Patent ID: 7943758

Claim:
A compound represented by the following formula: wherein of formula I represents a 2′-deoxyribonucleoside or its N-protected derivative, the substituent —O—(R 1 )Si(R 2 )—(C 6 H 3 R 6 )—(CH 2 ) n —O—P(OR 3 )N(R 4 )(R 5 ) is attached at the 3′ position of the sugar moiety of the nucleoside substituent; each of R 1 , R 2 , R 4 and R 5 is an alkyl or optionally substituted aryl group, wherein the optionally substituted aryl group has a substituent selected from the group consisting of C 1-5 alkyl, nitro, cyano, halo and methoxyl; R 3 is a protecting group; R 6 substituent of the benzene ring —(C 6 H 3 R 6 )— is selected from the group consisting of H, C 1-4 alkyl, halo, nitro, cyano and methoxyl; R 7 is H or 4,4′-dimethoxytrityl; and n is an integer of from 1 to 5.