New synthetic route to butanolide lignans by a ruthenium complex catalyzed hydrogenation of the corresponding Stobbe's fulgenic acids

Article abstract of DOI:10.3987/COM-88-4321

A new two-step total synthesis of butanolide lignans (or dibenzylbutyrolactone lignans) is described, which affords the title compounds in good yield and with a very short work-up time. It involves a ruthenium carbonyl hydride complex-catalyzed hydrogenation of the corresponding dibenzylidene succinic acids (fulgenic acids). Since the catalytic hydrogenation (second step) is a total yielding process, the overall yield determining step is the preparation of the fulgenic acid intermediates by the Stobbe condensation (first step), which has consequently been revised to improve many details. This simple process moreover allows hexadeuterated butanolide lignans to be readily obtained for isotopic dilution mass spectral measurements. The syntheses of a selection of lignans, namely enterolactone, matairesinol, hinokinin, dimethylmatairesinol and cordigerine, are described to illustrate the whole procedure.