Transformation of Glutamic
Acid into (S)-Benzyl 2-(dibenzylamino)-6-(dimethoxyphosphoryl)-5-oxohexanoate
for a Convenient Access to 5-Substituted Prolines
Transformation of Glutamic
Acid into (S)-Benzyl 2-(dibenzylamino)-6-(dimethoxyphosphoryl)-5-oxohexanoate
for a Convenient Access to 5-Substituted Prolines
(S)-2-Amino-4-(2-pentadecyl-1,3-dioxolan-2-yl)-butanoic acid, 11, Pdiob, a synthetic analogue C-isostere of palmitoylated cysteine, has been prepared starting from tetrabenzyl glutamic acid. The less hindered benzyl carboxylate ester was transformed into the corresponding beta-ketophosphonate and subjected to a Horner-Wadsworth-Emmons reaction followed by hydrogenation/hydrogenolysis. This product was used for the preparation on solid phase and under microwave dielectric heating of a highly lipidated peptide that can be considered as an acid stable analogue of the C-terminus of the H-Ras heptapeptides 180-186. (C) 2008 Elsevier Ltd. All rights reserved.
Transformation of Glutamic
Acid into (<i>S</i>)-Benzyl 2-(dibenzylamino)-6-(dimethoxyphosphoryl)-5-oxohexanoate
for a Convenient Access to 5-Substituted Prolines
l-Glutamic acid was transformed into β-keto-phosphonate in two steps. This compound was employed in the stereocontrolled synthesis of cis-5-substituted prolines through a Woodward-Horner-Emmons (WHE) reaction with different aldehydes followed by hydrogenolysis/hydrogenation-mediated ring closure. We found also that a one-pot sequential hydroformylation-WHE reaction was possible with cis-5-substituted prolines. In addition to differently functionalised prolines, an indolizidine amino acid with a structure related to constrained peptidomimetics was obtained.