Division of Agriculture and Agricultural Life Sciences, The University of Tokyo, Yayoi, Tokyo 113-8657, Japan.
Magn Reson Chem. 2012 Nov;50(11):713-6. doi: 10.1002/mrc.3866. Epub 2012 Sep 3.
An effective pulse sequence for measuring H-H coupling constants, named BASHD-J-resolved-COSY, has been developed. In the spin systems such as -CH(A)-CH(B)(CH(3))-CH(C)-, a methine proton H(B) splits into a multiplet owing to several vicinal couplings, resulting in attenuation of its cross-peak intensity. Therefore, the measurements of (3)J(H-H) with respect to H(B) are generally difficult in the E-COSY-type experiments. With the aim of accurate measurements of (3)J(H-H) in such a spin system, we have developed a new pulse sequence, which selectively decouples the secondary methyl group. The proposed pulse sequence provides the simplified cross-peak patterns, which are suitable for reliable measurements of (3)J(H-H) in a complicated natural product.
已经开发出一种用于测量 H-H 耦合常数的有效脉冲序列，命名为 BASHD-J-resolved-COSY。在-CH(A)-CH(B)(CH(3))-CH(C)-这样的自旋系统中，亚甲基质子 H(B)由于几个相邻耦合而分裂成一个多重峰，导致其交叉峰强度衰减。因此，在 E-COSY 类型的实验中，通常难以测量相对于 H(B)的 (3)J(H-H)。为了准确测量此类自旋系统中的 (3)J(H-H)，我们开发了一种新的脉冲序列，该序列选择性地去耦仲甲基。所提出的脉冲序列提供了简化的交叉峰图案，非常适合于复杂天然产物中 (3)J(H-H)的可靠测量。
