approach for the regiocontrolled preparation of pyrazoles bearing substituents on all three carbon atoms is described. Central to this method is the use of a switchable metal-directing group (MDG) to enable sequential direct lithiation of the 3- and 5-positions of the pyrazole ring. Pyrazole boronic esters obtained from these lithiated intermediates can undergo efficient Suzuki cross-coupling under
描述了用于在区域上可控制地制备在所有三个
碳原子上均带有取代基的
吡唑的模块化方法。该方法的核心是使用可转换的
金属导向基团(MDG),以实现
吡唑环的3位和5位的顺序直接
锂化。从这些
锂化
中间体获得的
吡唑硼酸酯可以在开发的非
水条件下进行有效的Suzuki交叉偶联,从而将不良的蛋白
水解性
脱硼降至最低。4-位的卤代提供了在剩余的
碳原子上进行取代的手段。