A unifying mechanism for the rearrangement of vinyl allene oxide geometric isomers to cyclopentenones

2014 ◽  
Vol 12 (39) ◽  
pp. 7694-7701 ◽  
Author(s):  
Adán B. González-Pérez ◽  
Alexander Grechkin ◽  
Ángel R. de Lera
Keyword(s):  
High Fidelity ◽  
Allene Oxide ◽  
Geometric Isomers ◽  
Allene Oxides

Z-Vinyl allene oxides are predicted to rearrange with high fidelity to stereodefined cyclopentenones through intermediate cyclopropanones.

Rearrangement of vinyl allene oxide geometric isomers to cyclopentenones. Further computational insights with biologically relevant model systems

2017 ◽  
Vol 15 (13) ◽  
pp. 2846-2855 ◽  
Author(s):  
Adán B. González-Pérez ◽  
Alexander Grechkin ◽  
Ángel R. de Lera
Keyword(s):  
Computational Study ◽  
Model Systems ◽  
Allene Oxide ◽  
Geometric Isomers ◽  
Relevant Model ◽  
Biologically Relevant ◽  
Biological Relevance ◽  
Naturally Occurring ◽  
Allene Oxides

A computational study of the rearrangement of vinyl allene oxides of biological relevance, which include alkyl (methyl, propyl) or unsaturated groups (allyl, crotyl) attached to the Csp3 atom has revealed interesting insights into the formation of naturally occurring cyclopentenones.

scholarly journals Expression of concern: A unifying mechanism for the rearrangement of vinyl allene oxide geometric isomers to cyclopentenones

2015 ◽  
Vol 13 (47) ◽  
pp. 11580-11580
Author(s):  
Richard Kelly
Keyword(s):  
Allene Oxide ◽  
Geometric Isomers

Expression of concern for ‘A unifying mechanism for the rearrangement of vinyl allene oxide geometric isomers to cyclopentenones’ by Adán B. González-Pérez et al., Org. Biomol. Chem., 2014, 12, 7694–7701.

scholarly journals Isolation and Characterization of Two Geometric Allene Oxide Isomers Synthesized from 9S-Hydroperoxylinoleic Acid by Cytochrome P450 CYP74C3

2013 ◽  
Vol 288 (29) ◽  
pp. 20797-20806 ◽  
Author(s):  
Alan R. Brash ◽  
William E. Boeglin ◽  
Donald F. Stec ◽  
Markus Voehler ◽  
Claus Schneider ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Cytochromes P450 ◽  
Structural Features ◽  
Allene Oxide ◽  
Uv Spectrum ◽  
Isolation And Characterization ◽  
Biphasic Reaction ◽  
Allene Oxides ◽  
Oxide Synthase ◽  
Hydroperoxylinoleic Acid

Specialized cytochromes P450 or catalase-related hemoproteins transform fatty acid hydroperoxides to allene oxides, highly reactive epoxides leading to cyclopentenones and other products. The stereochemistry of the natural allene oxides is incompletely defined, as are the structural features required for their cyclization. We investigated the transformation of 9S-hydroperoxylinoleic acid with the allene oxide synthase CYP74C3, a reported reaction that unexpectedly produces an allene oxide-derived cyclopentenone. Using biphasic reaction conditions at 0 °C, we isolated the initial products and separated two allene oxide isomers by HPLC at −15 °C. One matched previously described allene oxides in its UV spectrum (λmax 236 nm) and NMR spectrum (defining a 9,10-epoxy-octadec-10,12Z-dienoate). The second was a novel stereoisomer (UV λmax 239 nm) with distinctive NMR chemical shifts. Comparison of NOE interactions of the epoxy proton at C9 in the two allene oxides (and the equivalent NOE experiment in 12,13-epoxy allene oxides) allowed assignment at the isomeric C10 epoxy-ene carbon as Z in the new isomer and the E configuration in all previously characterized allene oxides. The novel 10Z isomer spontaneously formed a cis-cyclopentenone at room temperature in hexane. These results explain the origin of the cyclopentenone, provide insights into the mechanisms of allene oxide cyclization, and define the double bond geometry in naturally occurring allene oxides.

