Highly Enantioselective Fluorination of Unprotected 3-Substituted Oxindoles: One-Step Synthesis of BMS 204352 (MaxiPost)
摘要:
The catalytic enantioselective fluorination of N-H-free 3-substituted oxindoles was accomplished by a Sc(III)/N,N'-dioxide complex. Under mild reaction conditions, a series of 3-aryl- and 3-alkyl-3-fluoro-2-oxindoles were obtained in excellent yields (up to 98%) and enantioselectivities (up to 99% ee) by using N-fluorobisbenzenesulfonimide (NFSI) as the fluorination agent. MaxiPost was synthesized efficiently in 81% yield with 96% ee.
Catalytic asymmetric α‐arylation of N‐unprotected 3‐substituted oxindoles with diaryliodoniumsalts has been realized by a chiral Lewis acid promoted electrophilic addition and aryl‐rearrangement process. Single C3‐arylated products containing a quaternary carbon center were generated in high enantioselectivity and reactivity.
3‐substituted oxindoles to dienylketones has been developed. This procedure tolerates a relatively wide range of 3‐substituted oxindoles under mild conditions, facilitating the preparation of various chiral oxindoles with quaternary stereocenters. In addition, the reliable catalyst was found to be effective in the asymmetric 1,6‐addition of both δ‐unsubstituted and δ‐methyl‐substituted dienylketones, achieving
The asymmetric Michael addition/desymmetrization reaction catalyzed by a N,N′-dioxide-Sc(iii) complex was realized, leading to the succinimides with two kinds of stereogenic elements—atom chirality and axial chirality in up to 99% yield, 99% ee and >19 : 1 d.r.
Catalytic asymmetric sulfenylation of unprotected 3-substituted oxindoles has been developed via cooperative catalysis of a chiral N,N-dioxide-Sc(OTf)(3) complex and a Bronsted base. Utilizing readily available N-(phenylthio)phthalimide as the sulfur source, a wide range of optically active 3-phenylthiooxindoles were obtained in excellent yields with excellent enantioselectivities under mild reaction conditions.