Research On Plasmid-catalyzed Henry Reaction

Henry reaction is one of the most important reactions in forming C-C bond,because it can be the intermediates for synthesizing some important compounds,which has a broad range of value.This reaction was used to be catalyzed by chiral guanidines,chiral(thio)urea derivatives and cinchona alkaloids,but the solvents were mostly organic solvents,which were considerably harmful for the environment.Therefore,the most important point is Green Chemistry.Nowadays,DNA as a catalyst has attracted much more attention,because it can catalyze reactions in water and achieve a high ee value if it is combined with Cu(?)complex.This not only satisfies the need of production but also protects the environment.Although the DNA molecule has been recognized as the carrier of genetic information in vivo,the interest in DNA double helix structures has now expanded from biology to chemistry.Scientists have discovered that DNA can catalyze many reactions,such as Diels-Alder reaction,Michael additional reaction and so on.Salmon sperms DNA,human telomeric G-quadruplex,calf thymus DNA and some artificial DNA are the most common DNA catalysts.In this work,plasmid DNA was used to catalyze henry reaction and the salmon sperms DNA as control.First,we chose pure water as the solvent,which was beneficial to environment.Second,we optimized henry reaction conditions such as solvents,molar ratio of substrates,temperature,reaction time and metal ion.The results showed that the plasmid DNA could achieve a high yield(98%)after 20 min,which was much higher than that of salmon sperms DNA.Moreover,the plasmid DNA could be reused for ten times without loss of activity.In addition,the catalytic versatility of plasmid was identified as DNA displayed activity towards several nitroalkanes and different substituted benzaldehydes with different electron donating group and electron withdrawing group.The results showed that the steric hindrance plays an important role in this process.If the steric hindrance is too larger,it cannotactivate the reaction.Also,the aromatic aldehydes bearing strong or moderate electron-withdrawing groups reacted satisfactorily with nitromethane.In contrast,the benzaldehydes,p-hydroxy benzaldehyde,p-anisaldehyde did not react.Overall,this research not only presents the unmodified plasmid DNA can catalyze Henry reaction with high yield,but also provides a new option for DNA-based catalysis.It demonstrated that plasmid DNA can also be a biomolecular scaffold for chiral transfer and cause an additional rate acceleration.