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Journal articles on the topic 'Demethylation reaction'

Author: Grafiati

Published: 5 June 2025

Last updated: 1 August 2025

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1

Wang, Qing, Xinmin Wang, and Shuo Pan. "Effect of the Kerogen Molecular Structure on the Formation of Methane During Kerogen Pyrolysis." Australian Journal of Chemistry 72, no. 3 (2019): 174. http://dx.doi.org/10.1071/ch18428.

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In this study, density functional theory (DFT) at the GGA/RPBE level was employed to examine the effects of the kerogen microstructure on the formation mechanism of methane during the pyrolysis of kerogen. The calculations prove that the evolution of CH4 during kerogen pyrolysis corresponds to demethylation, and the process of forming methane involves the interaction of intramolecular hydrogen atom transfer and assistant hydrogen atom transfer. In all reaction paths, the energy barrier of path 5 is the smallest at 260.56kJmol−1. The energy barrier of path 6 is the largest at 554.36kJmol−1. The

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2

Thavaneswaran, Shanti, Kristy McCamley, and Peter J. Scammells. "N-Demethylation of Alkaloids." Natural Product Communications 1, no. 10 (2006): 1934578X0600101. http://dx.doi.org/10.1177/1934578x0600101008.

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The removal of an N-methyl group, or N-demethylation, is a useful chemical transformation in organic synthesis which has particular importance in the field of alkaloid chemistry. Historically, tertiary N-methyl alkaloids have been N-demethylated using the same methods as for N-dealkylating tertiary amines. Such methodologies have included the von Braun reaction, the use of chloroformate and azodicarboxylate reagents and the Polonovski reaction, amongst others. Photochemical and biochemical procedures have also been successfully employed. This review will examine these N-demethylation procedure

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3

Davydova, Nadezhda Y., David A. Hutner, Kari A. Gaither, Dilip Kumar Singh, Bhagwat Prasad, and Dmitri R. Davydov. "High-Throughput Assay of Cytochrome P450-Dependent Drug Demethylation Reactions and Its Use to Re-Evaluate the Pathways of Ketamine Metabolism." Biology 12, no. 8 (2023): 1055. http://dx.doi.org/10.3390/biology12081055.

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In a search for a reliable, inexpensive, and versatile technique for high-throughput kinetic assays of drug metabolism, we elected to rehire an old-school approach based on the determination of formaldehyde (FA) formed in cytochrome P450-dependent demethylation reactions. After evaluating several fluorometric techniques for FA detection, we chose the method based on the Hantzsch reaction with acetoacetanilide as the most sensitive, robust, and adaptable to high-throughput implementation. Here we provide a detailed protocol for using our new technique for automatized assays of cytochrome P450-d

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4

Fayyaz, Anam, Seddy Makwinja, Seppo Auriola, Hannu Raunio, and Risto Juvonen. "Comparison of In Vitro Hepatic Scoparone 7-O-Demethylation between Humans and Experimental Animals." Planta Medica 84, no. 05 (2017): 320–28. http://dx.doi.org/10.1055/s-0043-119886.

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AbstractScoparone is a natural bioactive compound in Chinese herbal medicines. It has numerous pharmacological actions, including liver protective, hypolipidemic, antitumor, and anti-inflammatory effects. The primary metabolism route of scoparone is O-demethylation to scopoletin or isoscopoletin catalyzed by CYP enzymes. The aims of our study were to identify the human CYP enzymes catalyzing scoparone 7-O-demethylation to scopoletin and to compare this oxidation reaction in liver microsomes among different species. A high throughput fluorescent-based assay method was developed to determine the

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5

Reid, Ian D. "Demethylation of the lignin model dimer 1-(3′,4′-dimethoxyphenyl)-2-(o-methoxyphenoxy)-propane-1,3-diol by the white-rot fungus Phlebia tremellosa." Canadian Journal of Botany 70, no. 3 (1992): 453–60. http://dx.doi.org/10.1139/b92-060.

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Phlebia tremellosa dealkylates nonphenolic β-O-4-linked lignin model dimers; the phenolic products are oxidized by laccase. There is no evidence of α,β-cleavage as catalyzed by lignin peroxidase in some other white rot fungi. Methanol is the product of demethylation of 1-(3′,4′-dimethoxyphenyl)-2-(o-methoxyphenoxy)-propane-1,3-diol, and the demethylation reaction can be assayed by the release of radioactive CH3OH from the 4′-O14CH3 labelled compound. In older cultures, the methanol is metabolized to CO2. Demethylation is stimulated by oxygen and blocked by several common metabolic inhibitors.

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6

Makino, Kosho, Yumi Hasegawa, Takahide Inoue, et al. "Chemoselective Demethylation of Methoxypyridine." Synlett 30, no. 08 (2019): 951–54. http://dx.doi.org/10.1055/s-0037-1612427.

