The synthesis of oligoribonucleotides VI. The synthesis of a hexadecamer by a block condensation approach

The synthesis of the 5′-monomethoxytrityl-2′-tert-butyldimethylsilyl-3′-levulinylribonucleosides 4 of the four major bases involved in the phosphite procedure for the synthesis of oligoribonucleotides is described along with the 2′,3′-isomeric derivatives 6 . This report describes a total protection system for nucleotide units which allows for the block condensation procedure to be used for the synthesis of long chains. The procedure is illustrated by the synthesis of a hexadecauridylic acid.