Organocatalytic Asymmetric Michael Addition of Pyrazolin-5-ones to Nitroolefins with Bifunctional Thiourea: Stereocontrolled Construction of Contiguous Quaternary and Tertiary Stereocenters

✍ Scribed by Yu-Hua Liao; Wen-Bing Chen; Zhi-Jun Wu; Xi-Lin Du; Lin-Feng Cun; Xiao-Mei Zhang; Wei-Cheng Yuan

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 209 KB
• Volume: 352
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/adsc.200900764

✦ Synopsis

Abstract

The first organocatalytic diastereo‐ and enantioselective Michael addition reaction of 4‐substituted‐pyrazolin‐5‐ones to nitroolefins has been developed with a chiral bifunctional thiourea as organocatalyst. A wide variety of desired multi‐substituted pyrazolin‐5‐one derivatives with contiguous quaternary and tertiary stereocenters are smoothly obtained in very good yields (up to 98%) with excellent enantioselectivities (up to>99% ee) and acceptable diastereoselectivities (up to 80:20). This experimentally simple process facilitates the access to various enantioenriched, multiply substituted pyrazolin‐5‐one derivatives, potential biologically active molecules, starting from readily available starting materials.