Large-scale solid-phase preparation of 3'-unprotected trinucleotide phosphotriesters--precursors for synthesis of trinucleotide phosphoramidites.

The approach to large-scale solid-phase synthesis of 3'-unprotected trinucleotide phosphotriesters has been developed. The trinucleotides have been synthesized in 5 g scale by phosphotriester approach using CPG with pore size 70A. Total yield of target products was 75-90%. The molar extinctions of trinucleotides at various wave-lengths were calculated; the experimental UV-spectra of trinucleotides show a good agreement with theoretical ones. The trinucleotides synthesized were used for synthesis of trinucleotide phosphoramidites - synthons for generation of DNA/peptide libraries.