- Identification of 2,2,7,8-Tetramethyl-1,2,3,4-tetrahydronaphthalene in Petroleum
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2,2,7,8-Tetramethyl-1,2,3,4-tetrahydronaphthalene, a proposed key intermediate in the degradation and aromatisation of triterpenoids of the oleanane skeletal-type, has been synthesized and identified in Cretaceous sediments and crude oils.
- Forster, Peter G.,Alexander, Robert,Kagi, Robert I.
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- Synthesis of regioisomeric dimethylbenzyl mercapturic acids anticipated from the metabolism of 1,2,3-trimethylbenzene
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The synthesis of two regioisomeric mercapturic acids, N-acetyl-S -(2,3-dimethylbenzyl)-L-cysteine and N-acetyl-S-(2,6-dimethylbenzyl)-L-cysteine, was undertaken to investigate the operation of mercapturic acid pathway in the metabolism of 1,2,3-trimethylbenzene. The method applied was based on that we described recently in the synthesis of mercapturic acids derived from m- and p-xylenes.
- Tsujimoto, Yuji,Noda, Tsutomu,Shimizu, Mitsuru,Moriwaki, Hiroshi,Tanaka, Masanobu
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- Structure and Selectivity in Anodic and Metal Ion Oxidations of Polyalkylbenzenes
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Positional selectivity and the partition deuterium isotope effect (kH/kD) have been determined in the chemical and electrochemical side-chain oxidation of alkyl aromatics by using 5-R-hemimellitenes (R = H, t-Bu) and 1,3-dimethyl-2-(trideuteriomethyl)-5-tert-butylbenzene as the substrates.Considering also the already available data for isodurene, it has been found that the positional selectivity is strongly influenced by the substrate structure in the anodic and CAN-promoted oxidations, both reactions exhibiting a very similar pattern.In contrast, Co(OAc)3, selectivities do not correlate with those of the anodic oxidation but with the selectivities of the side-chain bromination promoted by NBS.These results have been interpreted by suggesting that, as in the anodic oxidations, CAN-induced reactions involve first the formation of a radical cation intermediate which then loses a proton to give a benzylic free radical in the selectivity-determining step.The data for Co(III) would instead suggest a mechanism involving a hydrogen atom transfer, but this conclusion cannot yet be considered definitive.No simple correlation exists between selectivity data and the kH/kD values.
- Baciocchi, Enrico,Eberson, Lennart,Rol, Cesare
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- Microwave-heated γ-Alumina Applied to the Reduction of Aldehydes to Alcohols
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The development of cheap and robust heterogeneous catalysts for the Meerwein-Ponndorf-Verley (MPV) reduction is desirable due to the difficulties in product isolation and catalyst recovery associated with the traditional use of homogeneous catalysts for MPV. Herein, we show that microwave heated γ-Al2O3 can be used for the reduction of aldehydes to alcohols. The reaction is efficient and has a broad substrates scope (19 entries). The products can be isolated by simple filtration, and the catalyst can be regenerated. With the use of microwave heating, we can direct the heating to the catalyst rather than to the whole reaction medium. Furthermore, DFT was used to study the reaction mechanism, and we can conclude that a dual-site mechanism is operative where the aldehyde and 2-propoxide are situated on two adjacent Al sites during the reduction. Additionally, volcano plots were used to rationalize the reactivity of Al2O3 in comparison to other metal oxides.
