Suppression of Formation of N,N′-Dicyclohexylurea Derivatives During DCC-Activation of Proline-Containing Dipeptides |
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Authors: | Gregor Radau |
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Institution: | (1) Institute of Pharmacy, Ernst-Moritz-Arndt-University, Pharmaceutical/Medicinal Chemistry, D-17487 Greifswald, Germany, DE |
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Abstract: | Summary. The syntheses of dipeptide esters containing a C-terminal L-proline moiety using carbodiimides as coupling reagents strongly depend on the choice of appropriate conditions. Thus, the
use of DCC prefers the formation of the undesirable N,N′-dicyclohexylurea derivative 3 as a consequence of a CO → N-shift in the O-acyl isourea intermediate instead of the desired dipeptide ester 4. In our hands, only DIC was able to yield the desired product exclusively.
E-mail: radau@pharmazie.uni-greifswald.de
Received November 7, 2002; accepted December 4, 2002
Published online May 6, 2003 |
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Keywords: | , Carbodiimide, Dicyclohexylurea, Ester synthesis, |
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