Cyclopropanones. Formation of vinylcyclopropanols and their rearrangement to cyclobutanones

An efficient approach to synthesis of previously unavailable 2-substituted difluorocyclobutane building blocks was developed and applied on a multigram scale. The key step of the synthetic sequence included deoxofluorination of O-protected 2-(hydroxylmethyl)cyclobutanone. Dissociation constants (pK a) and log P values for 2,2-difluorocyclobutaneamine and 2,2-difluorocyclobutanecarboxylic acid or their derivatives were measured and compared with the values obtained for the corresponding 3,3-difluorocyclobutane derivatives and nonfluorinated counterparts. Three-dimensional structures of 2,2- and 3,3-difluorocyclobutanamines were compared using exit vector plot analysis of X-ray crystallographic data.

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“…The compound was obtained by a method of Wasserman and colleagues , in 68% yield. For spectral and physical data, see refs , .…”

Section: Experimental Sectionmentioning

confidence: 99%

Last of the gem-Difluorocycloalkanes: Synthesis and Characterization of 2,2-Difluorocyclobutyl-Substituted Building Blocks

et al. 2019

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“…Having delineated some suitable conditions, the scope and limitations of this methodology were investigated [17–27]. Some selected examples are collected in Table 1.…”

Section: Resultsmentioning

confidence: 99%

Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from β-hydroxyketones

Markó

Schevenels²

2013

Beilstein J. Org. Chem.

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SummaryThe assembly of (Z)-chloro-exo-methylenetetrahydrofurans by an original and connective anionic cascade sequence is reported. Base-catalysed condensation of β-hydroxyketones with 1,1-dichloroethylene generates, in moderate to good yields, the corresponding (Z)-chloro-exo-methylenetetrahydrofurans. Acidic treatment of this motif leads to several unexpected dimers, possessing unique structural features.

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“…3,3-Dichloro-2,2,4,4-tetramethylcyclobutanethione (1) was prepared from 3,3-dichloro-2,2,4,4-tetramethylcyclobutanone by thionation using P 4S10 in pyridine solution [5]. Diazomethane (2a) and diazoethane (2b ) were prepared from N-nitroso-N-methylurea and N-nitroso-Nethylurea, respectively [20]. 2-Diazopropane (2c) was prepared by oxidation of acetone hydrazone with yellow mercury oxide according to a known protocol [21].…”

Section: Methodsmentioning

confidence: 99%

New Thiocarbonyl Ylides Derived from 3,3‐Dichloro‐2,2,4,4‐tetramethylcyclobutanethione; Generation and Reactions.

et al. 2007

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The reaction of 3,3-dichloro-2,2,4,4-tetramethylcyclobutanethione (1) with diazo compounds yielded spirocyclic 2,5-dihydro-1,3,4-thiadiazoles 3, which decomposed at ca. 45°C to give the corresponding thiocarbonyl ylide of type 4. In the absence of trapping agents, these thiocarbonyl ylides underwent a 1,3-dipolar electrocyclization to yield spirocyclic thiiranes 5. On the other hand, the thiocarbonyl methanide 4a was efficiently intercepted with C C, C=C, C=O, C=S, and N=N dipolarophiles leading to the [2+3] cycloadducts. A non-stereoselective cycloaddition took place when 3a was decomposed in the presence of the very electron-deficient dicyanofumarate or maleate, indicating a two step mechanism via an intermediate zwitterion. Furthermore, the thiocarbonyl methanide 4a could be trapped by the imidazole-2-thione 7 to give the 1,3-adduct 8. Treatment of 3a with secondary amines led to amidrazones of type 25 via base-catalyzed ring opening and condensation reaction.

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Cyclopropanones. Formation of vinylcyclopropanols and their rearrangement to cyclobutanones

Cited by 46 publications

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Last of the gem-Difluorocycloalkanes: Synthesis and Characterization of 2,2-Difluorocyclobutyl-Substituted Building Blocks

Last of the gem-Difluorocycloalkanes: Synthesis and Characterization of 2,2-Difluorocyclobutyl-Substituted Building Blocks

Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from β-hydroxyketones

New Thiocarbonyl Ylides Derived from 3,3‐Dichloro‐2,2,4,4‐tetramethylcyclobutanethione; Generation and Reactions.

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