The present invention is concerned with a novel convergent route for synthesis of BCX-1777 and BCX-4430. Two key starting materials that were carefully chosen for cross-coupling were a stable sugar intermediate, unlike the imine intermediates in the prior art, and dihalogenated pyrrolopyrimidine intermediate. A chemoselective cross-coupling was achieved from the two key starting materials, which upon reduction and activation resulted in stereoselective formation of an advanced intermediate in 55% yield from protected D-ribonolactone in 6 steps. The advanced intermediate then served as a starting material for synthesis of BCX-1777 and BCX-4430 in 38% (over 8 steps) and 32% (over 9 steps) yields, respectively from protected D-ribonolactone.