Differentiation of regioisomers at N-15 natural abundance using gradient-enhanced H-1/N-15 HMBC NMR spectroscopy

摘要

The H-1/N-15 HMBC experiment at N-15 natural abundance using pulsed field gradients is a useful tool for chemical shift assignment and structure elucidation. This experiment assisted in the identification of regioisomers that could not be distinguished with conventional H-1/H-1 nuclear Overhauser or H-1/C-13 correlation NMR experiments. The natural abundance N-15 gradient-enhanced HMBC experiment was easily implemented, provided high-quality spectra and readily distinguished nitrogen-containing regioisomers. This experiment can aid in structure elucidation when traditional H-1 and C-13 experiments fail to provide unique structural assignment. (C) 1998 John Wiley & Sons, Ltd. [References: 21]