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Enantioselective syntheses of 2-amino-4-fluoropent-4-enoic acids. Isosteres of asparagine

✍ Scribed by Klaus W. Laue; Christian Mück-Lichtenfeld; Günter Haufe


Publisher
Elsevier Science
Year
1999
Tongue
French
Weight
649 KB
Volume
55
Category
Article
ISSN
0040-4020

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✦ Synopsis


Diastereoselective alkylation of (R)-(+)-camphor-based glycine or alanine esterimines with 3bromo-2-fluoropropene after hydrolytic deprotection gave (R)-(+)-2-amino-4-fluoropent-4-enoic acid with 38% overall yield and 90% ee, or (R)-(+)-2-amino-4-fluoro-2-methylpent-4-enoic acid (19% overall yield, 59% ee), respectively. Deprotection under drastic conditions was accompanied by hydrolysis of the fluorovinyl moiety to give (R)-(-)-2-aminoM-oxopentanoie acid hydroehloride with 28% overall yield and >95% ee. Ab initio calculations of acetamide and 2-fluoropropene as models for a primary amide or a fluorovinyl group despite of their different electronic structure show a similar electrostatic potential on the van der Waals surface suggesting their isosteric behavior.


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