BASHD-J-resolved-HMBC, an efficient method for measuring proton-proton and heteronuclear long-range coupling constants

Natural products often possess various spin systems consisting of a methine group directly bonded to a methyl group (e.g. -CHa-CHb(CH3)-CHc-). The methine proton H-b splits into a broadened multiplet by coupling with several vicinal protons, rendering analysis difficult of (n)J(C-H) with respect to H-b in the J-resolved HMBC-1. In purpose of the reliable and easy measurements of (n)J(C-H) and (n)J(H-H) in the aforesaid spin system, we have developed a new technique, named BASHD-J-resolved-HMBC. This method incorporates band selective homo decoupled pulse and J-scaling pulse into HMBC. In this method, high resolution cross peaks can be observed along the F-1 axis by J-scaling pulse, and band selective homo decoupled pulse simplified multiplet signals. Determinations of (n)J(C-H) and (n)J(H-H) of multiplet signals can easily be performed using the proposed pulse sequence. Copyright (c) 2013 John Wiley & Sons, Ltd.