Asymmetric transfer hydrogenation of a new N- tosyltetrahydrocarbazole-1-one ester with the Noyori-Ikariya catalyst

Enantioselective reduction of a new 1-oxotetrahydrocarbazole compound (ethyl 2-(1-oxo-9-tosyl-2,3,4,9-tetrahydro-1H-carbazol-2-yl)acetate) through asymmetric transfer hydrogenation by using the commercially available Noyori-Ikariya ruthenium catalyst and HCO2H/Et3N or HCO2H/DABCO as the hydrogen source have been investigated. High enantiomeric excesses (up to 96% ee) and moderate to good yields (24-72%) for corresponding alcohol and lactone compounds have been achieved. Structures of all compounds have been characterized by spectroscopic techniques.