Synthesis of 4-Substituted 3,5-Dinitro-1,4-dihydropyridines by the Self-Condensation of β-Formyl-β-nitroenamine
摘要:
3,5-Dinitro-1,4-dihydropyridines (DNDHPs) are readily constructed by the acid-promoted self-condensation of beta-formyl-beta-nitroenamines. In the DNDHPs, one molecule of the nitroenamine serves as a C3N1 building block and the other serves as a C2 block. This synthetic method does not require any special reagents and conditions. When the reaction is conducted in the presence of electron-rich benzene derivatives, arylation at the 4-position of DNDHP is achieved by trapping the 3,5-dinitropyridinium ion intermediate.
first and facilesynthesis of N,N′-dialkylated 2,6,9-triazabicyclo[3.3.1]nonadienes was achieved by the [4 + 4] self-condensation of β-formyl-β-nitroenamine in the presence of ammonium acetate. The 2,6- and 2,9-dialkylated products were found to be interconvertible when dissolved in a solvent. This isomerization proceeds through intramolecular ring transformation via a common intermediate under equilibrium