- 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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- 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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- 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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- 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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- Synthesis of Spiro[2.2]pentanes and Spiro[2.3]hexanes Employing the Me3Al/CH2I2 Reagent
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Substituted alkylidenecyclopropanes reacted with 5 equivalents each of Me3Al and CH2I2 at room temperature in hexane to give 1-mono- and 1,1-disubstituted spiro[2.2]pentanes in high yields. Surprisingly, the same reaction
- Ramazanov, Ilfir R.,Kadikova, Rita N.,Zosim, Tat'yana P.,Dzhemilev, Usein M.,de Meijere, Armin
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p. 7060 - 7067
(2017/12/28)
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- Palladium-catalyzed ring expansion reaction of (Z)-1-(1,3-butadienyl) cyclobutanols with aryl iodides. Stereospecific synthesis of (Z)-2-(3-aryl-1-propenyl)cyclopentanones
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Equation presented. A novel type of cascade ring expansion process has been developed by the palladium-catalyzed reaction of (Z)-1-(1,3-butadienyl) cyclobutanols with aryl iodides. The reaction proceeds in a stereospecific manner to produce (Z)-2-(3-aryl-
- Yoshida, Masahiro,Sugimoto, Kenji,Ihara, Masataka
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p. 1979 - 1982
(2007/10/03)
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- Convenient preparation method of β-silylated olefins by hydrosilylation of methylenecyclopropanes over Rh(I) complexes
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The catalytic hydrosilylation of methylenecyclopropanes with various substituents at the double bond in the presence of Rh(I) complexes occurs selectively with the cleavage of the cyclopropane ring. This is a convenient route to β-silicon-substituted olef
- Bessmertnykh,Donskaya,Tveritinova,Beletskaya
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p. 799 - 808
(2007/10/03)
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- Synthesis of alkylidenecyclopropanes via thermal cycloreversion of α-spirocyclopropyl-β-lactones
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An efficient two-step synthesis of alkylidenecyclopropanes is reported based on the addition of metallated cyclopropyl thiol esters to carbonyl compounds. Thermolysis of the resulting α-spirocyclopropyl-β-lactones at 105-150°C induces thermal [2+2] cycloreversion to furnish alkylidenecyclopropanes in good yield.
- Danheiser, Rick L.,Lee, Thomas W.,Menichincheri, Maria,Brunelli, Steven,Nishiuchi, Masaki
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p. 469 - 470
(2007/10/03)
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- REGIOSELECTIVE PALLADIUM(0) CATALYZED REDUCTION OF 1-ALKENYLCYCLOPROPYL ESTERS AS EQUIVALENT TO THE WITTIG REACTION
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Palladium(0) catalyzed reduction of 1-(1-alkenyl)- and 1-(1-cycloalkenyl)cyclopropyl esters provides an useful alternative to the Wittig reactions of cyclopropylidene triphenylphosphorane or of cyclopropenone hemiacetals and an easy route to strained meth
- Ollivier, Jean,Piras, Pier P.,Stolle, Andreas,Aufranc, Pierre,Meijere, Armin de,Salaun, Jacques
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p. 3307 - 3310
(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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- The chemistry of small-ring compounds. Part 51. Electron-transfer-initiated oxidation of some cyclopropylidene compounds
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Cyclopropylidene compounds of type 1 are found to quench the fluorescence of 9,10-dicyanoanthracene (DCA).Nevertheless photo-oxygenation, in the presence of DCA, leads under no circumstances to dioxetanes but (in ethanol) to a methoxy hydroperoxide 5, as tentatively shown in Scheme 2.This hydroperoxide undergoes acid rearrangement either to a lactone or to a cyclobutanone, depending on the reaction conditions (Scheme 3).
- Hofland, A.,Boer, Th. J.
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p. 558 - 562
(2007/10/02)
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- The chemistry of small-ring compounds. Part 47. Small-ring interference in the ozonolysis of cyclopropylidenecycloalkanes
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Ozonolysis of olefins Ia-c containing a cyclpropylidene group, does not follow the classical Criegee mechanism but gives the anomalous products IIa-c, IIIa-c, IVa-c, and Va-c, as outlined in Scheme 2.None of these oxidation products contains the cycloprop
- Heuvel, C. J. M. van den,Hofland, A.,Velzen, J. C. van,Steinberg, H.,Boer, Th. J. de
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p. 233 - 240
(2007/10/02)
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