FACILE SYNTHESIS OF 1,4-DIKETONES VIA PALLADIUM COMPLEX CATALYZED ISOMERIZATION OF ALKYNEDIOLS

Alkynediols isomerized under the catalysis of Pd2(dba)3.CHCl3 + 2n-Bu3P in acetonitrile at 80-degrees-C to give 1,4-diketones in high yields. This experimentally simple and economically synthetic method is illustrated with examples including substituents such as alkyl, alkenyl, and aryl groups. The order of reactivity of the substituents in this reaction is aryl greater-than-or-equal-to alkenyl > alkyl. Alkenyl-substituted alkynediols chemoselectively isomerized to the corresponding alpha,beta-unsaturated 1,4-diketones. The usefulness of this novel method is exemplified by the synthesis of dihydrojasmone.