Iodination of aromatic and heteroaromatic compounds in the presence of iodine and hydrogen peroxide in water: A balance between atom economy and high yields.

Abstract

INTRODUCTION Recently we published a work involving the efficient and selective diiodination of phenols using I2 and H2O2 30% in water. 1 Afterwards, we decided to subject aromatic and heteroaromatic compounds to the same reaction conditions, performing a balance between the amounts of the reagents and the yields obtained, aiming to the formation of interesting iodinated molecules in high yields. RESULTS AND DISCUSSION We treated phenol (1a) with 1.5 equiv. of I2 and 3 equiv. of H2O2 30% in water at 50 o C for 24 h and obtained 2,4,6-triiodophenol (2a) in a moderate yield of 65% (Table 1, entry 1). In the attempt of increasing this yield, we used 2 equiv. of I2 and 4 equiv. of H2O2 30% producing the triiodinated phenol 2a in a yield of 83% (entry 2). The aromatic compound 1b and the heteroaromatic compound 1c were subjected to the reaction with 2 equiv. of I2 and 4 equiv. of H2O2 30% resulting in the triiodinated products 2b and 2c, respectively, in good yields (entries 3 and 4). The balance between amounts of the reagents and yields obtained was extended for reactions of diiodination (entries 6 to 9) and for reactions of monoiodination (entries 10 to 15). In general, diiodinated and monoiodinated aromatic and heteroaromatic compounds were produced in considerable yields. CONCLUSION A balance between amounts of the reagents and the yields obtained was carried out for the reaction of iodination of aromatic organic compounds using I2 and H2O2 30% in water at 50 o C and interesting iodinated molecules were produced in good yields. ACKNOWLEDGEMENTS We thank CNPq and FUNDECT for support. REFERENCES