作者:Yuka Takahashi、Hirotaka Ikeda、Yuki Kanase、Kosho Makino、Hidetsugu Tabata、Tetsuta Oshitari、Satoshi Inagaki、Yuko Otani、Hideaki Natsugari、Hideyo Takahashi、Tomohiko Ohwada
DOI:10.1021/acs.joc.7b01759
日期:2017.11.3
that in the case of the E-conformation of N-acyl pyrazoles, such electron repulsion is small because of distance. The interbond energy calculations suggested that the Z-conformer is involved in strong vicinal σ–σ repulsion along the amide linkage between the σN1N2 and σC1C2 orbitals in the anti-periplanar arrangement and between the σN1C5 and σC1C2 orbitals in the syn-periplanar arrangement, which lead
检查了N-酰基唑(咪唑,吡唑和三唑)的构象性质。所述Ñ -2',4',6'-三氯唑类是在甲醇中在室温下稳定,观察7天中的5%三氟乙酸或5%三乙胺在CDCl存在没有水解产物3。高稳定性可以通过由苯甲酰基中的邻位取代基引起的位阻引起的双键酰胺特性来解释。虽然在N-酰基吡唑/三唑中观察到特定的E-酰胺优先性,但咪唑的酰胺产生E和Z的混合物。其中一个可以想到的想法合理化此构象偏好可以是在吡唑-2-氮(N两套孤对电子之间的排斥相互作用Ñ)和羰基的氧原子(N ø在)Ž的-conformation Ñ酰基吡唑/三唑。然而,对轨道相互作用的分析表明,在N-酰基吡唑的E-构象的情况下,由于距离,这种电子排斥力很小。的施工Interbond能量计算建议ž -conformer沿着σ之间的酰胺键参与强连位σ-σ斥力N1N2和σ C1C2轨道在抗-periplanar布置和σ之间N1C5和σ C1C2轨道在顺式-