4-Pyridylnitrene and 2-pyrazinylcarbene
Curt Wentrup1, Ales Reisinger, David Kvaskoff
1School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia.
Beilstein Journal of Organic Chemistry
|June 15, 2013
Summary
Flash vacuum thermolysis and matrix photolysis of 1,2,3-triazolo[1,5-a]pyrazine yield 2-diazomethylpyrazine. These methods also produce nitrene and carbene intermediates, leading to ring expansion and opening products.
Area of Science:
- Organic chemistry
- Photochemistry
- Thermochemistry
Background:
- 1,2,3-triazolo[1,5-a]pyrazine is a heterocyclic compound with potential applications in organic synthesis.
- Understanding the decomposition pathways of such compounds is crucial for developing new synthetic methodologies.
Purpose of the Study:
- To investigate the decomposition products of 1,2,3-triazolo[1,5-a]pyrazine using flash vacuum thermolysis (FVT) and matrix photolysis.
- To explore the reaction mechanisms involving nitrene and carbene intermediates generated from azidopyridine and tetrazolylpyrazine derivatives.
Main Methods:
- Flash vacuum thermolysis (FVT) of azidopyridine, 1,2,3-triazolo[1,5-a]pyrazine, and 2-(5-tetrazolyl)pyrazine.
- Matrix photolysis of 4-azidopyridine and 1,2,3-triazolo[1,5-a]pyrazine at low temperatures.
- Analysis of reaction products using spectroscopic techniques.
Main Results:
- Both FVT and matrix photolysis of 1,2,3-triazolo[1,5-a]pyrazine generated 2-diazomethylpyrazine.
- FVT of various precursors yielded products consistent with nitrene intermediates, such as 4,4'-azopyridine and cyanopyrroles.
- Matrix photolysis induced ring expansion of pyridylnitrene/pyrazinylcarbene to a diazacycloheptatetraene, which further photolyzed to a ketenimine.
Conclusions:
- Flash vacuum thermolysis and matrix photolysis are effective methods for generating reactive intermediates from nitrogen-rich heterocycles.
- The observed products indicate distinct reaction pathways under thermal and photolytic conditions, involving nitrenes, carbenes, and subsequent rearrangements.
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