- Dhokale, Bhausaheb,Susarrey-Arce, Arturo,Pekkari, Anna,Runemark, August,Moth-Poulsen, Kasper,Langhammer, Christoph,H?relind, Hanna,Busch, Michael,Vandichel, Matthias,Sundén, Henrik
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p. 6344 - 6355
(2020/10/28)
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- Total syntheses of multicaulins via oxidative photocyclization of stilbenes
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The Wittig reaction of 3-isopropyl-4-methoxybenzaldehyde and 2,3-dimethylbenzylphosphonium bromide afforded the corresponding stilbene mixture 16. Oxidative photocyclization of stilbene 16 with iodine facilitated the first total synthesis of 7-isopropyl-6
- Seinti, Hatice,Burmaolu, Serdar,Altunda, Ramazan,Seen, Hasan
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p. 2134 - 2137
(2014/12/11)
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- RENIN INHIBITORS
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Renin inhibitors, which are spirocyclic piperidine amides, of structural formula (I) and pharmaceutical compositions thereof useful in the treatment of cardiovascular diseases and renal insufficiency, wherein n, for each instance in which it occurs, is independently 0, 1, or 2; R1 is hydrogen, C1-6 -alkyl or C3-6 -cycloalkyl, wherein said C1-6 -alkyl or C3-6 -cycloalkyl group can be independently substituted with 1-3 halogens; A is (i) a five- or six-membered saturated or unsaturated heterocyclic or carbocyclic monocyclic ring or (ii) a five- or six-membered saturated or unsaturated heterocyclic or carbocyclic ring which is fused to another five- or six-membered saturated or unsaturated heterocyclic or carbocyclic ring, V is a bond or -(C=O)-, -CH(OH)-, -CH2- or =CH-; U is a bond or -CH2-, or for the case when V is =CH-, U is -CH=; X is =CH-, =CF-, =C(OR3)-, or -C=O-; and Y is =CH-, =CF-, =N-, or for the case when X is -C=O-, Y is -N(R3)-.
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Page/Page column 21
(2011/04/13)
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- Selective lithiation of 4- and 5-halophthalans
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The reaction of 4- and 5-halophthalans 5 with lithium and a catalytic amount of DTBB at -78 °C leads to the formation of the corresponding functionalized organolithium intermediates 6 and 11, which by reaction with carbonyl compounds give, after hydrolysis, the expected substituted phthalans 8 and 13, respectively. When after reaction with the carbonyl compound the system is allowed to react at 0 °C, a second lithiation occur: A reductive opening of the heterocycle takes place with some regioselectivity leading to new organolithium intermediates 9 and 14/15 that by reaction with electrophiles lead, after hydrolysis, to polyfunctionalized molecules 10 and 16/17, respectively.
- Garcia, Daniel,Foubelo, Francisco,Yus, Miguel
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experimental part
p. 991 - 1005
(2010/10/03)
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- [4+2] Cycloaddition of o-xylylenes with imines using palladium catalyst
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(Chemical Equation Presented) The cycloaddition of o-(silylmethyl)benzylic carbonates with imines proceeded in the presence of the Pd(η3- C3H5)Cp-DPPPent catalyst, affording the tetrahydroisoquinolines in good to high yiel
- Ueno, Satoshi,Ohtsubo, Masakazu,Kuwano, Ryoichi
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supporting information; experimental part
p. 12904 - 12905
(2009/12/05)
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- Process for producing cyclopropanecarboxylates
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There is disclosed a process process for producing a cyclopropanecarboxylate of formula (1): 1which process comprises reacting cyclopropanecarboxylic acid of formula (2): 2with a monohydroxy compound of formula (3): R6OH??(3),in the presence of a catalyst compound comprising an element of to Group 4 of the Periodic Table of Elements.
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- Binding activity of substituted benzyl derivatives of chloronicotinyl insecticides to housefly-head membranes, and its relationship to insecticidal activity against the housefly Musca domestica
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Variously substituted benzyl derivatives of chloronlcotinyl insecticides were synthesized with a wide range of substituents including halogens, NO2, CN, CF3 and small alkyl and alkoxy groups at the ortho, meta and para positions, as well as multiple-substituted benzyl analogues. Their binding activity to the α-bungarotoxin binding site in housefly (Musca domestica) head membrane preparations was measured. Among the compounds tested, the activity of the meta-CN derivative was the highest, being 20-100 times higher than those of imidacloprid, acetamiprid and nitenpyram. The synergized insecticidal activity against houseflies was also measured for selected compounds with the metabolic inhibitor, NIA16388 (propargyl propyl phenylphosphonate). For the nitromethylene analogues, including both benzyl and pyridylmethyl analogues, higher binding activity usually resulted in higher insecticidal activity. (C) 2000 Society of Chemical Industry.
