We previously reported that pyrimidine derivatives of methylated 2'-O,4'-C-methyleneoxy-bridged nucleic acid (Me-TaNA), a unique consecutive three-acetal-containing nucleic acid, are promising building blocks for chemically modified oligonucleotides. Herein, purine derivatives of Me-TaNA (Me-TaNA-A and -G) were synthesized and introduced into oligonucleotides. During the synthesis, we found stereoselective introduction of a substituent on the 4' carbons by using 2',3'-carbonate compounds as substrates. When forming duplexes with single-stranded RNA, the modified oligonucleotides, including purine derivatives of Me-TaNA, showed higher duplex stability than the natural oligonucleotide. This study enabled the use of Me-TaNA for the chemical modification of various oligonucleotide sequences because synthesis of Me-TaNAs with all four nucleobases was achieved.