MODIFIED OLIGONUCLEOTIDES WITH A 5'-5'-INTERBASE SEMIRIGID JUNCTION FOR ALTERNATE STRAND TRIPLEX FORMATION

Solid-phase synthesis of 5'-5'-linked oligonucleotides with opposite p olarities tethered via nucleic bases has been performed using a modifi ed dinucleoside bearing an H-phosphonate group at the 3'-position of o ne nucleoside and a dimethoxytrityl group-at the 3'-position of the se cond nucleoside. This system is aimed at forming a base tetrad at the junction in order to provide better stabilization. The linker used bet ween the two 5'-terminal bases in the same plane involves a triple bon d in order to rigidify the junction. The two oligonucleotide :chains a re either made of natural nucleosides or one of them is built With N3' -->P5' phosphoramidates. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.