- Cobalt(iii)-catalyzed redox-neutral [4+2]-annulation ofN-chlorobenzamides/acrylamides with alkylidenecyclopropanes at room temperature
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An efficient synthesis of substituted 3,4-dihydroisoquinolinones through [4+2]-annulation ofN-chlorobenzamides/acrylamides having a monodentate directing group with alkylidenecyclopropanes in the presence of a less expensive, highly abundant and air stable Co(iii) catalystviaa C-H activation is demonstrated. In this reaction, the N-Cl bond ofN-chlorobenzamide serves as an internal oxidant and thus an external metal oxidant is avoided. The 3,4-dihydroisoquinolinone derivatives are converted successfully into the highly useful imidoyl chloride derivatives. The deuterium labeling and kinetic isolabelling studies reveal that the C-H activation is a rate-determining step in this cyclization reaction.
- Ramesh, Balu,Jeganmohan, Masilamani
-
supporting information
p. 3692 - 3695
(2021/04/16)
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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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supporting information
p. 1626 - 1631
(2021/03/08)
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- 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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- Gem-Difluorination of Methylenecyclopropanes (MCPs) Featuring a Wagner-Meerwein Rearrangement: Synthesis of 2-Arylsubstituted gem-Difluorocyclobutanes
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The geminal difluorocyclobutane core is a valuable structural element in medicinal chemistry. Strategies for gem-difluorocyclobutanes, especially the 2-substituted cases, are limiting and often suffer from harsh reaction conditions. Reported herein is a m
- Lin, Peng-Peng,Huang, Long-Ling,Feng, Si-Xin,Yang, Shuang,Wang, Honggen,Huang, Zhi-Shu,Li, Qingjiang
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supporting information
p. 3088 - 3093
(2021/05/05)
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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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supporting information
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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supporting information
p. 9654 - 9658
(2021/12/14)
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- Nickel-Catalyzed Favorskii-Type Rearrangement of Cyclobutanone Oxime Esters to Cyclopropanecarbonitriles
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A nickel-catalyzed base-promoted rearrangement of cyclobutanone oxime esters to cyclopropanecarbonitriles was developed. The ring opening of cyclobutanone oxime esters occurs at the sterically less hindered side. A base-promoted nickelacyclobutane intermediate, formed in situ, is assumed to be involved in the formation of the product.
- Fang, Ping,Mei, Tian-Sheng,Shuai, Bin
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supporting information
p. 1637 - 1641
(2021/10/02)
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- Activation and Functionalization of C-C σ Bonds of Alkylidene Cyclopropanes at Main Group Centers
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Aluminum(I) and magnesium(I) compounds are reported for the C-C σ-bond activation of strained alkylidene cyclopropanes. These reactions result in the formal addition of the C-C σ bond to the main group center either at a single site (Al) or across a metal-metal bond (Mg-Mg). Mechanistic studies suggest that rather than occurring by a concerted oxidative addition, these reactions involve stepwise processes in which substrate binding to the main group metal acts as a precursor to α- or β-alkyl migration steps that break the C-C σ bond. This mechanistic understanding is used to develop the magnesium-catalyzed hydrosilylation of the C-C σ bonds of alkylidene cyclopropanes.
- Crimmin, Mark R.,Kong, Richard Y.
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supporting information
p. 11967 - 11971
(2020/08/06)
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- Ring opening of methylenecyclopropanes with halides in liquid sulfur dioxide
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Methylenecyclopropanes (MCP) undergo ring opening reactions with group I and II metal halides and ammonium halides in liquid SO2 to afford homoallylic halides, which are versatile reagents in organic synthesis. The developed reaction conditions are compatible with acid-labile substrates such as N-Boc-protected compounds. Liquid SO2 is a polar reaction medium with Lewis acid properties that solubilizes inorganic salts. The unique properties of SO2 were demonstrated by control experiments: 1) upon performing the reactions with the aforementioned salts in conventional solvents, the MCP ring opening was not observed either in the presence of catalytic amounts of H3PO4 (similar pKa to that of H2SO3), or in the absence of H3PO4; 2) a solution of SO2 in THF exhibited similar properties to that of liquid SO2.
