cas 708-76-9, 4,6-DIMETHOXYSALICYLALDEHYDE

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The synthesis of atalantrenes B, C and D, styrene-dimers from the seeds of Atalantia monophylla
Concise syntheses of three recently reported natural products from Atalantia monophylla are reported. The syntheses required the preparation and careful dimerization of highly electron rich styrenes under acidic conditions. The present work adds to a growing body of evidence that demonstrates that synthetic utility of chiral phosphoric acids in asymmetric reactions using styrene-type compounds.
Nielsen, Alexander J.,Deng, Zirou,McNulty, James
(2020/12/28)

Synthesis and structure-activity relationship studies of hydrazide-hydrazones as inhibitors of laccase from trametes versicolor
A series of hydrazide-hydrazones 1-3, the imine derivatives of hydrazides and aldehydes bearing benzene rings, were screened as inhibitors of laccase from Trametes versicolor. Laccase is a copper-containing enzyme which inhibition might prevent or reduce the activity of the plant pathogens that produce it in various biochemical processes. The kinetic and molecular modeling studies were performed and for selected compounds, the docking results were discussed. Seven 4-hydroxybenzhydrazide (4-HBAH) derivatives exhibited micromolar activity Ki = 24-674 μM with the predicted and desirable competitive type of inhibition. The structure-activity relationship (SAR) analysis revealed that a slim salicylic aldehyde framework had a pivotal role in stabilization of the molecules near the substrate docking site. Furthermore, the presence of phenyl and bulky tert-butyl substituents in position 3 in salicylic aldehyde fragment favored strong interaction with the substrate-binding pocket in laccase. Both 3- and 4-HBAH derivatives containing larger 3-tert-butyl-5-methyl- or 3,5-di-tert-butyl-2-hydroxy-benzylidene unit, did not bind to the active site of laccase and, interestingly, acted as non-competitive (Ki = 32.0 μM) or uncompetitive (Ki = 17.9 μM) inhibitors, respectively. From the easily available laccase inhibitors only sodium azide, harmful to environment and non-specific, was over 6 times more active than the above compounds.
Giurg, Miros?aw,Maniak, Halina,Matyja, Konrad,Talma, Micha?,Trusek, Anna
(2020/03/23)

METHODS OF TREATING CANCER WITH SMALL MOLECULE NF-kB INHIBITORS
The present invention provides, inter alia, compounds capable of inhibiting NF-κB. Pharmaceutical compositions containing and methods of using the compounds are also provided herein. Also provided are methods and kits for treating cancer and solid tumors in a subject, as well as methods and kits for inducing cancer cell death and apoptosis of a cancer cell, all utilizing the NF-κB inhibitors described herein.
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Paragraph 0433

(2019/01/15)

Synthesis and evaluation of methoxy substituted 2-benzoyl-1-benzofuran derivatives as lead compounds for the development adenosine A1 and/or A2A receptor antagonists
A series of fourteen methoxy substituted 2-benzoyl-1-benzofuran derivatives were synthesised and their affinities determined for adenosine A1 and A2A receptors via radioligand binding assays to establish the structure activity relationships pertinent for A1 and A2A affinity. Compound 3j (6,7-dimethoxybenzofuran-2-yl)(3-methoxyphenyl)methanone exhibited A1 affinity (A1Ki (rat) = 6.880 μM) as well as A2A affinity (A2AKi (rat) = 0.5161 μM). Compounds 3a–b & 3i–k exhibited selective affinity towards A1 with Ki values below 10 μM. The results indicate that C6,7-diOCH3 substitution on ring A in combination with meta (C3′)–OCH3 substitution on ring B is beneficial for A1 and A2A affinity and activity. Compounds 3a–b & 3j–k showed low cytotoxicity. Upon in vitro and in silico evaluation, compound 3j may be considered lead-like (i.e. a molecular entity suitable for optimization) and, thus, of value in the design of novel, potent and selective adenosine A1 and A2A receptor antagonists.
Aucamp, Janine,Janse van Rensburg, Helena D.,Legoabe, Lesetja J.,Terre'Blanche, Gisella
(2019/12/25)

