Action of toluene-p-thiol and triethylamine on fully protected thymidylyl-(3′→ 5′)-thymidine. Possible occurrence of thiolate ion-promoted internucleotide cleavage in the synthesis of oligonucleotides by the phosphotriester approach

Abstract

When 5′-O-methoxytetrahydropyranylthymidylyl-(3′→ 5′)-3′-O-methoxytetrahydropyranylthymidine o-chlorophenyl ester (12) is treated with an excess of toluene-p-thiol and triethylamine in acetonitrile solution at room temperature, it is cleaved to give 5′-O-methoxytetrahydropyranylthymidine 3′-(o-chlorophenyl) phosphate (10) and 5′-deoxy-5′-(p-tolylthio)-3′-O-methoxytetrahydropyranylthymidine(13). The bearing of this result on the synthesis of oligonucleotides by the phosphotriester approach is discussed.