Practical synthesis of 2'(3')-O-aminoacyl derivatives of CpA

Abstract

N-Tert-butyloxycarbonyl-L-phenylalanine reacts with 1 equivalent of 1,1'-carbonyldiimidazole and 5'-O-dimethoxytrityl-2'-tetrahydropyranyl-N⁴-dimethylaminomethylenecytidylyl-(3' 5')-N⁶-dimethylaminomethyleneadenosine (I) and affords 2'(3')-O-(N-tert-butyloxycarbonyl)-L-phenylalanyl derivative II. The compound II gives by the action of formic acid in aqueous 1-butanol the 2'-O-tetrahydropyranylcytidylyl-(3' 5')-2'(3)-O-(tert-butyloxycarbonyl)-L-phenylalanyladenosine (III), which affords cytidyl-(3' 5')-2'(3')-O-L-phenylalanyladenosine (IV) by treatment with 95% aqueous trifluoroacetic acid.