Demethylated product

An a-demethylated product (81) is formed unexpectedly when the tetrasubstituted pyrrole... 

Papaveraldine (Xanthaline), C2oHij05N. This substance forms colourless scales, m.p. 210°, yields well-crystallised yellow salts, which are dissociated in water, and reacts as a tertiary base, forming a methiodide, m.p. 133-5°. It gives an oxime existing in two stereoisomeric forms, and contains foru methoxyl groups. The demethylated product, papaveraldoline, Ci0H,ON(OH)4, has been prepared by Oberlin. Miss Dobson and W. H. Perkin have shown that the alkaloid, Xanthaline, isolated from opium by T. and H. Smith, is identical with papaveraldine. On reduetion with... 

When hydrogen chloride at 180° is used in place of acetic anhydride, the demethylated product, morphol, Ci4Hj(OH)2 is obtained. Consideration of its reactions led Vongerichten to foi mulate methylmorphol as 3-methoxy-4-hydroxyphenanthrene, identical with the product synthesised by Pschorr and Sumuleanu. ... 

The use of ultraviolet irradiation to transform cocaine (98), 3a-benzoyloxytropane (14), and tropacocaine (43) to the corresponding N-demethylated products has been described 107). 

A variety of protoberberines (86 or 88) were treated with primary or secondary amines in refluxing ethanol or methanol to give C-9- or C-l 1-aminated protoberberines (87 or 89) in 60-90% yield (Scheme 21). When bulky amines were used, the demethylation product was also obtained (69,70). 

Yoon and co-workers reported a methodology that yielded pyridopyrimidones 97 and 98 through the palladium-catalyzed coupling of iodouracil 94 with alkenes 95 and 96, respectively <00SC81>. It was noted that when the alkenes of type 95 (X = acetyl, ester, or nitrile) were employed, demethylated products 97 resulted, otherwise, the deaminated products 98 were favored. No mechanistic explanation of these results was supplied by the authors. 

In water, the percentage of these degradation products increased with time and amounted to one quarter of the remaining radiocarbon at 24 hr the quantity of 3-methyl-4-nitrophenol and both demethylated products is ca. 7% and 5.5%, respectively. Fenitrooxon was also detected. Because fenitrothion was stable in water under the present experimental conditions, these degradation products are presumably produced by fish metabolism. 

It is apparent that the aquatic echinoderm and terrestrial mammal deal with a chemical probe by very different metabolic pathways. The exclusive formation of oxidized ((T-demethylated) product in the mouse may partly reflect the animal s highly oxidizing environment, while the relatively anoxic marine environment is represented in the observed reduced metabolites of the sea urchin. 

The acid-catalyzed cyclization of properly substituted aminoacetaldehyde dialkyl acetals was shown to be a suitable method in the construction of a homo-isopavine (Scheme 39) (132a,172). Treatment of 7V-[l,3-bis(3,4-dimethoxy-phenyl)propyl]aminoacetaldehyde dimethyl acetal (175) with concentrated hydrochloric acid afforded the 7V-norhomoisopavine 176 in 39% yield. This cyclization was also accompanied by some O-demethylation. Product 176 could be readily N-methylated using formaldehyde and sodium borohydride to afford the homoisopavine ( )-177 (772). 

Plants and bacteria produce the reduced sulfur required for the synthesis of cysteine (and methionine, described later) from environmental sulfates the pathway is shown on the right side of Figure 22-13. Sulfate is activated in two steps to produce 3-phosphoadeno-sine 5 -phosphosulfate (PAPS), which undergoes an eight-electron reduction to sulfide. The sulfide is then used in formation of cysteine from serine in a two-step pathway. Mammals synthesize cysteine from two amino acids methionine furnishes the sulfur atom and serine furnishes the carbon skeleton. Methionine is first converted to 5-adenosylmethionine (see Fig. 18-18), which can lose its methyl group to any of a number of acceptors to form A-adenosylhomocysteine (adoHcy). This demethylated product is hydrolyzed to free homocys-... 

An a-demethylated product (116) is formed unexpectedly when the tetrasubstituted pyrrole (115) is reacted with p-nitrobenzenediazonium chloride <82JOC1750). M-f-Butylisoindole (117) couples with p-nitrobenzenediazonium fluoroborate to give the hydrazone (118) (80AG(E)320). 

Synaptic serotonin (5-hydroxytryptamine) transporters are inhibited by amphetamines, the tropane alkaloids cocaine and ecgonine [194] and by the indole alkaloid ibogaine (12-methoxyibogamine) and its demethylation product ibogamine [191, 195]. Hyperforin is a major antidepressant constituent of St. John s Wort (Hypericum perforatum) and inhibits serotonin uptake by elevating cytosolic Na+ [196]. The additional... 

