The total synthesis of pseudomonic acid C is described using an approach wh
ich gives access to analogues and putative biosynthetic precursors; the key
step is installation of the C-7 side-chain via alkylation of a trisubstitu
ted delta-lactone with complete stereocontrol and in 85% yield under condit
ions which avoid the possible competing elimination of a protected hydroxy
group beta to the carbonyl.