2-Chloro-1-methylpyridinium iodide, referred to as CMPI, is a commonly used condensation reagent. Its English name is 2-Chloro-1-methylpyridinium Iodide, and its molecular formula is C6H7ClIN. No. 14338-32-0, light yellow solid at room temperature, usually used in dichloromethane, tetrahydrofuran and acetonitrile. It is very stable at room temperature and stored in a cool and dry place.
When the carboxylic acid is activated, the chlorine at the 2-position of CMPI is subjected to nucleophilic attack by the carboxylic acid to generate 2-hydroxypyridine carboxylate, and its 2-position is then subjected to nucleophilic attack by the hydroxyl group to obtain the target ester (Formula 2). One equivalent of hydrogen chloride and one equivalent of hydrogen iodide are produced in the reaction, so two equivalents of alkali need to be consumed, and commonly used alkalis are Et3N, KHCO3 and K2CO3.
CMPI is also very high in selectivity and yield when closing rings to generate lactones, but generally only works well within seven-membered rings (Formula 3) and outside thirteen-membered rings (Formula 4), and works well in eight- to twelve-membered rings. Its dimer is produced when ringing. It is also very effective in the formation of bridged ring lactones.
CMPI is not as efficient as lactonization in promoting lactamization (Equation 5), but it is also moderately high. CMPI can also cause the intramolecular condensation reaction of aldehyde acids to generate chiral bridged lactone products (Formula 6). Carboxylic acids activated by CMPI can form β-lactams with imines (Equation 7).
When producing and preparing CMPI, its 2-position chlorine will be attacked by iodide ions to generate impurity 2-iodo-1-picoline chloride salt (Formula 8). The CMPI produced by our company can control this impurity at 1%. Within the industry-leading level.
Since its establishment, Highfine has focused on the R&D and production of products in the field of condensing agents and protective agents formed by characteristic amide bonds, and has high quality and large quantity in stock. Customers are welcome to purchase. For details, please visit Highfine's official website www.highfine.com.
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