[reaction: see text] The rhodium(I)-catalyzed methylenation of ketones using trimethylsilyldiazomethane proceeds to give the corresponding alkenes in good yields (60-97%). The use of an excess of 2-propanol and 1,4-dioxane as a solvent were instrumental to obtain the desired alkenes in high yields. Superior results were achieved with the rhodium(I)-catalyzed methylenation in comparison with the standard
Terminal alkenes have been efficiently prepared via a rhodium-catalyzed olefination procedure using Wilkinson’s catalyst in the presence of triphenylphosphine, 2-propanol and trimethylsilyldiazomethane. Optimized reaction conditions are described for aldehydes and ketones, as well as alternative work up procedures.
by a pathway involving carbon migration in the pinacol rearrangement step, to provide methoxy epimers of 1-(2-methoxycyclohexyl)cyclopentylcarboxaldehyde. Reaction of the corresponding E stereoisomer is more complex and yields a mixture of products resulting from both hydride and carbon migration in the pinacol rearrangement step.Key words: Prins cyclization, pinacol rearrangement, attached rings.
报道了使用频哪醇终止的 Prins 环化形成连接环的第一项研究。(Z)-或(E)-[2-(6,6-二甲氧基亚己基)环己醇的三异丙基甲硅烷基醚用SnCl 4 处理提供具有连接环的双环产物。该方法在 Z 亚烷基环己烷系列中合成有用,通过涉及频哪醇重排步骤中碳迁移的途径选择性地进行,以提供 1-(2-甲氧基环己基) 环戊基甲醛的甲氧基差向异构体。相应的 E 立体异构体的反应更为复杂,在频哪醇重排步骤中产生由氢化物和碳迁移产生的产物混合物。关键词:Prins 环化,频哪醇重排,连接环。