理性設計2-取代DMAP-N-氧化物作為醯基轉移催化劑
作者:
小柯機器人發布時間:2020/11/2 16:38:07
近日,河南師範大學Hai-Ming Guo及其研究組理性設計2-取代DMAP-N-氧化物作為醯基轉移催化劑,用於動態動力學拆分吖內酯。 相關論文於2020年10月29日發表於國際頂尖學術期刊《美國化學會志》上。
研究人員展示了一個新的概念,手性轉換2-取代DMAP到其DMAP-N-氧化物可以顯著提高催化活性,同時仍可作為醯基轉移催化劑。研究人員理性設計併合成了一種來自L-酪醯胺的新型手性2-取代DMAP-N-氧化物,將其用於動態動力學拆分吖內酯。使用簡單的甲醇作為親核試劑,可以以高產率(高達98%的產率)和對映選擇性(高達96%的ee)產生多種L-胺基酸衍生物。此外,α-氘取代L-苯丙氨酸衍生物也能獲得。
實驗和DFT計算表明,在2-取代的DMAP-N-氧化物中,氧原子充當親核位點,而N–H鍵充當H鍵供體。反應的高對映選擇性受空間因素控制,苯甲酸的加入通過參與氫鍵橋的構建而降低了活化能。理論化學研究表明,只有充分考慮手性催化劑的攻擊方向才能得到正確的計算結果。這項工作為利用吡啶環C2位置和發展手性2-取代DMAP-N-氧化物作為高效醯基轉移催化劑鋪平了道路。
附:英文原文
Title: Rational Design of 2-Substituted DMAP-N-oxides as Acyl Transfer Catalysts: Dynamic Kinetic Resolution of Azlactones
Author: Ming-Sheng Xie, Bin Huang, Ning Li, Yin Tian, Xiao-Xia Wu, Yun Deng, Gui-Rong Qu, Hai-Ming Guo
Issue&Volume: October 29, 2020
Abstract: A novel concept that conversion of chiral 2-substituted DMAP into its DMAP-N-oxide could significantly enhance the catalytic activity and still be used as an acyl transfer catalyst is presented. A new type of chiral 2-substituted DMAP-N-oxides, derived from l-prolinamides, has been rationally designed, facilely synthesized, and applied in the dynamic kinetic resolution of azlactones. Using simple MeOH as the nucleophile, various l-amino acid derivatives were produced in high yields (up to 98% yield) and enantioselectivities (up to 96% ee). Furthermore, α-deuterium labeled l-phenylalanine derivative was also obtained. Experiments and DFT calculations revealed that in 2-substituted DMAP-N-oxide, the oxygen atom acted as the nucleophilic site and the N–H bond functioned as the H-bond donor. High enantioselectivity of the reaction was governed by steric factors, and the addition of benzoic acid reduced the activation energy by participating in the construction of a H-bond bridge. The theoretical chemical study indicated that only when attack directions of the chiral catalyst were fully considered could the correct calculation results be obtained. This work paves the way for the utilization of the C2 position of the pyridine ring and the development of chiral 2-substituted DMAP-N-oxides as efficient acyl transfer catalysts.
DOI: 10.1021/jacs.0c09075
Source: https://pubs.acs.org/doi/10.1021/jacs.0c09075