The aza-Payne rearrangement: a synthetically valuable equilibration

Abstract

An aza-Payne rearrangement of N-activated 2-aziridinemethanols, synthesized in an optically active form, with potassium tert-butoxide (Bu^tOK), potassium hydride (KH), or sodium hydride (NaH) at near 0 °C in common aprotic solvents such as tetrahydrofuran (THF), toluene, or a mixed solvent of THF–HMPA followed by quenching at low temperature gives the corresponding epoxy sulfonamides in high yields. The anionic reaction intermediates, generated by treatment of 2-aziridinemethanols with a base, react readily in a one-pot manner with a variety of nucleophiles such as organocopper reagents, thiols, and trimethylsilyl cyanide to yield the optically active corresponding functionalized 1,2-amino alcohols in good yields. Upon exposure of 2,3-epoxy amines to an equimolar mixture of Bu^tOK and BuLi (super base) in a mixed solvent of THF and n-hexane at –78 °C, the equilibrium lies exclusively toward the hydroxyaziridine forming direction.