Cyclobutene

Salaün, Jacques; Fadel, Antoine

doi:10.1002/0471264180.os064.07

Cited by 3 publications

(4 citation statements)

References 17 publications

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“…Under condition (2), best exemplified by the acid-promoted rearrangement of aqueous cyclopropylmethanol, the distribution of products is determined by relative thermodynamic stability . In fact, treatment of cyclopropylmethanol with dilute HCl is the preferred method for preparing nearly pure cyclobutanol. , Under condition (3), popularized by Olah and co-workers, superacid media allow carbocations to persist long enough for complete structural characterization 6 Solution-Phase Cationic Cyclopropylmethyl Rearrangements …”

Section: Discussionmentioning

confidence: 99%

Cyclopropylmethyl/Cyclobutyl Rearrangements on Surfaces: Evidence for Transient Cation Formation near O-Covered Mo(110)

et al. 2007

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Rearrangement reactions of C4-alkoxides on O-covered Mo(110) have been studied using temperature-programmed reaction spectroscopy and reflection-absorption infrared spectroscopy. Cyclobutoxide on Mo(110), prepared from the corresponding alcohol or bromide, is described for the first time in detail. Several reaction mechanisms are considered for the ring-opening rearrangement of cyclopropylmethoxide during high-temperature annealing. In light of compelling new data, previous results are reinterpreted to support the formation of transient cations near O-covered Mo(110). For the first time, we present strong evidence for clean, heterolytic bond cleavage reactions over a metal surface. Our revised reactivity model is based on spectroscopic and reactivity data that show the rearrangement of cyclopropylmethyl groups to cyclobutyl groups and vice versa. Selectively deuterated 1,1-D2-cyclopropylmethanol was studied as a test of mechanism and as a probe for the lifetime of reactive intermediates. Isotopic scrambling observed for this substrate is consistent with the formation of a relatively long-lived carbocation during rearrangement. The intermediacy of transient cations is further invoked to explain the rearrangements that are now recognized to occur as alkyl bromides are transformed into alkoxides on Mo(110)-(1 x 6)-O. The observed ring expansion/contraction reactions are characteristic of a cationic process; carbon-centered radicals are not known to rearrange in this manner. However, in none of the cases discussed could contributions from radical pathways be completely ruled out. Our results are compared to analogous reactions in the vapor and solution phases. General trends governing rearrangement mechanisms on Mo(110) are presented with respect to metal-surface coverage, heteroatom incorporation, and temperature. Trends are discussed in the context of heterogeneous hydrocarbon oxidation.

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Section: Discussionmentioning

confidence: 99%

Cyclopropylmethyl/Cyclobutyl Rearrangements on Surfaces: Evidence for Transient Cation Formation near O-Covered Mo(110)

et al. 2007

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“…Method B (from cyclobutene) : Togni reagent II (78.2 g, 0.248 mol) and Cu(MeCN) 4 PF 6 (1.85 g, 4.96 mmol) were dissolved in MeCN (1 L). Then, cyclobutene [51] (16.1 g, 0.298 mol; see preparation of 25 ) and TMSN 3 (42.9 g, 372 mmol) were added under argon atmosphere, the mixture was stirred at rt for 12 h, and PPh 3 (102 g, 0.391 mol) was added in portions. When the gas evolution ceased, 4 M aq HCl (200 mL) was added at rt, the resulting mixture was stirred at rt overnight, then evaporated.…”

Section: Methodsmentioning

confidence: 99%

“…Then, the reaction mixture was stirred at 70 °C for 2 h, the manifold system was closed off from the reaction vessel, and the material collected in the first trap was slowly warmed. Cyclobutene was distilled at 2–3 °C into the second cooled trap [51] . A solution of TMSCN (74.0 g, 0.746 mol) and cyclobutene (32.3 g, 0.596 mol) in DMSO (100 mL) was added dropwise to a solution of Togni II reagent (157 g, 0.497 mol) and Cu(OTf) 2 (8.99 g, 24.9 mmol) in DMSO (1 L) under argon atmosphere maintaining the temperature below 60 °C (CAUTION: highly exothermic reaction occured upon addition of the solution of TMSCN and cyclobutene).…”

Section: Methodsmentioning

confidence: 99%

Fluoroalkyl‐Containing 1,2‐Disubstituted Cyclobutanes: Advanced Building Blocks for Medicinal Chemistry

et al. 2020

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Synthesis of previously unavailable 1,2‐disubstituted cyclobutane building blocks bearing mono‐, di‐ and trifluoromethyl groups are disclosed. The key steps included deoxofluorination or TMAF‐mediated nucleophilic substitution in the appropriate bifunctional cyclobutanes; for the CF3‐substituted derivatives, alternative methods based on cyano‐ or azidotrifluoromethylation of cyclobutene using the Togni reagent II were also proposed. All methods provided trans diastereomers of the target primary amines and carboxylic acids (6 representatives) and were suitable for their multigram preparation. Furthermore, dissociation constants (pKa) and lipophilicity (logP) values were measured to evaluate the effect of the fluoroalkyl substituents on acidity/basicity and lipophilicity of the building blocks obtained.

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“…5. General Procedure for the Sulfonylation of the Pyrrolidinols with Sulfonyl Chlorides: Method E [49]. To a solution of the N-protected pyrrolidinol (1.0 equivalent) in pyridine or triethylamine (20 mL) cooled to 0 ∘ C was added the sulfonyl chloride (1.2 equivalent) portionwise over 20 min.…”

Section: General Procedures For the Epoxidation Of The Pyrrolidinolmentioning

confidence: 99%

Development of Small Molecular Proteasome Inhibitors Using a Caenorhabditis elegans Screen

Nayak¹,

Fiaschi²,

King³

et al. 2020

Prime Archives in Chemistry

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We have developed a screening protocol to identify compounds with characteristics of small molecule proteasome inhibitors using the real-time analysis of the Caenorhabditis elegans germ line. This screen is able to identify compounds that induce germ line phenotypes characteristic of a reduction in proteasome function such as changes in polarity, aberrant nuclear morphology, and stimulation of apoptosis. This basic protocol is amenable to a high throughput (96-well) format and has been used successfully to identify multiple compounds for further analysis based on structural elements from the naturally occurring compounds lactacystin and the-lactone homologs omuralide and salinosporamide A. The further development of this assay system should allow for the generation of novel small molecule proteasome inhibitors in a genetically tractable whole animal amenable to biochemical analysis.

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Cyclobutene

Abstract: Cyclobutene intermediate: Cyclobutanol byproduct: 3‐buten‐1‐ol intermediate: cyclobutyl tosylate product: cyclobutene product: 1,2‐dibromocyclobutane

Cited by 3 publications

References 17 publications

Cyclopropylmethyl/Cyclobutyl Rearrangements on Surfaces: Evidence for Transient Cation Formation near O-Covered Mo(110)

Cyclopropylmethyl/Cyclobutyl Rearrangements on Surfaces: Evidence for Transient Cation Formation near O-Covered Mo(110)

Fluoroalkyl‐Containing 1,2‐Disubstituted Cyclobutanes: Advanced Building Blocks for Medicinal Chemistry

Development of Small Molecular Proteasome Inhibitors Using a Caenorhabditis elegans Screen

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