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A chemoselective demethylation method for various methoxypyridine derivatives has been developed. Treatment of 4-methoxypyridine with L-selectride in THF for 2 h at reflux temperature afforded 4-hydroxypyridine in good yield; no reaction to anisole occurred. The utility of our method was demonstrated by the efficient synthesis of the metabolic substances of the antiulcer agent omeprazole. Chemoselective demethylation at the site of 3,5-dimethyl-4-methoxypyridine in the presence of 4-methoxybenzimidazole was achieved.

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7

Turhanen, Petri A., Janne Weisell, and Jouko J. Vepsäläinen. "Preparation of mixed trialkyl alkylcarbonate derivatives of etidronic acid via an unusual route." Beilstein Journal of Organic Chemistry 8 (November 20, 2012): 2019–24. http://dx.doi.org/10.3762/bjoc.8.228.

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A method to prepare four (3a–d) trialkyl alkylcarbonate esters of etidronate from P,P'-dimethyl etidronate and alkyl chloroformate was developed by utilizing unexpected demethylation and decarboxylation reactions. The reaction with the sterically more hindered isobutyl chloroformate at a lower temperature (90 °C) produced the P,P'-diester (2) as a stable intermediate product. A possible reaction mechanism is discussed to explain these methyl substitutions. These unusual reactions also clarify why it is difficult to prepare alkylcarbonate prodrugs from bisphosphonates. The compounds prepared we

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8

Ramadas, Chavakula, Saladi J. S. Chakradhar, Rao Mutyala Narayana, Raju Maddala Vijaya, and Babu K. Raghu. "A green process for demethylation reaction in synthesis of raloxifene hydrochloride." Journal of Indian Chemical Society Vol. 96, Mar 2019 (2019): 391–93. https://doi.org/10.5281/zenodo.5651023.

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Research and Development, Aurobindo Pharma Limited, Survey No: 71 & 72, Indrakaran Village, Sangareddy Mandal, Medak Dist-502 329, Telangna, India <em>E-mail</em>: ramadas.chavakula@gmail.com Tyche Industries Limited, H. No. C-21/A, Film Nagar, Jubilee Hills, Hyderabad-500 093, India Department of Engineering Chemistry, Andhra University, Visakhapatnam-530 003, Andhra Pradesh, India <em>Manuscript received online 11 November 2018, revised 01 February 2019, accepted 08 February 2019</em> A green process for demethylation reaction in synthesis of raloxifene hydrochloride by using aluminium c

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9

Liu, Qian, Guan-xin Huang, Min-jie Liu, and Fen-Er Chen. "A Concise Total Synthesis of (±)-Camptothecin." Synthesis 51, no. 18 (2019): 3506–10. http://dx.doi.org/10.1055/s-0037-1611870.

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A total synthesis of racemic camptothecin, characterized by a concise construction of the ring systems and easy functional group transformation, is described. A domino reaction consisting of a Heck reaction and an aza-intramolecular Michael addition to form the C ring serves as the first key step in the synthesis. The D ring was constructed by a simple Wittig–Horner reaction followed by removal of the protective groups. Hydroxymethylation, demethylation, and lactone formation reactions were performed in one-pot to construct the E ring under hydrobromic acid conditions. This work provides an ef

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10

Moreira, Rui, Elba Ochoa, José Pinilla, António Portugal, and Isabel Suelves. "Liquid-Phase Hydrodeoxygenation of Guaiacol over Mo2C Supported on Commercial CNF. Effects of Operating Conditions on Conversion and Product Selectivity." Catalysts 8, no. 4 (2018): 127. http://dx.doi.org/10.3390/catal8040127.

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In this work, a Mo2C catalyst that was supported on commercial carbon nanofibers (CNF) was synthetized and tested in the hydrodeoxygenation (HDO) of guaiacol. The effects of operating conditions (temperature and pressure) and reaction time (2 and 4 h) on the conversion of guaiacol and products selectivity were studied. The major reaction products were cresol and phenol, followed by xylenols and toluene. The use of more severe operating conditions during the HDO of guaiacol caused a diversification in the reaction pathways, and consequently in the selectivity to products. The formation of pheno

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11

Awalt, Jon Kyle, Raymond Lam, Barrie Kellam, Bim Graham, Peter J. Scammells, and Robert D. Singer. "Utility of iron nanoparticles and a solution-phase iron species for the N-demethylation of alkaloids." Green Chemistry 19, no. 11 (2017): 2587–94. http://dx.doi.org/10.1039/c7gc00436b.

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12

Català-Moll, Francesc, Anna G. Ferreté-Bonastre, Tianlu Li, et al. "Activation-induced deaminase is critical for the establishment of DNA methylation patterns prior to the germinal center reaction." Nucleic Acids Research 49, no. 9 (2021): 5057–73. http://dx.doi.org/10.1093/nar/gkab322.

