Synthesis of the 3'-terminal decaribonucleoside nonaphosphate of yeast alanine transfer ribonucleic acid

Abstract

The preparation, by the phosphotriester approach, of UpCpGpUpCpCpApCpCpA (23) from three protected trinucleotide blocks (19a-c) is described. The use of the o-dibromomethylbenzoyl (DBMB) protecting group in oligoribonucleotide synthesis is described for the first time. Internucleotide linkages are protected by o-chlorophenyl groups which are finally removed by treatment sith the N1, N1, N3, N3-tetramethylguanidinium salt of syn-4-nitrobenzaldoxime. The first phosphorylation step (leading to phosphodiester intermediates) is carried out by treatment with o-chlorophenyl phosphorodi-(1,2,4-triazolide) (13a; Ar = 2-C1C6H4) and then with water and triethylamine. 1-Mesitylenesulphonyl-3-nitro-1,2,4-triazole (MSNT, 14) is used as the activating agent in the second phosphorylation step. © 1980.