Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• well-established reactions (Scheme 2). The indanone is formed by intramolecular Friedel–Crafts acylation of 2 under microwave radiation as reported by Oliverio et al. [23]. The second step is the demethylation of indanone methyl ether 3 by aluminium trichloride in toluene at reflux [24]. Two indanone

Synthesis and properties of sulfur-functionalized triarylmethylium, acridinium and triangulenium dyes

• Marco Santella,
• Eduardo Della Pia,
• Jakob Kryger Sørensen and
• Bo W. Laursen

Beilstein J. Org. Chem. 2019, 15, 2133–2141, doi:10.3762/bjoc.15.210

• groups by one primary amine gives acridinium-type ring systems (Figure 2, step 2) and is a key reaction for the formation of the unsubstituted triangulenium dyes shown in Figure 1b [19][20]. Finally, formation of oxygen bridges in the triangulenium system (Figure 2, step 3) involves demethylation

Synthesis and biological evaluation of truncated derivatives of abyssomicin C as antibacterial agents

• Leticia Monjas,
• Peter Fodran,
• Johanna Kollback,
• Carlo Cassani,
• Thomas Olsson,
• Maja Genheden,
• D. G. Joakim Larsson and
• Carl-Johan Wallentin

Beilstein J. Org. Chem. 2019, 15, 1468–1474, doi:10.3762/bjoc.15.147

• . Accordingly, structure–activity relationship (SAR) studies have been performed, which indicate that benzylation of the hydroxy group and the complete demethylation of the core structure of AbC retain the antibiotic activity towards MRSA while simultaneously decrease cytotoxicity towards various human cell

Fluorine-containing substituents: metabolism of the α,α-difluoroethyl thioether motif

• Andrea Rodil,
• Alexandra M. Z. Slawin,
• Nawaf Al-Maharik,
• Ren Tomita and
• David O’Hagan

Beilstein J. Org. Chem. 2019, 15, 1441–1447, doi:10.3762/bjoc.15.144

• with demethylation following subsequently at a slower rate. The experiments on the re-incubation of phenols 7 and 8 failed to lead to any further metabolism, where they appeared to be stable metabolites, certainly for the period (72 h) of the incubation. We were unable to observe a transformation from

• oxidation of thioether 4. This sulfone was then incubated with C. elegans and it gave rise to demethylated phenol 8 as the sole metabolite, consistent with an active demethylation capacity of this fungus. Non-oxidised phenol 10 was also not observed in this study. Overall this suggests that sulfoxidation is

• very active and outcompetes demethylation, however, that demethylation is significantly more active that the second oxidation of sulfoxides to sulfones. Incubation of naphthalene 5 with C. elegans, generated three new metabolites 11–13 which arose by oxidations at sulphur and hydroxylations of the

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• instability of the adduct under acidic conditions during ODN synthesis [7]. In recent years, applications of ODNs have extended to emerging areas such as nanotechnology [8][9], antisense drug development [10][11][12], DNA damage and repair [13][14], DNA methylation and demethylation [15][16][17][18], DNA

Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks

• Clémence Moitessier,
• Ahmad Rifai,
• Pierre-Edouard Danjou,
• Isabelle Mallard and
• Francine Cazier-Dennin

Beilstein J. Org. Chem. 2019, 15, 721–726, doi:10.3762/bjoc.15.67

• the addition of a protecting step of the unstable key intermediate 4,5-dihydroisobenzofuran-5-ol. Oxidation and deprotection steps were also studied in order to provide an effective availability of these two dialdehyde compounds that may increase their future applications. Keywords: demethylation

• -hydroxy-ortho-phthalaldehyde (6) through MAOS demethylation of 4-methoxy-ortho-phthalaldehyde (5b). Protection of 4,5-dihydroisobenzofuran-5-ol (3). Ratio quantity of OPA formed during the oxidation of 5-substituted-4,5-dihydroisobenzofuran-5-ol on SeO2 or DDQ. Supporting Information Supporting

Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• product 30 carrying an 8-OPMP group was obtained from PMP-protected polyketide 28. The endgame of a total synthesis of seragamide A (2) will have to address the macrocyclisation, desilylation of the threonine moiety, and O-demethylation of the D-iodotyrosine unit of 31. In orienting reactions on small