- Le?kovskis, Kristaps,Gulbe, Krista,Mishnev, Anatoly,Turks, Māris
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supporting information
(2020/10/19)
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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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- TFA-Catalyzed [3+2] Spiroannulation of Cyclobutanols: A Route to Spiro[cyclobuta[a]indene-7,1′-cyclobutane] Skeletons
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A straightforward method for the synthesis of spiro[cyclobuta[a]indene-7,1′-cyclobutane] derivatives from cyclobutanols has been developed via one-pot [3+2] spiroannulation. A series of new spiro[cyclobuta[a]indene-7,1′-cyclobutane] derivatives are facile
- An, Zhenyu,Liu, Yafeng,Sun, Yanwei,Yan, Rulong
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supporting information
p. 3812 - 3815
(2020/10/19)
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- Strain-Promoted Oxidation of Methylenecyclopropane Derivatives using N-Hydroxyphthalimide and Molecular Oxygen in the Dark
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The hydroperoxidation of alkylidenecyclopropanes and other strained alkenes using an N-hydroxylamine and molecular oxygen occurred in the absence of catalyst, initiator, or light. The oxidation reaction proceeds through a radical pathway that is initiated by autoxidation of the alkene substrate. The hydroperoxides were converted to their corresponding alcohols and ketones under mild conditions.
- Anderson, T. E.,Woerpel, K. A.
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supporting information
(2020/07/30)
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- Highly enantioselective nickel-catalyzed hydrocyanation of disubstituted methylenecyclopropanes enabled by taddol-based diphosphite ligands
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A vast range of novel TADDOL-based diphosphite ligands were first synthesized and applied in the nickel-catalyzed asymmetric hydrocyanation of disubstituted methylenecyclopropanes. By employing these new catalysts, the conversion of diverse methylenecyclo
- Yu, Rongrong,Fang, Xianjie
-
supporting information
p. 594 - 597
(2020/01/21)
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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
-
supporting information
p. 863 - 866
(2020/02/04)
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- Rhodium-Catalyzed Ring-Opening Hydroacylation of Alkylidenecyclopropanes with Chelating Aldehydes for the Synthesis of γ,δ-Unsaturated Ketones
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The first intermolecular ring-opening hydroacylation of alkylidenecyclopropanes with chelating aldehydes through a rhodium-catalyzed acrylamide-promoted protocol is reported. This highly efficient catalytic system enables the direct synthesis of a diverse
- Li, Hong-Shuang,Lu, Shi-Chao,Chang, Zhi-Xin,Hao, Liqiang,Li, Fu-Rong,Xia, Chengcai
-
supporting information
p. 5145 - 5150
(2020/07/04)
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- Transition Metal-Free Difunctionalization of C?C Bond with Sodium Sulfinates and Water Leading to (E)-1-Phenyl-4-sulfonylbut-1-enes
-
Without using any transitionmetal and base, an eco-friendly, practical and economical protocol has been established for the one-pot synthesis of diverse (E)-1-phenyl-4-sulfonylbut-1-enes from easily accessible starting materials. This strategy features a wide substrate scope, tolerates a broad range of functional groups, employs a less expensive oxidant, is operationally simple, and can be easily scaled-up. (Figure presented.).
- Wang, Qiao-Lin,Chen, Zan,Zhou, Quan,Zhou, Cong-Shan,Xiong, Bi-Quan,Zhang, Pan-Liang,Yang, Chang-An,Liu, Yu,Tang, Ke-Wen
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supporting information
p. 2315 - 2320
(2019/04/13)
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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.
