The facile one-pot synthesis of N α -(9-fluorenylmethoxycarbonyl)-O-(O′, O″-dialkylphosphoro)-l-tyrosines using dialkyl N, N-diethylphosphoramidites

Abstract

N α -(9-Fluorenylmethoxycarbonyl)-O-(O′, O″-dialkylphosphoro)-L-tyrosines (R = methyl, benzyl, tert-butyl) were prepared in high yield by a facile one-pot procedure which involved initial tert-butyldimethylsilyl protection of the carboxy terminus of N-Fmoc tyrosine followed by in situ phosphitylation of the tyrosyl hydroxyl group using dimethyl, dibenzyl or di-tert-butyl N,N-diethylphosphoramidite/1H-tetrazole, oxidation of the resultant dialkyl phosphite triester with tert-butyl hydroperoxide and finally cleavage of of the carboxy silyl group by mild acidolysis.