Copper-catalyzed C-H Nitration Of 1-naphthylaminde

1-naphthylamine compounds are important synthons in organic synthesis,and derivatives obtained by functionalization on naphthyl groups have an irreplaceable role in functional materials,drugs,dyes and electroluminescent materials.In recent years,the nitrification reaction of 1-naphthylamine compounds has attracted the attention of scientists.The nitration of direct selective carbon-hydrogen bonds can be achieved by inexpensive metal-catalyzed reactions,which is the mainstream of synthetic nitro compounds.It not only greatly improves the atomic economy of the reaction,but also conforms to the concept of green chemistry.The N,N bidentate coordination of N-?1-naphthylamino?pyridinecarboxamide was used to achieve C2,4 position double nitration and C-4 position mononitration of its derivatives.Using N-?1-naphthylamino?pyridinecarboxamide 1a as a template substrate,the optimal conditions for Cu-catalyzed direct nitration of C-H bond were as follows:Cu?OAc?₂?0.1equiv?as catalyst,TBN?unsaturated nitrite Butyl ester,4.0 equiv?as nitro source,PhI?OAc?₂as oxidant,and HOAc as solvent.The reaction is carried out at 50?for 24 hours,and the yield is up to 80%.Under the reaction conditions,nine new bisnitro compounds were synthesized and the nitration product at the C2 position when a substituent at the C4 position was synthesized.This method makes up for the deficiency of the conventional high temperature heating,and the copper catalyst used is inexpensive and non-toxic.The reaction system is simple,mild,and does not require any additives and ligands to be added,and has great application value.It is the first direct nitration reaction of C2 and C4 positions of1-naphthylamine.Using N-?1-naphthylamino?pyridinecarboxamide 1a as a template substrate,the optimum conditions for direct mononitration of Cu-catalyzed C-H bond are as follows:Cu?NO₃?₂·3H₂O?0.1 equiv?as catalyst,NaNO₂?1.5 equiv?as nitro source,K₂S₂O₈ as oxidant,HOAc as additive,and the reaction is carried out in CH₃CN at 100?for 12 hours,and the yield is up to 86%.Under the reaction conditions,six new mononitrification products at the C4 position were synthesized.The method has good regioselectivity and can realize a single C4 site nitration reaction.It provides a good idea and foundation for subsequent exploration.