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Abstract Activation-induced deaminase (AID) initiates antibody diversification in germinal center B cells by deaminating cytosines, leading to somatic hypermutation and class-switch recombination. Loss-of-function mutations in AID lead to hyper-IgM syndrome type 2 (HIGM2), a rare human primary antibody deficiency. AID-mediated deamination has been proposed as leading to active demethylation of 5-methycytosines in the DNA, although evidence both supports and casts doubt on such a role. In this study, using whole-genome bisulfite sequencing of HIGM2 B cells, we investigated direct AID involvemen

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13

Kohler, Amanda C., Matthew J. L. Mills, Paul D. Adams, Blake A. Simmons, and Kenneth L. Sale. "Structure of aryl O-demethylase offers molecular insight into a catalytic tyrosine-dependent mechanism." Proceedings of the National Academy of Sciences 114, no. 16 (2017): E3205—E3214. http://dx.doi.org/10.1073/pnas.1619263114.

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Some strains of soil and marine bacteria have evolved intricate metabolic pathways for using environmentally derived aromatics as a carbon source. Many of these metabolic pathways go through intermediates such as vanillate, 3-O-methylgallate, and syringate. Demethylation of these compounds is essential for downstream aryl modification, ring opening, and subsequent assimilation of these compounds into the tricarboxylic acid (TCA) cycle, and, correspondingly, there are a variety of associated aryl demethylase systems that vary in complexity. Intriguingly, only a basic understanding of the least

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14

Rosevear, J., and JFK Wilshire. "Preparation of Some 2-(Methoxyphenyl)-2H-benzotriazoles and the Corresponding Hydroxyphenyl Compounds." Australian Journal of Chemistry 40, no. 10 (1987): 1663. http://dx.doi.org/10.1071/ch9871663.

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The reaction of several substituted o- nitronitrosobenzenes with O- and p- anisidine , and 2,4- dimethoxyaniline in acetic acid gives in good yield the corresponding enitroazobenzenes which are readily reduced with thiourea dioxide ( formamidinesulfinic acid) to the corresponding 2-(methoxypheny1)-2H-benzotriazoles, demethylation of which furnished the corresponding 2- (hydroxypheny1)-2H-benzotriazoles. Demethylation of the dimethoxy derivatives was best accomplished with boron tribromide in methylene chloride, the methoxy group located ortho to the benzotriazole ring being demethylated more r

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15

Mingyi, Wang, Yang Hongfang, Wu Anxin, and Pan Xinfu. "Facile Total Synthesis of Isopregomisin." Journal of Chemical Research 23, no. 2 (1999): 158–59. http://dx.doi.org/10.1177/174751989902300246.

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Isopregomisin, a diarylbutane-lignan, has been synthesized by a short and efficient route starting from pyrogallol; the synthesis involves a novel selective demethylation reaction and the coupling reaction of the Grignard reagent produced from an aryl bromopropane with ( E)-2- tert-butyl-3-phenyloxaziridine.

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16

Uk, Kim Chong, Karel Jeřábek, Zdeněk Prokop, and Karel Setínek. "Kinetics of ethylbenzene hydrogenolytic dealkylation on Ni-Al2O3 catalyst." Collection of Czechoslovak Chemical Communications 54, no. 2 (1989): 316–20. http://dx.doi.org/10.1135/cccc19890316.

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Kinetic equation was found for dealkylation of ethylbenzene at the presence of hydrogen on a Ni-Al2O3 catalyst at 330 °C which indicates a complicated course of this vapor phase catalytic reaction. Similar character of reaction course showed also the demethylation of toluene on the same kind of catalyst and at the same reaction conditions. These results differ from results obtained for this reaction previously.

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17

Florio, S., and L. Troisi. "Reaction of bistrimethylsilylperoxide with 2-benzothiazolylalkyllithiums: An unprecedented demethylation." Tetrahedron Letters 30, no. 28 (1989): 3721–24. http://dx.doi.org/10.1016/s0040-4039(01)80493-7.

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18

Chan, Anthony T. C., Qian Tao, Keith D. Robertson, et al. "Azacitidine Induces Demethylation of the Epstein-Barr Virus Genome in Tumors." Journal of Clinical Oncology 22, no. 8 (2004): 1373–81. http://dx.doi.org/10.1200/jco.2004.04.185.

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PurposeTo determine whether therapy with a DNA methyltransferase inhibitor is effective in achieving demethylation and gene re-expression in tumor DNA in patients.MethodsBiopsy specimens were obtained from patients with Epstein-Barr virus-associated tumors, enrolled on a clinical trial of 5-azacitidine, within 72 hours of the conclusion of the last infusion of the first cycle of therapy, and compared to pretreatment specimens. Methylation-specific polymerase chain reaction, bisulfite genomic sequencing, and immunohistochemistry were used to assess demethylation and gene re-expression.ResultsSu

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19

Satsuma, Koji, Minoru Masuda, and Kiyoshi Sato. "O-Demethylation and Successive Oxidative Dechlorination of Methoxychlor by Bradyrhizobium sp. Strain 17-4, Isolated from River Sediment." Applied and Environmental Microbiology 78, no. 15 (2012): 5313–19. http://dx.doi.org/10.1128/aem.01180-12.

