Chiral triaryl phosphates promote the enantioselective iodolactonization of 4-substituted 4-pentenoic acids to give the corresponding iodolactones in high yields with high enantioselectivity. N-Chlorophthalimide (NCP) is employed as a Lewis acidic activator and oxidant of I2 for the present iodolactonization. In combination with 1.5 equivalents of NCP, only 0.5 equivalents of I2 are sufficient to generate the iodinating reagent.
Keywords: asymmetric catalysis; cyclization; iodine; lactones; organocatalysis.
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