Short, Enantiospecific Syntheses of Indolizidines 209B and 209D, and Piclavine A from Diethyl-L-Glutamate

✍ Scribed by Charles W. Jefford; Krzysztof Sienkiewicz; Steven R. Thornton

• Book ID: 102859866
• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: German
• Weight: 906 KB
• Volume: 78
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19950780610

✦ Synopsis

Abstract

The 1__H__‐pyrrole derivative obtained from diethyl L‐glutamate hydrochloride and tetrahydro‐2,5‐dimethoxyfuran was cyclized with BBr~3~ to ethyl (5__S__)‐5,6,7,8‐tetrahydro‐8‐oxoindolizine‐5‐carboxylate (18). Catalytic hydrogenation of 18 over Pd/C in AcOH gave ethyl (5__S__,8a__R__)‐octahydroindolizine‐5‐carboxylate (21), whereas hydrogenation over Rh/Al~2~O~3~ in EtOH/AcOH 99:1 afforded mainly ethyl (5__S__,8__S__,8a__S__)‐octahydro‐8‐hydroxyindolizine‐5‐carboxylate (22). By functional‐group interconversions, 21 was transformed into piclavine A (1) and indolizidine 209D (2). Similarly, (5__R__,8__R__,8a__S__)‐octahydro‐5‐pentylindolizine‐8‐methanol (37), the final relay for indolizidine 209B (3), was obtained from 22.