Synthesis 2007(17): 2720-2730  
DOI: 10.1055/s-2007-983783
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Two Dipeptide Isosteres Containing Di- and Trisubstituted E-Configured Double Bonds

Nina G. Bandur, Klaus Harms, Ulrich Koert*
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35043 Marburg, Germany
Fax: +49(6421)2825677; e-Mail: koert@chemie.uni-marburg.de;
Further Information

Publication History

Received 26 April 2007
Publication Date:
12 July 2007 (online)

Abstract

The stereoselective syntheses of a Tyr-Tyr and a Pro-Pro E-alkene isostere are described. While the Tyr-Tyr isostere was synthesized following a convergent olefination strategy, the trisubstituted E-configured double bond of the Pro-Pro isostere was generated by an Ireland-Claisen rearrangement. The configuration of all key intermediates containing new stereocenters was determined by X-ray crystallography.

9

Since the TBDPS-protected compound 6 was not crystalline, the Me-protected derivative was prepared and used to obtain a crystal structure. The crystal data has been deposited in the Cambridge Crystallographic Data Centre as supplementary publication No. CCDC 616493. Crystal data: C21H23NO5, M = 369.40, orthorhombic, P212121, a = 7.0200(4) Å, b = 13.4213(10) Å, c = 19.5897(12) Å, α = 90°, β = 90°, γ = 90°, V = 1845.7(2) Å3, Z = 4, D calcd = 1.329 g/cm3, 16972 collected reflections, 3696 independent (R int = 0.0390), R1 = 0.0265, wR2 = 0.0686 (all data).