Axially Chiral C2-Symmetric N-Heterocyclic Carbene (NHC) Palladium Complex-Catalyzed Asymmetric Fluorination and Amination of Oxindoles
作者:Rui Zhang、De Wang、Qin Xu、Jiajun Jiang、Min Shi
DOI:10.1002/cjoc.201200289
日期:2012.6
Chiral C2‐symmetric N‐heterocyclic carbene (NHC) palladium diaquo complex 5b prepared from (S)‐BINAM was found to be a fairly effective catalyst for the enantioselective asymmetric fluorination of oxindoles to give the corresponding products in moderate enantioselectivities along with good to excellent yields.
Iron(iii)–salan complexes catalysed highly enantioselective fluorination and hydroxylation of β-keto esters and N-Boc oxindoles
作者:Xin Gu、Yan Zhang、Zhen-Jiang Xu、Chi-Ming Che
DOI:10.1039/c4cc01631a
日期:——
Chiral iron(III)âsalan complexes catalysed highly enantioselective α-fluorination and α-hydroxylation of β-keto esters and N-Boc oxindoles to give the corresponding products in high yields and good-to-excellent ee values under mild reaction conditions.
Structurally modified N-fluorobenzenesulfonimides (NFSIs) have been used to study the enantioselective fluorination of oxindoles in the presence of a bis-cinchona alkaloid, (DHQD)(2)PHAL, as the catalyst. We observe that the NFSI analogues bearing two tert-butyl groups at the para-position of the symmetric phenyl rings led to an enhanced enantioselectivity in most cases (up to 96% ee) compared with the unmodified NESIs (less than 69% ee). (C) 2013 Elsevier Ltd. All rights reserved.