钴催化的高效贝克曼重排反应

利用廉价易得的氟硼酸钴水合物, 在温和、 无添加剂的空气条件下, 高效催化酮肟衍生物的贝克曼重排反应, 底物的普适性和官能团的兼容性均较理想, 产物收率最高达97%. 基于该高活性的氟硼酸钴水合物, 实现了10 g级二苯甲酮肟的贝克曼重排反应, 收率为71%. 同时, 也实现了钴催化酮类衍生物和盐酸羟胺的一步法贝克曼重排反应, 产物最高收率为94%, 反应体系中无溶剂及添加剂, 反应体系的原子经济性和底物普适性较好.

A Highly Efficient Co-catalytic Beckmann Rearrangement Reaction†

Beckmann rearrangement reaction represents one of the most significant reactions in organic synthesis, and plays a very important role in the field of synthetic chemistry. The traditional Beckmann rearrangement reactions generally require high temperature and strong acids, and suffer from harsh conditions and serious environmental pollution. In this work, based on the efficient and commercial available cobalt tetrafluoroborate hexahydrate, the catalyst systems capable of highly efficient catalytic Beckmann rearrangement of ketoxime derivatives were developed, providing the amides with broad functional-group compatibility and high yields(up to 97%). With the active Co-catalyst in hands, the catalytic system also successfully conducted the transformantion on a 10 gram-grade scale, gaving the desirable product in 71% yield. Moreover, the Co-catalyzed Beckmann rearrangement reaction was extended to a one-pot protocol using ketone and hydroxylamine hydrochloride as reactive materials, offering the yield of products up to 94%. The novel system proceeded with additives and solvent free, and showed high atom-economy and good functional-group tolerance.