On Rh2(OAc)4-catalysed decomposition of 1-diazo-4-(2-methoxyphenyl)butan-2-one (9) and its methyl-substituted analogue (18), norcaradienones 10 and 19, respectively, were observed as the only regioisomers resulting from intramolecular cyclopropanation, indicative of attack by the metal carbene away from the methoxy group; to explain the transformation of 10 and 19 into dihydroazulenones 15 and 23, interconversion of 10 and 19 into their isomers 14 and 22 must be invoked, and an ionic âring-walkâ rearrangement is suggested for such an isomerization.
在Rh2(OAc)4催化下,1-重氮-4-(2-
甲氧基苯基)丁-2-酮(9)及其甲基取代类似物(18)、降
冰片二烯酮10和19分别被观察为分子内
环丙烷化反应产生的唯一区域异构体,表明
金属羰基远离甲氧基的攻击;为了解释10和19转化为二氢氮
茚酮15和23,必须将10和19转化为其异构体14和22,并建议这种异构化发生离子“环游”重排。