Iron-Catalyzed Synthesis of 2H-Imidazoles from Oxime Acetates and Vinyl Azides under Redox-Neutral Conditions

Abstract

A novel and versatile method for the synthesis of 2H-imidazoles via iron-catalyzed [3 + 2] annulation from readily available oxime acetates with vinyl azides has been developed. This denitrogenative process involved N-O/N-N bond cleavages and two C-N bond formations to furnish 2,4-substituted 2H-imidazoles. This protocol was performed under mild reaction conditions and needed no additives or ligands. Furthermore, this is a green reaction involving oxime acetate as internal oxidant, acetic acid, and nitrogen as byproducts.

Synthesis of β-Sulfonyl Enamines via Iodine-Catalyzed Reaction between Vinyl Azides and Sodium Arylsulfinates

“…The method does not need to use metal catalyst, and has the advantages of simple conditions, short reaction time and wide substrate application range. Keywords iodine catalysis; vinyl azide; free radical addition; sulfonyl enamine 乙烯基叠氮化合物 [1][2][3] 是同时具有双键和叠氮基团 的分子, 该类分子由 Forster 和 Newman [4] 首次提出并报 道, 到现在已经有近一百年的历史 [5][6] . 其拥有单独的烯 烃或叠氮基结构所没有的独特性质, 它可以作为亲电试 剂 [7][8] 、亲核试剂 [9][10][11][12][13] 或自由基受体 [14][15][16][17][18][19] 等, 同时能够通 过多种反应途径生成各类高反应活性的中间体 [20] , 因 此这类化合物在有机合成方面具有非常重要的作用.…”

α-Substituted vinyl azides: an emerging functionalized alkene

“…49 The azirine arising from the decomposition of the vinyl azide undergoes nucleophilic attack by benzylamine at the 2-position to yield imine 39, which in turn reacts with the imine generated in situ by I 2 /TBHT-mediated oxidation of benzylamine, delivering An iron(II)-catalyzed [3+2] annulation of oxime acetates 43 and vinyl azides has been developed for the synthesis of a wide range of 2,2,5-trisubstituted 2H-imidazoles 46 (Scheme 14). 52 Imine anion 44, generated from 43 by Fe-mediated reduction, coupled with the 2H-azirine by C2-N ring opening to give intermediate 45. This underwent cyclization / electron transfer to Fe(III), which on deprotonation afforded product 46.…”

Zn-Catalyzed Beckmann Rearrangement Reaction

“…以 1a (10 g, 50.7 mmol)作底物, 氟硼酸锌水合物(1.7 g, 5.0 mmol, 10 mol%)为催化剂, 乙腈(100 mL)作为溶剂, 100 ℃回流反 与已报道的锌催化酮与盐酸羟胺的一步法反应体 系相比 [20,22] , 本体系反应条件较温和、 催化剂廉价易得、 产物收率高, 为酮与盐酸羟胺的一步法贝克曼重排反应 提供了一种"锌"方法. [23] 、 1b [25] 、 1c [25] 、 1d [26] 、1e [23] 、1f [23] 、1g [23] 、1h [23] 、1i [23] [28] 、2b [25] 、2c [25] 、2e [29] 、2f [30] 、2g [30] 、2h [30] 、 2i [31] 、2j [32] 均与文献报道中核磁数据相符. …”