Asymmetric Friedel–Crafts alkylation of indoles with 2-nitro-3-arylacrylates catalyzed by a metal-templated hydrogen bonding catalyst
摘要:
An asymmetric Friedel-Crafts alkylation of indoles with 2-nitro-3-arylacrylates catalyzed by a metal-templated hydrogen bonding catalyst has been established. The asymmetric induction relies on chirality transfer solely from the octahedral metal stereocenter via three weak hydrogen bonds. All the products are provided with good to excellent enantioselectivities while modest diastereoselectivities, which can be converted into a variety of valuable indole-containing chiral building blocks including tryptophan derivatives. (C) 2015 Elsevier Ltd. All rights reserved.
The synthesis of five-membered rings using fluoromethylene transfer chemistry is an attractive method for building fluorinated products of high value. This work demonstrates for the first time that one-fluorine-one-carbon modification of a substrate could be a viable strategy to access monofluorinated five-membered rings. The synthetic methodology was developed to access monofluorinated isoxazoline-N-oxides
Catalytic Asymmetric Formal [4 + 1] Annulation Leading to Optically Active <i>cis</i>-Isoxazoline <i>N</i>-Oxides
作者:Zugui Shi、Bin Tan、Wendy Wen Yi Leong、Xiaofei Zeng、Min Lu、Guofu Zhong
DOI:10.1021/ol102181r
日期:2010.12.3
The catalytic asymmetric synthesis of densely functionalized cis-isoxazoline N-oxides was realized with novel use of an organocatalyst, (S)-2-(azidodiphenylmethyl)pyrrolidine (4e) (Tan, B.; Zhu, D.; Zhang, L.; Chua, P. J.; Zeng, X.; Zhong, G. Chem.-Eur. J. 2010, 16, 3842; Olivares-Romero, J. L.; Juaristi, E. Tetrahedron 2008, 64, 9992), via an elegant formal [4 + 1] annulation strategy using readily available 2-nitroacrylates and alpha-iodoaldehydes.