Organocatalytic and Stereoselective [3 + 2] Cycloadditions of Azomethine Imines with α,β-Unsaturated Aldehydes

✍ Scribed by Wei Chen; Xiang-Hong Yuan; Rui Li; Wei Du; Yong Wu; Li-Sheng Ding; Ying-Chun Chen

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 113 KB
• Volume: 348
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/adsc.200606102

✦ Synopsis

Abstract

Bipyrazolidin‐3‐one derivatives are biologically significant compounds and their importance has increased in the past decades. In this paper, the first stereoselective [3 + 2] dipolar cycloadditions of azomethine imines with α,β‐unsaturated aldehydes catalyzed by readily available α,α‐diarylprolinol salts are reported, providing a facile route to the synthesis of various chiral bipyrazolidin‐3‐one derivatives under mild conditions. The organocatalyst 1 g with strongly electron‐withdrawing groups exhibited the best stereoselectivity (exo:endo up to 98:2, for exo product up to 97 % ee), in the combination with trifluoroacetic acid.