Constituents of West African Medicinal Plants XXV. Isolation of Oblongine from Tiliacora dinklagei and the Synthesis of Oblongine and Related Benzylisoquinoline Alkaloids

Abstract

An investigation of the water-soluble alkaloid fraction of the roots of T. dinklagei resulted in the isolation of the novel benzylisoquinoline alkaloid, oblongine (17). The identity of the isolated oblongine (17) was established by spectral means as well as by synthesis. During the course of the synthesis, several compounds (11, 12,13, 15,16,18, and 19) not previously reported were prepared. Their properties as well as those of certain related compounds are presented.

Quaternary Alkaloids from Litsea cubeba and Cryptocarya konishii

“…To our knowledge, this is the first natural occurrence of this compound. Its physical data, except for the optical property, were identical to those reported for the synthetic racemate (6).…”

“…The location of the MeO function was assigned to C-7 based on an nOe's, which enhanced the doublet at 6.99 (H-6) upon irradiation of the MeO signal. These data and the levorotatory property showed 3 to be (-)-oblongine (5)(6)(7)(8).…”

“…were assigned by correlation with a model compound, juziphine [6], which is the corresponding tertiary base of 3 (9), and with the quaternary effect on 13C nmr deduced from pavine alkaloids (10). These assigned data are listed in Table 1.…”

Cytotoxic and Antimalarial Alkaloids from the Tubers of Stephania pierrei

“…For paper XXII, see Likhitwitayawuid et al (1). [1} (7,8), (-)-asimilobine-2-0^-D-glucoside [2}, (-)-anonaine [3} ( 9), (-)-isolaureline [4} (10), (-)-xylopine [5} (10), (-)-roemeroline [6} (11), (-)-dicentrine [7} (12)(13)(14), ( -)-nordicentrine [8}, ( -)-phanostenine [9} (15), cassythicine [10} (14,16), and magnoflorine [11} (17)(18)(19)(20); (b) the tetrahydroprotoberberines (-)-tetrahydropalmatine {12} (21-23), (-)-capaurine [13} (24-27), ( -)-thaicanine [14} (23), (-)-corydalmine [15} (25,26), ( -)-N-methyltetrahydropalmatine [16} (28), (-)-xylopinine [17} (22), and (-)-tetrahydrostephabine [18} (29); (c) the tetrahydrobenzylisoquinolines (+)reticuline [19} (30,31), (+)-codamine [20} (32,33), and (±)-oblongine [21} (34,35); (d) the hasubanan ( -)-delavaine [22} (36) and the morphinan (-)-salutaridine [23} (37,38). Compounds 2 and 8 are hitherto unknown alkaloids.…”

Additional Alkaloids of Pachygone ovata

“…Elution of this column with CHCl3-MeOH (98:2) afforded a colorless residue (35 mg) which on treatment with MeOH gave norjuziphine (20 mg) as colorless crystals, Rf0.34, mp 155-157°(MeOH), [cxJ23d + 12°(c 0.43, MeOH); uv, max (MeOH) 284 nm (sh) (log 3.22), 280(3.26) and 234(3.52); cd, [ ]288 +2,280. 36); ir, v max (KBr) 3260 cm-3010, 2930, 2830, 1612, 1590, 1515, 1490, 1435, 1380, 1340, 1240, 1170, 1160, 1100, 1045, 995, 955, 920, 850, 838, 805, 795, 788, and 750; pmr (MeOH-d4 + TMS), 3.82 (s, 3H, OCH3), 6.53 (d, 2H, J=8Hz, ArH), 6.72 (d, 1H, J=8Hz, ArH), 6.79 (d, lH,/=8Hz, ArH), and 7.09 (d, 2H,/=8Hz, ArH); ms, mlz 285 (<1%)(M+), 178(100), 163 (33) and 107 (10). The structure was confirmed via the preparation of the methiodide salt by the treatment of norjuziphine (15 mg) in Me2CO (10 ml) with methyl iodide (0.5 ml) under reflux fot 48 h. Evaporation of the solvent yielded a residue whose ir spectrum was identical with authentic 2-methyl-7-methoxy-8,4'-dihydroxy-l-benzyl-l,2,3,4-tetrahydroisoquinoline methiodide (oblongine methiodide) (38). Isolation of liriodenine.-The nonphenolic alkaloids (315 mg) obtained from combined fractions 15-34 of the hplc column were chromatographed over silica gel-Celite (4:1) (80 g).…”