Thebaine isolation

The first scheme for the separation of the six chief alkaloids of opium, VIZ., morphine, codeine, thebaine, papaverine, narcotine and narceine, is probably that of Plugge. Much later Kljatschkina investigated for each of these six bases the properties by means of which isolation and estimation could probably be effected and, on the basis of the results, devised a plan for such analyses. More recently Anneler has published a detailed account of a scheme with the same objective. l Attention had already been given to complex, systematic analyses of this kind, in connection with examination of the mixtures of opium alkaloids, which have long been in use in medicine in these at first only morphine and other alkaloids were determined, but in the more recent schemes provision is made for the estimation of each alkaloid. ... 

Laudanosine, C21H27O4N. This alkaloid occurs in the liquor from which thebaine is precipitated, and can be isolated by Hesse s method. The crude alkaloid is purified by extraction with small quantities of ether, in which laudanosine is soluble, and finally by precipitation with potassium iodide. The free base crystallises from hot benzene in needles, m.p. 89°, [ ] f 103-23° (EtOH), is soluble in alcohol, chloroform, hot benzene or... 

Thebaine, CjgHgiOgN. This base, which occurs in opium to the extent of 0-1 to 1 per cent., was first obtained by Pelletier and Thiboumery, who regarded it as isomeric with morphine, and named it paramorphine. It was examined by Kane, who first called it thebaine, and by Anderson, who described a method of isolation and provided the formula given above. It remains in the mother liquor after the removal of morphine and eodeine hydrochlorides in Gregory s process, and in Hesse s method of isolating it from this source is obtained as the acid tartrate. This is crystallised from hot water, and the alkaloid regenerated from it is reerystallised from dilute alcohol, from which it separates in leaflets, or from dry alcohol in prisms, m.p. 193°, — 218-6° (EtOH) or — 229-5°... 

Thebainone (Schopf), CigHjjOgN. This substance, which must be distinguished from Pschorr s thebainone (metothebainone of Schopf (see p. 248) ), is formed, along with the latter in the reduction of thebaine by stannous chloride in hydrochloric acid, and was isolated by Schopf and Hirsch. Its prior isolation by Pschorr, as confirmed by Morris and Small, has been referred to already. It crystallises with 0-5 HjO, has m.p. 151-2°, yields a hydriodide, m.p. 258-9°, methiodide, m.p. 223°, and an oxime, m.p. 185-6°. On catalytic hydrogenation it yields dihydrothebainone (LI), and can be degraded to 3 4 6-triacetoxyphenanthrene, m.p. 165-7°. On this basis formula (XLIX) is assigned to it. The mechanism of the formation of codeinone, thebainone and mefathebainone from thebaine is discussed by Schopf and Hirsch. ... 

As in the case of the steroids, introduction of additional nuclear substituents yields morphine analogs of increased potency. The more important of these are derived from one of the minor alkaloids that occur in opium. Thebaine (14), present in crude opium in about one-tenth the amount of morphine, exhibits a reactive internal diene system that is well known to undergo various addition reactions in a 1,4 manner (e.g., bromination). Thus, reaction with hydrogen peroxide in acid may be visualized to afford first the 14-hydroxy-6-hemiketal (15). Hydrolysis yields the isolated unsaturated ketone (16). Catalytic reduction... 

Salutaridinol 7-0-acetyltransferase catalyzes the conversion of the phenanthrene alkaloid salutaridinol to salutaridinol-7-Oacetate, the immediate precursor of thebaine along the morphine biosynthetic pathway in P. somniferum (Fig. 10.7).26 Acetyl CoA-dependent acetyltransferases have an important role in plant alkaloid metabolism. They are involved in the synthesis of monoterpenoid indole alkaloids in medicinal plant species such as Rauwolfia serpentina. In this plant, the enzyme vinorine synthase transfers an acetyl group from acetyl CoA to 16-epi-vellosimine to form vinorine. This acetyl transfer is accompanied by a concomitant skeletal rearrangement from the sarpagan- to the ajmalan-type (reviewed in2). An acetyl CoA-dependent acetyltransferase also participates in vindoline biosynthesis in Catharanthus roseus, the source of the chemotherapeutic dimeric indole alkaloid vinblastine (reviewed in2). Acetyl CoA deacetylvindoline 4-O-acetyltransferase catalyzes the last step in vindoline biosynthesis. A cDNA encoding acetyl CoA deacetylvindoline 4-0-acetyltransferase was recently successfully isolated.27... 

The first group contains the natural products morphine, codeine and thebaine, which have been isolated from the natural product opium. In addition, the group contains various semi-synthetic derivatives of morphine, codeine and thebaine, which are prepared by chemical modifications of these natural products... 

