| Nitrogen-containing heterocyclic compounds are important organic compounds with good biological activity.They are widely found in natural products,drug structures and material molecules.Nitrogen-containing heterocyclic rings containing cyanide(-CN)functional groups are widely used in chemical organic synthesis,medicine,pesticides,materials and spices.However,the reaction conditions of traditional synthesis of cyano-heterocyclic compounds are more demanding,requiring the use of transition metal catalysts and stoichiometric metal salts as accelerators,and most cyanidation reactions take metal cyanide as the source of cyanide,which is highly toxic and easy to cause environmental pollution,metal waste and other problems.Therefore,it is necessary and significance to develop synthetic methods that environmentally friendly,simple to operate,and mild in reaction conditions to construct cyano-heterocyclic compounds.In this paper,cyano-substituted nitrogen-containing heterocyclic compounds were synthesized from ammonium thiocyanate as green cyanogen source with pyridine or quinoline compound and benzylamine in the absence of transition metal catalyst.This paper consists of three parts.The first part is a review of the research progress of Strecker reaction.In the second part,cyanide-substituted imidazole[1,5-a]pyridine was synthesized by one-pot method based on Strecker reaction using ammonium thiocyanate as cyanogen source and its biological activity was studied.In the third part,quinoline-2-formaldehyde compounds was synthesized with iodine pentoxide as oxidant at room temperature.The main research contents are as follows:1.Synthesis and bioactivity of cyano-substituted imidazole[1,5-a]pyridine compoundsBased on Strecker reaction,cyano-substituted imidazole[1,5-a]pyridine was synthesized by multi-component one-pot reaction with pyridine-2-formaldehyde and benzylamine using ammonium thiocyanate as cyanide source.By optimizing the conditions of solvent,oxidant and reaction temperature,it was found that the cyano-substituted imidazole[1,5-a]pyridine compound could be obtained with higher yield when dimethyl sulfoxide was used as solvent and diiodine pentoxide was used as oxidant at 100? for 5 hours.In the study of substrate universality,it was found that the electronic effect had no obvious influence on the reaction,and the reaction slightly affected by the spatial effect.What's more,the substrate scope is broad.It is found that ?-aminonitrile is an important intermediate in this reaction.Finally,the bioactivity of the obtained compounds was studied,and it was found that the compounds with halogen substituents and quinoline parent nuclei had certain antibacterial activity.In this multi-component reaction,cyano-substituted imidazolazo[1,5-a]pyridine with structural diversity was synthesized by direct one-step method using cheap and easily available starting materials and green and safe NH4SCN as the replacement of cyanidation reagent.The reaction conditions were mild and the operation was simple.2.Selective oxidation of 2-methylquinoline to quinoline-2-formaldehydeIn the I2O5/DMSO system,the direct oxidation of 2-methylquinoline to quinoline-2-formaldehyde was realized at room temperature.This not only avoids the use of transition metal catalyst,the reaction under 25? air atmosphere,also does not need high temperature and high pressure,mild reaction conditions and simple practical operation,in line with the development requirements of green chemistry.In addition,combining with previous studies on the synthesis of cyano-substituted imidazole[1,5-a]quinoline using quinoline-2-formaldehyde,benzylamine and ammonium thiocyanate as model substrates,a two-step one-pot synthesis of cyano-substituted imidazole[1,5-a]quinoline using 2-methylquinoline as substrate was achieved.The reaction conditions of this method are simple and mild,which provides a novel strategy in the field of the 2-methylquinoline compounds.Figure[33]Table[14]Reference[91]... |
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