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A general and efficient rhodium-catalyzed ortho -alkylation of N -arylpyrazoles has been accomplished with cyclopropanols as coupling partners. The reaction involves cleavage of both a C–H bond of the arene and a C–C bond of the cyclopropanol, and it offers access to a diversity of substituted 1-(ortho -alkylaryl)-1 H -pyrazoles in good to excellent yields. In addition, nonsymmetrical dialkylation and a preliminary mechanistic investigation are also discussed. [ABSTRACT FROM AUTHOR]

A one-step catalytic oxidant-free synthesis of unsaturated ketones from 1,2-disubstituted cyclopropanols is reported. Previously for this transformation, only two- and three-step protocols have been developed. The reaction proceeds under irradiation with visible light in the presence of catalytic amounts of both an acridinium photocatalyst and a cobaloxime complex. 2-Aryl-substituted cyclopropanols react giving α,β-unsaturated ketones, while dehydrogenative ring opening of 2-alkyl-substituted substrates affords mixtures of α,β- and β,γ-enones. The reaction starts with one-electron oxidation of a cyclopropanol to cyclopropyloxy radical, presumably, by the photoexcited acridinium catalyst. We also found that Co(dmgBF2)2 (MeCN)2 complex under an air atmosphere and irradiation with blue LEDs or upon heating can serve as a hydroxycyclopropane oxidant. [ABSTRACT FROM AUTHOR]

This short review summarizes the most recent developments (since 2010) in the tandem cyclization/cycloaddition of allene intermediates-, generated from the copper-catalyzed cross-coupling of diazo compounds with terminal alkynes, to afford cyclic compounds. 1 Introduction 2 Cyclization 2.1 Cyclization with Nucleophiles 2.2 Cyclization with Electrophiles 2.3 6π-Electrocyclization 2.4 Other Cyclization 3 Cycloaddition 4 Conclusion [ABSTRACT FROM AUTHOR]

A novel method for preparing aromatic compounds containing cyclopropoxy via nucleophilic aromatic substitution reaction (SN Ar) of fluoroaromatic compounds with cyclopropanol under relatively mild conditions is presented. As compared to the approaches reported previously for preparing 1-(cyclopropyloxy)-2-nitrobenzene, the one proposed in this work is simplified without sacrificing the yields: When the reaction was performed at 75 °C with Cs2 CO3 as the base and DMF as solvent, after 6 h the yield was up to 90%. Finally, various fluoroaromatic compounds were employed as substrates for a test that proves a wide application scope of the method. [ABSTRACT FROM AUTHOR]

Since their discovery, metal homoenolates have been widely explored as carbon-based nucleophiles for the ß-functionalization of carbonyl derivatives. Only recently has it been reported that metal homoenolates can react as carbonyl electrophiles. In this context, we have recently discovered that cyclopropylamines can be prepared from cyclopropanols via zinc homoenolate intermediates. This Synpacts article will present an overview of the reactivity of homoenolates and our strategy to employ these intermediates for the synthesis of cyclopropylamines. Key mechanistic observations and their influence on reaction optimization will also be discussed. 1 Introduction 2 Homoenolates as Nucleophiles--Selected Reactivity 3 Homoenolates as Electrophilic Reagents 4 Conclusion [ABSTRACT FROM AUTHOR]

β-Keto radicals can be readily generated from single-electron oxidation and ring opening of cyclopropanols. Herein, we report new ways of trapping β-keto radicals derived from Mn(III)-mediated oxidative cyclopropanol ring opening with biaryl isonitriles and N-aryl acrylamides derived from anilines. Through tandem radical cyclization processes, substituted phenanthridines and oxindoles can be synthesized in one step and good to excellent yield. These new synthetic methods feature broad substrate scope and mild reaction conditions, efficiently form two carbon-carbon bonds, and use cheap and commercially available manganese salts as oxidants. Concomitant installation of ketone functionality in the final products provides a handle for further functionalization of these important and biologically relevant scaffolds. [ABSTRACT FROM AUTHOR]

