Reactivity of tetrazolo[1,5-a]pyrimidines in click chemistry and hydrogenation

  1. Elisandra ScapinORCID Logo,
  2. Geórgia C. Zimmer,
  3. Jean C. B. VieiraORCID Logo,
  4. Catarina A. B. Rodrigues,
  5. Carlos A. M. Afonso,
  6. Nilo ZanattaORCID Logo,
  7. Helio G. Bonacorso,
  8. Clarissa P. Frizzo and
  9. Marcos A.P. MartinsORCID Logo

Submitting author affiliation: Federal University of Santa Maria, Santa Maria, Brazil

Beilstein Arch. 2021, 202159.

Published 16 Aug 2021

  • Preprint


Herein, we explore the synthetic potential of tetrazolo[1,5-a]pyrimidines to obtain new pyrimidine derivatives by click chemistry and hydrogenation. Click chemistry reactions of the trifluoromethyltetrazolo[1,5-a]pyrimidines with terminal acetylenes produced unprecedented trifluoromethylated triazolylpyrimidines in excellent yields (84-98 %) in which one of them was active against all tested microorganisms, presenting moderate MIC values (62.5-15.62 mg/ml). Hydrogenation was carried out using Pd/C-H2 in MeOH under conventional, photochemical, and pressure (5 bar) conditions. The hydrogenation was an excellent method to obtain 2-amino-6-aryl-4-trifluoromethyl pyrimidines and/or 2-amino-6-aryl-4-trifluoro methyltetrahydro pyrimidines with a preference for 2-aminopyrimidine formation. The photochemical hydrogenation was the fastest and only pathway to reduce aryl-brominated substrate for the product without dehalogenation. Trifluoromethyl-substituted tetrazolo[1,5-a]pyrimidines reacted to 2-amino-6-aryl-4-trifluoromethyl pyrimidine formation in preference to the formation of the corresponding tethaydropyrimidines. However, the hydrogenation of non-trifluoromethylated tetrazolo[1,5-a]pyrimidines showed a preference for tetrahydropyrimidine formation.

Keywords: Pyrimidines; hydrogenation; click chemistry; trifluoromethyl; photochemical reaction

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Scapin, E.; Zimmer, G. C.; Vieira, J. C. B.; Rodrigues, C. A. B.; Afonso, C. A. M.; Zanatta, N.; Bonacorso, H. G.; Frizzo, C. P.; Martins, M. A. Beilstein Arch. 2021, 202159. doi:10.3762/bxiv.2021.59.v1

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