AZA-PAYNE REARRANGEMENT OF ACTIVATED 2-AZIRIDINEMETHANOLS AND 2,3-EPOXY AMINES UNDER BASIC CONDITIONS

An aza-Payne rearrangement of activated 2-aziridinemethanols with t-BuOK, NaH, or KH at near 0 degrees C in common solvents such as THF, toluene, 1,2-dimethoxyethane, 1,4-dioxane, or a mixed solvent of THF-HMPA followed by quenching at -78 degrees C gives the corresponding epoxysulfonamides. Exposure of N-tosyl-(2S)-azetidinemethanol (36) and N-tosyl-(S)-prolinol (37) to NaH or KH in dichloromethane yielded only the respective dimeric compounds that resulted by joining 2 equiv of reactant through a methylene group. Reaction of N-tosyl-(2S,3S)-3-methyl-2-aziridinemethanol (9) and its (2R,3S)-isomer 23 with Gilman reagents (R(2)CuLi; R = Me and Bu) or ''higher order'' cuprates [R(2)Cu(CN)Li-2; R = Me and Bu] yielded the two expected aziridine ring-opening products. In sharp contrast, treatment of 9 and 23 with ''lower order'' cuprates afforded rearrangement-opened products. Thus, if the nucleophile is highly reactive, then the expected nucleophilic ring opening of the aziridine predominates. However, if the nucleophile is less reactive, then it becomes possible to cleave the resulting rearranged epoxide. Upon exposure of 2,3-epoxy amines to an equimolar mixture of t-BuOK-n-BuLi in a mixed solvent of THF and n-hexane at -78 degrees C, the equilibrium lies exclusively toward the hydroxy aziridine forming direction.