Palladium-catalyzed Dearomatization/Alkynylation Of Indole

Alkynyl compounds are widely used in laboratory and factory production due to their active chemical properties.Therefore,the introduction of carbon-carbon triple bond in molecules has been one of the hot topics in organic chemistry.In this dissertation,we have developed palladium-catalyzed intramolecular dearomatization/alkynylation of indoles.The alkynylation reaction of indole was achieved by changing the alkynylation reagents and screening of ligands.Both non-asymmetric and asymmetric synthesis have been realized.A series of fused indolines with C2-quaternary center and 3-triple bond were obtained.In the non-asymmetric work,the palladium and monophosphate ligands were used as the catalytic system,and the dearomatization/alkynylation of the indole derivatives was successfully achieved with the propionic acid as the alkynylation reagents.After the systematic optimization of reaction condition through solvent screening,examination of palladium sources,investigation of ligands and so on,the optimal condition was defined as: Pd(dba)2 as catalyst,PCy3·HBF4 as ligand,Et3 N and DMSO as the base and solvent,the reaction temperature is 100 oC.The reaction yield was 41%-73%,and substrate tolerate is good.In the asymmetric work,the palladium and chiral ligands were used as the catalytic system,and the asymmetric dearomatization/alkynylation of the indole derivatives was successfully achieved.After the systematic optimization of reaction condition through solvent screening,examination of palladium sources,investigation of chiral ligands and so on.the optimal condition was defined as: Pd(dba)2 as catalyst,L9 as ligand,K2CO3 as the base and MTBE or MTBE/THF as the solvent,the reaction temperature is 100 oC.The reaction can proceed smoothly with 50-90% yield and 78-97% ee,and the reaction substrate tolerate is excellent.