Jung Michael E, Ho David G
Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095, USA.
Org Lett. 2007 Jan 18;9(2):375-8. doi: 10.1021/ol062980j.
The hindered diene 1 reacts with 3-methylcyclohexenone 6 catalyzed by triflimide to produce the Mukaiyama Michael product 7 (low-temperature quenching) or the [4+2] cycloadduct 8 (quenching at 0 degrees C). Reaction of the hindered diene 23 with 2-methylcyclohexenone 12 with 5:1 AlBr3:AlMe3 afforded a 71% yield of a 1.9:1 mixture of two cycloadducts. Hydrolysis of the major isomer gave the dione 27', a model for the BCD ring system of pentacyclic triterpenes. [reaction: see text].
受阻二烯1在三氟甲磺酸亚胺催化下与3-甲基环己烯酮6反应，生成向山迈克尔产物7（低温淬灭）或[4+2]环加成产物8（0℃淬灭）。受阻二烯23与2-甲基环己烯酮12在5:1的AlBr₃:AlMe₃存在下反应，得到两种环加成产物的1.9:1混合物，产率为71%。主要异构体水解得到二酮27'，它是五环三萜BCD环系的模型。[反应：见正文]