- Nishiwaki, Hisashi,Nakagawa, Yoshiaki,Takeda, David Y.,Okazawa, Atsushi,Akamatsu, Miki,Miyagawa, Hisashi,Ueno, Tamio,Nishimura, Keiichiro
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p. 875 - 881
(2007/10/03)
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- Aromatic Spiranes XX [1]: Syntheses of Dimethylsubstituted 2-Carboxymethyl-indan-1-ones and Benzylchlorides as Synthones for Syntheses of di- to tetramethylsubstituted Spirobiindandiones
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The isomeric dimethyl methylbenzoates 5, obtained from the bromides via Grignard reactions with dimethylcarbonate, were reduced with LiAlH4 to the hydroxymethyl derivatives 6. The latter were then transformed both to the benzylchlorides 7 (with SOCl2) and to the aldehydes 8 (with pyridinium chlorochromate). Knoevenagel-Doebner reaction of 8 afforded the acrylic acids 9 which (after hydrogenation to 11) were cyclized to the desired indanones 12 with polyphosphoric acid. On the other hand, 12c and 12e were prepared from dimethyl 3-chloropropiophenone (14) by warming with sulfuric acid. After NaH-catalyzed reaction with dimethylcarbonate, the indanones 12 gave the ketoesters 15 which then could be hydrogenated to the indanes 16. All reactions proceeded with satisfactory to excellent yields (60-90%).
- Neudeck
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p. 185 - 200
(2007/10/03)
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- 4. Synthese von Plectranthonen, diterpenoiden Phenanthren-1,4-chinonen
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The following phenanthrene-1,4-diones have been synthesized by using the photocyclization of the corresponding highly substituted stilbenes as the key step: 3-hydroxy-5,7,8-trimethyl-2-(prop-2-enyl)phenanthrene-1,4-dione (1), (RS)-, (R)-, and (S)-2--1-methylethyl)acetate (2, 31, and 32, resp.), 3-hydroxy-7,8-dimethyl-2-(prop-2-enyl)phenanthrene-1,4-dione (3), 3-hydroxy-7,8,10-trimethyl-2-(prop-2-enyl)phenanthrene-1,4-dione (4), 5,7,8-trimethyl-2-(prop-2-enyl)phenanthrene-1,4-dione (17) and 3-hydroxy-2-methylphenanthrene-1,4-dione (42).The quinones 1 and 3 proved to be identical with recently isolated plectranthons A and C.Compounds 2, 31, and 32 exhibited the same UV/VIS, IR, 1H-NMR and mass spectra as natural plectranthon B, but had different melting points.This might be due either to crystal modifications or to diastereoisomerism caused by the helical structure of the phenanthrene-1,4-dione skeleton.The spectral data of synthetic 4 were not compatible with those of natural plectranthon D for which structure 4 had been proposed based mainly on 1H-NMR arguments concerning the chemical shifts of H-C(9) and H-C(10) in 1-3.Extensive 1H-NMR investigations have now revealed that the currently stated assignments of the H-C(9)/H-C(10) AB system have to be reversed for highly substituted phenanthrene-1,4-diones: in the model compounds 2-methylphenanthrene-1,4-dione (41) and 2, H-C(10) resonates at lower field as expected (peri-position), whereas in the highly substituted congeners 1, 2, 3, 31, and 32, H-C(9) is shifted paramagnetically, a fact which had lead to the erroneous assignment of structure 4 for natural plectranthon D.
- Kaliakoudas, Dimitrios,Eugster, Conrad Hans,Rueedi, Peter
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- Structure and Synthesis of Pallescensin E Utilising a Modified Wadsworth-Emmons Reaction
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A modified Wadsworth-Emmons reaction using a catalytic amount of 15-crown-5 has been employed in the synthesis of the naturally occurring furosesquiterpene pallescensin E.The structure of this compound has been confirmed by comparison of its spectral data with those of the synthesised isomer, 9,10-dihydro-7,8-dimethyl-4H-benzocycloheptafuran.
- Baker, Raymond,Sims, Russell
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p. 3087 - 3091
(2007/10/02)
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- SYNTHESIS OF PALLESCENSIN-E : USE OF CROWN ETHER IN THE WADSWORTH PROCEDURE FOR OLEFIN FORMATION
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The furanosesquiterpene, pallescensin-E has been prepared by a route involving reaction of a dimethyl 3-furylmethyl phosphonate anion with 2,3-dimethylbenzaldehyde in the presence of 15-crown-5; this reaction has been shown to have general applicability.
- Baker, R.,Sims, R. J.
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p. 161 - 162
(2007/10/02)
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