Highly regioselective and practical synthesis of 1-acyl-5-hydroxypyrazolines and 1-acyl pyrazoles from 1,2-allenic ketones and hydrazides
作者:Shenghai Guo、Jiliang Wang、Dongqiang Guo、Xinying Zhang、Xuesen Fan
DOI:10.1016/j.tet.2012.07.046
日期:2012.9
A mild and highly regioselective synthesis of 1-acyl-5-hydroxypyrazolines has been achieved through the condensation of 1,2-allenic ketones with hydrazides in the absence of any catalyst. Moreover, the obtained 1-acyl-5-hydroxypyrazolines can be easily transformed into 1-acyl pyrazoles under the promotion of BF3·Et2O. It was also found that 1-acyl pyrazoles can be produced directly from allenic ketones
在不存在任何催化剂的情况下,通过1,2-炔酮与酰肼的缩合,已实现了1-酰基-5-羟基吡唑啉的温和且高度区域选择性的合成。此外,在BF 3 ·Et 2 O的促进下,所获得的1-酰基-5-羟基吡唑啉可以容易地转化为1-酰基吡唑。还发现1-酰基吡唑可以直接由烯丙基酮和酰肼通过一锅法。