Fig. 2. (A) and (B) Selected 1H–13C HMBC correlations for caulamidine A (1). (C) 1H–15N HMBC correlations. (D) Additional correlations in LR-HSQMBC with respect to 1H–13C HMBC (orange arrows) and additional correlations in HSQMBC-TOCSY with respect to LR-HSQMBC and HMBC (green arrows). (E) Key 1,1-HD-ADEQUATE correlations revealed quaternary carbons adjacent to protonated centers. (F) NOESY and ROESY correlations used to assign the relative configuration.
