Enantioselektive Synthese von (2R)-2-Methylserinen

Type of Publication: Journal article
URI (citable link): http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-47650
Author: Schöllkopf, Ulrich; Groth, Ulrich; Hartwig, Wolfgang
Year of publication: 1981
Published in: Liebigs Annalen der Chemie ; 1981, 12. - pp. 2407-2418
Summary:
Aldehydes and ketones react with the lithiated bislactim ether 3 of cyc[o-(L-Ala-L-Ala) with 81 to > 95% asymmetric induction (d. e. = diastereomeric excess) at C-3; (R) configuration is formed predominantly. - A model concept for the asymmetric induction is proposed. - With aldehydes or unsymmetrical ketones C-7 of the adducts 6 becomes a chiral center, too. (R) configuration is induced here [for the (3R)-isomers] with d. e. 47-73%. Hydrolysis of the addition products 6 (0.25 N HCI, room temperature) gives L-Ala-OCH, and (2R)-2-methylserine methyl esters 7. Both compounds can be separated either at the ester stage by distillation or - if 7 is thermolabile - after further hydrolysis at the amino acid stage.
Summary in another language:
Die Umsetzung des lithiierten Bislactimethers 3 von cyclo-(r-Ala-L-Ala) mit Aldehyden und Ketonen vollzieht sich mit 83 bis > 95% asymmetrischer Induktion (d. e. = diastereomeric excess) an C-3, wobei die (R)-Konfiguration induziert wird. - Eine Modellvorstellung zur Deutung dieser ungewohnlich hohen Induktion wird diskutiert. - Bei Aldehyden oder unsymmetrischen Ketonen wird auch C-7 der Addukte 6 zu einem Chiralitatszentrum; hier wird [bei den (3R)-Isomeren] mit 47-73% d. e. ebenfalls (R)-Konfiguration induziert. - Hydrolyse der Addukte 6 (0.25 N HCI, Raumtemperatur) liefert neben L-Ala-OCH3 die (2R)-2-Methylserin-methylester 7. Die beiden Verbindungen lassen sich entweder auf der Stufe der Ester destillativ trennen oder - wenn 7 thermolabil ist - nach weiterer Hydrolyse auf der Stufe der Aminosäuren.
Subject (DDC): 540 Chemistry
Link to License: In Copyright

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SCHÖLLKOPF, Ulrich, Ulrich GROTH, Wolfgang HARTWIG, 1981. Enantioselektive Synthese von (2R)-2-Methylserinen. In: Liebigs Annalen der Chemie(12), pp. 2407-2418

@article{Schollkopf1981Enant-9598, title={Enantioselektive Synthese von (2R)-2-Methylserinen}, year={1981}, number={12}, journal={Liebigs Annalen der Chemie}, pages={2407--2418}, author={Schöllkopf, Ulrich and Groth, Ulrich and Hartwig, Wolfgang} }

2011-03-24T18:13:02Z Schöllkopf, Ulrich Enantioselektive Synthese von (2R)-2-Methylserinen deu Groth, Ulrich Groth, Ulrich terms-of-use 2011-03-24T18:13:02Z Zuerst erschienen in: Liebigs Annalen der Chemie 1981, 12, S. 2407-2418 Aldehydes and ketones react with the lithiated bislactim ether 3 of cyc[o-(L-Ala-L-Ala) with 81 to > 95% asymmetric induction (d. e. = diastereomeric excess) at C-3; (R) configuration is formed predominantly. - A model concept for the asymmetric induction is proposed. - With aldehydes or unsymmetrical ketones C-7 of the adducts 6 becomes a chiral center, too. (R) configuration is induced here [for the (3R)-isomers] with d. e. 47-73%. Hydrolysis of the addition products 6 (0.25 N HCI, room temperature) gives L-Ala-OCH, and (2R)-2-methylserine methyl esters 7. Both compounds can be separated either at the ester stage by distillation or - if 7 is thermolabile - after further hydrolysis at the amino acid stage. application/pdf Hartwig, Wolfgang Hartwig, Wolfgang Schöllkopf, Ulrich 1981

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