- -
-
Paragraph 2408; 2626-2627
(2019/08/20)
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- Visible-Light-Catalyzed C-C Bond Difunctionalization of Methylenecyclopropanes with Sulfonyl Chlorides for the Synthesis of 3-Sulfonyl-1,2-dihydronaphthalenes
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A novel visible-light-catalyzed sulfonylation/arylation of carbon-carbon σ-bond with sulfonyl chlorides for the synthesis of 3-sulfonylated 1,2-dihydronaphthalenes is developed. This difunctionalization proceeds via a sequence of C=C bond sulfonylation, C-C σ-bond cleavage, and intramolecular cyclization, and the experiment result shows that the C-C σ-bond difunctionalization reaction includes a radical process. This strategy provides a simple and convenient route for difunctionalization of C-C bonds with an aromatic carbon and a sulfonyl radical by one-pot construction of a C-S bond and a new C-C bond.
- Liu, Yu,Wang, Qiao-Lin,Chen, Zan,Zhou, Quan,Li, Hua,Zhou, Cong-Shan,Xiong, Bi-Quan,Zhang, Pan-Liang,Tang, Ke-Wen
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p. 2829 - 2839
(2019/03/07)
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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
-
supporting information
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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supporting information
p. 14291 - 14294
(2019/12/02)
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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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supporting information
p. 409 - 412
(2018/01/27)
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- Organoselenium-Catalyzed Oxidative Ring Expansion of Methylenecyclopropanes with Hydrogen Peroxide
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Catalyst screening and optimization of reaction conditions allowed control of the organoselenium-catalyzed oxidative ring expansion of highly active methylenecyclopropanes to give substituted cyclobutanones selectively. This protocol employs H2O2 as a clean oxidant and generates no waste and, therefore, provides green access to useful, but not readily available, substituted cyclobutanones under mild conditions.
- Yu, Lei,Chen, Fenglin,Ding, Yuanhua
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p. 1033 - 1037
(2016/04/05)
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- A new protocol for nickel-catalysed regio- and stereoselective hydrocyanation of allenes
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Regio- and stereoselective hydrocyanation under nickel catalysis is described. This report shows that allenyl C-C double bonds are discriminated and converted to the corresponding carbonitriles as a single product. The key functionalities for achieving high regio- and stereocontrol are aryl and cyclopropyl groups in the substrates. This journal is
- Arai, Shigeru,Hori, Hiroto,Amako, Yuka,Nishida, Atsushi
-
supporting information
p. 7493 - 7496
(2015/05/04)
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- Synthesis of benzylidenecyclopropanes from γ-halopropyl pentachlorophenyl sulfones using a Julia-Kocienski olefination
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Simple, one-step synthesis of benzylidenecyclopropanes from γ-halopropyl pentachlorophenyl sulfones using a Julia-Kocienski olefination is reported. Georg Thieme Verlag Stuttgart.
- Ma?kosza, Mieczys?aw,Bujok, Robert
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p. 586 - 588
(2008/12/22)
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- A new entry to alkylidenecyclopropanes through a Ramberg-Backlund rearrangement of cyclopropylsulfones
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The first use of the Ramberg-Backlund rearrangement of cyclopropylsulfones in the synthesis of alkylidenecyclopropanes is reported.
- Bernard, Angela M.,Frongia, Angelo,Piras, Pier P.
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p. 801 - 817
(2007/10/03)
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- Thermolysis of 1-(1-aryl-1-bromomethyl)cyclopropyl bromides: A reinvestigation
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Two compounds, the (Z)- and (E)-isomers of 2,4-dibromo-1-p-tolyl-1-butene 2a and 3a, respectively, were isolated in 65% total yield when 1-(1-bromo-1-p-tolylmethyl)cyclopropyl bromide (1a) was heated at 150 °C for 1 h. 1,1-Dibromo-2-p-tolylcyclobutane (4a
- Nordvik, Tore,Brinker, Udo H.
