A range of C-4 and C-5 acylated 1-benzyloxypyrazoles (7a–e) and (4) have been prepared via Pd(0) catalysed cross-coupling between acid chlorides and 1-benzyloxy-4-(tributylstannyl)pyrazole (8) or 1-benzyloxypyrazol-5-ylzinc chloride. 3-Acylated 2-(4-methoxybenzyl)-2H-pyrazole 1-oxides (15a–f) were formed by reaction between
the 3-magnesiated 2H-pyrazole 1-oxide (14) and acid chlorides. The benzyl group of 4 and 7a and the 4-methoxybenzyl (PMB) group of 15a were removed by treatment with conc. HCl or TFA in the presence of water, furnishing the corresponding C-acylated 1-hydroxypyrazoles.
通过
钯(0)催化酸
氯化物与 1-苄氧基-4-(三
丁基锡烷基)
吡唑(8)或 1-苄氧基
吡唑-5-基
氯化锌之间的交叉偶联,制备了一系列 C-4 和 C-5 乙酰化 1-苄氧基
吡唑(7a-e)和(4)。通过 3-
镁化 2H-
吡唑 1-氧化物(14)与酸
氯化物反应,生成 3-酰化 2-(4-甲氧基苄基)-2H-
吡唑 1-氧化物(15a-f)。4 和 7a 的苄基以及 15a 的 4-甲氧基苄基(PMB)通过在有
水的情况下用浓
盐酸或反式
脂肪酸处理去除,得到相应的 C-酰化的 1-羟基
吡唑。