An Efficient Asymmetric Synthesis of Tarchonanthuslactone

An efficient and straightforward ten‐step asymmetric synthesis of the polyketide tarchonanthuslactone (1) in good overall yield (21% starting from chloro lactone 5) and with excellent diastereomeric and enantiomeric excesses (de, ee ⩾ 96%) is described. The new synthetic route is based on the α,β‐unsaturated δ‐lactone building block 5, available in enantiopure form (ee > 99%) through an enzymatic procedure, and its conversion into methyl ketone 11 by an Umpolung strategy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)