PURPOSE: To esterify an α-amino-protected amino acid, by esterfying an α-amino- suitably protected amino acid in an aprotic and non-basic solvent in the presence of 2,4,6-mesitylene-1-sulfonyl-3-nitro-1,2,4-triazolide and a weak base.
CONSTITUTION: In the esterification of a protected amino acid, especially α- amino-protected amino acid, with an alcohol component in the presence of 2,4,6-mesitylene-1-sulfonyl-3-nitro-1,2,4-triazolide(MSNT) and a weak base, the esterification is effected in an aprotic and non-basic solvent (e.g. dichloromethane, THF) in the presence of N-methylimidazole(MeIm) under mild conditions. Preferred molar ratio of amino acid:MSTN:MeIm is 1:1:1 or less (especially 0.75) or less. As the alcohol component are used low molecular components such as protecting groups, polymer components such as soluble carriers or solid carriers.
RONARUDO FURANKU