An Optimized Preparation of 1,1-Dimethylallyl Esters and Their Application to Solid-Phase Peptide Synthesis
A one-step preparation of 1,1-dimethylallyl (DMA) esters was optimized for the C-terminal protection of a range of Fmoc-protected amino acids. This preparation is not sensitive to the scale of reaction and affords the corresponding DMA esters in 70-99% yield with high regioselectivity. Additionally, these DMA-protected amino acids were used with the backbone amide linker (BAL) of Albericio and Barany and found to resist diketopiperazine formation during the synthesis of a series of tripeptide esters. C-terminal DMA protection is compatible with the BAL linkage and allows for standard Fmoc-based methods to be used throughout the synthesis.
Hostetler, Matthew A.,Lipton, Mark A.
p. 7762 - 7770
(2018/07/05)

SMALL MOLECULE NF-kB INHIBITORS
The present invention provides, inter alia, compounds capable of inhibiting NF-κB. Pharmaceutical compositions containing and methods of using the compounds are also provided herein.
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Paragraph 0123

(2017/07/14)

LATENT ACIDS AND THEIR USE
Compounds of the formula (I) and (IA) wherein X is -O(CO)-; R1 is C1-C12haloalkyl or C6-C10haloaryl; R2 is located in position 7 of the coumarinyl ring and is OR8; R2a, R2b and R2C independently of each other are hydrogen; R3 is C1-C8haloalkyl or C1-C8haloalkyl; R4 is hydrogen; and R8 is C1-C6alkyI; are suitable as photosensitive acid donors in the preparation of photoresist compositions such as used for example in the preparation of spacers, insulating layers, interlayer dielectric films, insulation layers, planarization layers, protecting layers, overcoat layers, banks for electroluminescence displays and liquid crystal displays (LCD).
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Page/Page column 105; 107

(2016/09/22)

Synthesis of Allyl- and Prenylcoumarins via Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination
Allyl, dimethylallyl, crotyl, and prenyl ethers of various aromatic ortho-hydroxy carbonyl compounds undergo a tandem sequence of Claisen rearrangement, carbonyl olefination, and cyclization upon microwave irradiation in the presence of a stabilized ylide. The products are multiply substituted 6- or 8-allylated or prenylated coumarins (2H-chromen-2-ones).
Schmidt, Bernd,Riemer, Martin
supporting information
p. 141 - 149
(2015/12/26)

Tandem Chloropalladation/Cyclization and Dearomative Cyclization toward Functionalized Tricyclic Bridged [3.2.1] Skeleton Compounds
A palladium-catalyzed tandem reaction is reported that involves chloropalladation/cyclization and dearomative cyclization to construct a tricyclic bridged [3.2.1] carbocyclic-skeleton and oxa- and aza-skeletons. In this domino process, a level of ring strain and other competitive reactions, i.e., protonolysis, β-hydride elimination, and chlorination of the C-Pd bond, were suppressed to the lowest level under mild reaction conditions.
Dong, Yi,Du, Nana,Li, Xueyuan,Zheng, Litao,Liu, Gang
supporting information
p. 4110 - 4113
(2015/09/01)

Divergent and concise total syntheses of dihydrochalcones and 5-deoxyflavones recently isolated from Tacca species and Mimosa diplotricha
Dihydrochalcones and 5-deoxyflavones are types of compounds possessing various biologically interesting properties. Herein, we report the concise and divergent total syntheses of several naturally occurring dihydrochalcones and 5-deoxyflavones from readily available starting materials. The divergent strategy is based around manipulation of a common chalcone scaffold and features application of Algar-Flynn-Oyamada oxidation and benzoquinone C-H activation methodologies. These are the first reported total syntheses of these biologically interesting compounds and the concise and flexible route should be readily amenable to future analogue generation. Furthermore, this work provides an illustration of the utility of divergent synthesis for the expedient and step-economical preparation of natural product libraries.
Sum, Tze Han,Sum, Tze Jing,Stokes, Jamie E.,Galloway, Warren R.J.D.,Spring, David R.
p. 4557 - 4564
(2015/06/08)

2H-chromenes generated by an iron(III) complex-catalyzed allylic cyclization
A straightforward method based on an iron(III) complex-catalyzed cyclization of 2-(1-hydroxyallyl)phenols is reported to access a large variety of 2H-chromenes. This method was applied to the total synthesis of a natural product, tephrowatsin B.
Calmus,Corbu,Cossy
supporting information
p. 1381 - 1386
(2015/05/19)

3-KETOCOUMARINES FOR LED PHOTOCURING
The present invention relates to 3-ketocoumarines which can be used as photoinitiators in LED photocuring and to a process for curing compositions comprising said 3-ketocoumarines.
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Paragraph 0099; 0100

(2015/10/05)

