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The stereochemistry of the addition of titanium enolates of N-propionyl-oxazolidin-2-ones to 5- and 6-membered N-acyliminium ions

✍ Scribed by Ronaldo A. Pilli; Conceição de Fátima Alves; Maria Alice Böckelmann; Yvonne P. Mascarenhas; J. Geraldo Nery; Ivo Vencato

Book ID
104261192
Publisher
Elsevier Science
Year
1999
Tongue
French
Weight
268 KB
Volume
40
Category
Article
ISSN
0040-4039

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✦ Synopsis

The stereochemistry of the addition of the N-propionyl titanium enolates 2a and 2b to 5-and 6-membcred 2ethoxycarbamates la-f was investigated. The addition proceeded stereoseleetively to afford the corresponding (2S,l'S)-2-substituted pyrrolidines as the major diastere~isomer. Despite the lack of reactivity between 2ethoxypiperidine lb and N-propionyl titanium enohtes 2a and 2b, less bulky carbamate groups on 2ethoxypiperidines ld and If restored reactivity and the corresponding 2-substituted piperidines were obtained in moderate to good yields although with poor diastereoselection.

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