• DOI:10.1021/JO0256991
• Corpus ID: 33631413

2-pyrazinylnitrene and 4-pyrimidylnitrene. Ring expansion to 1,3,5-triazacyclohepta-1,2,4,6-tetraene and ring opening to (2-Isocyanovinyl)carbodiimide.

@article{Addicott20022pyrazinylnitreneA4,
  title={2-pyrazinylnitrene and 4-pyrimidylnitrene. Ring expansion to 1,3,5-triazacyclohepta-1,2,4,6-tetraene and ring opening to (2-Isocyanovinyl)carbodiimide.},
  author={Chris Addicott and Ming Wah Wong and Curt Wentrup},
  journal={The Journal of organic chemistry},
  year={2002},
  volume={67 24},
  pages={
          8538-46
        }
}

• C. Addicott, M. W. Wong, C. Wentrup
• Published 31 October 2002
• Chemistry
• The Journal of organic chemistry

Tetrazolo[1,5-a]pyrazine/2-azidopyrazine 9T/9A undergo photolysis in Ar matrix at cryogenic temperatures to yield 1,3,5-triazacyclohepta-1,2,4,6-tetraene 21 as the first observable intermediate, and 1-cyanoimidazole 11 and (2-isocyanovinyl)carbodiimide 22 as the final products. The latter tautomerizes to 2-(isocyanovinyl)cyanamide 23 on warming to 40 K. The same intermediate 21 and the same final products are obtained on matrix photolysis of the isomeric tetrazolo[1,5-c]pyrimidine/4-azidopyrimidine 24T/24A. These photolysis results as well as those of the previously reported thermal ring contraction of (15)N-labeled 2-pyrazinyl- and 4-pyrimidylnitrenes to 1-cyanoimidazoles can all be rationalized in terms of selective ring opening of 21 or nitrine 10 to a nitrile ylide zwitterion 28 prior to formation of the final products, 11 and 22. The results are supported by high-level ab initio and DFT calculations (CASPT2-CASSCF(6,6), G3(MP2), and B3LYP/6-31+G) of the energies and IR spectra of the intermediates and products.