Efficient trapping of ketone enolates with acrylate and β-sulfonylacrylate thioesters, β-sulfonyl, β-sulfinyl- and β-chloro-vinyl ketones; facile preparation of a hydrind-anone, cis-dimethyloctalone, and unsaturated 1, 5-dicarbonyl compounds

Tandem conjugate addition-ring closure involving reaction of the lithium enolate arising from conjugate addition of lithiated (E)-but-2-enyldiphenylphosphine oxide to 2-methyl-cyclopent-2-enone with two moles of t-butylthioacrylate generates a hydrindanol, and, in the presence of copper(1), a lactone derived from the hydrindanol. β-Sulfonylacrylate phenyl and t-butyl thioesters, β-chlorovinyl, β-sulfonyl- and β-sulfinyl-vinyI ketones react with the foregoing enolate, and with the enolate generated through conjugate addition of a methylcuprate to 2-methylcyclohexenone to give unsaturated 1, 5-dicarbonyl compounds. The β-chlorovinyl ketones in particular react rapidly and in high yield. 2-Methylcydohexenone has thereby been converted into a cis-dimethyl octalone; the conversion illustrates the effectiveness of β-chlorovinyl methyl ketone in the Robinson annelation. Reactions of the lithium enolate and titanium enol of 2, 6-dimethylcyclohexanone with the β-substituted enones to give the corresponding unsaturated 1, 5-dicarbonyl compounds and other products are also recorded.