Download PDF
Synlett 1999; 6: 935-939
DOI: 10.1055/s-0031-1289595
letter

© Georg Thieme Verlag KG Stuttgart · New York

Configurational and Conformational Control on Formation and Oligomerization of 2-C Mono-Arylated Pseudo-Proline Dipeptide Building Units by Aromatic Stacking Interactions

Michael Keller, Manfred Mutter, Christian Lehmann
  • Institut de Chimie Organique, Université de Lausanne, BCH-Dorigny, CH-1015 Lausanne, Switzerland Fax +41(21)692 3955; E-mail: Christian.Lehmann@ico.unil.ch and Manfred.Mutter@ico.unil.ch
Further Information

Publication History

Publication Date:
10 November 2011 (online)

  PDF Download  Permissions and Reprints All articles of this category

Abstract

Electrophilically induced cyclic acetal formation of the O-benzyl dipeptide esters Fmoc-NMeIle-Thr-OBn (1) and of Fmoc-Pro-Thr-OBn (6) has been observed to lead predominantly to the (R) diastereomers 2b and 8b at the 2-C position of the resulting substituted 1,3-oxazolidine (YPro) unit, while upon acetalization of the corresponding O-methyl ester 4 the 2-C(S) epimer 5a is predominantly formed under the same proton catalyzed cyclization conditions. With boron trifluoride etherate as Lewis acid the reaction is particularly fast and leads selectively to the prolyl threonine derived 2-C(R) dipeptide building block 8b, which could conveniently be assembled into a nonamer with a virtually solvent independent CD-spectrum of the polyproline type I (cis amide bonds).

Key words

acetals - peptide analogues/mimetics - substituent effects - stereocontrol