Formylation of electron-rich aromatic rings mediated by dichloromethyl methyl ether and TiCl4: Scope and limitations
Here the aromatic formylation mediated by TiCl4 and dichloromethyl methyl ether previously described by our group has been explored for a wide range of aromatic rings, including phenols, methoxy- and methylbenzenes, as an excellent way to produce aromatic aldehydes. Here we determine that the regioselectivity of this process is highly promoted by the coordination between the atoms present in the aromatic moiety and those in the metal core.
Ramos-Tomillero, Iván,Paradís-Bas, Marta,De Pinho Ribeiro Moreira, Ibério,Bofill, Josep María,Nicolás, Ernesto,Albericio, Fernando
supporting information
p. 5409 - 5422
(2015/05/13)

A concise synthesis of viscolin, and its anti-inflammatory effects through the suppression of iNOS, COX-2, ERK phosphorylation and proinflammatory cytokines expressions
In the present report, a concise synthesis of viscolin (1) has been achieved. The anti-inflammatory effect of viscolin was investigated in vitro and in vivo. Viscolin blocked the expression of iNOS and COX-2, and it also inhibited the ERK for the activation of NF-κB in LPS-stimulated RAW 264.7 macrophages. Western blotting and immunohistochemical analysis revealed that viscolin decreased Carr-induced iNOS and COX-2 expressions. These results could help to deduce the anti-inflammatory mechanisms.
Huang, Guan-Jhong,Bhaskar Reddy, M. Vijaya,Kuo, Ping-Chung,Huang, Chieh-Hung,Shih, Hung-Cheng,Lee, E.-Jian,Yang, Mei-Lin,Leu, Yann-Lii,Wu, Tian-Shung
experimental part
p. 371 - 378
(2012/03/26)

Synthetic Flavonoids and Pharmaceutical Compositions and Therapeutic Methods of Treatment of HIV infection and other pathologies
A compound, pharmaceutical composition and method for the treatment of mammals wherein the active therapeutic agent is a compound having the structure: wherein: R1 is an electronegative substituent, R2 is R1 or alkyl,R3 is H or O-alkyl,R4 and R5 are the same or different and are alkyl andR6 is H or OH.
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Page/Page column 4

(2012/10/23)

2,2,4,6,7-Pentamethyl-2,3-dihydrobenzofuran-5-methyl (Pbfm) as an alternative to the trityl group for the side-chain protection of cysteine and asparagine/glutamine
The benzyl derivative of the Pbf group, which is the most commonly used side-chain protecting group for Arg, has been proposed for the protection of the side chains of Cys, Asp, and Glu. In the three cases, the new protecting group (Pbfm) was removed with a high concentration of TFA during the cleavage and global deprotection step. In addition, the Pbfm group can be removed from the Cys residue by using very dilute TFA solutions. Furthermore, when Cys is protected with the Pbfm group, it can be removed by oxidative treatment, thereby directly rendering the disulfide bridge on the solid phase.
Garcia, Oscar,Bofill, Josep M.,Nicolas, Ernesto,Albericio, Fernando
experimental part
p. 3631 - 3640
(2010/08/22)

Formylation of activated arenes by phenyl formate: Implications for the mechanism of the Fries rearrangement of aryl formates
We present an NMR and DFT investigation of the reaction of phenyl formate with 3-methoxyphenol and 3,5-dimethoxyphenol with excess BCl3. The products obtained (3-methoxy- and 3,5-dimethoxy-salicylaldehyde, respectively) are the same as those resulting from the Fries rearrangement of 3-methoxy- and 3,5-dimethoxy-phenyl formate. These results represent a novel regioselective synthetic route to aromatic aldehydes, using phenyl formate as a source of formylating agent. They also unambiguously prove that the Fries rearrangement of aryl formates (that we recently investigated in J. Org. Chem. 71, 9331-9340, 2006) is intermolecular: the intermediate formyl chloride is released in situ and, in turn, it formylates the intermediate dichloroborate ester of 3-methoxy- and 3,5-dimethoxy-phenol in a second independent step. The -BCl2 moiety bound to the aryl oxygen of the substituted phenol interacts with the formyl chloride strongly favouring the ortho substitution. Copyright
Bagno, Alessandro,Kantiehner, Willi,Saielli, Giacomo
experimental part
p. 682 - 687
(2009/04/04)