A novel and practical asymmetric synthesis of eptazocine hydrobromide

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan,
• Kuaile Lin and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• acetic acid gave compound 8 in 83% yield. Eventually, target compound 1 was obtained from 8 via demethylation with 48% aqueous HBr solution. Conclusion In summary, we developed a new and efficient synthesis of eptazocine hydrobromide involving enantioselective phase-transfer catalyzed alkylation of 1

The enzymes of microbial nicotine metabolism

• Paul F. Fitzpatrick

Beilstein J. Org. Chem. 2018, 14, 2295–2307, doi:10.3762/bjoc.14.204

• oxidative demethylation of 4-(methoxymethyl)phenols via a quinone methide intermediate [28][29]. Based on this precedent and the assumption that DHNO oxidizes the C2–C3 bond, Koetter and Schultz [27] proposed the mechanism shown in Scheme 5 for DHNO. However, members of the p-cresol methylhydroxylase

• , no mechanistic studies have been reported. Two pathways have been identified for further metabolism of N-methylaminobutyrate. pAO1 contains separate genes for enzymes catalyzing the oxidative demethylation of N-methylaminobutyrate to form 4-aminobutyrate, mabo, and its oxidative deamination to form

• it contains covalently-bound FAD and produces hydrogen peroxide as a product in addition to 4-aminobutryate [5][38]. Mabo also catalyzes the oxidative demethylation of sarcosine. Based on these results, the mechanism of the enzyme is similar to that of sarcosine oxidase, direct oxidation of the C–N

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• respective sulfuranyl radical. Subsequent oxidation closes the catalytic cycle and generates a sulfur-centred cation. Finally, demethylation affords the desired substituted benzothiophene. In 2016, Yuan and co-workers developed a different synthesis of benzothiophenes (Scheme 36) [71]. They found, that a

• radical, which cyclizes to the respective sulfuranyl radical. Oxidation of this intermediate by the radical cation of the superbase closes the electron transfer cycle. Rearomatization of the benzothiophene proceeds via demethylation, accomplished by a hydroxide anion. They were able to perform the

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• observed demethylation of the methoxy group at C-6. Dauriporphinoline (5) was synthesized in 58% yield using the same protocol starting from the methyl ester 10b, once again under hydrolysis of the 6-methoxy group. In order to explore the scope of this new cyclization methodology, we further investigated

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• points out the high reactivity of the intermediate dicationic species D. The formation hydroxy-substituted oxadiazoles 2g (Table 2, entry 11), 2o and 2p (Table 2, entry 20), 2w (Table 2, entry 25), and 2x (Table 2, entry 26) may be explained by demethylation of the corresponding methoxy group under

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• efficient synthesis of (±)-xanthorrhizol (8) [39]. The authors prepared the intermediate 7 by dialkylation of 6 and attempted to carry out a one-pot decyanation and demethylation [40] with a suspension of lithium in THF. The target compound 8 was obtained in 74% yield together with 24% of the byproduct 9

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• )pyridine (3) [43] with 2-methoxy-6-bromomethylnaphthalene (4) [44] gave the corresponding (naphthylmethyl)pyridinium bromide 5 in 62% yield. Subsequent treatment of this intermediate with aq HBr (48%) led to acid-catalyzed cyclization and elimination of water, as well as to demethylation of the ether group

Symmetry-based approach to oligostilbenoids: Rapid entry to viniferifuran, shoreaphenol, malibatol A, and diptoindonesin G

• Youngeun Jung,
• Dileep Kumar Singh and
• Ikyon Kim

Beilstein J. Org. Chem. 2016, 12, 2689–2693, doi:10.3762/bjoc.12.266

• diptoindonesin G, a potent cytotoxic and immunosuppressant agent [16][17], by using a highly efficient domino cyclodehydration/intramolecular Friedel–Crafts acylation/regioselective demethylation sequence as a key transformation. Very recently, a dual functional role of diptoindonesin G in modulating α and β

Synthesis of medronic acid monoesters and their purification by high-performance countercurrent chromatography or by hydroxyapatite

• Elina Puljula,
• Jouko Vepsäläinen and
• Petri A. Turhanen

Beilstein J. Org. Chem. 2016, 12, 2145–2149, doi:10.3762/bjoc.12.204

• which one of the methyl groups was removed by selective demethylation with tributylamine. The resulting mono N,N,N,tributyl-N-methylammonium salt of the triester was then refluxed with the desired alkyl tosylate in acetonitrile. The resulting mixed tetraesters 2a–g were purified by column chromatography

