Development of new synthetic methods based on in-situ-generated hypervalent organoiodine reagents.

Abstract

HYpervalent organoiodine reagents have attracted much interest in the last twenty years due to their powerful oxidizing capabilities and low toxicity. Besides the alcohol oxidation, many other oxidative transformations have been established using hypervalent iodine reagents and highly toxic solvents. These newly developed oxidative transformations make use of more environmentally friendly conditions to prepare important pharmaceutical and industrial products from some simple, inexpensive starting materials. The preparation of terminally-oidinated esters uses elemental iodine and hydrogen peroxide as a co-oxidant in an alcoholic solvent. Elemental iodine is a nontoxic, abundant resource that leaves no harmful by-products after the reaction completion, while hydrogen peroxide disproportionates into water and singlet molecular oxygen. Terminally-iodinated esters can be used in a variety of subsequent reactions such as nucleophilic substitutions and carbonyl additions/substitutions. a,B-Unsatturated ketones and a-trifluoroacetylated ketones are derived from cyclic and ayclic and acyclic ketones and hypervalent iodine reagents generated in-situ from iodobenzene and potassium peroxymonosulfate (OXONE). OXONE, which is slightly soluble in most organic solvents is directly converted to potassium sulfate which is nontoxic and can be filtered from the reaction mixture preceeding the reaction workup. Finally, variously-substituted quinone derivatives are generated from benzamide starting materials using a polymeric iodosylbenzene sulfate generated in-situ that has good solubility in organic solvents. Quinone derivatives are especially important in natural products and can be further manipulated due to their highly functionalized nature. These new reactions may be used in the future in preparing important industrial and pharmaceutical products due to their simple yet environmentally safe conditions.