A Reexamination of the Robinson Annelation of 2-Methylcyclohexanone with 3-Penten-2-one and 4-Phenyl-3-buten-2-one
作者:Mitsuko Kikuchi、Akira Yoshikoshi
DOI:10.1246/bcsj.54.3420
日期:1981.11
The reported Robinson annelation of 2-methylcyclohexanone with 3-penten-2-one has been reexamined. In contrast to the previous result, it was found that the reaction product was not only obtained in a low yield, but also the solvent-depending stereoselectivity in the formation of cis-4,4a-dimethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one (3a) and its trans isomer (3b) was considerably lower than that reported. As expected, regioisomers, 4β,8α-dimethyl-4,4aβ,5,6,7,8-hexahydronaphthalen-2(3H)-one and 4β,8β-dimethyl-4,4aα,5,6,7,8-hexahydronaphthalen-2(3H)-one, were also formed in the annelation. A similar tendency was observed in the reaction with 4-phenyl-3-penten-2-one. The annelation products, 3a, 3b, cis-4-phenyl-4a-methyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one, and trans-4-phenyl-4a-methyl-4,4a,5,6,7,8-hexahydronaphthalen-2 (3H)-one, were also synthesized by an alternative route.
我们重新研究了 2-甲基环己酮与 3-戊烯-2-酮的罗宾逊环化反应。与之前的结果不同,研究发现反应产物不仅产率低,而且在生成顺式-4,4a-二甲基-4,4a,5,6,7,8-六氢萘-2(3H)-酮(3a)及其反式异构体(3b)时,溶剂决定的立体选择性也比报道的低得多。正如预期的那样,在环化过程中还生成了 4β,8α-二甲基-4,4aβ,5,6,7,8-六氢萘-2(3H)-酮和 4β,8β-二甲基-4,4aα,5,6,7,8-六氢萘-2(3H)-酮这两种区域异构体。在与 4-苯基-3-戊烯-2-酮的反应中也观察到类似的趋势。此外,还通过另一种方法合成了环化产物 3a、3b、顺式-4-苯基-4a-甲基-4,4a,5,6,7,8-六氢萘-2(3H)-酮和反式-4-苯基-4a-甲基-4,4a,5,6,7,8-六氢萘-2(3H)-酮。