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p. 7092 - 7093
(2007/10/03)
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- CuX2-Mediated Halogenation of Alkylidenecyclopropanes: A Highly Efficient and Stereoselective Method for the Preparation of Z-2, 4-Dihalobutenes
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A convenient and efficient method for the synthesis of (Z)-2,4- dihalobutenes, a useful building block in organic synthesis, was reported in good yield by the reaction of alkylidenecyclopropanes and CuX2 (or CuI/I2).
- Zhou, Hongwei,Huang, Xian,Chen, Wanli
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p. 2080 - 2082
(2007/10/03)
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- Asymmetric dihydroxylations of aromatic cyclopropylidenes
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A number of aromatic cyclopropylidenes have been converted to diols using the Sharpless asymmetric dihydroxylation (AD) procedure. The enantiomeric ratios were determined by chiral phase HPLC by comparison with their racemates.
- Diffendal, Jason M.,Filan, John,Spoors, P. Grant
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p. 6137 - 6139
(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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- 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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- 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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- Polylithiumorganic compounds -19. Regioselective carbon-carbon σ-bond scission followed by a 1,6-proton shift upon the reductive metalation of benzylidenecyclopropane derivatives with lithium metal
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Depending on the substituent α-substituted benzylidenecyclopropanes (32) react more or less readily with lithium dust (2% sodium) in diethyl ether whereby a regioselective scission of only the cyclopropane σ-bond cis to the phenyl ring takes place. Upon raising the temperature the primarily formed 1,3-dilithiumorganic compound due to an agostic interaction rearranges by a 1,6-proton shift into a doubly bridged 1,4-dilithio compound. With α-methylbenzylidenecyclopropane (32c) this rearrangement was shown to occur intermolecularly via a trilithiumorganic compound 56. The suggested mechanism of these reductive metalation reactions via a bisected radical anion 87 where the lithium is mainly bound to the cyclopropyl carbon atom and oriented syn to the phenyl ring, was supported by MNDO (geometries) and ab initio (energies) calculations.
- Maercker, Adalbert,Daub, Volker E. E.
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p. 2439 - 2458
(2007/10/02)
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- Biscyclopropyl titanocene: A novel reagent for the synthesis of alkylidene and vinyl cyclopropanes
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Alkylidene cyclopropane derivatives are obtained by reaction of biscyclopropyl titanocene with several types of carbonyl compounds, including aldehydes, ketones and esters. In some cases the isomeric vinyl cyclopropane products are also obtained. Biscyclopropyl titanocene also reacts with alkynes forming, after acidification, the corresponding vinyl cyclopropanes.
- Petasis, Nicos A.,Bzowej, Eugene I.
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p. 943 - 946
(2007/10/02)
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- Energy Well of the Orthogonal Trimethylenemethane. - 1-Methylene-2-phenylcyclopropane Thermolysis
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From the heat of hydrogenation of 5, the activation enthalpy for the racemization of the title compound, and the oxygen dependance of the trapping rate of the intermediate diradical 8 the energy profile for the degenerate methylene-cyclopropane rearrangement can be constructed, which leads to heats of formation for the triplet and singlet state of the diradical 8 of ΔHf0 93.9 and 95.6 kcal mol-1, respectively. - Key Words: Diradicals / Oxygen trapping / Energy well / Heat of formation / Heat of hydrogenation
- Roth, Wolfgang R.,Winzer, Markus,Lennartz, Hans-Werner,Boese, Roland
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p. 2717 - 2726
(2007/10/02)
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- OLIGOMETHYLENATION OF PHENYLALLENE WITH DIAZOMETHANE IN THE PRESENCE OF PALLADIUM DIACETATE
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In the reaction of phenylallene with diazomethane in the presence of palladium(II) acetate oligomethylenation takes place in addition to cyclopropanation.It leads to the inclusion of three and four equivalences of methylene in the allene molecule.
- Lukin, K. A.,Zefirov, N. S.