Three-component synthesis of highly functionalized aziridines containing a peptide side chain and their one-step transformation into β-functionalized α-ketoamides

• Lena Huck,
• Juan F. González,
• Elena de la Cuesta and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2016, 12, 1772–1777, doi:10.3762/bjoc.12.166

• ether function existent in aziridine derivatives 2 because of the presence of the 2-methoxy substituent would furnish oxonium species 7 via a Neber reaction. Its O-demethylation by the trifluoroacetate anion would yield compound 8, whose amino group would finally be trifluoroacetylated by the methyl

Syntheses of dibenzo[d,d']benzo[2,1-b:3,4-b']difuran derivatives and their application to organic field-effect transistors

• Minh Anh Truong and
• Koji Nakano

Beilstein J. Org. Chem. 2016, 12, 805–812, doi:10.3762/bjoc.12.79

• -isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (iPrO-Bpin) gave boronate ester 7 in 57% yield. Then, terphenyl 9 was synthesized via palladium-catalyzed Suzuki–Miyaura cross coupling of boronate ester 7 with 2,3-difluoro-1,4-diiodobenzene (96% yield) and subsequent demethylation (95% yield). Finally, the

• -ol in two steps according to the literature [23][48], and used for the synthesis of boronate ester 10 (45% yield). The following cross coupling (80% yield), demethylation (85% yield), and the double cyclization (87% yield) gave the target syn-DNBDF 6. The obtained syn-DBBDF 5 is soluble in common

Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• distance and degree of conjugation between the two subunits (Figure 2). DMB was chosen due to its superior stability compared to the hydroquinone counterpart during the synthesis. The corresponding hydroquinone analogue can be achieved by straightforward demethylation with BBr3 [8][9][10]. The electronic

Carbon–carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

• Tsuyuka Sugiishi,
• Hideki Amii,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2015, 11, 2661–2670, doi:10.3762/bjoc.11.286

• [40][41] (Scheme 7). The demethylation of ClCF2CO2Me proceeds by iodide, followed by decarboxylation of the resulting chlorodifluoroacetate to provide difluorocarbene (:CF2), trapped by fluoride to give the CF3− species. This reacts with CuI leading to CF3Cu. The method described above for the

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• of 3,5-dimethylcycloheptatrienecarboxylic acid to 3,5-dimethoxycycloheptatriene, bromination of the latter in chloroform to give β-methoxytropone and its subsequent demethylation [13]. The more general approach to β-tropolone was based on the multistep transformation of 3,4,5-trimethoxybenzoic acid

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• subjected to cerium ammonium nitrate for oxidative demethylation and the amino quinone formed cyclized to afford neoamphimedine (12, Scheme 4) [62]. Two synthetic routes, illustrated in Scheme 2 and Scheme 3, were used to prepare neoamphimedine (12) where the second description was shorter and more

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• , 268 and [2.n]metacyclophane 269 were isolated (61–87%). Finally, demethylation of compound 269 with BBr3 in CH2Cl2 gave cyclophane 270 (Scheme 43). [2 + 2 + 2] Co-trimerization: In 2003, Tanaka and Shirasaka [176] have reported a one-step synthesis of [6]metacyclophane 273 by a [2 + 2 + 2] co

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• diethyl (2-(4-methoxynaphthalen-1-yl)-2-oxoethyl) phosphate (1,4-MNA DEP, 14b, 92%). The hydroxy analog (1,4-HNA DEP, 14a, Scheme 1C), was synthesized from methoxynaphthone 12 by demethylation with thiophenol giving acetylnaphthol 15 in moderate yield (42%). Protection with TBSCl gave 16 (86%) followed by

Relay cross metathesis reactions of vinylphosphonates

• Raj K. Malla,
• Jeremy N. Ridenour and
• Christopher D. Spilling

Beilstein J. Org. Chem. 2014, 10, 1933–1941, doi:10.3762/bjoc.10.201

• 14b. Analysis of the TBAI allylation mechanism suggested that a good approach to mono-allyl phosphonate 14a would be a stoichiometric demethylation followed by a rapid allylation under ambient conditions. During the synthesis of phosphonate based ionic liquids, Sachnov et al. showed that