The effect of the nitrogen non-bonding electron pair on the NMR and X-ray in 1,3-diazaheterocycles
作者:Cesar Garcías-Morales、Selene H. Martínez-Salas、Armando Ariza-Castolo
DOI:10.1016/j.tetlet.2012.04.077
日期:2012.6
The effect of the nitrogen nonbonding electron pair on the 1JC,H values of 1,3-diazaheterocycles was analyzed and compared to 1,5-diazabiciclo[3.2.1]octanes, which have a restricted conformation. The 1JC,H values were measured by observing the 13C satellites in the 1H NMR spectra and then determining the 1H-coupled 13C NMR spectra. The 1JC,H values are 10 Hz larger when the α-hydrogen is synperiplanar
分析了氮非键电子对对1,3-二氮杂杂环的1 J C,H值的影响,并将其与1,5-二氮杂双[3.2.1]辛烷具有受限的构象进行了比较。的1 Ĵ C,H通过观察测定值13个在C卫星1 1 H NMR谱,然后确定所述1 H-耦合13 C NMR光谱。的1 Ĵ C,H的值是10赫兹时较大的α氢是synperiplanar而非antiperiplanar到氮上,其用作的轨道的实验证据的非键电子对Ñ Ñ →σ∗ C,H ap相互作用。此外,还讨论了由氮孤对与赤道氢的反键轨道(β位)相互作用产生的同分异构效应(n N →σ ∗ C(β),H eq)。