A squaramide-catalysed asymmetric cascade Michael addition/acyl transfer reaction between unsaturated
1Key Laboratory of Medical Molecule Science & Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Beijing 100081, People's Republic of China. dudm@bit.edu.cn.
Abstract:
An efficient and practical organocatalytic asymmetric strategy was developed using unsaturated benzothiophenones and α-nitroketones catalysed by bifunctional squaramide via Michael addition and acyl transfer steps. A broad range of chiral acyloxybenzothiophene derivatives were obtained in good yields (up to 97%) with excellent enantioselectivities (up to 98% ee). What's more, employing different chiral squaramide catalysts and unsaturated benzothiophenones can deliver the acyloxy unit at the 2-position or 3-position of benzothiophene.
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