Effective synthesis of C-nucleosides with 2′,4′-BNA modification

The effective synthesis of some C-nucleosides with 2′-O,4′-C-methylene bridged nucleic acid (2′,4′-BNA) modification was accomplished by using the coupling reaction of a tetrahydrofurancarbaldehyde with the magnesium or lithium derivatives of aromatic heterocycles followed by the Mitsunobu cyclization. Moreover, it was clearly shown by 1H NMR spectra and X-ray crystallography that the sugar conformation in the synthesized C-nucleosides, independent of the nucleobases, was fixed in N-form.