Methyl β-methoxycrotonate is alkylated regiospecifically, through the anion, in the α-position. Enolsilylation of the resulting β, γ-unsaturated ester affords the corresponding 1, 1, 2, 3- tetrasubstituted butadiene. Cycloaddition of the latter to the appropriate halogenated benzoquinone, followed by various transformations, provides the first recorded syntheses of several natural products derived from 6-ethyl-7-methoxyjuglone.