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ABSTRACTO-Demethylation of insecticide methoxychlor is well known as a phase I metabolic reaction in various eukaryotic organisms. Regarding prokaryotic organisms, however, no individual species involved in such reaction have been specified and characterized so far. Here we successfully isolated a bacterium that mediates oxidative transformation of methoxychlor, includingO-demethylation and dechlorination, from river sediment. The isolate was found to be closely related toBradyrhizobium elkaniiat the 16S rRNA gene sequence level (100% identical). However, based on some differences in the physi

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20

Wigle, Tim J., Kerren K. Swinger, John E. Campbell, et al. "A High-Throughput Mass Spectrometry Assay Coupled with Redox Activity Testing Reduces Artifacts and False Positives in Lysine Demethylase Screening." Journal of Biomolecular Screening 20, no. 6 (2015): 810–20. http://dx.doi.org/10.1177/1087057115575689.

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Demethylation of histones by lysine demethylases (KDMs) plays a critical role in controlling gene transcription. Aberrant demethylation may play a causal role in diseases such as cancer. Despite the biological significance of these enzymes, there are limited assay technologies for study of KDMs and few quality chemical probes available to interrogate their biology. In this report, we demonstrate the utility of self-assembled monolayer desorption/ionization (SAMDI) mass spectrometry for the investigation of quantitative KDM enzyme kinetics and for high-throughput screening for KDM inhibitors. S

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21

Blaim, K., and R. Ciszewska. "Badania procesu demetylacji nikotyny w warunkach in vivo [Investigations of nicotine demethylation process in vivo]." Acta Agrobotanica 26, no. 2 (2015): 303–9. http://dx.doi.org/10.5586/aa.1973.028.

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Investigations were carried out on intact leaves of <i>Nicotiana alata</i> which contain practically not alkaloids. Whey these leaves are infiltrated with nicotine it undergoes some chemical changes rather quickly. After introducing the nicotine into the leaves the alkaloid composition was investigated in three day intervals after the infiltration was stopped. No oxynicotine was present in the investigated material. The formation of nornicotine was determined quantitatively in outer and internal layers of the leaf blade. On the basis of these results determination of order and rate

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22

Nakano, Yuji, G. Paul Savage, Simon Saubern, Peter J. Scammells, and Anastasios Polyzos. "A Multi-Step Continuous Flow Process for the N-Demethylation of Alkaloids." Australian Journal of Chemistry 66, no. 2 (2013): 178. http://dx.doi.org/10.1071/ch12463.

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Dextromethorphan was N-demethylated using the non-classical Polonovski reaction under continuous flow conditions, in two steps: initial N-oxidation with m-chloroperbenzoic acid followed by iron-catalysed N-demethylation of the resulting N-oxide.

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23

Wang, Miao, Yadong Zhao, and Jiebing Li. "Demethylation and other modifications of industrial softwood kraft lignin by laccase-mediators." Holzforschung 72, no. 5 (2018): 357–65. http://dx.doi.org/10.1515/hf-2017-0096.

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Abstract Substitution of phenol in phenol-formaldehyde (PF) resin preparations by technical lignins is hindered by the inherently lower reactivity of lignin compared to phenol. Demethylation of an industrial softwood kraft lignin (SKL) to improve its reactivity is the focus of this paper. To this purpose, kraft lignin (KL) was treated with two commercial laccases, NS51002 (L1) and NS51003 (L2), for 24 h in combination with three mediators, 2,2′-azinobis-(3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1-hydroxybenzotriazole (HBT) and 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)

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24

Dai, Ziru, Guibo Sun, Jiada Yang, et al. "Interspecies Variation in NCMN-O-Demethylation in Liver Microsomes from Various Species." Molecules 24, no. 15 (2019): 2765. http://dx.doi.org/10.3390/molecules24152765.

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NCMN (N-(3-carboxy propyl)-4-methoxy-1,8-naphthalimide), a newly developed ratiometric two-photon fluorescent probe for human Cytochrome P450 1A (CYP1A), shows the best combination of specificity and reactivity for real-time detection of the enzymatic activities of CYP1A in complex biological systems. This study aimed to investigate the interspecies variation in NCMN-O-demethylation in commercially available liver microsomes from human, mouse, rat, beagle dog, minipig and cynomolgus monkey. Metabolite profiling demonstrated that NCMN could be O-demethylated in liver microsomes from all species

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25

Sun, Yujun, Michael Fenster, Annie Yu, Richard M. Berry, and Dimitris S. Argyropoulos. "The effect of metal ions on the reaction of hydrogen peroxide with Kraft lignin model compounds." Canadian Journal of Chemistry 77, no. 5-6 (1999): 667–75. http://dx.doi.org/10.1139/v99-036.

