Patent ID: 8158775

Claim:
A method for producing an oligonucleic acid derivative of formula (11), comprising the step of: reacting (a) tetra-n-butylammonium fluoride (TBAF) and (b) a sulfoxide-based solvent or an amide-based solvent or a mixture thereof, each of which optionally contains THF, wherein the sulfoxide-based solvent represents dimethylsulfoxide or ethyl methyl sulfoxide; and the amide-based solvent represents N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide or N-methylpyrrolidone; with an oligonucleic acid derivative of formula (10) to produce the oligonucleic acid derivative (11) wherein, in formulae (10) and (11), each B independently represents a nucleobase; n is 1 to 200; each Q independently represents O or S; each R independently represents H, hydroxyl, halogen, alkoxy, alkylthio, alkylamino, dialkylamino, alkenyloxy, alkenylthio, alkenylamino, dialkenylamino, alkynyloxy, alkynylthio, alkynylamino, dialkynylamino or alkoxyalkyloxy, and at least one R is hydroxyl; Z represents H, a phosphate group or a thiophosphate group; and R 1 represents a substituent of formula (3) wherein, in formula (3), R 11 , R 12 and R 13 are the same or different and each represents hydrogen or alkoxy; and each R 4 independently represents H, halogen, alkoxy, alkylthio, alkylamino, dialkylamino, alkenyloxy, alkenylthio, alkenylamino, dialkenylamino, alkynyloxy, alkynylthio, alkynylamino, dialkynylamino, alkoxyalkyloxy or a substituent of formula (4), and at least one R 4 is a substituent represented by the following general formula (4) wherein, in the general formula (4), WG 1 represents cyano, nitro, alkylsulfonyl, arylsulfonyl or halogen.