A logical extension of FI A with serial EC-LC-MS is to incorporate a separation technique to further characterize the products. Figure 8.2 is an example of precolumn EC oxidation of tamoxifen. With the EC cell at 500 mV, the total ion chromatogram (TIC) shows two primary peaks corresponding to starting material (tamoxifen) and, at an earlier retention time, an N-demethylated product. With the precolumn EC cell at 1000 mV (Fig. 8.3), additional peaks are evident, including possible aromatic... 

No differences were observed5 in the enzymic oxidation of putrescine and TV-methylputrescine by plant extracts of a cultivar of N. tabacum that had a high nicotine content and one with a high content of nornicotine (7). Thus a high nornicotine (7) content cannot be attributed to direct oxidation of putrescine, and this supports evidence which shows nornicotine (7) to be a demethylation product of nicotine. 

Castedo et al. (26) have used 13C NMR to resolve the structure of an O-demethylation product of papaverinol (31) obtained by treatment of the compound with sulfuric acid. It is known that when a phenol is transformed to its phenoxide the para carbon is shielded (5). When the spectra of the demethylation product and its anion were examined it was observed that C-l was shielded by —8.3 ppm in the anionic compound. It was apparent therefore that demethylation had occurred at C-4 and not at C-3 as originally suggested. 

Liquid-phase fluorination of methyl-substituted benzene derivatives depends strongly on the structure and concentration of the substrate, its molar ratio to xenon difluoride and the catalyst used (Scheme 32). HF-catalyzed fluorination of 1,2,4,5-tetramethylbenzene with an equimolar amount of xenon difluoride gave a small amount of 1,4-difluoro product, while reaction with two equivalents of xenon difluoride also gave the demethylated product l-fluoro-2,4,5-trimethylbenzene, which was also formed by HF-catalyzed fluorination of 1,3,4-trimethylbenzene34. In contrast, trifluoroacetic acid catalyzed fluorination is much more complex, and forms the four products l-(trifluoromethyl)-2,3,5,6-tetrametylbenzene, 2,4,5-trimethylbenzyl trifluoroacetate, l-fluoro-2,3,5,6-tetramethyl-benzene and l-(trifluoromethyl)-2,3,4,5-tetramethylbenzene, the distribution depending on the amount of trifluoroacetic acid used. Similar results were also observed in the fluorination of 1,2,3-trimethylbenzene and 1,3,5-trimethylbenzene34. 

LMW yeast Se compounds is given [46], It was assumed that adenosylselenoho-mocysteine (AdoSe-Hcy), which had been identil>ed in yeast by different authors [51, 63], could be a demethylation product of adenosylselenomethionine (AdoSe-Met). The latter compound is formed when selenomethionine enters the pathway of its S analog in enzymatic transmethylation. For the safe detection of AdoSe-Met, an LMW fraction of Se enriched yeast was obtained by homogenization of fresh cells and precipitation of proteins with HCIO4 at 0°C. The identification and/or conf>rmation of species observed by ion-pairing (IP) HPLC-ICP-MS was accomplished by spiking the samples with both commercial and laboratory-synthesized standards, and by electrospray (ES) MS. 

An -demethylated product 144 is formed when the tetrasubstituted pyrrole 143 is reacted with />-nitrobcn/.cncdia/.o-nium chloride.. Y-/-llutylisoindole 145 couples with/i-nitrobenzenediazonium fluoroborate to give the hydrazone salt 146. 

Use of methylene chloride as solvent consistently leads to higher yields of demethylated product (V), accompanied mostly by a decrease in recovered starting material. Lower oxygen yields are also observed at all temperatures except at —78°C. 

When Porter and Coscia published their reviews (2, 3) no total synthesis of a picrotoxane had come forth. Even the partial syntheses were not well developed, as mubironine A (97), an oxidation product of dendrobine (82), was not known as natural product at that time. The same is true for nordendrobine, the demethylation product of dendrobine (82), now known as mubironine B (98). Partial syntheses in the 1970s were made to determine the structure or absolute configuration of new picrotoxanes and are described earlier in this chapter. 

O-demethylated products account for about 17% of the urinary material. About 16% of a dose is eliminated in the faeces. 

In the primary reductive step, oxygen from air or Fe(III) ions function as electron acceptor. The radical cation l+ , generated in the oxidative counterpart, loses a proton, affording the strongly reducing a-amino radical (Figure 10), which injects an electron into the conduction band of CdS. Hydrolysis of the resulting iminium salt leads finally to the secondary amine. Repetition of this multi-step reaction affords the completely demethylated product 2. 

A similar treatment of stable keteneiminium triflate 72 with sodium bis(trimethylsilyl)amide generates azomethine ylide 73, together with a small amount of the demethylated product of 72. Ylide 73 undergoes readily dimerizes, leading to l,4-diethyl-2,5-bis[2,2-dimethyl-l-(t-butyl)propyridene]-piperazine when no dipolarophile is present. The trapping of ylide 73 with electron-deficient olefins is completely unsuccessful because these activated olefins cannot withstand such strongly basic conditions. The only dipolar-... 

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