Cyanuric Chloride as a Mild and Active Beckmann Rearrangement Catalyst

Abstract

The first general organocatalytic Beckmann rearrangement of ketoximes into amides has been realized by the catalytic use of cyanuric chloride. Furthermore, acids such as HCl and ZnCl2 are effective as cocatalysts with cyanuric chloride. For example, azacyclotridecan-2-one, which is synthetically useful as a starting material for nylon-12, was prepared in quantitative yield by the Beckmann rearrangement of cyclododecanone oxime (100 mmol scale) catalyzed by cyanuric chloride (0.5 mol %) and ZnCl2 (1 mol %).

Organocatalyzed Beckmann rearrangement of cyclohexanone oxime by trifluoroacetic acid in aprotic solvent

“…Respect to other organocatalyzed Beckmann rearrangements this reaction is a step forward because of the facile separation of the catalyst from the reaction mixture [15,16,23]. The reaction is also environmental friendly due to the almost complete reuse of the catalyst and of the solvent, without the inconvenience of undesired byproducts.…”

“…A catalytic process has been developed by using TCT in the presence of ZnCl 2 as Lewis acid at 353-373 K in CH 3 CN. In such a system, however, substrates like cycloalkanone oximes do not react [16].…”

Scaffold Preparation and Parallel Synthesis of Arrays of 5,6,7,8‐Tetrahydropyrrolo‐azepinones in the Solution Phase

“…[16] Beckmann rearrangement of product 11 was attempted under different reaction conditions. Mildly acidic conditions did not give any results, [17] whereas the starting material (TLC analysis) totally disappeared on addition of 11 to polyphosphoric acid (PPA) at 120°C and by stirring the mixture at this temperature for 15 min. Pyrrolo-azepinecarboxylic acid 12 was obtained in high conversion (all the starting material was consumed after 15 min), but in poor isolated yields.…”

Zn-Catalyzed Beckmann Rearrangement Reaction

“…迄今, 液相贝克曼重排反应普遍具有条件温和、操 作简便、产物选择性好等优势而具有广阔的应用前景, 成为科学界的重点研究目标 [2] . 近年来, 三氯化铝 [3] 、三 氟化硼 [4] 等强路易斯酸, 卤代烃 [5] 、磷酞氯 [6] 、酰氯 [7] 等 有机小分子化合物, 临界水 [8] 、 离子液体 [9] 被陆续应用于 贝克曼重排反应研究. 然而上述方法均存在一定局限: 强路易斯酸毒性和腐蚀性很大, 不利于实际操作且会造 成一定的环境污染; 有机小分子催化剂中一般需要加入 过量添加剂才能使重排反应顺利进行, 原子经济性差; 临界水或离子液体溶剂或催化剂普遍价格昂贵, 产物难 以分离, 不利于实际生产应用.…”