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The H-1,N-15-HMBC experiment is a very useful tool for the structure determ
ination of alkaloids. In conjunction with the computer program COCON, we sh
ow how H-1,N-15-HMBC derived connectivity information can assist in the ass
ignment of constitution, by greatly reducing the number of possible structu
res compatible with a given data set. The method is illustrated for the mar
ine natural products oroidin (1) and manzacidin A (2).