Due to their high strain, unique bonding and relative ease of ring-cleavage, and because they are readily accessible, cyclopropanols have been employed in an increasing number of transition-metal-catalyzed C-C and C-X (X = heteroatom) bond-forming reactions. We review the recent literature and organize all the methods developed along mechanistic lines. 1 Introduction and Scope 2 C-C Bond Formation via Catalytic Generation and Coupling of Cyclopropanol-Derived Homoenolates 3 C-N Bond Formation via Catalytic Generation and Coupling of Cyclopropanol-Derived Homoenolates 4 C-C Bond Formation via Stoichiometric Generation and Coupling of Cyclopropanol-Derived Homoenolates 5 Ring Expansion of Cyclopropanols to Cyclobutanones via Transition-Metal-Catalyzed Wagner-Meerwein Shift 6 Transition-Metal-Catalyzed Rearrangement of Cyclopropanols to Cyclopentenones and Cyclohexenones 7 Synthesis of Medium-Size Rings via Multicomponent Reactions Involving Cyclopropanols 8 C-C and C-X Bond Formation via Free-Radical Fragmentation of Cyclopropanols 9 Summary and Outlook. [ABSTRACT FROM AUTHOR]

A new silver-promoted oxidative ring opening/alkynylation of cyclopropanols with ethynylbenziodoxolones (EBX) is described. This method enables the formation of alkylated alkynes via a sequence of ring opening and alkynylation. Control experiments support a radical mechanism in this silver-promoted method. [ABSTRACT FROM AUTHOR]

Strained alcohols have featured prominently in a wide array of transition-metal-catalyzed cross-coupling reactions, but methods involving cyclopropanols have only been developed relatively recently. In this account, we describe our group's work in this area, and we provide a concise summary of other palladium-catalyzed methods for C-C bond-forming reactions using cyclopropanols. 1 Introduction 2 Cross-Coupling Reactions Using Strained Tertiary Alcohols 3 Base- or Acid-Mediated Ring-Opening Reactions of Strained Alcohols 4 Palladium-Catalyzed Cross-Coupling Reactions of Cyclopropanols 4.1 Palladium-Catalyzed Cross-Coupling Reactions of Cyclopropanols with Aryl Halides 4.2 Palladium-Catalyzed Cross-Coupling Reactions of Cyclopropanols with Benzyl Halides 4.3 Palladium-Catalyzed Cross-Coupling Reactions of Cyclopropanols with Acyl Halides 4.4 Direct Arylation Using Cyclopropanol-Derived Palladium Homoenolates 4.5 Synthesis of Quinolines from Cyclopropanols 5 Conclusions [ABSTRACT FROM AUTHOR]

The cross-coupling of unprotected ortho-bromoanilines with cyclopropanols yields quinolines in a single operation via an intramolecular condensation and palladium-catalyzed oxidation sequence. The reaction tolerates a variety of cyclopropanols and substituted bromoanilines. Deuterium-labeling experiments provide direct evidence of a second equivalent of bromoaniline serving as the terminal oxidant. [ABSTRACT FROM AUTHOR]

Spirocyclic sulfates of 2- and 3-(hydroxyalkyl)cyclopropanols, obtainable through the Kulinkovich reaction from β-and γ- hydroxy carboxylic acid esters, respectively, were synthesized for the first time. The possibility of regio- and stereoselective alkylating the spirocyclic sulfates by using Normant homocuprates has been demonstrated. [ABSTRACT FROM AUTHOR]

An efficient transformation of 2-(1-hydroxyalkyl)-1-alkylcyclopropanols, obtained from α,β-unsaturated ketones, to β,γ-unsaturated ketones was achieved by trifluoroacetic acid (TFA)-mediated reaction. [ABSTRACT FROM AUTHOR]

An introduction to articles published within the issue is presented, including one by I. A. Tonks on the synthesis of pyrroles, another by J.-H. Li on the tandem ring-opening/alkynylation of cyclopropanols by ethynyl benziodoxolones, and one on the novel synthetic approach to the antibacterial platencin.