Synthesis Of Aromatic Compounds By Novel Tandem Reactions Involving Aryl Ring Construction

Aromatic annulation is one of the most efficient methods in the construction of various aryl backbone,particularly the polycyclic backbone,it is also an important research area in organic synthesis.This thesis reports the research on the synthesis of benzene derivatives,1,2,3-triazoles and quinolines tandem reactions involving aryl ring annulation.Three sections of research works are included.First section,the synthesis of benzaldehydes via benzannulation.Using acyclic vinyl aldehydes and N,N-disubstituted tertiary enaminones as substrates,the featured amine elimination on the tertiary enaminones took place smoothly to achieve the[4+2]aromatic annulation of enaminones and dienals in the presence of co-solvent system of acetic acid and ethanol,which enabled the synthesis of benzaldehydes.Under the same conditions,by the in situ aza-Michael addition of the secondary amine to alkyl propiolates,the analogous reactions were also accomplished to provide ester functionalized benzaldehydes.Second section,the enaminone-azide cyclization for the synthesis of1,2,3-triazoles in water.Employing water as the sole medium,the cyclization of N,N-dimethyl enaminones and tosyl azide was realized at 40 ~oC without using any catalyst or additive.Thus efficiently synthesized a series of 4-acyl-NH-1,2,3-triazoles.The third section,iron-catalyzed three-component aromatic annulation synthesizing 2,4-disubstituted quinolines.Utlizing the green biomass-derived ethyl lactate as the reaction medium and substrate,the three-component,one-pot reactions using additionally anilines and aldehydes gave rise to 2,4-disubstituted quinolines.The work provides a environmentally benign new route the quinolines synthesiso.