- PYRIMIDOPYRIMIDINES, PYRIMIDOPYRIMIDOAZEPINES, AND AN IMIDAZOTRIAZINE BY THREE COMPONENT REACTION
-
Recent examples of the three component reaction: iminophosphoranes / isocyanates / heteroarenes (imines) are described.The uracil (1) affords with O-methyl-ε-caprolactim ether and isocyanates the pyrimidopyrimidoazepines (6a-c) and with benzylideneaniline (8) the pyrimidopyrimidines (9a-d), while azodicarboxylate gives the isofervenuline, pyrimidotriazine (11).Furthermore, pyrimidopyrimidine (15) is obtained via 14 from 1, N-phenylbenzimidoyl chloride (13), and phenylisocyanate, while the tautomeric mixture 17A 17B results from treatment of 6-aminouracil (16) with 13; interception with dimethyl acetylenedicarboxylate gives the pyridopyrimidine (19).
- Wamhoff, Heinrich,Schmidt, Andreas
-
-
Read Online
- Photochemistry of Heterocycles, 8. The Photoreaction of 2,5-Diaryl-1,3,4-oxadiazoles with 1,3-Dimethyluracils. A New and Simple Synthesis of 1,2,4,5-Tetrazines
-
Upon UV-irradiation 2,5-diaryl-1,3,4-oxadiazoles 2a-g do not undergo (2+2)-cycloaddition with 1,3-dimethyluracil, but instead ring cleavage occurs to afford the benzoylhydrazones 3a-e as well as the decomposition products 4-6.With 6-chloro-1,3-dimethyluracil (1b) 3h is formed, which in turn photoeliminates benzoyl chloride to give the pyrazolopyrimidine 7.Saponification of 3a gives smoothly 5-benzoyl-1,3-dimethyluracil (photoselective 5-benzoylation). - A new and simple synthesis of 3,6-disubstituted 1,2,4,5-tetrazines from aroylhydrazines is described, employing the system triphenylphosphane/hexachloroethane/triethylamine.
- Farkas, Lajos,Keuler, Josef,Wamhoff, Heinrich
-
p. 2566 - 2574
(2007/10/02)
-