Michael Addition versus 1,3-Cycloaddition Reactions of Pyridinium Ylides with (Arylmethylene)isoxazol-5-ones: Diastereoselective Formation of 4-[1-Aryl-2-(1-pyridinio)ethyl]isoxazolium-5-olates

✍ Scribed by Risitano, Francesco ;Grassi, Giovanni ;Bruno, Giuseppe ;Nicolò, Francesco

• Book ID: 102365953
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 489 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719970224

✦ Synopsis

Abstract

The reactions of (arylmethylene)isoxazol‐5‐ones 1 with pyridinium ylides 2 lead to the diastereoselective formation of olates 4. The reasons for the favored Michael addition and the unsuccessful subsequent cyclization to fused O‐heterocycles are discussed on the basis of X‐ray analysis as well as ^1^H‐NMR and chemical evidences.