A CYTOSINE ANALOG CONTAINING A CONFORMATIONALLY FLEXIBLE ACYCLIC LINKER FOR TRIPLEX FORMATION AT SITES WITH CONTIGUOUS G-C BASE-PAIR

Two nucleoside derivatives of the pyrimidine bases T and m(5ox)C have been prepared with flexible acyclic carbohydrate linkers. A new proced ure, beginning with (R)-(-)-2,2-dimethyl-1,3-dioxolane-4-methanol perm its the preparation of the stereochemically pure acyclic derivatives o f both protected nucleoside analogues without contamination by a probl ematic rearrangement product. By simply increasing the flexibility of the carbohydrate portion of the am(5ox)C nucleoside derivative, 15-mer triplexes containing five contiguous G-C base pairs exhibit a 7-8 deg rees C increase in T-m value. (C) 1997 Elsevier Science Ltd. All right s reserved.