1. Stephaoxocanine, a Novel Dihydroisoquinoline Alkaloid from Stephania cepharantha
2. We propose the name of “stephaoxocane” for skeletonA.Thus,1is mentioned as 12R, 15R-3,4,14,15-tetrahydro-6,7-dimethoxy-12-hydroxystephaoxocane
3. mp 188–191[ddot]C, slight yellow needles from ether; [α]D25+ 30[ddot] (c0.89, CHCI3); UV (MeOH) λmaxnm (log ϵ): 340 (3.89), 247 (4.51), 235sh (4.44); IR (KBr) cm−1: 3400, 1659, 1613, 1578, 1475, 1427, 1305, 1286, 1228; CD (MeOH) Δϵ(nm):1.7 (346),1.2 (320), + 7.5 (266),0.3 (252), + 0.6 (231),3.2 (217); EI-MS (30 eV)m/z(%): 311 (M+, 76), 296 (89), 282 (19), 268 (100), 252 (15), 224 (8); HR-MSm/z: 311.1127 (C18H17NO4requires 311.1155)
4. High-field FT NMR application of Mosher's method. The absolute configurations of marine terpenoids
5. A solution ofR-(+)-MTPA (15 mg), DCC (18 mg), and 4-dimethylaminopyridine (6 mg) in CH2Cl2(1 ml) was added to 2 (4 mg) in CH2Cl2(0.5 mL) at room temperature. After 5 h, the solution was filtered, and the filtrate was concentrated. The residue was subjected to preparative TLC [EtOAc:Et2NH (19:1)] to yield theR-MTPA ester (2a) (6 mg, 88%). TheS-MTPA ester (2b) was prepared in the same manner