Synthesis of N-heterocycles, beta-amino acids, and allyl amines via aza-payne mediated reaction of ylides and hydroxy aziridines
申请人:Borhan Babak
公开号:US20090012120A1
公开(公告)日:2009-01-08
An ylide-based aza-Payne rearrangement of 2,3-aziridin-
1
-ols leads to an efficient process for the preparation of pyrrolidines. The aza-Payne rearrangement under the basic reaction conditions favors the formation of epoxy amines. Subsequent nucleophilic attack of the epoxide by the ylide yields a bis-anion, which upon a 5-exo-tet ring closure yields the desired pyrrolidine, thus completing the relay of the 3-membered the 5-membered nitrogen containing ring system. This process takes place with complete transfer of stereochemical fidelity, and can be applied to sterically hindered aziridinols.
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.
Diastereomerically and Enantiomerically Pure 2,3-Disubstituted Pyrrolidines from 2,3-Aziridin-1-ols Using a Sulfoxonium Ylide: A One-Carbon Homologative Relay Ring Expansion
作者:Jennifer M. Schomaker、Somnath Bhattacharjee、Jun Yan、Babak Borhan
DOI:10.1021/ja065833p
日期:2007.2.1
An ylide-based aza-Payne rearrangement of 2,3-aziridin-1-ols leads to an efficient process for the preparation of pyrrolidines. The aza-Payne rearrangement under basic reaction conditions favors the formation of epoxy amines. Subsequent nucleophilic attack of the epoxide by the ylide yields a bis-anion, which upon a 5-exo-tet ring-closure yields the desired pyrrolidine, thus completing the relay of