‘One-pot’ synthesis of 4-substituted 1,5-diaryl-1H-pyrazole-3-carboxylates via lithium tert-butoxide-mediated sterically hindered Claisen condensation and Knorr reaction
作者:Jian-An Jiang、Wei-Bin Huang、Jiao-Jiao Zhai、Hong-Wei Liu、Qi Cai、Liu-Xin Xu、Wei Wang、Ya-Fei Ji
DOI:10.1016/j.tet.2012.11.012
日期:2013.1
A concise ‘one-pot’ synthesis of a variety of 4-substituted 1,5-diaryl-1H-pyrazole-3-carboxylates has been developed in moderate to good yields with excellent regioselectivity. Less cost lithium tert-butoxide has been identified as a base for sterically hindered Claisen condensation to efficiently generate the labile 3-substituted 4-aryl-2,4-diketoesters. Furthermore, extensive studies lead to a ‘one-pot’
已经开发了一种简单的“一锅法”合成的各种4-取代的1,5-二芳基-1 H-吡唑-3-羧酸酯,具有中等到良好的产率,具有出色的区域选择性。成本较低的叔丁醇锂已被确定为空间受阻克莱森(Claisen)缩合反应的碱,可有效生成不稳定的3-取代的4-芳基-2,4-二酮酸酯。此外,广泛的研究通过克莱森缩合反应和克诺尔反应相结合而合成“有价值的4-取代的1,5-二芳基-1 H-吡唑-3-羧酸酯”的“一锅法”工艺。