Allene oxide synthases and allene oxides

2002 ◽  
Vol 68-69 ◽  
pp. 423-431 ◽  
Author(s):  
Nathalie Tijet ◽  
Alan R Brash
Keyword(s):  
Allene Oxide ◽  
Allene Oxides

Photochemical generation and 1H NMR detection of alkyl allene oxides in solution

2005 ◽  
Vol 83 (9) ◽  
pp. 1347-1351 ◽  
Author(s):  
Leah E Breen ◽  
Norman P Schepp ◽  
C-H Edmund Tan
Keyword(s):  
Nmr Spectroscopy ◽  
Significant Influence ◽  
Alkyl Group ◽  
Room Temperature ◽  
Nucleophilic Attack ◽  
Allene Oxide ◽  
Lifetime Measurements ◽  
H Nmr ◽  
Photochemical Generation ◽  
Allene Oxides

Irradiation of substituted 5-alkyl-4,5-epoxyvalerophenones leads to the formation of alkyl allene oxides that, in some cases, are sufficiently long-lived to be detected at room temperature by 1H NMR spectroscopy. Absolute lifetime measurements show that the size of the alkyl group has a significant influence on the reactivity of the allene oxide, with tert-butyl allene oxide having a lifetime of 24 h in CD3CN at room temperature that is considerably longer than the 1.5 h lifetime of the ethyl allene oxide. The allene oxides react rapidly with water to give α-hydroxyketones. The mechanism involves nucleophilic attack to the epoxide carbon to give an enol, which can also be detected as an intermediate by 1H NMR spectroscopy.Key words: allene oxides, mechanisms, absolute reactivity, kinetics, photochemistry.

scholarly journals Correction and removal of expression of concern: A unifying mechanism for the rearrangement of vinyl allene oxide geometric isomers to cyclopentenones

2017 ◽  
Vol 15 (13) ◽  
pp. 2856-2856 ◽  
Author(s):  
Richard Kelly
Keyword(s):  
Allene Oxide ◽  
Geometric Isomers

Correction and removal of expression of concern for ‘A unifying mechanism for the rearrangement of vinyl allene oxide geometric isomers to cyclopentenones’ by Adán B. González-Pérez et al., Org. Biomol. Chem., 2014, 12, 7694–7701.

Entry into the Allene Oxide-Cyclopropanone System via Vinylsilanes. IV. Reaction of Allene Oxides with Cyclopentadiene

Heterocycles ◽  
1977 ◽  
Vol 7 (2) ◽  
pp. 913 ◽  
Author(s):  
Tak Hang Chan ◽  
Beng Soon Ong ◽  
Tak-Hang Chan
Keyword(s):  
Allene Oxide ◽  
Allene Oxides

Using the Theory of Planned Behavior to Predict Faking in Selection Exercises Varying in Fidelity

2018 ◽  
Vol 17 (3) ◽  
pp. 155-160 ◽  
Author(s):  
Daniel Dürr ◽  
Ute-Christine Klehe
Keyword(s):  
Theory Of Planned Behavior ◽  
Planned Behavior ◽  
Predictive Validity ◽  
Group Discussion ◽  
Role Play ◽  
Selection Procedure ◽  
High Fidelity ◽  
Selection Research ◽  
Play Group

Abstract. Faking has been a concern in selection research for many years. Many studies have examined faking in questionnaires while far less is known about faking in selection exercises with higher fidelity. This study applies the theory of planned behavior (TPB; Ajzen, 1991 ) to low- (interviews) and high-fidelity (role play, group discussion) exercises, testing whether the TPB predicts reported faking behavior. Data from a mock selection procedure suggests that candidates do report to fake in low- and high-fidelity exercises. Additionally, the TPB showed good predictive validity for faking in a low-fidelity exercise, yet not for faking in high-fidelity exercises.

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