The total synthesis of the ionophore antibiotic X-14547A (indanomycin)(1) is described by using a convergent strategy. 2-Ethylvalerolactone was converted into ethyl (E, E, E)-ll-[[(/3- methoxy) ethoxy] methoxy]-6-ethyl-2, 7, 9-undecatrienoate (8) in eight steps. Intramolecular Diels-Alder reaction of 8 at 110 OC followed by deprotection to give the racemic tricyclic lactone 7 proceeded with very high stereoselectivity (> 90%) and in 38% overall yield from ...
