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Facile Synthesis of Diastereoisomerically and Optically Pure 2-Substituted Hexahydro-1H-pyrrolizin-3-ones

✍ Scribed by Romain Siegrist; Corinne Baumgartner; Paul Seiler; François Diederich

Publisher
John Wiley and Sons
Year
2005
Tongue
German
Weight
160 KB
Volume
88
Category
Article
ISSN
0018-019X

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✦ Synopsis

We report a short synthetic route that provides optically active 2-substituted hexahydro-1H-pyrrolizin-3ones in four steps from commercially available Boc (tert-but(oxy)carbonyl))-protected proline. Diastereoisomers (À)-11 and (À)-12 were assembled from the proline-derived aldehyde (À)-8 and ylide 9 via a Wittig reaction and subsequent catalytic hydrogenation (Scheme 3). Cleavage of the Boc protecting group under acidic conditions, followed by intramolecular cyclization, afforded the desired hexahydro-1H-pyrrolizinones (À)-1 and ()-13. Applying the same protocol to ylide 19 afforded hexahydro-1H-pyrrolizinones (À)-25 and (À)-26 (Scheme 5). The absolute configuration of the target compounds was determined by a combination of NMR studies (Figs. 1 and2) and X-ray crystallographic analysis (Fig. 3).

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