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Selektive Amidspaltung bei Peptiden mit alpha,alpha-disubstituierten alpha-Aminosäuren


Wipf, Peter; Heimgartner, Heinz (1987). Selektive Amidspaltung bei Peptiden mit alpha,alpha-disubstituierten alpha-Aminosäuren. Helvetica Chimica Acta, 70:354-368.

Abstract

A new synthesis of dipeptides with terminal alpha,alpha-disubstituted alpha-amino acids, using 2,2-disubstituted 3-amino-2H-azirines 1 as amino-acid equivalents, is demonstrated. The reaction of 1 with N-protected amino acids leads to the corresponding dipeptide amides in excellent yield. It is shown that the previously described selective hydrolysis (HCl, toluene, 80°, or HCI, MeCN/H2O, 80°) of the terminal amide group results in an extensive epimerization of the second last amino acid. An acid-catalyzed enolization in the intermediate oxazole-5(4H)-ones is responsible for this loss of configurational integrity. In the present paper, a selective hydrolysis of the terminal amide group under very mild conditions is described: In 3N HCI (THF/H2O 1:1), the dipeptide N,N-dimethylamides or N-methylanilides are hydrolized at 25-35° to the optically pure dipeptides in very good yield.

Abstract

A new synthesis of dipeptides with terminal alpha,alpha-disubstituted alpha-amino acids, using 2,2-disubstituted 3-amino-2H-azirines 1 as amino-acid equivalents, is demonstrated. The reaction of 1 with N-protected amino acids leads to the corresponding dipeptide amides in excellent yield. It is shown that the previously described selective hydrolysis (HCl, toluene, 80°, or HCI, MeCN/H2O, 80°) of the terminal amide group results in an extensive epimerization of the second last amino acid. An acid-catalyzed enolization in the intermediate oxazole-5(4H)-ones is responsible for this loss of configurational integrity. In the present paper, a selective hydrolysis of the terminal amide group under very mild conditions is described: In 3N HCI (THF/H2O 1:1), the dipeptide N,N-dimethylamides or N-methylanilides are hydrolized at 25-35° to the optically pure dipeptides in very good yield.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:German
Date:1987
Deposited On:21 May 2014 14:43
Last Modified:05 Apr 2016 17:52
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung, F. Hoffmann-La Roche & Co. AG, Basel

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