Synthesis of pseudo-Ribofuranoses by Stereocontrolled Reactions on 4- Hydroxycyclopent-2-enylmethanol Derivatives.

The diol 3 is a major product formed from a Prins reaction on cyclopentadiene and was readily converted into the derivatives 4–7. The latter compounds were obtained in states of high optical purity by using both enzyme-catalysed hydrolysis and esterification reactions. Osmium tetraoxide transformed the ene diol derivatives 4–7 into the corresponding alcohols 8–11. In this way the alcohol (+)-6 was used to prepare (–)-pseudo-β-ribofuranose (–)-2, and the alcohol (–)-4 was used to synthesize (+)-pseudo-α-ribofuranose (+)-1.