A homogeneous catalyst system for the asymmetric cis-hydrogenation of 2, 5-disubstituted furans leading to 2', 3'-dideoxynucleoside analogues is described. Best enantioselectivities (ee values of up to 72%) were obtained with cationic rhodium complexes ligated by diphospholanes of the butiphane family. The selectivity of the hydrogenation was reversed by the addition of a base or a polar protic solvent in certain cases. Ferrocene-and proline- ...
