Kizhner Research Center, National Research Tomsk Polytechnic University, 30 Lenin Ave., 634050 Tomsk, Russia.
Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3 Lavrentiev Ave., 630090 Novosibirsk, Russia.
Molecules. 2021 Jan 14;26(2):413. doi: 10.3390/molecules26020413.
Carboxylation of bis(pyrazol-1-yl)alkanes by oxalyl chloride was studied. It was found that 4,4'-dicarboxylic derivatives of substrates with electron-donating methyl groups and short linkers (from one to three methylene groups) can be prepared using this method. Longer linkers lead to significantly lower product yields, which is probably due to instability of the intermediate acid chlorides that are initially formed in the reaction with oxalyl chloride. Thus, bis(pyrazol-1-yl)methane gave only monocarboxylic derivative even with a large excess of oxalyl chloride and prolonged reaction duration. An alternative approach involves the reaction of ethyl 4-pyrazolecarboxylates with dibromoalkanes in a superbasic medium (potassium hydroxide-dimethyl sulfoxide) and is suitable for the preparation of bis(4-carboxypyrazol-1-yl)alkanes with both short and long linkers independent of substitution in positions 3 and 5 of pyrazole rings. The obtained dicarboxylic acids are interesting as potential building blocks for metal-organic frameworks.
研究了双（吡唑-1-基）烷与草酰氯的羧化反应。发现用这种方法可以制备具有给电子甲基和短链接体（一至三个亚甲基）的底物的 4,4'- 二羧酸衍生物。较长的链接体导致产率显著降低，这可能是由于与草酰氯反应最初形成的中间酸氯不稳定。因此，即使使用过量的草酰氯和延长的反应时间，双（吡唑-1-基）甲烷也只得到单羧酸衍生物。另一种方法涉及在强碱介质（氢氧化钾-二甲基亚砜）中用乙基 4-吡唑羧酸酯与二溴烷反应，适用于制备具有短和长链接体的双（4-羧基吡唑-1-基）烷，与吡唑环的 3 和 5 位的取代无关。所得到的二羧酸作为潜在的金属有机骨架的构建块很有趣。
