Treatment of the 3-halo-2-cyclohexen-1-ones 11–15 and 17 with an excess of lithium dimethylcuprate provided good to excellent yields of the corresponding 3,3-dimethylcyclohexanones 21–24. Similar reactions involving the β-bromo cyclopentenones 19 and 20 stopped at the monoaddition stage, producing the cyclopentenones 40 and 43. Reaction of the β-bromo cyclohexenones 12 and 15 with 1.1 equiv. of lithium dimethylcuprate did not effect clean conversion of these substrates into the corresponding 3-methyl-2-cyclohexen-1-ones. When a series of β-bromo enones 12, 14–19 were allowed to react with the lithium (phenylthio)(alkyl)cuprates 44–47, the corresponding β-alkyl enones were, in general, produced cleanly and efficiently. However, reaction of 3-bromo-2-methyl-2-cyclopenten-1-one (19) with the cuprate reagent 44 gave mainly the β-phenylthio enone 49. This undesired result could be avoided by employing, in the place of 19, the β-iodo cyclopentenone 50, which reacted smoothly with 44 to give a high yield of 2,3-dimefhyl-2-cyclopenten-1-one (40). Reaction of 3-bromo-2-cyclohexen-1-one (14) with 3 equiv. of the mixed vinylcuprate reagent 48 gave 3-(3-butenyl)-2-cyclohexen-1-one (32). Alkylation of 1,3-cyclopentanedione with (Z)-1-chloro-2-pentene afforded compound 51, which was converted into the β-bromo enone 52. Treatment of the latter substance with lithium dimethylcuprate provided (Z)-jasmone (53).
将3-卤代-
2-环己烯-1-酮11-15和17与过量的二甲基
溴化锂处理,得到相应的
3,3-二甲基环己酮21-24,收率良好至优良。涉及β-
溴代
环戊烯酮19和20的类似反应在单加成阶段停止,产生
环戊烯酮40和43。β-
溴代
环己烯酮12和15与1.1当量的二甲基
溴化锂反应未对这些底物进行干净转化为相应的
3-甲基-2-环己烯-1-酮产生影响。当一系列β-
溴代烯酮12、14-19与苯基
硫代烷基
铜盐44-47反应时,通常产生相应的β-烷基烯酮,而且效率高。然而,3-
溴代-2-甲基-2-
环戊烯-1-酮(19)与
铜盐试剂44反应主要产生β-苯基
硫代烯酮49。通过使用β-
碘代
环戊烯酮50代替19,可以避免这种不良结果,后者与44反应顺利,产生高收率的2,3-二甲基-2-
环戊烯-1-酮(40)。3-
溴代-
2-环己烯-1-酮(14)与混合
乙烯铜盐试剂48的3当量反应产生3-(3-
丁烯基)-
2-环己烯-1-酮(32)。
1,3-环戊二酮与(Z)-1-
氯-
2-戊烯烷基化生成化合物51,进一步转化为β-
溴代烯酮52。后一物质经二甲基
溴化锂处理得到(Z)-
茉莉酮(53)。