Abstract:
A convenient and general synthesis of various 4-substituted-3-iodocoumarins and 4,5-disubstituted-3-iodobutenolides is described via an exclusive 6-endo-dig-iodocyclization of 3-ethoxy-1-(2-alkoxyphenyl)-1-ols and 5-endo-dig-iodocyclization of 1-alkoxy-4-ethoxy-3-yn-1,2-diols respectively. The reaction is carried out in very mild conditions using I2 in CH2Cl2 or toluene at room temperature. Oxygen in OMe and OMOM groups were used as efficient nucleophiles for this intramolecular cyclization to obtain the products in good to excellent yields.
