Unequivocal determination of caulamidines A and B: application and validation of new tools in the structure elucidation tool box.

ABSTRACT: Ambiguities and errors in the structural assignment of organic molecules hinder both drug discovery and total synthesis efforts. Newly described NMR experimental approaches can provide valuable structural details and a complementary means of structure verification. The caulamidines are trihalogenated alkaloids from a marine bryozoan with an unprecedented structural scaffold. Their unique carbon and nitrogen framework was deduced by conventional NMR methods supplemented by new experiments that define 2-bond heteronuclear connectivities, reveal very long-range connectivity data, or visualize the 35,37Cl isotopic effect on chlorinated carbons. Computer-assisted structural elucidation (CASE) analysis of the spectroscopic data for caulamidine A provided only one viable structural alternative. A

SUBMITTER: Milanowski DJ 

PROVIDER: S-EPMC5868047 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature