Active Fluoro-intermediate for Fluorinated Heterocycles

制备了三氟乙酰亚氨基金属(Li，Zn，Pd)和碲化物作为三氟乙酰亚氨基碳负离子和相应自由基的前驱体，并用于合成含氟氮杂环化合物。碲化物的光解导致C-Te键的均裂断裂，生成所需的三氟乙酰亚氨基，该自由基经历分子内环化。反应生成3-氧基-2-三氟甲基吲哚(3)。同时，钯催化的三氟乙酰亚胺基碘的碳烷氧基化以及随后的烷基化和氢化提供了各种含氟氨基酸。碘与锂的交换反应生成了在-65℃以下稳定的烷基化的乙酰亚胺基锂。用这些新开发的方法合成了一些有趣的杂环(2)-(4)。

Trifluoroacetimidoyl metals (Li, Zn, Pd) and telluride have been prepared as precursors for the trifluoroacetimidoyl carbanion and the corresponding radicals and have been employed for the synthesis of fluorinated nitrogen heterocycles. Photolysis of the telluride leads to homolytic cleavage of the C-Te bond to generate the desired trifluoroacetimidoyl radical which undergoes intramolecular cyclization. The reaction provided 3-oxy-2-trifluoro methyl indols (3). Meanwhile, palladium catalyzed carboalkoxylation of the trifluoroacetimidoyl iodides and subsequent alkylation and hydrogenation provided various kinds of fluorinated -aminoacids. Lithium-iodine exhange reaction of the iodides generated the acetimidoyl lithium which is stable below -65 C and alkylated. By these newly developed methods, some interesting heterocycles (2) - (4) have been synthesized.