Tunable Regioselective Allylic Alkylation/Iodination of Imidazoheterocycles in Water
Suvam Paul, Tathagata Choudhuri, Sourav Das, Ramendra Pratap, Avik Kumar Bagdi*
*Department of Chemistry, University of Kalyani, Kalyani 741235, India,
Email: avikchem18
klyuniv.ac.in
S. Paul, T. Choudhuri, S. Das, R. Pratap, A. K. Bagdi, J. Org. Chem., 2024, 89, 1492-1504.
DOI: 10.1021/acs.joc.3c02091
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Abstract
The switchable roles of allylic alcohol and molecular iodine as reagents and catalysts enable regioselective allylic alkylation and iodination of imidazoheterocycles. While iodine catalyzes the allylation of a library of imidazoheterocycles and other electron-rich heterocycles, a mixture of allylic alcohol and I2 is also beneficial for the iodination of imidazoheterocycles at room temperature.
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proposed mechanism
Details
The article discusses a novel methodology for the tunable regioselective allylic alkylation and iodination of imidazoheterocycles in water using a combination of allylic alcohol and molecular iodine (I2). The study demonstrates the dual role of allylic alcohol and I2, where allylic alcohol acts as a reagent and I2 as a catalyst for allylic alkylation, and vice versa for iodination. The methodology is efficient for a variety of imidazoheterocycles and other electron-rich heterocycles, achieving high yields. The use of water as a solvent aligns with green chemistry principles, making the process environmentally friendly. The research highlights the importance of I2 in activating allylic alcohol through halogen bonding, as confirmed by mechanistic and NMR studies. The optimized conditions for allylic alkylation involve using 10 mol % I2 in water under reflux, while iodination is effectively carried out at room temperature with catalytic amounts of allylic alcohol. The study also explores the substrate scope, demonstrating the methodology's versatility and efficiency. This approach offers a sustainable and scalable solution for the functionalization of heterocycles, with potential applications in pharmaceuticals and materials science.
Key Words
imidazo[1,2-a]pyridines, iodination
ID: J42-Y2024
