Scission, par la phénylhydrazine, du groupe «phtalyle» d'acides aminés et de peptides N‐phtalylés

Abstract

The phtalyl group of N‐phtalyl derivatives of amino acids and peptides is removed in one step by heating in alcoholic solution with phenylhydrazine and a tertiary base.

Methyl 2-((Succinimidooxy)carbonyl)benzoate (MSB): A New, Efficient Reagent forN-Phthaloylation of Amino Acid and Peptide Derivatives

“…( S )- N α -Phthaloylphenylalanine (6a): white solid (0.59 g, 100%); mp 183−185 °C (lit 2a. mp 183−185 °C); HPLC R t = 13.70 min; [α] D −212 ( c = 1.0, EtOH); 1 H NMR (200 MHz, CDCl 3 ) δ 3.61 (d, J = 8.7 Hz, 2H), 5.25 (t, J = 8.7 Hz, 1H), 7.20 (m, 5H), 7.65−7.84 (m, 4H), 9.38 (bs, 1H); 13 C NMR (50 MHz, CDCl 3 ) δ 34.5, 53.2, 123.6, 126.9, 128.6, 128.9, 131.5, 134.2, 136.5, 167.5, 174.5; MS ( m / z ) 296 (M + H) + , 318 (M + Na) + .…”

“…Moreover, the fact that the phthaloyl group can easily be cleaved under mild conditions makes it very advantageous for the protection of amino groups during syntheses . However, available routes for the synthesis of N -phthaloylamino acids are limited. − Among these, the fusion of amino acids with phthalic anhydride is a widely used methodology. 2a, For some amino acids good yields are obtained, but in some cases the conditions used are so drastic that racemization occurs. 2a,4a,c Furthermore, amino acids with functionalized side chains failed to give the desired phthaloylated products 4b. The extent of this racemization was limited by performing the reactions in boiling solvents and in the presence of bases such as triethylamine .…”