Chiral Cyclopentadienyl Rhodium-Catalyzed Enantioselective C-H Functionalization Of Indoles

Chiral indole moieties are among the most important heterocyclic structural motifs,existing widely in a large number of natural products,pharmaceuticals,and functional materials.Therefore,the development of efficient,atom-economical processes for the synthesis of enantioenriched indole derivatives through C-H functionalization of indoles has received intensive attention.In this thesis,to achieve asymmetric C-H functionalization of indoles at C2 position,a series of chiral rhodium complexes bearing monocyclopentadienyl ligands embedded in chiral binaphthyl backbones were synthesized,which can act as excellent catalysts for the enantioselective C-H annulation of O-pivaloyl 1-indolehydroxamic acid with a diazo compound.In this paper,different substitutes were introduced to(S)-BINOL to form 3,3’-functionlized BINOL-derivatives,which could be converted to final cyclopentadienyl compounds through methylation,halogenation,cyclization and isomerization.The metalation of the cyclopentadienyl ligands with[Rh(C2H4)2Cl]2 afforded chiral Rh(Ⅰ)complexes,which can be transferred to a chiral Rh(Ⅲ)dimer by treatment with I2.These rhodium complexes will be used as catalysts in next chapter.We illustrated that chiral rhodium-catalyzed enantioselective C-H annulation of O-pivaloyl 1-indolehydroxamic acid with diazo compounds,leading to formation of C-H annulation products in high yield up to(95%)and excellent enantioselectivity up to(90%ee).The chiral rhodium complexes could also serve as a catalyst for the reaction of 4-methyl-N-(naphthalen-1-yl)benzenesulfonamide and an alkene,which gave an oxidative coupling product with an enantiomeric ratio(er)of 78:22.