Chemistry of Sponges, IX. New Diterpenes from the Marine Sponge Dictyodendrilla cavernosa

Complete assignment of the 1H NMR data and reassignment of 13C NMR data of four spongian diterpenes

“…The proton attached to C‐6 resonating at δ H 1.34 was assigned to the β axial position based upon it showing three large couplings. Assignment of the carbon resonances in 1 using HSQC and HMBC correlations indicated that Kieran and coworkers correctly assigned all carbons . The 13 C NMR data reported by Hambley and coworkers contained two anomalous shifts (δ C 36.7 and δ C 169.5) that should be corrected to δ C 35.7 (C‐8) and δ C 179.0 (C‐16).…”

“…This terpene was isolated and published serendipitously by both Kernan and coworkers from Dictyodendrilla camosa and by Hambley and coworkers from Chelonaplysilla violacea in 1990 while a third publication by Pattenden and coworkers reported its total synthesis in 1998. [3,4,8] Hambley and coworkers provided the most comprehensive assignment of the 1 H NMR data, while Kernan and coworkers, although reporting most of the 1 H chemical shifts, only assigned the protons predominantly around Rings C and D. The 1 H NMR assignments reported by Pattenden and coworkers were limited to Ring D protons. A comparison of 1 H NMR data that we obtained experimentally with those published previously identified several anomalous assignments.…”

“…These included spongian-16-one (1), dendrillol-1 (2), -2 (3), and aplyroseol-6 (4, Figure 1). [3][4][5][6] Examination of the NMR data in the literature for 1-4 indicated that there were several inconsistencies in the NMR assignments for these compounds, and in addition, incomplete 1 H NMR data sets were present for Compounds 2-4. Herein, we provide an unambiguous and complete set of 1 H and 13 C NMR spectroscopic data (acquired at 800 MHz) for four members of this diverse class of spongian diterpenoids.…”

Author Index To Volume 2

“…Aplyroseol-14 (4, R 1 = R 3 = H, R 2 = CH 2 OAc) and aplyroseol-16 (4, R 1 = OH, R 2 = CH 2 OAc, R 3 = OAc) have been isolated more recently also from the sponge Aplysilla rosea [24], whereas the cytotoxic γ-lactone spongian-16-one (4, R 1 = H, R 2 = Me, R 3 = H) has been found in several species such as Dictyodendrilla cavernosa [22], Chelonaplysilla violacea [16,23], Aplysilla var. sulphurea [24], and also in the mollusks Chromodoris obsoleta [17], C. petechialis [25], and C. inopinata [18].…”

“…6 ). For example, compound 11 was isolated from the sponge Dictyodendrilla cavernosa and is the first anhydride isolated from a marine sponge [22]. Lactol 12 also called aplyroseol-15, was isolated from Aplysilla rosea and is characterised by an oxidation pattern between a lactone and an anhydride [24].…”