Rational design of inhibitors of VirA-VirG two-component signal transduction
VirA-VirG two-component system regulates the vir (virulence) operon in response to specific host factors (xenognosins) in the plant pathogen Agrobacterium tumefaciens. Using whole cell assays, stable inhibitors inspired by the labile natural benzoxazinone inhibitor HDMBOA are developed. It is found that aromatic aldehydes represent a minimal structural unit for activity. In particular, 3-hydroxy-4,6-dimethoxy-3H-isobenzofuran-1-one (HDI) was found to have the highest activity, making it the most potent developed inhibitor of virulence gene expression in Agrobacterium.
Maresh, Justin,Zhang, Jin,Tzeng, Yih-Ling,Goodman, Nora A.,Lynn, David G.
p. 3281 - 3286
(2008/02/08)

Efficient two-step synthesis of salicylaldehydes via directed ortho-lithiation of in situ N-silylated O-aryl N-isopropylcarbamates
O-Aryl N-isopropylcarbamates, conveniently prepared from phenols and isopropyl isocyanate, are subjected to an efficient ortho-lithiation protocol to afford the corresponding salicylaldehydes in a one-pot operation in high yields. Georg Thieme Verlag Stuttgart.
Kauch, Matthias,Hoppe, Dieter
p. 1575 - 1577
(2007/10/03)

Regioselective synthesis and estrogenicity of (±)-8-alkyl-5,7- dihydroxy-4-(4-hydroxyphenyl)-3,4-dihydrocoumarins
Nine new (±)-8-alkyl-5,7-dihydroxy-4-(4-hydroxyphenyl)-3,4- dihydrocoumarins have been synthesized from 2,4,6-trimethoxybenzaldehyde via a short, efficient, and regioselective pathway, together with the unsubstituted analogue (±)-5,7-dihydroxy-4-(4-hydroxyphenyl)-3,4-dihydrocoumarin. The compounds were tested for estrogenic activity using a yeast-based estrogen screen. Weak estrogenicity was determined for seven members of the series.
Roelens, Frederik,Huvaere, Kevin,Dhooge, Willem,Van Cleemput, Marjan,Comhaire, Frank,De Keukeleire, Denis
p. 1042 - 1051
(2007/10/03)

o-Formylation of electron-rich phenols with dichloromethyl methyl ether and TiCl4
o-Formylation of electron-rich phenols is accomplished with dichloromethyl methyl ether and TiCl4. The reaction gives excellent yields, good regioselectivity, and does not leading to diformylation.
García, Oscar,Nicolás, Ernesto,Albericio, Fernando
p. 4961 - 4963
(2007/10/03)

Synthesis of novel flavonoid derivatives as potential HIV-integrase inhibitors
Eighteen novel flavonoid derivatives - substituted chalcones and flavones were synthesized and characterized by using NMR, IR, UV/Vis spectroscopy and elemental analysis. The target compounds were achieved by using a sequence of simple and effective reactions starting from phloroglucinol. The initial hydroxyl groups were protected by methylation and in the final flavones the 5-OH group was selectively demethylated by means of AlBr3. 5-methoxy flavones exhibit a strong fluorescence, which was quenched after the removal of the methyl group.
Mateeva, Nelly N.,Kode, Rao N.,Redda, Kinfe K.
p. 1251 - 1258
(2007/10/03)

Scale-up of a Vilsmeier formylation reaction: Use of HEL Auto-MATE and simulation techniques for rapid and safe transfer to pilot plant from laboratory
The application of reaction calorimetry and process modelling to allow for the rapid and safe scale-up of a Vilsmeier formylation reaction to the pilot plant will be described. This transformation was a key step in the preparation of the backbone amide linker (the so-called "BAL" handle) for solid-phase chemistry. In particular, use was made of Auto-MATE equipment from Hazard Evaluation Laboratories (HEL) and "Reaction Simulator" software to derive a thermokinetic model which allowed us to simulate heat-flow data on-scale. The model was then refined using a HEL SIMULAR 1-L calorimeter, and a direct comparison of the data showed there to be a 20% error in the enthalpy data gathered from the smaller Auto-MATE. The use of a preformed Vilsmeier reagent and dichloromethane as a reaction solvent gave a "square-wave" profile typical of a feed-controlled reaction. These conditions were successfully scaled to a 50-L pilot-plant vessel.
Dyer, Ulrich C.,Henderson, David A.,Mitchell, Mark B.,Tiffin, Peter D.
p. 311 - 316
(2013/09/06)

