Abstract
(1′R, 3′S and R, 5′S)-4′-Oxo-2′-oxabicyclo[3.1.0]hexan-3′-yl pyrimidines and purines were synthesized from ribonucleosides in 2-5 steps. The configurations of the base moieties in the cyclopropano keto-nucleosides were determined by NOE difference spectroscopy.