Following the isolation of morphine by Serturner in 1805 further alkaloids were isolated from opium, for example narcotine in 1817, codeine in 1832, thebaine in 1835 and papaverine in 1848. 

The isolation of the cDNAs encoding the enzymes involved in diverse isoquinoline alkaloid formation in plants and microorganisms allowed the first metabolic engineering routes to be developed and paved the way for new ways of future production of isoquinoline alkaloids. For instance, transgenic opium poppy plants were created in which codeinone reductase was suppressed by RNAi, resulting in the substitution of morphine synthesis with the non-narcotic precursor reticuline [110]. In a similar approach, RNAi suppression or overexpression of salutaridinol 1-0-acetyltransferase in opium poppy led to accumulation of salutaridine or increase of morphine, codeine and thebaine content [111], suppression of the BBE led to accumulation of berberine in California poppy cells [112],... 

Thebaine was isolated from opium in 1835 by Pelletier (439). The therapeutic applicability of thebaine was studied by Balint et al. (440). It was found to be more toxic than morphine. It is a more effective narcotic but a weaker analgesic than morphine. The analgesic effect of thebaine in doses of 0.01 g/kg is greater than that of amidopyrine this effect persists, however, only over a period of 30 min. Dihydro-thebaine is somewhat more effective but it is more toxic (441). The number and the location of the double bonds in ring D of the morphinane skeleton is of importance for the analgesic effect. Teraoko... 

Precursors such as reticuline 10 were synthesized labelled with 14C (O and N methyl groups) and with 3H in the aromatic nuclei. Labelling could also be done in the two 2-carbon bridges. We also synthesized from thebaine the key alkaloid 11 for the first time. Unlike the situation with Pummerer s ketone 11 did not close to 12 spontaneously. Later on, alkaloid 11 was isolated from a Brazilian plant. From correspondence with Prof. R. A. Barnes, we realized that the two were probably identical, which was confirmed by an exchange of specimens. So, we used thereafter the name salutaridine, given by our Brazilian colleagues. 

A series of dibenzazonines with the general structure 111 (R, R, = H, alkyl, alkoxy, halo R2 = H, alkyl R3 = H, alkyl, alkanoyl n = 1,2) were prepared from thebaine (45) and found to have antiarrhythmic activity similar to that of procainamide and local anaesthetic activity lasting longer than that of tetracaine (45). One compound of this series, named asocainol (111, R = R, = H, R2 = Me, R3 = H, n = 2), is a useful drug whose mechanism of action in isolated guinea pig papillary muscles has been studied in detail (78, 79). 

Varieties of Papaver somniferum with varying content of morphine alkaloids have been studied, and varieties having a genetically governed low alkaloid content have been identified.143 The dynamics of the variation of amount of morphine and codeine present in P. somniferum with time of harvesting of the capsule have been studied.144 The thebaine content of P. bracteatum in relationship to plant development has been studied, and strains have been isolated from which may be obtained a dried latex that contains >55% thebaine, corresponding theoretically to a yield of 58 kg ha-1 or approximately 50 kg ha-1 from harvested capsule.145... 

Two isomeric IV-oxides of morphine, of codeine, and of thebaine have been isolated from P. somniferum, and the thebaine V-oxides are also present in P. bracteatum. The oxides have, in each case, also been prepared by the N-oxidation of the free bases. N.m.r. spectroscopic studies suggest that the nitrogen-oxygen bond is axial in the major isomer and equatorial in the minor.146... 

Papaver Alkaloids.—Biosynthesis of morphine (36) occurs, in Papaver somniferum, through reticuline (33) by way of thebaine (35). The sequence from (35) to (36) involves, inter alia, two O-demethylations, with that at the methoxy-group at C-6 occurring first.1,2 Confirmation that the other methoxy-group is not demethylated first in this Papaver species obtains from the failure to detect oripavine (37), which is found in other Papaver species, as a natural constituent of P. somniferum. The experiment involved attempted isolation of radioactive (37), using inactive alkaloid as carrier, following a feeding experiment with radioactive reticuline (33).37... 

Codeine, 14-hydroxycodeine, neopine, and O-methylflavinantine have been isolated from Papaver bracteatum,146 flavinantine and amurine from Meconopsis cambrica,113 isosinoacutine from Stephania elegans,174 and a new alkaloid, tridictyophylline, for which the structure (96) was determined by X-ray crystallography, from Triclisia dictyophylla.175 Bound morphine, codeine, and thebaine have been found in P. bracteatum and P. somniferum,176 and the effect of the period of maturation of the plants on the yield of these three alkaloids from P. somniferum has been studied.177,178 Codeine has been isolated from cell suspension cultures of P. somniferum under conditions where no morphine, norcodeine, or thebaine could be detected.179... 