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The aromatic hydroxyaldehydes 3a-3g, 5a-Sf, 8, 10 can be prepared by the action of BCl3, BBr3 or trifluoromethanesulfonic acid, on the aryl formates 1a-1f, 4a-e, 7, 9 via Fries rearrangement. BBr3 is more effective than BCl3. The activating ability of BBr3 can be improved by addition of FeCl3. Rearrangements which are induced by trifluoromethanesulfonic acid can give rise to the formations of regioisomers, which might be different from the products formed when the reaction is performed with Lewis acids. The yields of the aldehydes are lowered by subsequent condensation reactions. This view was confirmed by the isolation of a condensation product, which was characterized as a dibenzo[a,j]xanthene derivative 6 by crystal structure analysis. For the Fries rearrangement of formyl groups a new mechanism is proposed. 2-Hydroxy-1-naphthaldehyde 5c can be obtained in good yield from formic acid, BBr3, and 2-naphthol.
Ziegler, Georg,Haug, Erwin,Frey, Wolfgang,Kantlehner, Willi
p. 1178 - 1187
(2007/10/03)

A mild and chemoselective dealkylation of alkyl aryl ethers by cerium(III) chloride-NaI
The alkoxy groups present ortho to carbonyl group in alkoxybenzaldehydes are selectively deprotected in high yields leaving other alkoxy groups unaffected by cerium(III) chloride-NaI in refluxing acetonitrile under neutral reaction conditions.
Yadav,Subba Reddy,Madan,Riaz Hashim
p. 738 - 739
(2007/10/03)

Preparation and application of the 5-(4-(9-fluorenylmethyloxycarbonyl) aminomethyl-3,5-dimethoxyphenoxy)-valeric acid (PAL) handle for the solid-phase synthesis of C-terminal peptide amides under mild conditions1-3
The acid-labile 5-(4-(9-fluorenylmethyloxycarbonyl) aminomethyl-3,5-dimethoxyphenoxy)valeric acid (PAL) handle 1 is described for the solid-phase synthesis of C-terminal peptide amides. The pure para isomer of 1 was prepared by each of two efficient five-step routes, in overall yields from 52% to 74%. The handle 1 was coupled onto a variety of amino group-containing supports to provide a general starting point for stepwise assembly of peptide chains according to a wide range of chemistries. In particular, protocols based on the base-labile N(α)-9-fluorenylmethyloxycarbonyl (Fmoc) group worked well with PAL handle 1. For small model peptides, final cleavage of tert-butyl side-chain protecting groups and of the anchoring linkage proceeded smoothly in trifluroacetic acid-dichloromethane-dimethyl sulfide (14:5:1) (reagent A) at 25 °C for 2 h. For cleavage of complex peptides that contain several sensitive side-chain functionalities, or that include arginine residues blocked with the 4-methoxy-2,3,6-trimethylphenylsulfonyl (Mtr) or 2,2,5,7,8-pentamethylchroman-6-ylsulfonyl (Pmc) groups, a mixture of trifluoroacetic acid-thioanisole-1,2-ethanedithiol-anisole (90:5:3:2) (reagent R), applied for 2-8 h at 25 °C, was preferred. A side reaction involving alkylation at tryptophan was elucidated, and conditions were developed to minimize its occurrence. The methodology was demonstrated by syntheses of over a hundred peptides, among which acyl carrier protein (65-74) amide (natural and retro sequences), luteinizing hormone-releasing hormone, adipokinetic hormone, PHI porcine fragment (18-27), and human gastrin-I are highlighted in this report. In comparative studies, the yields and purities of peptide amides prepared with PAL were shown to be equivalent or superior to those found for products prepared by alternative procedures from the recent literature.
Albericio,Kneib-Cordonier,Biancalana,Gera,Masada,Hudson,Barany
p. 3730 - 3743
(2007/10/02)

Process for nucleophilic fluoroalkylation of aldehydes
Aryl difluoromethyl sulfone adds to alkehydes under phase transfer conditions to give novel substituted alcohols of the general formula wherein R is an aryl, cycloaliphatic, sec- or tert-aliphatic, or heterocyclic group and Ar is an aryl group. The substituted alcohols of formula I are of particular utility as intermediates in the synthesis of a variety of useful end products. For example, the products of formula I may be utilized in desulfonylation reactions, oxidation reactions and fluorination reactions.
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(2008/06/13)

