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建立了一种简单有效的合成功能化烯胺的新方法.在有机小分子硫脲的催化下(50 mol%),在混合溶剂中[CH2Cl2/DMF=1∶1(V/V)],室温下各种α,β-邻位氨基溴的酮和α,β-邻位氨基溴的酯均能几乎定量的转变成相应的α,β-脱氢氨类化合物(收率90%～99%).硫脲催化邻位氨基溴转变成α,β-脱氢氨类化合物的新方法,具有反应条件温和、操作简便、收率高、催化剂廉价易得等特点.全文共考察了32种不同结构α,β-邻位氨基溴的酮和α,β-邻位氨基溴的酯反应情况,证明该方法具有广泛的适应性.实验中发现,α,β-邻位氨基溴的酮和α,β-邻位氨基溴的酯在发生消除反应时,要经过一个形成氮丙啶的中间过程,再由氮丙啶的开环反应形成最终产物(α,β-脱氢氨类化合物).因此不论反应底物为α-氨基-β-溴结构还是α-溴-β-氨基结构,通过分子内的亲核取代反应所形成的氮丙啶结构单元具有相似的立体结构,而氮丙啶的开环具有区域专一性,因此所得到的最终产物也具有区域专一性(烯键上的氨基均处在羰基的α-位).所提出的硫脲催化邻位氨基溴转变成α,β-脱氢氨的可能机理,很好地解释了该反应的区域专一性.所有的产物结构均经过了1H NMR,13C NMR及高分辨质谱的确证.
A simple and effective new method for the synthesis of functionalized enamines was established. [CH2Cl2 / DMF = 1: 1 (V / V)] in a mixed solvent under the catalysis of small organic thiourea (50 mol% At room temperature, the ketones of various α, β-ortho-amino bromides and the α, β-ortho-amino bromides were almost quantitatively converted into the corresponding α, β-dehydroamino compounds (yield 90% ~ 99 %) .A new method of thiourea to catalyze the conversion of ortho-amino bromine to α, β-dehydroamino compounds is characterized by its mild reaction conditions, easy operation, high yield and low cost and availability of catalyst.This dissertation investigated 32 species The esterification reaction of ketones with α, β-ortho-position with different structures and α, β-ortho-amino bromides showed that this method has a wide range of adaptability. It was found that the ketone and The α, β-ortho-aminobromide ester undergoes an intermediate reaction to form an aziridine in the elimination reaction, and then undergoes the ring-opening reaction of aziridine to form the final product (α, β-dehydroamino compound) Thus, the aziridine structure units formed by the intramolecular nucleophilic substitution reaction have the similarities whether the reaction substrate is an α-amino-β-bromine structure or an α-bromo-β-amino structure Body structure, and the ring opening of aziridine is regio-specific so the resulting final product is also region specific (the ethylenic amino groups are all in the alpha position of the carbonyl group.) The proposed thiourea catalysis The possible mechanism for the conversion of the adjacent amino bromide to α, β-dehydroammonium is well explained by the region specificity of the reaction, all of which have been confirmed by 1H NMR, 13C NMR and high resolution mass spectrometry.