ABSlRACl?
The oxrmthin rwoid components of msfa kersttngU L. hrve ban found to be 2-hydrory-UKI I I-hydmx -cmthin&onc (Ir unl lb). SUUCI~~ Ia wa undid by rcsuhr of mclhylrtiom ( Ia + Ic + ti J md NOE studies. A s&ctiw INEPT NhtR rachniquc was employed IO support uncguivarlly the I I -hydmxycmthin&me (I b) ass~gnnxn~ Quassia amora L. rnd Q. Gnornba L. (Simuou bweu) hm been employed In primitive mcdicrl ucrtments for c~ccr.* In I973 Qvusio (Picrru&&on) ktrringir was collectad in Gh~r UXI 1n CIOYI prepped in the U.S. N11ion1l clam Institute's @ICI) prognms fuchcd amRmrd tin SMUS rgrinst TIC P388 lymphayuc kukemir (PS syswm). By 197s Kupch~ was rbk to rcpt~~f titian of Ihc Ps rciv~ A '3~yQrodl~thiom. 1 rypicll SimMubruc qurrsin& . 8 from this plmt. Subsequently. t?om pi of the SUIK cdlerdon of Q. Lrstiagii. we isolrrcd Ihe oxaanthim llkrloids 2hydroxy-cmthin-bone (la)9.'0 U-XI I I-hydroxycmthin-6-o (lb). ".I3 AI thr~ point ruthcnric specimens of these pcarbolines WCR non rvaihbk and it baamt ncccssuy IO p1~5scly lauc the oxygen subrritumu. The cmlhin-bone nuckus of both ~ubolines wu esubhshcd by ularviokt. infrared. high field (400 MHz) NMR UNI w specml srudks. The hydroxy substitucnts were Iailed 1s follows. Melhylrrion of p urbolme IB donled both 0 (Ic) rnd N-methyl (21) dcrivrtivcr. 1 rest111 only consistent with 1 2-hydrory group in qullibrium with the carrsponding 1midc (2b). A series of NOE erperimenu confmned this conclusmn.lmdirfion of the mcthoxy gmup (k) proton at 6 4.09 produced 11.5% cnchmccmcnt of rhc sigul it 8 7.409 WI). Sirumrion of ti H-l singkt t!?Tata! H-II (3.X.) Md Ihe mcthoxy group (0.7%. sa 3). Similuly. the H-4 proton ~1s cnhmccd (4.5%) by irndlrrmg the singlet (a 6 3.799 ppm) exhibited by the N-Methyl proton of unidc 2r(d.. 4). Thus, the suuc~urt v/u established 1s 2-hydrory-cmfhu&onc rnd its ~u~omer cmthin-2.6dlw (Zb). Compuison of the physical ud spccarl dru of the sazond p tubdim (lb) i&ted with lhox of 8-hydroryunthm-bone (Id)" md II-hydroxy-crnthln-bone 11.1' did na rJlow 1 cku choice. So NOE expcnments werr undcrt&cn (cf. 5). As no effect on Ihc indok ring protons wu noted upon imdirriocr of H-l. substitution II C-II seemed likely. Thus sckctivc INEPT NMR expchncnu WCTC rpplred IO confm Ihe NOE mull. I5 The sign& of the pnnon-bunng crsboclr were assigned fig. I) on the buis of 1 'H-I% twodimcnriorul chemiul shift calr~~on spauum. Assignment of Ihc nmunmg cubon -Md choice of M II-hydmxy-a %hydmxycMthia&onc rssignmnl w&s ti using sclativc INEPT techniques 'Ihe poron-daoupkd I)C-NMR spectrum of ~linc lb exhibited reven cubonr conmining one hydrogen (CH). six fully subsritutal uomuic cubons Md one cuboclyl & (Fig. Ir). Cubom I2 was expcvd to show a slgnificmt long range coupling with H-l. H-8 (in lieu of 1 C-II proton) md H-IO. As illusuatcd in Figs. lb rod k, selective imdirtion of H-l (11 6 8.KIl ppm) crusai potiution uansfcr 10 C-l2 (111.90 ppm) md C-U (131.09 ppm). Spauum lb (J=7 Hz) uncovered 1 nthcz srmll mnsfcr from H-l IO C-12 md 1 luger rnnsfcz IO C-IS. The other significurt signal present II 146.10 ppm (spccuum lb) wu rtuibacd IO Ihc two bond coupling between H-l UXI C-2. The effect WLI more pronounced in spcctnun Ic wb the poltio~n WI&T YIL( eminrl for ooupling coouu~( of 4 Hr The hncz spauum displayed morr trmsfcr to C-12 ud none to C-15. The IWO bond coupling constmts between IH UKI 1% 1rt usually very smrll. whcnrs thru bond couplings mz on [he o&r of 4 u) IO Hz. I6 Gncmlly. the rhm bond couphng between 1 poton md 1 cubon locited on IWO difleennt rings acur it the lowu end of rhlr range.