A reexamination of the Robinson annelation of 2-methylcyclohexanone with 3-penten-2-one and 4-phenyl-3-buten-2-one.
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概要
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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 <I>cis</I>-4,4a-dimethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3<I>H</I>)-one (<B>3a</B>) and its <I>trans</I> isomer (<B>3b</B>) was considerably lower than that reported. As expected, regioisomers, 4β,8α-dimethyl-4,4aβ,5,6,7,8-hexahydronaphthalen-2(3<I>H</I>)-one and 4β,8β-dimethyl-4,4aα,5,6,7,8-hexahydronaphthalen-2(3<I>H</I>)-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, <B>3a</B>, <B>3b</B>, <I>cis</I>-4-phenyl-4a-methyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3<I>H</I>)-one, and <I>trans</I>-4-phenyl-4a-methyl-4,4a,5,6,7,8-hexahydronaphthalen-2 (3<I>H</I>)-one, were also synthesized by an alternative route.
- 公益社団法人 日本化学会の論文