A Highly Efficient Friedel–Crafts Reaction of 3‐Hydroxyoxindoles and Aromatic Compounds to 3,3‐Diaryl and 3‐Alkyl‐3‐aryloxindoles Catalyzed by Hg(ClO4)2⋅3 H2O |
| |
Authors: | Feng Zhou Zhong‐Yan Cao Jing Zhang Prof?Dr Hai‐Bo Yang Prof?Dr Jian Zhou |
| |
Institution: | Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663N, Zhongshan Road, Shanghai 200062 (China), Fax: (+86)?21‐6223‐4560 |
| |
Abstract: | We report a highly efficient Friedel–Crafts reaction of 3‐alkyl or 3‐aryl 3‐hydroxyoxindoles with a variety of aromatic and heteroaromatic compounds to unsymmetrical 3,3‐diaryloxindoles or 3‐alkyl‐3‐aryloxindoles, which are interesting medicinal targets and useful building blocks for the synthesis of natural products. Hg(ClO4)2 ? 3 H2O was identified as a powerful catalyst for this reaction, and is significantly more efficient than other screened metal perchlorate hydrates and Brønsted acids such as HOTf and HClO4. The high catalytic property of Hg(ClO4)2 ? 3 H2O originates from the unprecedented dual activation effects of aromatic mercuration, which could generate a strong protic acid to facilitate the generation of a carbocation at the C3‐position of oxindoles and simultaneously form the more reactive nucleophilic reaction partner. |
| |
Keywords: | atom economy carbocations Friedel– Crafts reaction mercury natural products |
|
|