of titanium(IV) isopropoxide in catalytic amounts to afford 1-(1-alkoxy)alkyl-1-cyclopropanols which under acidic catalysis cleanly rearrange into 2-substituted cyclobutano
- Shevchuk,Kulinkovich
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p. 491 - 495
(2007/10/03)
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- New opportunities for α-ketenyl radicals in ring synthesis
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Unsaturated acyl radicals are shown to be useful precursors to α- ketenyl radical intermediates which are then used in the synthesis of aromatic cyclic ketones. The behaviour of cyclopropyl acyl radicals is also described, in particular the 8-endo-trig cyclisation of 3-substituted cyclopropyl acyl radicals to give bicyclo[6.1.0]nonanones, and in the synthesis of cyclic enol lactones.
- De Boeck, Benoit,Herbert, Nicola,Pattenden, Gerald
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p. 6971 - 6974
(2007/10/03)
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- Novel access to neopentyl-type halogenated cyclopentanoids via olefinic cyclobutanols
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The iodonium ion-mediated ring expansion of olefinic cyclobutanols 20, 21, and 25 gave mixtures of iodoalkylated cyclopentanones 33a-c and 34a-c. On the other hand, the same reaction of 29, 30, and 32 stereoselectively afforded iodoalkylated cyclopentanon
- Nemoto, Hideo,Shiraki, Motohiro,Fukumoto, Keiichiro
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p. 1347 - 1348
(2007/10/03)
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- Ring-enlargement of Cyclopropylacylsilanes with Sulfuric or Triflic Acid. Selective Formation of Cyclobutanones or 2-Silyl-4,5-dihydrofurans
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Reaction of cyclopropylacylsilanes with sulfuric or triflic acid in aprotic solvent affords the corresponding cyclobutanone or 2-silyl-4,5-dihydrofuran derivatives, depending upon the substituents on the three-membered ring or acid used.The use of triflic
- Nakajima, Tadashi,Segi, Masahito,Mituoka, Takeshi,Fukute, Yasuyuki,Honda, Mitsunori,Naitou, Kaneyuki
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p. 1667 - 1670
(2007/10/02)
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- Vinyl cyclobutanol strategy for halogenated cyclopentanoids
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The iodonium ion mediated ring expansion of the olefinic cyclobutanols 19, 20 and 22 gave the mixture of iodoalkylated cyclopentanones 27a-c and 28a-c, respectively. On the other hand, the same reaction of 24-26 afforded stereoselectively the iodoalkylated cyclopentanones 27d and 27e.
- Nemoto, Hideo,Shiraki, Motohiro,Fukumoto, Keiichiro
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p. 8799 - 8802
(2007/10/02)
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- A Novel and Efficient Route to Chiral A-Ring Aromatic Trichothecanes - The First Enantiocontrolled Total Synthesis of (-)-Debromofiliformin and (-)-Filiformin
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The first examples of asymmetric dihydroxylation (AD) of the cyclopropylidene derivatives 12a-e followed by enantiospecific 1,2-rearrangement of the resulted diols 13a-e to give the optically active cyclobutanones 15a-d and 11, and also the first enantioc
- Nemoto, Hideo,Miyata, Junji,Hakamata, Hideki,Nagamochi, Masatoshi,Fukumoto, Keiichiro
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p. 5511 - 5522
(2007/10/02)
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- The First Example of Asymmetric Dihydroxylation of Cyclopropylidene Derivatives --- An Enantioenriched Formal Total Synthesis of (-)-Filiformin
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The first example of asymmetric dihydroxylation (AD) of the cyclopropylidene derivatives 4a-e followed by enantiospecific 1,2-rearrangement of the resulted diols 5a-e to give the optically active cyclobutanones 7a-e was reported.The synthesis of 7e consti
- Nemoto, Hideo,Miyata, Junji,Hakamata, Hideki,Fukumoto, Keiichiro
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p. 1055 - 1058
(2007/10/02)
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- Vinyl Cations. 41. Influence of 4-Aryl and 4-Alkyl Substituents on the ?-Route Solvolyses of Homopropargyl Esters
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The four 4-substituted-homopropargyl tosylates and triflates 6b-e (R=phenyl, p-tolyl, anisyl, and cyclopropyl) have been synthesized and solvolyzed under various conditions, as have 2-cyclopropyl-1-cyclobutenyl triflate (11-OTf) and nonaflate (11-ONf).In addition, the solvolyses of pent-3-yn-1-yl tosylate (6a-OTs, R=methyl) and triflate (prepared previously) are reported.The ratios of C-3 ring to C-4 ring 3 ring/C4ring)> products are recorded for the reactions in various solvents.As expected, ring closure (kΔ) increases and solvent displacement (kS, SN2) decreases with decreasing nucleophilicity of solvent.Temperature effects are noted for the sovolyses of tosylates 6a-e in 100percent TFE buffered with Na2CO3 in which kΔ increases with increasing temperature.The result is explained by decomposition of the intimate ion pair with temperature, whereupon elimination to the enyne becomes smaller and ring closure (kΔ) increases at the expense of elimination.The possibility of intervention of nonclassical vinyl cations is discussed, as are other mechanistic implications.
- Collins, Clair J.,Hanack, Michael,Stutz, Herbert,Auchter, Gerhard,Schoberth, Winfried
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p. 5260 - 5268
(2007/10/02)
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