INTRODUCTION OF “SOLUBILIZING GROUP” TO NUCLEOTIDE SYNTHESIS: STANNYL ESTER OF NUCLEOTIDES AS USEFUL INTERMEDIATE IN UNSYMMETRICAL ALKYL NUCLEOSIDE DIPHOSPHATE SYNTHESIS
5'-phosphate with trichloroacetic anhydride, trichloroacetyl chloride, and tribromoacetyl bromide was studied in dimethylformamide and acetonitrile in the presence of tertiary amines. The first two reactions gave the mixed anhydride of trichloroacetic and thymidylic acids (acyl phosphate) as the major product and P1, P2-dithymidine 5'-pyrophosphate as the byproduct. The third reaction proceeded by a more complicated