Developments of new methods of NMR for stereochemistry of complicated chain structure compound s

为了观察远距离JCH耦合和JHH耦合，我们开发了选择性j分辨HMBC、选择性cosy - j分辨HMBC和选择性j分辨hmqc。远距离碳氢偶联（JC-H）的测定在天然产物的立体化学研究中越来越重要。j -分辨HMBC-1方法具有较高的灵敏度，是实现这一目的的首选方法。然而，由于H-H耦合和远距离JC-H，交叉峰的形状变得复杂，导致复杂自旋系统的分析困难。为了克服这些与J-resolved HMBC-1相关的问题，我们开发了一种新的技术，选择性J-resolved HMBC。新方法将质子-质子解耦到j -分辨的HMBC-1中，可以抑制JH-H，并且只观察到具有短T2的复杂分子的远程C-H偶联。选择性COSY-J-resolved HMBC我们提出一个改进的版本，命名为选择性COSY-J-resolved HMBC。该方法提高了j -分辨HMBC或选择性j -分辨HMBC中甲基连接的甲基质子信号的交叉峰灵敏度，并能确定其长范围的JCH耦合。j -分辨HMBC或选择性j -分辨HMBC是通过j -缩放脉冲序列到HMBC来观察远距离JCH耦合。将该方法应用于模型化合物波霉素和单唑霉素的测定，证明了该方法可用于复杂分子JC H的测定。H-H - J偶联常数的分析对天然有机化合物的相对立体化学研究具有重要意义。重叠质子或强耦合质子使H-H - J耦合常数的分析变得困难。这个问题可以通过利用一个与13C相连的质子来解决。在强耦合的HA和HB自旋体系中，HA与13C相连，HB与12C相连构成周耦合质子体系，导致HA和HB之间通过CA-HA j偶联传播的化学位移差异较大。因此，通过分析HA可以清楚地确定HA- hb J常数。为了克服这一问题，我们开发了一种新的方法，即通过解耦两个相邻的质子来选择性j -分辨HMQC。将该方法应用于结构复杂的模型化合物单唑霉素的立体化学研究，证明了该方法的有效性。少

In order to observe long range JCH couplings and JHH couplings, we have developed Selective J-resolved HMBC, Selective COSY-J-resolved HMBC and Selective J-resolved-HMQC.Selective J-resolved HMBCDetermination of long-range C-H couplings (JC-H) is getting important for stereochemical studies of natural products. The J-resolved HMBC-1 method is a method of choice for this purpose with high sensitivity. The shapes of cross peaks, however, become complex by H-H couplings and long-range JC-H resulting in difficult analysis of complicated spin systems. In order to overcome these problems associated with J-resolved HMBC-1, we have developed a new technique, Selective J-resolved HMBC. The new method incorporating proton-proton decoupling into J-resolved HMBC-1 enables to suppress JH-H and to observe only long-range C-H couplings with complicated molecules having short T2.Selective COSY-J-resolved HMBCWe present an improved version named Selective COSY-J resolved HMBC. This method enhances the … More sensitivity of cross peaks of methine proton signals attached to a methyl group in J-resolved HMBC or Selective J-resolved HMBC, and enables to determine its long range JCH couplings. J-resolved HMBC or Selective J-resolved HMBC were developed for observation of long range JCH couplings by the J-scaling pulse sequence into HMBC. Application of this new technique to model compounds, portmicin and monazomycin, proved that this method is useful for determination of JC H of complicated molecules.Selective J-resolved HMQCAnalysis of H-H J coupling constants is important for relative stereochemical studies of natural organic compounds. Overlapping protons or strongly coupled protons make analysis of H-H J coupling constant difficult. This problem can be solved by utilizing a proton attached to 13C. In a strongly coupled HA and HB spin system, HA attached to 13C and HB connected to 12C constitute a week coupled proton system resulting in a large chemical shift difference between HA and HB spread by CA-HA J-coupling. Thus the HA-HB J constant can be clearly determined by analyzing HA. In order to overcome this problem, we developed a new method, selective J-resolved HMQC by decoupling two adjacent protons. Application of this method to a model compound, monazomycin with a complicated structure proved its effectiveness for stereochemical studies. Less