Laser-induced carbene-carbene rearrangement in solution: the diphenylcarbene-fluorene rearrangement

Régimbald-Krnel, Michèle J. and Wentrup, Curt (2013) Laser-induced carbene-carbene rearrangement in solution: the diphenylcarbene-fluorene rearrangement. Journal of Organic Chemistry, 78 17: 8789–8795-8789–8795. doi:10.1021/jo401607m

Author Régimbald-Krnel, Michèle J.
Wentrup, Curt
Title Laser-induced carbene-carbene rearrangement in solution: the diphenylcarbene-fluorene rearrangement
Journal name Journal of Organic Chemistry   Check publisher's open access policy
ISSN 0022-3263
Publication date 2013-09-06
Sub-type Article (original research)
DOI 10.1021/jo401607m
Volume 78
Issue 17
Start page 8789–8795
End page 8789–8795
Total pages 7
Place of publication Washington, DC, United States
Publisher American Chemical Society
Collection year 2014
Language eng
Formatted abstract
Diphenylcarbene (DPC) generated by high-intensity laser photolysis of diphenyldiazomethane rearranges to fluorene (FL) by two distinct mechanisms as revealed by methyl-group labeling. Thus, excimer laser irradiation of p,p′-dimethyldiphenyldiazomethane generates 3,6-dimethylfluorene (3,6-DMF) and 2,7-dimethylfluorene (2,7-DMF), which were identified by fluorescence measurements as well as GC-MS and comparison with authentic materials. 3,6-DMF corresponds to direct bond formation between ortho positions in DPC, referred to as ortho,ortho′ coupling. 2,7-DMF corresponds to a carbene–carbene rearrangement, whereby DPC undergoes ring expansion to phenylcycloheptatetraene (PhCHT) followed by ring contraction to o-biphenylylcarbene (o-BPC), which then cyclizes to FL. The carbene–carbene rearrangement dominates over the ortho,ortho′ coupling under all conditions employed. The ortho,ortho′ coupling must take place in a higher excited state (most likely S2 or T1) of DPC, because it is not observed at all under thermolysis conditions, where only S1 and T0 are populated. The carbene–carbene rearrangement may take place either in a hot S1 state or more likely in a higher excited state (S2 or T1).
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Chemistry and Molecular Biosciences
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Created: Mon, 02 Sep 2013, 14:46:36 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences