ISSN:
0170-2041
Keywords:
1,4-Oxazines, chiral
;
Pipecolic acid derivatives
;
Amino acids
;
2-Piperidinecarboxylic acid derivatives
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Asymmetric Synthesis with Chiral 1,4-Oxazine-2,5-diones: Preparation of Enantiomerically Pure 2-Substituted Pipecolic Acid Derivatives Herrn Prof. Dr. H.-D. Stachel mit den besten Wünschen zum 65. Geburtstag gewidmet.A new asymmetric synthesis of α-amino acids is presented. This synthesis is based on the chiral 1,4-oxazine-2,5-diones 5 and 14 relying on the α-hydroxy acid 12 as a chiral auxiliary. A base-mediated alkylation of these chiral amino acid building blocks (5, 12) with different alkyl halides proceeds, after deprotonation with sec-butyllithium, with high yields and excellent d.s. (up to 99.5/0.5). As exemplified by the synthesis of 15 (in comparison to that of 7a) the absolute configuration of the stereocenter in the amino acid unit is determined by the sequence the substituents are introduced. In the enolate 6 and in that of 14 the electrophile adds consistently to the re face of the prochiral carbon. From the alkylation products the corresponding 2-substituted pipecolic acid derivatives are obtained in good yields upon hydrolysis under basic or acidic conditions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199319930179
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