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Short, Enantiospecific Syntheses of Indolizidines 209B and 209D, and Piclavine A from Diethyl‐ L ‐Glutamate
Author(s) -
Jefford Charles W.,
Sienkiewicz Krzysztof,
Thornton Steven R.
Publication year - 1995
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19950780610
Subject(s) - chemistry , indolizidine , carboxylate , derivative (finance) , stereochemistry , methanol , hydrochloride , catalysis , pyrrole , medicinal chemistry , organic chemistry , financial economics , economics , alkaloid
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 .