水相介质中碳酸钾/硫脲联合促进邻位氨基溴转变成α,β-脱氢氨的研究

建立了在水相介质中, 在碳酸钾/硫脲联合促进下, 具有邻位氨基溴的酯和邻位氨基溴的酮在室温下发生溴化氢消除反应, 高收率地制备α,β-脱氢氨(功能化烯胺)的新方法. 共考察了23种不同结构α,β-邻位氨基溴的酯和α,β-邻位氨基溴的酮的反应情况, 证明该方法具有广泛的适应性. 实验发现, 无论底物为α-氨基-β-溴结构还是α-溴-β-氨基结构, 反应过程中都要经过一个氮丙啶过程, 而氮丙啶的开环是区域专一的, 因此产物具有区域专一性(烯键上的氨基均处在羰基的α-位). 所有产物的结构均经过核磁共振波谱及高分辩率质谱确证. 克量级放大实验结果表明, 该方法具有一定的用于工业化生产的可行性.

α,β-Vicinal Bromoamine Compounds Converted into α,β-Dehydroamino Derivatives Promoted by Combination of Potassium Carbonate and Thiouea in Water†

In order to promote further development of green chemistry, an easy and efficient new method for the synthesis of fuctionalized enamines from α,β-vicinal bromoamine compounds promoted by combination of potassium carbonate and thiouea in water at room temperature was developed, and the nearly quantitative yields of much products were obtained(up to 99%). 23 structurally different substrates were investigated. The results indicate that the protocol could tolerate various vicinal bromoamine compounds including α,β-vicinal bromoamine esters and ketones. During the elimination process of HBr from vicinal bromoamine compounds, the corresponding intermediate aziridines must be formed. Herein, no matter the substrate was α-amino-β-bromo or α-bromo-β-amino in structurally, the aziridines skeleton in structurally was similar to each other formed from the intramolecular nucleophilic replacement reaction fashion. Because of ring-open reaction of the aziridines have full regiospecificity, the obtained final products are full regiospecificity, too. The structures of all products were confirmed by ¹H NMR, ¹³C NMR and HRMS analysis. When the gram level substrate was tested with this protocol, the nearly quantitative yield of the product was obtained, too. This result indicated that the new method could be possible applied in the industrialization.