Study On The Synthesis Of Silalactones With Benzene Structure And The Oxidation&Ring Expansion Derivatization Of Polysubstituted Benzene

Zirconocene reagents have great applications in metal organic chemistry.They can undergo a variety of reactions such as cycloaddition and coupling,and are of great significance for the discovery of new drugs and new materials.Although there has been a great deal of research on the synthesis of poly-substituted benzenes by zirconocene reagents,there are few reports on the formation of silalactones with benzene structure and the derivatization of poly-substituted benzene under the induction by zirconocene reagents.In this way,many new molecular skeletons can be obtained.Based on the research of zirconium chemistry in our previous research,a new method to synthesize several new sillactones with benzene structure is discovered.Mediated by zirconocene reagent,the alkyne substrate reacts with the Negishi reagent ZrCp₂Bu₂ to afford the Zirconacyclopentadienes,which participates the[2+2+2]cycloaddition reaction with alkynes and followed by derivation reaction under the action of iodinated reagents.The yield of sillactone a is 43%,the yield of sillactone b is 36%,and the structures are confirmed by ¹H NMR and ¹³C NMR.In the meantime,the coupling of halogenated aromatics and zirconacyclopentadienes mediated by zirconocene reagent is also studied,and the structure of conjugated dienes is obtained.For the obtained benzene ring-containing sillactone and conjugated diene,single crystal analysis is performed.Secondly,ester-based derivatization of poly-substituted benzenes with ester groups induced by zirconocene reagents is also studied.The ester groups of poly-substituted benzene is reduced with lithium aluminum hydride to obtain the structure of benzyl alcohol.Under the action of oxidants,such as oxidant?PDC,PCC,DDQ,Swern,Dess-Martin and so on?,several novel molecular frameworks that have not been reported yet are discovered.The yield of 5,6-dipropyl-1-?3H?-isobenzofuran-one is 47%-54%,the yield of 4,5,6,7-tetrapropyl-1-?3H?–isobenzofuran is 81%-85%,the yield of 4,5,6,7-tetrapropyl-1,3-dihydroisobenzofuran-1-ol is 63%,and their structures are confirmed by NMR.In this paper,the ring-expanded derivatization of poly-substituted benzene induced by the zirconocene reagent is also studied.The benzyl alcohol structure is obtained by the reduction of the ester groups in the presence of lithium aluminum hydride.After the benzyl alcohol is halogenated,the halogenated benzyl alcohol reacts with the butynedioic acid diester under the action of dibutyl zirconocene.The ester groups of the expanded dihydroanthracene derivative undergoes reduction in the presence of lithium aluminum hydride,and then under the oxidative effect of PDC oxidant,two kinds of novel molecular framework structures that have not been reported are discovered.Dihydroanthracene[2,3-C]furan-1-?3H?-one was obtained in a yield of68%;4,6,7,8,9,11-hexamethyl-5,10-Anthracene[2,3-C]furan-1-?3H?-one in 61%yield.This article can not only broaden the use of zirconocene reagents and zirconylcyclopentadiene,but also provide a method for the synthesis of several new framework molecules,and lay the foundation for the future application of these molecules.