A Convenient Synthesis of Prenylated Isoflavones: Synthesis of Licoricone and Related Compounds
The condensation of 6',7-bis(benzoyloxy)-2',4'-dimethoxyisoflavone (18) with 2-methyl-3-buten-2-ol, followed by hydrolysis of the resultant 6',7-bis(benzoyloxy)-2',4'-dimethoxy-3'-(3-methyl-2-butenyl)isoflavone (19) gave 6',7-dihydroxy-2',4'-dimethoxy-3'-(3-methyl-2-butenyl)-isoflavone (licoricone) (1).Its isomer, 6',7-dihydroxy-2',4'-dimethoxy-5'-(3-methyl-2-butenyl)-isoflavone (2), was also synthesized from 7-benzoyloxy-6'-hydroxy- or 6',7-bis(benzoyloxy)-2',4'-dimethoxy-5'-(3-methyl-2-butenyl)isoflavone (11 or 20).Keywords - isoflavone; selective prenylation (3-methyl-2-butenylation); prenylated isoflavone; 6',7-dihydroxy-2',4'-dimethoxy-3'-(3-methyl-2-butenyl)isoflavone (licoricone); 6',7-dihydroxy-2',4-dimethoxy-5'-(3-methyl-2-butenyl)isoflavone; 6-hydroxy-2,4-dimethoxybenzaldehyde
Tsukayama, Masao,Horie, Tokunaru,Fujimoto, Kunihiro,Nakayama, Mitsuru
p. 2369 - 2374
(2007/10/02)

Trimethoxyphenyl Compounds, XI. Constituents of Hagenia abyssinica, 2: Synthesis of Phloracylophenones Containing One Phloroglucinol Unit
For the Koso constituents K6 and K8, we previously proposed the structures 1a, b and 2a, b.These assignments have been confirmed by synthesis. - Keywords: Flores koso, Revised Structure, Synthesis of Phloroglucinols
Schiemenz, Guenter Paulus,Behrens, Heinz,Ebert, Claus Peter,Maienschein, Konrad,Schroeder, Jens-Michael
p. 681 - 692
(2007/10/02)

SYNTHESES OF LICORICONE AND ITS ISOMER
The condensation of 6',7-dibenzoyloxy-2',4'-dimethoxyisoflavone with 2-methyl-3-buten-2-ol, followed by the hydrolysis of the resultant 3'-(3-methyl-2-butenyl)isoflavone afforded licoricone.Its isomer, 5'-(3-methyl-2-butenyl)isoflavone, was also synthesized from 7-benzoyloxy or 6',7-dibenzoyloxyisoflavone in a similar manner.
Tsukayama, Masao,Fujimoto, Kunihiro,Horie, Tokunaru,Masumura, Mitsuo,Nakayama, Mitsuru
p. 261 - 264
(2007/10/02)

Naturally Occurring Dibenzofurans. Part 4. Synthesis of Dibenzofurandiols by Annelation of Benzofurans
Methyl 3-acetylbenzofuran-2-ylacetate (8) undergoes C-methylation affording methyl 2-(3-acetylbenzofuran-2-yl)propionate (13).These compounds and similar oxo esters undergo ready cyclization to dibenzofurandiols on treatment with sodium methoxide in boiling methanol.A convenient synthesis of dimethyl furan-2,5-diylacetate (30) is described, as are attempts to synthesize 1,3,7,9-tetramethoxy-2,8-dimethyldibenzofuran (3).
Carvalho, Christopher F.,Sargent, Melvyn V.
p. 1605 - 1612
(2007/10/02)

Ortho Effect in the Fragmentation of 2-Acetoxychalcones under Electron Impact
2-Acetoxychalcones decompose under electron impact conditions by loss of an acetoxy fragment to form flavylium ions.The effect is restricted to the ortho position and is reduced after hydrogenation of the chalcone double bond.The intense flavylium ion originates as shown by specific labelling with 18O-from two different fragmentation lines: (a) direct loss of an acetoxy radical by cleavage of the phenolic Ar-O bond and (b) sequential elimination of ketene and a hydroxy radical.
Mentlein, Rolf,Vowinkel, Erich
p. 330 - 333
(2007/10/02)

A C-Methylbiflavone from Cephalotaxus harringtonia K. Koch
6-C-Methyl-7-O-methylamentoflavone (1) isolated from the leaves of Cephalotaxus harringtonia K.Koch (Cephalotaxaceae) has been identified on the basis of the spectral data of its hexamethyl ether (1a) and its penta-acetate (1b).The location of the C-methyl group was first deduced from 1H n.m.r. studies with a lanthanide shift reagent and confirmed by a synthesis of the hexamethyl ether (1a).
Agil, Mohammad,Rahman, Wasiur,Hasaka, Noriko,Okigawa, Masayoshi,Kawano, Nobusuke
p. 1389 - 1392
(2007/10/02)