3-pyridazinylnitrenes and 2-pyrimidinylnitrenes

Torker, Sebastian, Kvaskoff, David and Wentrup, Curt (2014) 3-pyridazinylnitrenes and 2-pyrimidinylnitrenes. Journal of Organic Chemistry, 79 4: 1758-1770. doi:10.1021/jo4027897

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Author Torker, Sebastian
Kvaskoff, David
Wentrup, Curt
Title 3-pyridazinylnitrenes and 2-pyrimidinylnitrenes
Journal name Journal of Organic Chemistry   Check publisher's open access policy
ISSN 0022-3263
Publication date 2014-02-21
Year available 2014
Sub-type Article (original research)
DOI 10.1021/jo4027897
Open Access Status File (Author Post-print)
Volume 79
Issue 4
Start page 1758
End page 1770
Total pages 13
Place of publication Washington, DC United States
Publisher American Chemical Society
Language eng
Subject 1605 Policy and Administration
Abstract Mild flash vacuum thermolysis of tetrazolo[1,5-b]pyridazines 8T generates small amounts of 3-azidopyridazines 8A (8aA, IR 2145, 2118 cm-1; 8bA, 2142 cm-1). Photolysis of the tetrazoles/azides 8T/8A in Ar matrix generates 3-pyridazinylnitrenes 9, detected by ESR spectroscopy (9a: D/hc = 1.006; E/hc = 0.003 cm-1). Cyanovinylcarbenes 11, derived from 4-diazobut-2-enenitriles 10, are also detected by ESR spectroscopy (11a: D/hc = 0.362; E/hc = 0.021 cm-1). Carbenes 11 rearrange to cyanoallenes 12 and 3-cyanocyclopropenes 13. Triazacycloheptatetraenes 20 were not observed in the photolyses of 8. Photolysis of tetrazolo[1,5-a]pyrimidines/2- azidopyridmidines 18T/18A in Ar matrices at 254 nm yields 2-pyrimidinylnitrenes 19, observable by ESR, UV, and IR spectroscopy (19a: ESR: D/hc = 1.217; E/hc = 0.0052 cm-1). Excellent agreement with the calculated IR spectrum identifies the 1,2,4-triazacyclohepta-1,2,4,6-tetraenes 20 (20a, 1969 cm -1; 20b, 1979 cm-1). Compounds 20 undergo photochemical ring-opening to 1-isocyano-3-diazopropenes 23. Further irradiation also causes Type II ring-opening of pyrimidinylnitrenes 19 to 2-(cyanimino)vinylnitrenes 21 (21a: D/hc = 0.875; E/hc = 0.00 cm-1), isomerization to cyaniminoketenimine 25 (2044 cm-1), and cyclization to 1-cyanopyrazoles 22. The reaction mechanisms are discussed and supported by DFT calculations on key intermediates and pathways. There is no evidence for the interconversion of 3-pyridazinylnitrenes 9 and 2-pyrimidinylnitrenes 19.
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Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Chemistry and Molecular Biosciences
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