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Peroxide bleaching is significantly affected by transition and alkaline earth metals. Isolating the effects of different transition and alkaline earth metals on the reactions of peroxide with different representative lignin structures allows the separation of the positive from the negative contributions of these metal ions. In this work, five monomeric or dimeric phenolic lignin model compounds were treated with alkaline hydrogen peroxide in the absence or presence of Mn2+, Cu2+, Fe3+, and Mg2+. We followed the disappearance of the starting material and the progress of demethylation, radical c

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26

Khandapu, Bala Murali Krishna, Baby Ramana Mutchu, Vijaya Durga Thripuram, et al. "Reaction of O-methylated flavones with semicarbazide: Serendipitous selective demethylation." Organic Communications 11, no. 2 (2018): 116–22. http://dx.doi.org/10.25135/acg.oc.44.18.02.068.

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27

Bhutani, Kamlesh K., and Raj M. Vaid. "An unusual oxidative demethylation reaction of conessine with N-bromosuccinimide." Tetrahedron Letters 29, no. 3 (1988): 359–60. http://dx.doi.org/10.1016/s0040-4039(00)80095-7.

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28

Stecca, Claudine, Jean Cumps, and Martine Duverger-Van Bogaert. "Enzymic N-demethylation reaction catalysed by red blood cell cytosol." Biochemical Pharmacology 43, no. 2 (1992): 207–11. http://dx.doi.org/10.1016/0006-2952(92)90279-r.

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29

Sato, Nobuhiro, and Hiroyuki Endo. "Methylation of Phenolic Hydroxyl Group and Demethylation of Anisoles." Journal of Chemical Research 2009, no. 4 (2009): 229–30. http://dx.doi.org/10.3184/030823409x431328.

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A mild methylation of phenolic hydroxyl groups with iodomethane was enabled in the presence of sodium bis(trimethylsilyl)amide at room temperature. The reverse reaction, namely demethylation of methyl phenyl ethers, was easily achieved by microwave heating with neat iodotrimethylsilane.

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30

Hu, Jianan, Mini Sajan, and Arun P. Kulkarni. "Lipoxygenase-Mediated N-Demethylation of Imipramine and Related Tricyclic Antidepressants in the Presence of Hydrogen Peroxide." International Journal of Toxicology 18, no. 4 (1999): 251–57. http://dx.doi.org/10.1080/109158199225404.

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In this study, we examined the ability of soybean lipoxygenase to mediate the N-demethylation of imipramine and related drugs in the presence of hydrogen peroxide. Formaldehyde generation resulting from the N-demethylation of imipramine, a prototype drug, was found to depend on incubation time, and the concentration of the enzyme, imipramine, and hydrogen peroxide. Under optimal assay conditions, Vmax values of 14 to 18 nmol formaldehyde/min/nmol enzyme or 133 to 164 nmol formaldehyde/min/mg protein were observed. An inhibition of formaldehyde and desipramine formation by nordihydroguaiaretic

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Wang, Yafen, Chaoxing Liu, Xiong Zhang, et al. "Gene specific-loci quantitative and single-base resolution analysis of 5-formylcytosine by compound-mediated polymerase chain reaction." Chemical Science 9, no. 15 (2018): 3723–28. http://dx.doi.org/10.1039/c8sc00493e.

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Urmann, Corinna, and Herbert Riepl. "Semi-Synthetic Approach Leading to 8-Prenylnaringenin and 6-Prenylnaringenin: Optimization of the Microwave-Assisted Demethylation of Xanthohumol Using Design of Experiments." Molecules 25, no. 17 (2020): 4007. http://dx.doi.org/10.3390/molecules25174007.

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The isomers 8-prenylnaringenin and 6-prenylnaringenin, both secondary metabolites occurring in hops, show interesting biological effects, like estrogen-like, cytotoxic, or neuro regenerative activities. Accordingly, abundant sources for this special flavonoids are needed. Extraction is not recommended due to the very low amounts present in plants and different synthesis approaches are characterized by modest yields, multiple steps, the use of expensive chemicals, or an elaborate synthesis. An easy synthesis strategy is the demethylation of xanthohumol, which is available due to hop extraction

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Tretyn, Andrzej, Wiesława Bobkiewicz, Małgorzata Tretyn, and Leszek Michalski. "The identification of acetylcholine and choline in oat seedlings by gas chromatography and nuclear magnetic resonance (NMR)." Acta Societatis Botanicorum Poloniae 56, no. 3 (2014): 499–511. http://dx.doi.org/10.5586/asbp.1987.046.

