Asymmetric Friedel-Crafts alkylations of indoles with nitroalkenes catalyzed by Zn(II)-bisoxazoline complexes.
[reaction: see text] A novel asymmetric Friedel-Crafts alkylation of indoles with nitroalkenes catalyzed by Zn(II)-bisoxazoline complexes has been developed. The nitroalkylated indoles are synthesized in excellent yields and high enantioselectivities (up to 90% ee). The effects of ligand structure, metal salt, and solvent on the reaction are discussed. The substrates of the reaction can be aromatic, heteroaromatic, and even aliphatic nitroalkenes. The high reactivity and selectivity of the reaction are presumptively attributed to the activation and asymmetric induction of chiral Lewis acids coordinated by nitroalkene substrates through a 1,3-metal bonding model.
Jia
Yi-Xia
YX
State Key Laboratory and Institute of Element Organic Chemistry, Nankai University, Tianjin 300071, China.
Zhu
Shuo-Fei
SF
Yang
Yun
Y
Zhou
Qi-Lin
QL