Synthesis of oligodeoxynucleotides containing thymidines linked via an internucleosidic‐(3′‐5′)‐methylene bond

Condensation of N3-benzoyl-5′-O-dimethoxytrityl-3′-O-(4-penten-1-oxymethyl)-thymidine with N3-benzoyl-3′-O-methoxyacctyl-thymidine, in the presence of N-iodosuccinimide, afforded a fully-protected thymidine dimer having an internucleosidic-(3′-5′)-methylene linkage. The latter was utilized in the preparation, in solution and on a solid support, of DNA-fragments containing one or more T-CH2-T dimer(s).