Conjugate addition of a variety of Grignard reagents to 2-cyclopentenone followed by cyclopropanation of the resulting enol ethers gave a range of substituted cyclopropyl silyl ethers in good yield. Treatment of these cyclopropyl silyl ethers with ferric chloride in DMF gave the one carbon ring expanded beta-chloro ketones which were eliminated to the corresponding 4- substituted-2-cyclohexenones.
[reaction: see text] Bicyclo[4.3.0]nonanes (hydrindanes) and bicyclo[3.3.0]octanes (octahydropentalenes) are easily synthesized by palladium-catalyzed cycloalkenylations. Additionally, benzo-fused bicyclo[3.3.0]octanes are prepared for the first time through intramolecular coupling between silyl enol ethers and aromatic rings in the presence of catalytic palladium acetate.
Iron(III) mediated transformations of trimethylsilyloxy cyclopropyl ethers
作者:Kevin I. Booker-Milburn、David F. Thompson
DOI:10.1016/0040-4020(95)00817-r
日期:1995.11
Conjugate addition of a variety of Grignard reagents to 2-cyclopentenone gave a number of silyl enol ethers (1) which were Created with Et2Zn/CH2I2 to give the corresponding cyclopropyl silyl ethers (2) in good yield. Ferric chloride ring expansion followed by base elimination of the resulting β-chloro ketones gave the 4-substituted-2-cyclohexenones (4) in moderate to good overall yield. The overall
在2-环戊烯酮中共轭添加各种格氏试剂,得到了许多甲硅烷基烯醇醚(1),它们由Et 2 Zn / CH 2 I 2生成,以高收率得到了相应的环丙基甲硅烷基醚(2)。氯化铁环膨胀,然后碱消除所得的β-氯代酮,以中等至良好的总收率得到4-取代的2-环己烯酮(4)。整个过程提供了从2-环戊烯酮到这些烯酮的方便的三步路线。