Synthesis of oligodeoxynucleotides using the oxidatively cleavable 4-methoxytritylthio (MMTrS) group for protection of the 5′-hydroxyl group

Abstract

We examined the synthesis of oligodeoxynucleotides containing all four nucleobases using the 4-methoxytritylthio (MMTrS) group for protection of the 5′-hydroxyl group. The MMTrS group could be introduced into 3′-O-TBDMS-deoxycytidine, -deoxyadenosine and -deoxyguanosine with the appropriate base protecting groups using strong bases such as n-butyl lithium and lithium hexamethyldisilazide. Because the MMTrS group could be removed by oxidation with an aqueous I2 solution, the oxidation of internucleotidic phosphite intermediates could be performed simultaneously. Thus, the nucleotide chain could be extended in a three-step protocol that comprised coupling, capping and oxidation/deprotection. Oligodeoxynucleotides with 10 and 20 mixed-base sequences could be synthesized using this protocol.