Thermische Umlagerung von 2-Oxa-bicyclo [3.3.1]-non-7-en-3-on; eine neuartige Lactonumlagerung. Vorläufige Mitteilung

✍ Scribed by György Fráter

• Publisher: John Wiley and Sons
• Year: 1979
• Tongue: German
• Weight: 145 KB
• Volume: 62
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19790620231

✦ Synopsis

Thermal Rearrangement of 2‐Oxa‐bicyclo [3.3.1]‐non‐7‐en‐3‐ones; a Novel Lactone Rearrangement

Lactone (+)‐2 was prepared by iodolactonisation and subsequent elimination in 51% yield from the known acid (+)‐1 (Scheme 1). Alkylation of (+)‐2 furnished (+)‐3a, (+)‐3b and (+)‐3c, respectively (Scheme 2). Heating of (+)‐3a in boiling DMF racemized the compound ((+)‐3a ⇆ (−)‐4a). Heating of (+)‐3b and (+)‐3c, respectively, equilibrated them with (−)‐4b and (−)‐4c, respectively. This results are interpreted as a [3.3]‐sigmatropic rearrangement with a transition state as depicted in a.