[GRAPHICS]Pure alpha -azido acids were prepared using an efficient diazo transfer method followed by buffered workup, These building blocks were used to prepare small peptides on Wang resin by two approaches, Peptides prone to diketopiperazine formation were prepared in good yields by coupling acids to resin bound iminophosphoranes during Fmoc-Wang synthesis, The iminophosphoranes can also be hydrolyzed under neutral conditions to provide unprotected amines ready for further coupling.
Preparation of (R)-2-azidoesters from 2-((p-nitrobenzene)sulfonyl)oxy esters and their use as protected amino acid equivalents for the synthesis of di- and tripeptides containing D-amino acid constituents
作者:Robert V. Hoffman、Hwa-Ok Kim
DOI:10.1016/s0040-4020(01)92245-8
日期:1992.4
(R)-2-Azidoesters and their derived (R)-2-azido acids are readily prepared from common aminoacids by an inversion methodology that employs (S)-2-nosyloxyesters as key intermediates. The (R)-2- azidoesters can be used as protected aminoacid equivalents in peptide synthesis. Basic hydrolysis frees the carboxyl group. Triphenylphosphine/water is used to free the amine group. By these reactions a variety
A directed chiral synthesis of amino acids from boronic esters
作者:Donald S. Matteson、Ellen C. Beedle
DOI:10.1016/s0040-4039(00)96547-x
日期:1987.1
Conversion of (s)-pinanediol (1S)-1-haloalkylboronates to (1R)-1-azido boronates, homologation with (dichloromethyl)lithium to 1-chloro-2-azido boronates, oxidation with sodium chlorite to the α-azido acids, and catalytic hydrogenation yielded L-amino acids, 92-96% enantiomeric excess.
Facile and efficient formation and dissociation of a pseudo[2]rotaxane by a slippage approach using pillar[5]arene-based cyclic host liquid and solvent
A pillar[5]arene-based pseudo[2]rotaxane was synthesizedusing a slippage method by only heating an axle with bulky valine derivative ends in a cyclic host liquid (CHL), which is liquid at room...