Neopetrothiazide: An Intriguing Pentacyclic Thiazide Alkaloid from the Sponge <i>Neopetrosia</i> sp.
Dongdong Wang, Wei Jiang, Chang‐Kwon Kim, Heidi R. Bokesch, Girma M. Woldemichael, Berkley E. Gryder, John Shern, Javed Khan, Barry R. O’Keefe, John A. Beutler, Kirk R. Gustafson
Abstract
Neopetrothiazide (1), a pentacyclic isoquinoline quinone, was isolated from a Neopetrosia sp. sponge. The structure elucidation was facilitated by utilizing long-range heteronuclear single quantum multiple bond correlation (LR-HSQMBC) and heteronuclear multiple bond correlation (HMBC) nuclear magnetic resonance (NMR) pulse sequences optimized to detect four- and five-bond 1H–13C heteronuclear correlations. These NMR experiments can help assign proton-deficient structural motifs like neopetrothiazide (1), which has 14 contiguous nonprotonated centers (C, N, and S). Neopetrothiazide (1), with an unprecedented thiazide-fused structural scaffold, is the first natural product containing a thiazide moiety.