The vinylketene-acylallene rearrangement: Theory and experiment

Bibas H., Wong M.W. and Wentrup C. (1997) The vinylketene-acylallene rearrangement: Theory and experiment. Chemistry - A European Journal, 3 2: 237-248. doi:10.1002/chem.19970030212


Author Bibas H.
Wong M.W.
Wentrup C.
Title The vinylketene-acylallene rearrangement: Theory and experiment
Journal name Chemistry - A European Journal   Check publisher's open access policy
ISSN 0947-6539
Publication date 1997-01-01
Year available 1997
Sub-type Article (original research)
DOI 10.1002/chem.19970030212
Open Access Status Not yet assessed
Volume 3
Issue 2
Start page 237
End page 248
Total pages 12
Place of publication WEINHEIM
Publisher WILEY-V C H VERLAG GMBH
Language eng
Subject 1600 Chemistry
Abstract Alkoxyvinylketenes 4 are generated by flash vacuum thermolysis (FVT) or photolysis of 3-alkoxycyclobutenones 3. The thermal interconversion of 4 and allene carboxylic acid esters 5 under FVT conditions is demonstrated by Ar matrix FTIR spectroscopy. In addition, ethoxyvinylketene 4 b undergoes thermal elimination of ethene with formation of s-cis- and s-trans-acetylketene (8). An analogous aminovinylketene-to-allenecarboxamide conversion is observed on FVT of 3-dimethylaminocyclobutenone 3 c. A facile 1,3-chlorine migration in 2,3-buta-dienoyl chloride (5 d) is also reported. Consistent with the experimental observations, 1,3-methoxy, 1,3-chloro, and 1,3-dimethylamino migrations in vinylketene are calculated (G2(MP2,SVP) level) to have moderate barriers of 169, 157, and 129 kJ mol(-1), respectively, significantly less than the corresponding 1,3-H shift barrier (273 kJ mol(-1)). The stabilization of the four-center transition structures is rationalized in terms of the donor-acceptor interaction between the lone pair electrons of the migrating donor substituent and the vacant central carbon p orbital of the ketene LUMO. The predicted migratory aptitude in the series of substituted vinylketenes, R-C(=CH2)-CH=C=O, is in the order N(CH3)(2)>SCH3>SH>Cl>NH2>OCH3>OH>F>H>CH3, and correlates well with the electron-donating ability of the R group.
Keyword ab initio calculations
allenes
ketenes
matrix isolation
rearrangements
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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