Regioselective Synthesis of α-Fluorinated Cyclopentenones by Organocatalytic Difluorocyclopropanation and Fluorine-Directed and Fluorine-Activated Nazarov Cyclization
作者:Kohei Fuchibe、Ryo Takayama、Takaharu Yokoyama、Junji Ichikawa
DOI:10.1002/chem.201604578
日期:2017.2.24
α,β‐unsaturated ketones, underwent proton sponge‐catalyzed difluorocyclopropanation with trimethylsilyl 2,2‐difluoro‐2‐fluorosulfonylacetate in a regioselective manner, leading to 1,1‐difluoro‐2‐siloxy‐2‐vinylcyclopropanes in good yields. The cyclopropanes thus obtained were in turn subjected to fluoride‐ion‐catalyzed ring opening to afford 1‐fluorovinyl vinyl ketones (i.e., Nazarov precursors). Treatment
由α,β-不饱和酮制得的甲硅烷基二烯醇醚经质子海绵催化的2,2-二氟-2-氟磺酰乙酸三甲基甲硅烷基以区域选择性方式生成二氟环丙烷化反应,生成1,1-二氟-2-甲硅烷氧基-2-乙烯基环丙烷丰产。依次将如此获得的环丙烷进行氟离子催化的开环反应,得到1-氟乙烯基乙烯基酮(即Nazarov前体)。与我的前体的处理3的Si + B(OTF)4 -区域选择性地促进了环化纳扎罗夫,速率和区域选择性其中被急剧由氟取代基,其因此促进了生物有为α-fluorocyclopentenone衍生物有效合成增强。