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A new phosphitylating agent, compatible with the Fmoc/t-butyl strategy for the production of phosphotyrosine containing peptides was synthesized. Our results demonstrated that high yields and high purities of phosphotyrosine peptides can be obtained using this phosphitylating agent.

It is shown in this work that FMOC amino acid chlorides are also applicable to solid-phase syntheses by the simple expedient of in situ conversion to the appropriate N-hydroxybenzotriazole ester via reaction with a 1:1 mixture of HOBt and an appropriate tertiary amine. In cases where acid chlorides are inaccessible due to side-chain incompatibility, pentafluorophenyl esters or BOP-induced couplings represent convenient spot substitutes

Unhindered carboxylic acids were converted to their (±)-1-(4-methoxyphenyl)ethyl (Mpe) esters in good yields by condensation with (±)-1-(4-methoxyphenyl)ethanol under mild conditions. The Mpe esters were rapidly and quantitatively cleavable by either 1% TFA in CH 2 Cl 2 or 10% DCA in CH 2 Cl 2 , conditions which leave Boc, t-butyl ester and ether intact. An Mpe ester was removed by hydrogenolysis much more slowly than the analogous benzyl ester.

Pour prevenir la racemisation pendant la synthese peptidique, les auteurs ont essaye d'utiliser les groupes protecteurs p-phenylazobenzoyl et p-phenylazobenzoyloxycarbonyl pour la synthese de di- et tripeptides

Le substituant fluorenyl-9 methylene est etudie en tant que groupe N-protecteur d'α-aminoacides ou d'α-aminoesters permettant d'eviter la racemisation lors de synthese peptidique. La protection des α-aminoacides se fait par la reaction de ceux-ci avec l'[hydroxy methoxy methyl]-9 fluorene