Regiospecific α-Substitution of Crotonic Esters. Synthesis of Naturally Occurring Derivatives of 6-Ethyljuglone

Article abstract of DOI:10.1016/S0040-4020(01)87099-X

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.