Asymmetric Hydrogenation of 3,5-Dioxoesters Catalyzed by Ru-binap Complex: A Short Step Asymmetric Synthesis of 6-Substituted 5,6-dihydro-2-pyrones

Article abstract of DOI:10.1016/S0040-4020(01)86300-6

Asymmetric hydrogenation of 3,5-dioxoesters 1a-c using Ru2Cl4((R) or (S)-binap)2(NEt3) as the catalyst gave dominantly anti 3,5-dihydroxyesters 2, which were then converted into unsaturated lactones 5a-b (ca. 80percent e.e.).The pathway of the hydrogenation reaction was also investigated by asymmetric hydrogenation of (R)- or (S)-5-hydroxy-3-oxoesters 8a-c.It was revealed that the Ru-binap catalyzed hydrogenation of 1a-b proceed dominantly via the β-diketone mode.A convenient asymmetric synthesis of hydroxylactone 3c and unsaturated lactone 5c was presented.Key words: 3,5-dioxoester; Ru-binap catalyst; asymmetric hydrogenation; asymmetric synthesis; lactone