Long-range ¹H-¹H NMR correlation: Extending connectivities to remote bonds via an intermediate heterospin

An out-and-stay 2D proton - proton NMR correlation experiment is proposed to detect long-range proton- proton connectivities up to six and seven bonds away. The magnetization flow pathway is based on a consecutive, dual-step J(CH) -transfer mechanism and it allows one to trace out 1H -1H connectivities between protons belonging to different spin systems. This novel experimental scheme will be particularly useful in cases when carbon resonances overlap, providing connectivity information that could not be obtained in a HMBC experiment. The success of the experiment is demonstrated in the structural studies of a wide variety of chemical compounds. Copyright © 2008 John Wiley & Sons, Ltd.