The products (predominantly unsaturated aldehydes) from photolysis in methanol of a series of 6,6-dimethylbicyclo[3.1.1]heptan-2-ones are reported. These results are rationalized on the basis of stereochemical interactions and the apparent preference for cleavage to occur adjacent to the less highly substituted α-carbon but more stable alkyl radical. It is concluded that the photochemical behavior of α-cyclobutyl ketones displays a closer parallel to the α-cyclopropyl ketones than previously recognized and that cleavage will occur preferentially on the side of the carbonyl group remote from the four-membered ring whenever possible. The synthetic steps involved in the preparation of the ketones from 'pinene' precursors are described.
在甲醇中光解一系列6,6-二甲基双环[3.1.1]庚烷-2酮所产生的产品(主要是不饱和醛)已被报道。这些结果基于立体化学相互作用和对于裂解在次级α-碳旁边但更稳定的烷基自由基的明显偏好进行了解释。结论是α-环丁基酮的光化学行为与α-环丙基酮之间存在更为密切的平行关系,而且裂解会倾向于在可能的情况下首选发生在远离四元环的羰基一侧。描述了从“蒎烯”前体制备酮所涉及的合成步骤。