Study On The Reaction Behavior Of Alkenyl Palladium In The Synthesis Of Indenes And Fluorene Derivatives

Polycyclic aromatic hydrocarbon structures are ubiquitous in the molecules of compounds such as medicines and materials,and are a wide range of structural units.Therefore,the synthesis of polycyclic aromatic hydrocarbon compounds has been receiving the attention of synthetic chemists.Compared with other traditional synthetic methods,the synthesis methods using transition metal catalysis have been favored by researchers in recent decades due to their excelent functional group compatibility and extremely high reaction efficiency.Among them,transition metal palladium is one of the most researched metals.Especially in the construction of polycyclic aromatic hydrocarbon compounds,the insertion of acetylene by aryl palladium is the most effective and very critical step.Through the insertion of aryl palladium to an alkyne,an active reaction intermediate——alkenyl palladium and many reactive functional groups such as alkynes,aryls,cyano groups,carbonyl groups,etc.,can be formed for the synthesis of various polycyclic rings.Aromatic hydrocarbon compounds.Our group has successfully realized alkenyl palladium to alkyne insertion,combined with aryl C-H bond activation to synthesize tetraaryl substituted naphthalene derivatives;and alkenyl palladium via CO insertion and aryl C-H bond activation to synthesize indolones work.The research work of this thesis is based on the previous work of this group.The activation of alkenyl palladium to benzylic CH is taken as an entry point.The reaction behavior of alkenyl palladium has been explored.The results are as follows:1.Using o-bromotoluene and diarylacetylene as substrates,aryl palladium is inserted to diarylacetylene to form alkenyl palladium intermediate,and the hydrazine C-H bond is activated to construct indene and its derivative.The raw materials of the reaction are simple and easy to obtain,and the design of the series reaction could construct two new C-C bonds in one reaction,making the reaction more efficient and more economical.Through the screening of the reaction conditions,we achieved a better reaction selectivity,that is,the product are mainly indene and its derivatives.At the same time,however,we isolated by-products——9-methylene fluorene derivatives,that could not be completely inhibited.2.In the work of the benzylic C-H activated by alkenyl palladium to synthesize indene and its derivatives,we have isolated 9-methylene fluorene derivatives.This result suggests that there is a competition process for 1,4-Pd migration in the presence of alkenyl palladium to activate the benzylic C-H.Therefore,my second research work focused on the 1,4 migration of palladium.Using simple and readily available bromobenzene compounds and diarylacetylene compounds as substrates,the reaction conditions were carefully selected,and finally palladium acetate was used as catalyst,and tert-butyl diphenylphosphine was used as ligand to synthesize 9-methylene fluorene derivatives with high selectivity.The reaction has good functional group compatibility and provides another effective synthetic route for the synthesis of fluorene derivatives.