Model Studies Related to Synthesis and 1,4-Dipolar Cycloaddition Reactions of Mesoionic Heterocycles
作者:Yvette Abd El-Sayed Issac
DOI:10.1246/bcsj.72.503
日期:1999.3
The reaction of 2-(substituted amino)pyridine with reactive malonic acidderivatives provided an extremely facile synthesis of the mesoionic compound 4-oxo-4H-pyrido[1,2-a]pyrimidin-1-ium-2-olates. N,N′-Disubstituted amidine reacted with diethyl malonate to afford 4-quinolone in a one-pot cyclization and rearrangement (type A/I) of 4-oxopyridiniumolate 6. The latter compound was isolated via a reaction
Crosss-conjugated and Pseudo-Cross-conjugated Mesomeric Betaines, 19. Cycloaddition Products from Mesomeric Pyrimidiniumolates and TCNE and Their Thermal Ring Transformation Reaction
作者:Thomas Kappe、Wolfgang Lube、Kurt Thonhofer、Christph Kratky、Ulrike G. Wagner
DOI:10.3987/com-94-s56
日期:——
The bicyclic pyrido-pyrimidine mesoion (2) reacts with TCNE under the loss of HCN to yield the tricyanovinylated derivative (3). However, monocyclic pyrimidine betaines (4a-d) (substituted at C-5) afford with TCNE 1,4-dipolar cycloaddition products (5a-d). Compounds (5c,d) (with CH2 groups at the malonyl moiety) rearrange above 200 OC under the loss of HCN and phenyl isocyanate to yield cyclo-penta[d]pyrimidines (6a,b).