Xenimanadins A–D, a family of xenicane diterpenoids from the Indonesian soft coral Xenia sp.

Bioactive Xenicane Diterpenoids from the Taiwanese Soft Coral Asterospicularia laurae

“…Preliminary inspection of conjugated diene that was linked to an O-bearing tertiary C-atom connected to two Me groups. These data suggested the presence of the same side-chain moieties as that of xenimanadin B [13]. The most noticeable difference detected in the 13 C-NMR data of 6 was the replacement of MeO by OH groups at C(1) (d(C) 100.1 (d) and C(15) (d(C) 70.9 (s)), and replacement of MeO by a H-atom at C(3) (d(C) 69.2 (t); Table 2).…”

“…These data suggested the presence of the same side-chain moieties as that of xenimanadin B [13]. The most noticeable difference detected in the 13 C-NMR data of 6 was the replacement of MeO by OH groups at C(1) (d(C) 100.1 (d) and C(15) (d(C) 70.9 (s)), and replacement of MeO by a H-atom at C(3) (d(C) 69.2 (t); Table 2). The 1 H, 1 H-COSY NMR spectrum suggested the presence of three spin systems as shown in Fig.…”

“…[12], Indonesian soft coral Xenia sp. [13], Xenia viridis [14], Xenia elongata [15], and formosan soft coral Clavularia inflata var. luzoniana [16].…”

“…The HMBCs HÀC(1)/C(11a) and C(3), and HÀC(3)/C(4), C(12), and C(4a) supported the presence of a pyran ring. On the basis of these COSY and other HMBCs, compound 2 was determined as a new xeniolide [13] with a cyclononane ring fused to a 7,8-epoxy ring. The configurations of all stereogenic centers was elucidated from NOESY experiments on 2 as shown in Fig.…”

“…The (E)-geometry of the C(4)¼C (12) (11) suggested a trans ring junction, which implied that HÀC(4a) was a-oriented. The NOESY correlations HÀC(4a)/HÀC (13) and HÀC(4a)/HÀC (8) suggested that these H-atoms were on the face (a) opposite to HÀC(11a). The b-configuration of HÀC (18) was determined by the series of NOESY correlations Me(18)/HÀC(9b)/HÀC(10b)/HÀC(11ab).…”