1,3-Dipolar Cycloadditions, 100. Nitrones and Electrophilic Acetylenes; a New Rearrangement of 2,3-Dihydroisoxazoles

✍ Scribed by Huisgen, Rolf ;Giera, Henry ;Polborn, Kurt

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 666 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719970810

✦ Synopsis

Abstract

The readiness of 4‐isoxazolines, the 1,3‐cycloadducts of nitrones to acetylenic compounds, to undergo rearrangement is notorious. The cycloadducts of the ketonitrones 5 and 6 to dimethyl acetylenedicarboxylate, dicyanoacetylene, and methyl propiolate were isolated and characterized. The 4‐isoxazolines 7 and 8 harbor the tetramethylcyclobutanone ring; they isomerize (7 at 45°C, 8 at −10°C) to enamine β‐carbonyl compounds 16 and 17 which are derived from the ring‐enlarged tetramethylpyrrolidin‐3‐one. The structure of 16 was elucidated by X‐ray analysis.