3-Silylated furfurals, readily prepared in three steps from biomass-derived furfural and 5-methylfurfural, are converted into 3-silylated 2-furyl carbinols upon condensation with organomagnesium or organolithium reagents. The hydroxy unit of the carbinol adducts can be exploited to promote C3(sp2)–Si bond functionalization through intramolecular activation. Two approaches were contemplated for this purpose. Activation by alkoxides of the C3–SiEt3 or C3–SiMe2t-Bu bonds was ineffective. Conversely, treatment of the C3-benzyldimethylsilyl-appended derivatives with tetrabutylammonium fluoride led to cyclic siloxanes, which revealed to be competent donors for copper-catalyzed cross-coupling reactions, such as arylation reactions catalyzed by Pd2(dba)3/CuI, as well as allylation and methylation reactions catalyzed by CuI⋅PPh3. C3-Benzyldimethylsilyl-appended furfurals are thus introduced as versatile platforms, providing a modular access to 3-substituted 2-furyl carbinols from renewable feedstock.
3 硅烷化糠醛很容易通过三个步骤从生物质衍生的糠醛和 5-甲基糠醛中制备出来,在与有机镁或有机锂试剂缩合后转化为 3 硅烷化 2-糠醇。通过分子内活化作用,可利用这些烷醇加合物的羟基单元促进 C3(sp2)-Si 键官能化。为此考虑了两种方法。C3-SiEt3 或 C3-SiMe2t-Bu 键的烷氧基活化效果不佳。相反,用四丁基氟化铵处理 C3-苄基二甲基硅烷添加衍生物会产生环状硅氧烷,这些环状硅氧烷是铜催化的交叉偶联反应(如 Pd2(dba)3/CuI 催化的芳基化反应)以及 CuI⋅PPh3 催化的烯丙基化和甲基化反应的有效供体。因此,C3-苄基二甲基硅基添加的呋喃类化合物是一种多功能平台,为从可再生原料中获得 3-取代的 2-呋喃基甲醇提供了模块化途径。