Regiospecific synthesis of 1,5-disubstituted-1H-pyrazoles containing differentiated 3,4-dicarboxylic acid esters via Suzuki coupling of the corresponding 5-trifluoromethane sulfonates
作者:Peter S. Dragovich、Thomas M. Bertolini、Benjamin K. Ayida、Lian-Sheng Li、Douglas E. Murphy、Frank Ruebsam、Zhongxiang Sun、Yuefen Zhou
DOI:10.1016/j.tet.2006.11.053
日期:2007.1
A general procedure is described for the regiospecific preparation of 1-substituted-5-hydroxy-1H-pyrazoles containing differentiated ester moieties at the 3- and 4-positions. This process involves the coupling of monosubstituted benzyl carbazates with various malonyl chlorides or acids, deprotection of the coupling products via catalytic hydrogenation, and subsequent derivatization of the resulting
描述了用于在3位和4位含有分化的酯部分的1-取代的5-羟基-1 H-吡唑的区域特异性制备的一般程序。该方法涉及单取代的苄基氨基甲酸酯与各种丙二酰氯或酸的偶合,通过催化氢化使偶合产物脱保护,然后用单烷基草酰氯将所得的酰肼衍生化。5-羟基-1 H-吡唑很容易转化为相应的三氟甲烷磺酸盐,它们通过钯介导的铃木与各种硼酸(芳基,杂芳基和烯基)的偶联,产率中等至优异(24-92%) 。存在于所得的1,5-二取代-1 H之一中的酯基通过选择性水解或转化为相应的二羧酸衍生物,然后进行选择性单酯化,进一步修饰-吡唑。