Asymmetric synthesis of all the stereoisomers of tarchonanthuslactone

We describe herein an efficient synthesis of all the four stereoisomers of tarchonanthuslactone from (R)-3-hydroxy butanoate, easily prepared from l-threonine. The approach involves the use of a β,γ-unsaturated δ-lactone as an intermediate, obtained via a Kulinkovich reaction followed by a ring-closing metathesis strategy.