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Four methods of isolation and purification of choline esters from green 7-day-old oat ( <em>Avena sativa</em> L. cv. Diadem) seedlings were tested The results showed that the best recovery of acetylcholine and choline from plant tissues was obtained using an extraction solution composed of 15% 1N formic acid and 85%, acetone followed by precipitation of both these substances with ammonium reineckate. The presence of acetylcholine and choline in the plant extracts was confirmed by nuclear magnetic resonance (NMR) and gas chromatography. In the case of gas chromatography, after isola

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Jílek, Jiří, Jiří Holubek, Emil Svátek, Jiří Schlanger, Josef Pomykáček, and Miroslav Protiva. "Highly polar potential metabolites of the neuroleptic agent oxyprothepin: Synthesis of 2-hydroxy-8-methylsulfonyl and 3-hydroxy-8-methylsulfonyl derivatives of 10-[4-(3-hydroxypropyl)piperazino]-10,11-dihydrodibenzo[b,f]thiepin." Collection of Czechoslovak Chemical Communications 50, no. 2 (1985): 519–37. http://dx.doi.org/10.1135/cccc19850519.

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The acid XI, obtained by reaction of (2-iodo-5-methoxyphenyl)acetic acid with 4-(methylsulfonyl)thiophenol (VIII) in dimethylformamide in the presence of potassium carbonate and copper, was transformed via intermediates XIIa-XIVa to compound XVa. Demethylation with boron tribromide afforded compound III, the potential metabolite of oxyprothepin (II). Its oxidation with hydrogen peroxide in acetic acid gave the sulfoxide XVII, which is a further potential metabolite. A reaction of 2-iodo-4-methoxybenzoic acid with VIII and potassium carbonate in dimethylformamide in the presence of copper affor

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35

Kimura, Yuki, Ryo Kato, Kin-ichi Oyama, Tadao Kondo, and Kumi Yoshida. "Efficient Preparation of Various O-Methylquercetins by Selective Demethylation." Natural Product Communications 11, no. 7 (2016): 1934578X1601100. http://dx.doi.org/10.1177/1934578x1601100722.

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penta-O-Methylquercetin (2) was prepared by permethylation of quercetin (1). Selective demethylation of 2 using either BBr3 or BCl3/TBAI ( tetra-butylammonium iodide) gave five O-methylquercetins (3-6), with satisfactory yields. The reaction can be easily scaled-up. We established an efficient and large-scale preparation of O-methylquercetins.

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Wang, Dao Wu, Xiao Long Li, Xin Xia Feng, Jin Long Zheng, and Long Zhang. "Synthesis of Tetrahydropalmatine." Advanced Materials Research 850-851 (December 2013): 1193–96. http://dx.doi.org/10.4028/www.scientific.net/amr.850-851.1193.

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Tetrahydropalmatine in overall yield of 18% was synthesized from alkaloids in Coptids Rhizoma with the similar structure of isoquinoline by a three-step reaction of alkaloids preparation, demethylation or demethylene-dioxy, deoxidation, methylation and so on. The structure was confirmed by 1H-NMR IR and ESI-MS.

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Kuang, Chunxiang, Rong Wang, Menghan Cui, and Qing Yang. "A Facile Total Synthesis of Mubritinib." Synthesis 53, no. 05 (2021): 978–82. http://dx.doi.org/10.1055/a-1351-2370.

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AbstractA five-step, practical, and concise total synthesis of mubritinib is described. The synthesis utilized Friedel–Crafts acylation, click reaction, reduction, and demethylation for the construction of the triazole ring system as key steps. Another important feature of this synthesis is the Bredereck oxazole synthesis. The main advantages of this process are the improved yield and decreased number of reaction steps, which paves the way for the industrial-scale synthesis of mubritinib.

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38

Rajput, Santosh, Valerio Falasca, Mohan Bhadbhade, David StC Black, and Naresh Kumar. "Synthesis and Anticancer Activity of 3,4-Diaryl-1,2-dihydro- and 1,2,3,4-Tetrahydroquinolines." Molecules 29, no. 17 (2024): 4273. http://dx.doi.org/10.3390/molecules29174273.

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Tetrahydroquinolines are key structures in a variety of natural products with diverse pharmacological utilities and other applications. A series of 3,4-diaryl-5,7-dimethoxy-1,2,3,4-tetrahydroquinolines were synthesized in good yield by reacting 3-aryl-5,7-dimethoxy-2,3-dihydroquinolin-4-ones with different Grignard reagents followed by the dehydration of the intermediate phenolic compounds. Subsequent reduction and deprotection were carried out to achieve the desired tetrahydroquinolone moiety. The lead compound 3c showed low micromolar inhibition of various cancer cell lines. Demethylation un

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39

Chavan, Arun B., Sanjeev M. Reddy, and G. Krishna Chaitanya. "Elucidating Reaction Mechanism of Gefitinib- An Anticancer Drug by Computational Technique." Oriental Journal Of Chemistry 40, no. 3 (2024): 835–40. http://dx.doi.org/10.13005/ojc/400327.

