Synthese von bromosubstituierten Butenoliden II

✍ Scribed by Roger Martin; Christopher B. Chapleo; Karen L. Svanholt; André S. Dreiding

• Publisher: John Wiley and Sons
• Year: 1976
• Tongue: German
• Weight: 308 KB
• Volume: 59
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19760590811

✦ Synopsis

Synthesis of Bromosubstituted Butenolides II.

Methyl 4,4′‐dibromosenecioate (2) was prepared by double N‐bromosuccinimide bromination of methyl senecioate (1) and converted to methyl 4,4′‐diiodo‐senecioate (3) with sodium iodide and to 3‐bromomethyl‐2‐buten‐4‐olide (4) with aqueous hydrobromic acid. A mixture of methyl (Z)‐ and (E)‐4‐bromosenecioate (8 and 9) yielded 3‐methyl‐2‐butenolide (5) with aqueous hydrobromic acid and a mixture of (Z)‐and (E)‐4‐methoxy‐senecioic acid (10 and 11) with methanolic potassium hydroxide. N‐Bromosuccinimide treatment of the butenolide 5 afforded 4‐bromo‐3‐methyl‐2‐buten‐4‐olide (6) and 4,4‐dibromo‐3‐methyl‐2‐buten‐4‐olide (7).