ISSN:
1434-193X
Keywords:
N-Acyliminium
;
Pyrrolidine
;
Indolizidine
;
Pyrrolizidine
;
Stereoselective
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Enantiopure bicyclic 5-ethoxytetrahydropyrrolo[1,2-c]oxazol-3-one 1b was prepared in two steps from the known tosylate 4, which is readily available from (S)-pyroglutamic acid. Trapping of the N-acyliminium ion (I), generated in situ from 1b in the presence of Lewis acid, with various silylated π-type nucleophiles gave rise selectively to trans adducts 2. The usefulness of this stereoselective access to trans-2,5-disubstituted pyrrolidines was illustrated by formal syntheses of 3,5-disubstituted indolizidine toxins, starting from 5-allyltetrahydropyrrolo[1,2-c]oxazol-3-one 2a. Moreover, an enantiodivergent synthesis of the pyrrolizidine alkaloids (+) and (-)-xenovenine was achieved starting from the same chiral building block 2a.
Type of Medium:
Electronic Resource
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