Synthesis Of N-F Reagents And Their Applications On The Enantioselective Fluorination Of Oxindoles

Firstly, this artical focused on the synthesis of several N-F reagents.The synthesis of N-F reagents1is similar with the common synthesis of NFSI, and in this paper we improved the purification method to get higher purity. The route of preparing N-F reagents2adopted a new way. which was simple and convenient. Compound3c, as a kind of derivative of Selectfluor, was prepared in a new and simple method, which would have potential commercial value.Then the enantioselective fluorination of oxindoles5was studied. The catalysts and the bas was screened, and according the experimental data we chose (DHQD)2ANQ as catalyst, K2CO3as the base. Then the N-F reagents1,2,3c and4e was screened, and the results indicates that compound2b,2c and2f as fluorination reagents led to a good enantioselectivity of the prudouct6a (up to94%ee). Due to that the catalyst should be added10mol%if using2c, but only5mol%catalyst was needed if using2b. And that preparing2b was more convenient than2f. We chose2b as the fluorinating reagent for the enantioselective fluorination reactions of oxindoles. In the reaction system, the yield of6was higher than that described in literature. At the same time, the reaction time was shortened from5days to1.5days. And the highest enantioselectivity of6could arrive at95%ee.At last,3c as a new fluorinating reagent was applied to the same enantioselective fluorination of oxindoles5. High yield and enantioselectivity up to55%ee was gotten.