Structure and reactivity of D-ribofuranosylpyrimidine homo-C-nucleosides halogenated on the bridge C-atom

Abstract

The reactions of the ylide (2a) with the D-ribose derivative (1) led to protected 4-chloro-6[chloro(β-D-ribofuranosyl)methyl]pyrimidine homo-C-nucleosides (3). Configuration at the bridge C-α of compounds (3) was established by comparison with the resulting products of the iodine-induced cyclisation of the unsaturated derivatives (E,Z)-(4c), i.e. compounds (α,β)-(6), as well as by spectroscopic methods (¹H and ¹³C n.m.r., N.o.e.-difference NOESY) and by chemical transformation to the C-nucleosides (12) and (13).