NUCLEIC ACID SYNTHESIS METHOD USING SEGMENT-TYPE AMIDITE

The purpose of the present invention is to provide a method for synthesizing an oligonucleotide by using a segment-type amidite. An oligonucleotide production method comprising at least one coupling step for coupling a nucleoside phosphoramidite with a thiol group or a hydroxyl group at the 3' or 5' of a nucleoside or a nucleotide in the presence of an activator, wherein, in the at least one coupling step, said nucleoside phosphoramidite has (a) two or more nucleoside portions or (b) at least one nucleoside portion and a linker portion, and said activator has a structure represented by formula (1) (in formula (1), X represents an organic base) or by formula (2) (in formula (2), R1 and R2 are each independently selected from the group consisting of H, straight chain or branched chain C1-7 alkyl groups and optionally substituted aromatic groups).