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(I), a lactone derived from the hydrindanol. β-Sulfonylacrylate phenyl and t-butyl thioesters, β-chlorovinyl, β- sulfonyl- and β-sulfinyl-vinyl 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-Methylcyclohexenone 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.
串联共轭加成-环闭合反应涉及将
锂化的(E)-
2-丁烯基二苯氧化膦与 2-甲基-
2-环戊烯酮共轭加成而生成的烯酸
锂与两摩尔的
硫代
丙烯酸叔丁酯反应,生成氢
茚醇,并在
铜(I)存在下生成氢
茚醇衍生的内酯。β-磺酰基
丙烯酸酯苯基和 t-丁基
硫代酯、β-
氯乙烯基、β-磺酰基和 β-磺酰基
乙烯基酮与上述烯醇发生反应,并与 2-甲基
环己烯酮与甲基缩二
脲共轭加成生成的烯醇发生反应,生成不饱和的 1,5-二羰基化合物。其中,β-
氯乙烯酮的反应速度快,产率高。2-Methylcyclohexenone 由此转化为顺式二甲基辛酮;这一转化说明了 β-
氯乙烯基甲基酮在罗宾逊环化反应中的有效性。此外,还记录了 2,6-二甲基
环己酮的
锂烯醇和
钛烯醇与 β-取代烯酮的反应,从而得到相应的不饱和 1,5-二羰基化合物和其他产物。