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The present investigation centres on the application of quantum chemistry to clarify the innovative synthetic pathway for Gefitinib derived from methyl 2-isocyano-4,5-dimethoxybenzoate. This pathway encompasses various chemical reactions such as cyclization, halogenation, regioselective demethylation, Williamson's ether synthesis, and nucleophilic aromatic substitution. The reaction necessitates the presence of four intermediate species and yields a total of 11 transition states [TS]. The energies of each reactant, intermediate, and product were determined through the utilisation of density fu

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40

Capanema, E. A., M. Y. Balakshin, C. L. Chen, J. S. Gratzl, and A. G. Kirkman. "Oxidative Ammonolysis of Technical Lignins. Part 3. Effect of Temperature on the Reaction Rate." Holzforschung 56, no. 4 (2002): 402–15. http://dx.doi.org/10.1515/hf.2002.063.

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Summary The effect of the reaction temperature on the kinetics and the reaction mechanism of oxidative ammonolysis of Repap organosolv lignin have been studied. The reaction was conducted in 0.8 M Nh4oh solution under oxygen pressure of 12 bar and at three different temperatures, 70 °C, 100 °C and 130 °C. The resulting N-modified lignins were analyzed by elemental and methoxyl group. About 20–25% of maximum nitrogen content is incorporated into the lignin very fast, in 1–2 min of the reaction. The reaction kinetics then follows a pseudo-first order reaction law and consists of two phases. The

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41

Stenmark, Heather G., Antony Brazzale, and Zhenkun Ma. "Biomimetic Synthesis of Macrolide/Ketolide Metabolites through a SelectiveN-Demethylation Reaction." Journal of Organic Chemistry 65, no. 12 (2000): 3875–76. http://dx.doi.org/10.1021/jo000055j.

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42

Nagieb, Z. A. "Demethylation of thiolignin by reaction with potassium dichromate ? a kinetic study." Wood Science and Technology 19, no. 3 (1985): 233–42. http://dx.doi.org/10.1007/bf00392052.

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43

Clezy, PS, MW Duncan, and GA Smythe. "Preparation of a Deuterated Analog of Tetrahydropapaveroline Suitable for Use as an Internal Standard for G.C./M.S. Analysis of This Alkaloid: Retro Pictet-Spengler Condensation." Australian Journal of Chemistry 41, no. 4 (1988): 483. http://dx.doi.org/10.1071/ch9880483.

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Attempts to prepare deuterated analogues of salsolinol and tetrahydropapaveroline by exchange procedures in D2O have demonstrated that the Pictet-Spengler reaction is a reversible process. Tetrahydropapaveroline can be readily obtained from papaverine by reduction with Zn/HCl followed by demethylation in a process which can conveniently be adapted to produce a (2H3)analogue.

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44

Koroleva, Polina I., Andrei A. Gilep, Sergey V. Kraevsky, Tatiana V. Tsybruk, and Victoria V. Shumyantseva. "Improving the Efficiency of Electrocatalysis of Cytochrome P450 3A4 by Modifying the Electrode with Membrane Protein Streptolysin O for Studying the Metabolic Transformations of Drugs." Biosensors 13, no. 4 (2023): 457. http://dx.doi.org/10.3390/bios13040457.

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In the present work, screen-printed electrodes (SPE) modified with a synthetic surfactant, didodecyldimethylammonium bromide (DDAB) and streptolysin O (SLO) were prepared for cytochrome P450 3A4 (CYP3A4) immobilization, direct non-catalytic and catalytic electrochemistry. The immobilized CYP3A4 demonstrated a pair of redox peaks with a formal potential of −0.325 ± 0.024 V (vs. the Ag/AgCl reference electrode). The electron transfer process showed a surface-controlled mechanism (“protein film voltammetry”) with an electron transfer rate constant (ks) of 0.203 ± 0.038 s−1. Electrochemical CYP3A4

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45

Kurasz, Karolina, Joanna Rzeszowska-Wolny, Ryszard Oliński, Marek Foksiński, and Krzysztof Fujarewicz. "The Role of Different TET Proteins in Cytosine Demethylation Revealed by Mathematical Modeling." Epigenomes 8, no. 2 (2024): 18. http://dx.doi.org/10.3390/epigenomes8020018.

