Synthesis of 5-substituted-3,4-dihydroxycyanopyrrolidines. An easy access to polyhydroxyprolines

A novel procedure for the synthesis of cyanopyrrolidines is presented. Starting from conveniently functionalized d-ribose, d-mannose, d-(l)-arabinose, the compounds were efficiently synthesised in four steps in overall good yields. Transformation into proline derivatives and preliminary evaluation of these derivatives in organocatalysis is also described.