Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO: reaction development and application to the formal synthesis of (−)-galanthamine
作者:Cheng-Hang Liu、Zhi-Xiang Yu
DOI:10.1039/c6ob00660d
日期:——
A Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO has been developed to synthesize functionalized 2-methylidene-3,4-cyclohexenones. The scope of this methodology has been investigated, showing that various functional groups can be tolerated. Both di- and tri-substituted allenylcyclopropanes can be applied to this cycloaddition and the [5 + 1] cycloadducts with the E configuration
Efficient and stereoselective rearrangement catalyzed by only one mole-percent gold(I) chloride/silver(I) trifluoromethanesulfonate of Baylis-Hillman acetates afforded 2-(acetoxymethyl)alk-2-enoates under mild reaction conditions in good to high yields with 100% E-selectivity. For cyclohex-2-enone-derived Baylis-Hillman acetates, the reaction gave 2-alkylidenecyclohex-3-enones in good yields.
Abstract An efficient NaNO2-catalyzed synthesis of 2-methylene-3-cyclohexenones from easily accessible cyclohexenone-MBH acetates has been established for the first time. Target products were rapidly generated in moderate to high yields and with relatively high E/Z selectivity. Easy operation, good functional group tolerance, mild reaction conditions and the practicality of high efficiency of NaNO2