Ketene-Ketene interconversion. 6-Carbonylcyclohexa-2,4-dienone-hepta-1,2,4, 6-tetraene-1,7-dione-6-oxocyclohexa-2,4-dienylidene and wolff rearrangement to fulven-6-one

Koch, Rainer, Blanch, Rodney J. and Wentrup, Curt (2014) Ketene-Ketene interconversion. 6-Carbonylcyclohexa-2,4-dienone-hepta-1,2,4, 6-tetraene-1,7-dione-6-oxocyclohexa-2,4-dienylidene and wolff rearrangement to fulven-6-one. Journal of Organic Chemistry, 79 15: 6978-6986. doi:10.1021/jo5011087


Author Koch, Rainer
Blanch, Rodney J.
Wentrup, Curt
Title Ketene-Ketene interconversion. 6-Carbonylcyclohexa-2,4-dienone-hepta-1,2,4, 6-tetraene-1,7-dione-6-oxocyclohexa-2,4-dienylidene and wolff rearrangement to fulven-6-one
Journal name Journal of Organic Chemistry   Check publisher's open access policy
ISSN 1520-6904
0022-3263
Publication date 2014-08-01
Year available 2014
Sub-type Article (original research)
DOI 10.1021/jo5011087
Volume 79
Issue 15
Start page 6978
End page 6986
Total pages 9
Place of publication Washington, DC, United States
Publisher American Chemical Society
Collection year 2015
Language eng
Formatted abstract
6-Carbonylcyclohexa-2,4-dienone (1) has been generated by flash vacuum thermolysis (FVT) with Ar-matrix isolation of methyl salicylate (7), 2-phenylbenzo-1,3-dioxan-4-one (8), phthalic peranhydride (9), and benzofuran-2,3-dione (11) and also by matrix photolysis of 9, 11, and 2-diazocyclohepta-4,6-dien-1,3-dione (12). In each case, FVT above 600 °C results in decarbonylation of 1 and Wolff rearrangement to fulven-6-one (13) either concertedly or via open-shell singlet 6-oxocyclohexa-2,4-dienylidene (18). Ketenes 1 and 13 were characterized by IR spectroscopy. Photolysis of matrix-isolated 1 at 254 nm also results in the slow formation of 13. The sequential formation of ketenes 1 and 13 from 7 has also been monitored by FVT-mass spectrometry, and 13 has been trapped with MeOH to afford methyl 1,3-cyclopentadiene-1- and -2-carboxylates 15 and 16. FVT of methyl salicylate-1-13C 7a revealed a deep-seated rearrangement of the 13C-labeled 1a to hepta-1,2,4,6-tetraen-1,7-dione (17a) by means of electrocyclic ring opening followed by a facile 1,5-H shift and recyclization prior to CO-elimination and ring contraction to 13C-labeled 13. The rearrangement mechanism is supported by M06-2X/6-311++G(d,p) calculations, which predict feasible barriers for the FVT rearrangements and confirm the observed labeling pattern in the isolated methyl salicylate 7a/7b and methyl cyclopentadienecarboxylates 20 and 21 resulting from trapping of 13 with MeOH.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Chemistry and Molecular Biosciences
 
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