Asymmetric synthesis of dibenzylbutyrolactones and aryltetralin lignan lactones by tandem conjugate addition to a chiral butenolide
- 1 January 1993
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 21,p. 2621-2629
- https://doi.org/10.1039/p19930002621
Abstract
Addition of sulfur-stabilised carbanions to (–)-5-(1-menthyloxy)furan-2(5H)-one followed by reaction with an aromatic aldehyde affords a short synthesis of enantiomerically pure dibenzylbutyrolactone derivatives. Desulfurisation with NaBH4/NiCl2 proceeds in almost quantitative yield, and reduction with NaBH4/KOH gives the parent dibenzylbutyroactones including (–)-6-epi-podorhizol. These undergo cyclisation with acid to give homochiral aryltetralins including (–)-deoxyisopodophyllotoxin in high yield.Keywords
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