The acetylation of morphine and of codeine by aspirin202 and the enzymatic hydrolysis of heroin203 and the reduction of codeinone204 have been studied. Dihydronorcodeine and dihydromorphine have been isolated from urine as metabolites of dihydrocodeine.205 Patents have been published covering the preparation of -(cyclopropylmethyOnormorphine,206 the conversion of thebaine into codeinone,207 and the preparation of nalorphine 6-sulphate.208 Salts of codeine and ethylmorphine with 5-carboxymethyl-2-thio-l,3-thiazan-4-one have been prepared.209 The circular dichroism210,211 and fluorescence characteristics212 of morphine and related bases have been studied. 

Isolation of the alkaloids from the latex of the opium poppy, Papaver somniferum, led to the identification of over 20 compounds (Fig. 11.1). The most abundant alkaloids were morphine (1), codeine (2), thebaine (3), noscapine (4), and papaverine (5). 

Conversion of (S)-reticuline to its ( )-epimer is the first committed step in morphinan alkaloid biosynthesis in certain species. 1,2-Dehydroreticuline reductase catalyzes the stereospecific reduction of 1,2-dehydroreticuline to (7 )-reticuline.39 Intramolecular carbon-carbon phenol coupling of (if)-reticuline by the P450-dependent enzyme salutaridine synthase (STS) results in the formation of salutaridine.40 The cytosolic enzyme, salutaridine NADPH 7-oxidoreductase (SOR), found in Papaver bracteatum and P. somniferum, reduces salutaridine to (7S)-salutaridinol.41 Conversion of (7S)-salutaridinol into thebaine requires closure of an oxide bridge between C-4 and C-5 by acetyl coenzyme A salutaridinol-7-0-acetyltransferase (SAT). The enzyme was purified from opium poppy cultures and the corresponding gene recently isolated (Fig.7.2).42,43 In the last steps of morphine... 

In 1803 the German pharmacist Seturner achieved the isolation of morphine as one of the active ingredients of opium. He named the compound after Morpheus, Ovid s god of dreams, the son of sleep. Among the other alkaloids of opium are codeine, isolated in 1832, thebaine, narceine, narcotine, and papaverine. From the isolation of pure morphine to the elucidation of its structure by first Gulland and Robinson(1,2) and later Schopf(3) took another 120 years. A total synthesis by Gates and Tschudi(4,5) confirmed the structure in the early 1950s. 

During a study of the nitration of thebaine with tetranitromethane,(287) the unusual epoxide 183 was isolated when the nitration was performed in the presence of air. In establishing the structure of 183, two products (210a and b) oxygenated at C-10 were isolated. 

Diethylazodicarboxylate may be employed as a reagent for the N-demethylation of thebaine to northebaine via an N-Me addition product. However, when thebaine was dissolved in diethylazodicarboxylate and allowed to stand, the hexacyclic product 251 was isolated,<9a) presumably from the Diels-Alder intermediate 249, and after hydrolysis gave 250. The putative intermediates 249 and 250 defied isolation. 

Morphine and related alkaloids are specific to the genus Papaver (Berberidaceae), although the antipodal series of alkaloids is distributed in the Menisperma-ceae. Early in the biosynthesis of morphine, an inversion at C-1 of (5)-reticuline occurs, followed by ortho-para benzylic coupling to afford salutaridine. Stereospecific reduction and cyclization-elimination affords the 4,5-Ether bridge and thebaine. The dominant pathway from this point involves neopinone, codeinone, codeine, and morphine. Again, most of the enzymes in this sequence were isolated and characterized by Zenk s group (Fig. 30). 

Semi-Synthetic Transformations of the Morphine Alkaloids Although it has been synthesised (ref 61), (now by four distinct routes) morphine (63), a powerful analgesic is readily available from the natural source, opium obtained from Papaver somniferum as the major alkaloid present (approx. 10%) and indeed the first to be isolated by Serturner in 1803, while the methyl ether, codeine (64) which comprises only 0.5% is relatively weakly active. Thebaine (65) a third component of opium is non-analgesic but is important as an intermediate for the formation of codeine, a somewhat scarce commodity (ref. 62) but a valuable mild analgesic and anti-tussive in great demand. It is best prepared from morphine by methylation with phenyl trimethylammonium ethoxide the by-product consisting of dimethylaniline (ref.63). 

Alkaloid isolation and structural elucidation is summarized in Table 6. In addition to known constituents, codeine and neopine have been isolated from Papaver brac-teatum Although callus cells from this plant contain thebaine at early stages of subculturing, only traces are found later. - ° Thebaine was identified among seventeen isoquinoline alkaloids detected in, or isolated from P. syriacum. ... 

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