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- AN EFFICIENT METHOD FOR THE PREPARATION OF ALKYLIDENECYCLOPROPANES
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Yields obtained from Wittig reactions with cyclopropylidenetriphenylphosporane are greatly improved by addition of the phase-transfer catalyst, TDA-1.
- Stafford, Jeffrey A.,McMurry, John E.
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p. 2531 - 2534
(2007/10/02)
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- A CONVENIENT ROUTE TO ALKYLIDENECYCLOPROPANES FROM CYCLOPROPYLDIPHENYLPHOSPHINE OXIDE AND CARBONYL COMPOUNDS
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Alkylidenecyclopropanes were readily prepared by thermal decomposition of the potassium or lithium salt of the adduct formed from the treatment of cyclopropyldiphenylphosphine oxide with n-butyl lithium and a carbonyl compound.
- Meijs, Gordon F.,Eichinger, Peter C. H.
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p. 5559 - 5560
(2007/10/02)
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- CYCLOPROPANATION OF ALLENES WITH DIAZOMETHANE IN THE PRESENCE OF PALLADIUM(II) COMPOUNDS
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The reaction of substituted allenes with diazomethane in the presence of palladium(II) compounds takes place at the less substituted double bond with the formation of the corresponding methylenecyclopropanes.
- Zefirov, N. S.,Lukin, K. A.,Timofeeva, A. Yu.
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p. 2246 - 2248
(2007/10/02)
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- Synthesis and Addition Reactions of 2-Phenyl-1-cyclopropene-1-carboxylates
-
From the olefins 1, 2, and 4 - 7 the 1-chloro-1-cyclopropanecarboxylic acids 15 - 20 are prepareded via the dichlorocyclopropanes 8, 9, and 11 - 14.The trans-isomers 15a - 20a were readily separated.Spiropentane 10 undergoes anionic ring cleavage with BuLi to give finally the ester 33.The tert-butyl esters 21 - 26 yield with KOtBu the cyclopropene esters 27 - 32.The trans-esters 21a - 26a react much faster than the cis-esters b.At C-3 unsubstituted chlorocyclopropane esters, e.g. 34, do not give stable cyclopropene esters even with lithium dialkylamides.Diazomethane adds to the esters 27 - 32 to give the pyrazolines 38 - 43, their isomers a and b being separable.With traces of base the bicyclic pyrazolines are cleaved to 1,4-dihydropyridazines 44 - 46.Cyclopropenes 27 - 30 react with thiophenolate to form the isomeric products 47 - 50; malonate adds to 28 and 31 to give 51, 52.With malononitrile via subsequent reactions the cyclopentadienes 55 - 57 are obtained.
- Norden, Wolfgang,Sander, Volker,Weyerstahl, Peter
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p. 3097 - 3111
(2007/10/02)
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- Reactions of the Cyclopropanone Hemiketal Magnesium Salt with Some Nucleophilic Reagents
-
Cyclopropanol (5), 1-(arylethynyl)cyclopropanol (7), 1-(3-hydroxypropyl)cyclopropanol derivative 10, 1-(2-propynyl)cyclopropanol (14), cyclopropanone cyanohydrin (19), 1-(aminomethyl)cyclopropanol (21) derivatives, benzylidenecyclopropanes 32, and ethyl cyclopropylideneacetate (38) have been prepared from the magnesium salt of cyclopropanone hemiketal 3. 3-Cyclopropylidene-1-propanol (12) and 3-cyclopropylidene-1-propyne (16) have been obtained from the cyclopropanols 10 and 14, respectively. Some reactions of this new synthon were specific. On the other hand, 3 did not undergo the nucleophilic addition of sulfur and nitrogen ylides; it underwent oxidizing ring opening with BrZnCH2COOEt and induced the decomposition of diazomethane.
- Salauen, Jacques,Bennani, Fatima,Compain, Jean-Claude,Fadel, Antoine,Ollivier, Jean
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p. 4129 - 4135
(2007/10/02)
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