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In living cells, some reactions can be conducted by more than one enzyme and sometimes it is difficult to establish which enzyme is responsible. Such is the case with proteins from the TET family, capable of converting 5-methyl-2’-deoxycytidine (5-mdC) in DNA to 5-(hydroxymethyl)-2’-deoxycytidine (5-hmdC) and further to 5-formyl-2’-deoxycytidine (5-fdC) and 5-carboxy-2’-deoxycytidine (5-cadC). The estimation of the efficiency of particular TETs in particular oxidative reactions and different cell types is important but experimentally difficult. Here, we propose an approach with mathematical mo

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46

Buncel, Erwin. "1999 R.U. Lemieux Award Lecture Adventures with azo-, azoxy-, and hydrazoarenes: from the Wallach to the benzidine rearrangement. Molecular electronics." Canadian Journal of Chemistry 78, no. 10 (2000): 1251–71. http://dx.doi.org/10.1139/v00-126.

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The author's studies with aromatic azo-, azoxy-, and hydrazo-dye molecules, comprising kinetic and equilibrium investigations, as well as synthesis of novel molecules having photogenic properties, are described under the following highlights: A. Wallach rearrangement and cognate studies with azoxyarenes (1) Elucidation of the mechanism of the Wallach rearrangement of azoxybenzene through the kinetic observation of a two-proton process which, together with a pKa study, was interpreted on the basis of formation of a deoxygenated, dicationic, symmetrical species as a key, short-lived reaction i

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47

Wei, Xianfeng, Xuelong Hu, Rilei Yu, Shengbiao Wan, and Tao Jiang. "Efficient Total Synthesis of Lissodendrin B, 2-Aminoimidazole Marine Alkaloids Isolated from Lissodendoryx (Acanthodoryx) fibrosa." Marine Drugs 18, no. 1 (2019): 36. http://dx.doi.org/10.3390/md18010036.

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Lissodendrin B is a 2-aminoimidazole alkaloid bearing a (p-hydroxyphenyl) glyoxal moiety that was isolated from the Indonesian sponge Lissodendoryx (Acanthodoryx) fibrosa. We reported the first efficient total synthesis of Lissodendrin B. The precursor 4,5-disubstituted imidazole was obtained through Suzuki coupling and Sonogashira coupling reactions from 4-iodoimidazole. C2-azidation and reduction of the azide then provided the core structures of Lissodendrin B. Subsequent triple-bond oxidation, demethylation, and deacetylation gave the final product. The synthesis approach consists of ten st

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48

Červená, Irena, Jiří Holubek, Emil Svátek, and Miroslav Protiva. "Potential antidepressants: 4-(Aminoalkoxy)thioxanthones." Collection of Czechoslovak Chemical Communications 53, no. 6 (1988): 1307–16. http://dx.doi.org/10.1135/cccc19881307.

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Four different approaches were used for preparing a series of the title compounds. Reactions of the sodium salt of 4-hydroxythioxanthone (V) with dimethylaminoalkyl chlorides gave the ethers VI and VII. Partial demethylation of VII via the carbamate IX afforded the secondary amine VIII. Reactions of the 4-bromobutoxy compound XI with amines resulted in II, XII, and XIII. Reaction of V with 1-chloro-2,3-epoxypropane and the following treatment of the resulting XIV with 2-propanamine gave the amino alcohol XV. The xanthone III was obtained via XVIII similarly like II. The products, especially II

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49

Wang, Qian, Xia-li Liao, Cheng Xiang, and Jian Yang. "A Practical Synthesis of the Flavone, Scutellarein." Journal of Chemical Research 41, no. 3 (2017): 157–59. http://dx.doi.org/10.3184/174751917x14873588907765.

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A practical and economical five-step synthesis of the flavone scutellarein has been achieved in 60% overall yield using the available and cheap 2,6-dimethoxy-1,4-benzoquinone as starting material. The reaction sequence involved reduction to the corresponding quinol, Friedel-Crafts acetylation, Claisen-Schmidt condensation with p-methoxybenzaldehyde, cyclisation and demethylation. The procedure is operationally simple and amenable to scale-up synthesis.

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HARDEO, N. SINGH, and PRASAD SINGH RAMAYAN. "A New Synthesis of a Naturally Occurring lsocoumarin. 3,4-Dimethyl-8-hydroxyisocoumarin (Oospolactone)." Journal of Indian Chemical Society Vol. 65, Oct 1988 (1988): 685–87. https://doi.org/10.5281/zenodo.6076346.

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Department of Chemistry, Bhagalpur University, Bhagalpur-812 007 <em>Manuscript received 13 May 1988, accepted 8 July 1988</em> 3,4-Dimethyl-8-methoxyisochroman (5a) on oxidation furnishes 3,4-dimethyl-8- methoxy-3,4-dihydroisocoumarin (6a), and demethylated with hydriodic acid to 3,4- dimethyl-8-hydroxy-3,4-dihydroisocoumarin (7a). Treatment of 6a with<em> N</em>-bromosuccinimide followed by refluxing with triethylamine furnishes 3 4-dimethyl-8-methoxyisocoumarin (8a) which on demethylation with hydriodic acid yields 3,4-dimethyl-8-hydroxyisocoumarin (oospolactone) (9a) Compound 5a and 3,4-dl

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