22422-19-1Relevant academic research and scientific papers
A combined computational and experimental investigation of the oxidative ring-opening of cyclic ethers by oxoammonium cations
Loman, Jacob. J.,Carnaghan, Emma R.,Hamlin, Trevor A.,Ovian, John M.,Kelly, Christopher B.,Mercadante, Michael A.,Leadbeater, Nicholas E.
, p. 3883 - 3888 (2016/05/24)
The propensity of oxoammonium cations to facilitate the oxidative ring-opening of cyclic ethers to their corresponding distal hydroxy ketones is investigated. The reaction has been evaluated using experimental and computational methods to gain deeper insight into trends in reactivity.
Synthesis of 7-substituted derivatives of 5, 8-dimethylisoquinoline
Nagao, Yukinori,Hirota, Katsuaki,Tokumaru, Mizuho,Kozawa, Kozo
experimental part, p. 593 - 602 (2009/09/28)
7-Bromo-5,8-dimethylisoquinoline was selectively synthesized by the bromination of 5,8-dimethylisoquinoline obtained in five steps from p-xylene as a starting material. Further,7-bromo-5,8-dimethylisoquinolinegave 7-amino-5,8-dimethylisoquinoline by the reaction with ammonia and various 7-anilino-5,8-dimethylisoquinolines via a palladium-catalyzed coupling reaction with anilines.
Aromatic Spiranes XX [1]: Syntheses of Dimethylsubstituted 2-Carboxymethyl-indan-1-ones and Benzylchlorides as Synthones for Syntheses of di- to tetramethylsubstituted Spirobiindandiones
Neudeck
, p. 185 - 200 (2007/10/03)
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%).
SCHWEFELVERBINDUNGEN DES ERDOELS XXII. ALKYL-10,11-DIHYDRODIINDENOTHIOPHENE
Boberg, Friedrich,Deters, Karin,Schulz, Juergen,Torges, Karl-Franz
, p. 69 - 80 (2007/10/03)
The one-pot syntheses of alkyl-10,11-dihydrodiindenothiophenes (3) by bromination and sulfurization of alkylindan-1-ones without substituents at C-2 (1) has been studied with 14 1 with C1-C4-rests at the benzene and or the cyclopentane ring. 9 dialkyl-3 and 3 tetraalkyl-3 are prepared in yields of 7-66percent; an octamethyl-3 is detected by tlc and ms. 2 dialkyl-3 are prepared too by an independent syntheses from dimethyl 2,5-bis(methylphenyl)thiophene-3,4-dicarboxylates (13).The mechanism of the one-pot syntheses, which gives diindeno-1,4-dithiines too,is discussed.The oxidation of 4 3 has been studied.Key words: Alkylindan-1-ones, alkyl-10,11-dihydrodiindenothiophenes, alkyldiindeno-1,4-dithiines, one-pot syntheses of anellated thiophenes, oxidation of anellated thiophenes.
Electron Paramagnetic Resonance Spectra of the Radical Cations of Some Benzocyclobutenes, Benzocyclopentenes and Benzocyclohexenes
Avila, David V.,Davies, Alwyn G.,Li, Elizabeth R.,Ng, Kai M.
, p. 355 - 362 (2007/10/02)
1,2,4,5-Tetrahydrobenzodicyclobutene, 1,2,3,5,6,7-hexahydrobenzodicyclopentene and 1,2,3,4,6,7,8,9-octahydrobenzodicyclohexene, and their dimethyl derivatives, and tetramethylbenzocyclo-butene, -pentene and -hexene have been prepared.All except the first compound have been oxidised to their corresponding radical cations, and the EPR spectra have been analysed by assigning McConnell-type Q-values to the substituents in the benzene ring.It is suggested that the ordering of the orbital energy levels (ΨA above ΨS) in 3,6-dimethylbenzobiscyclobutene and -pentene is a manifestation of the Mills-Nixon effect, and results from rehybridisation of the strained molecular framework.In the radical cations of 5,10-dimethyl-1,2,3,4,6,7,8,9-octahydrobenzodicyclohexene and 5,6,7,8-tetramethyl-1,2,3,4-tetrahydrobenzocyclohexene the total unpaired electron density, as implied by the McConnell type of relationship, appears to be less than unity.Various possible causes of this are examined.
Modern Friedel-Crafts chemistry XIII. Intra- and intermolecular cyclization of some carbonyl derivatives under Friedel-Crafts conditions
Khalaf, Ali A.,Abdel-Wahab, Aboel-Magd A.,El-Khawaga, Ahmed M.,El-Zohry, Maher F.
, p. 285 - 291 (2007/10/02)
Carbonyl group deactivation in the cycloalkylation of aryl haloalkyl ketones was studied.Ketones 1-5 were prepared and subjected to treatment with AlCl3, AlCl3/H2SO4 and H2SO4 catalysts.Whereas AlCl3 catalyst gave no cyclization products, the use of AlCl3/H2SO4 and H2SO4 catalysts afforded the corresponding indanones and/or tetralones (6-11).The intermediate p-methylacrylophenone (12) was also obtained in the case of ketone 2.Furthermore intermolecular cyclizations of benzene, toluene and p-xylene with 3-chloropropionyl chloride (13) and 4-chlorobutyryl chloride (14) were investigated.In the presence of AlCl3/CH3NO2 catalyst, only the corresponding aryl haloalkyl ketones (1-5) were formed whereas the use of AlCl3 catalyst gave, in addition, some cyclic ketones.However, the use of AlCl3/H2SO4 catalyst gave only the corresponding cyclic ketones (6-11).Results are discussed and mechanisms are suggested.In conclusion, carbonyl group deactivation for ring closure is demonstrated in the investigated ketones and cyclization can only effected under strenuous conditions.
Stereopopulation Control. 8. Rate and Equilibrium Enhancement in the Formation of Homophthalic Anhydrides
Hillery, Paul S.,Cohen, Louis A.
, p. 2760 - 2770 (2007/10/02)
The kinetics of cyclization of α,α,3,4,6-pentamethylhomophthalic acid have been measured in sovent acetonitrile at 28.5 deg C, using as catalysts a series of acids ranging in strength from perchloric to acetic.In the presence of 0.12 M HClO4, t1/2 for acid anhydride formation = 0.3 s.For the stronger acid catalysts, kcycl is a linear function of catalyst concentration; for the weak acids, however, a change in rate-limiting step is revealed by curvature in the plots of ktotobsd vs. .All the weak acids show the same limiting value, 6.45E-3 min-1; this value is considered to be the rate constant for uncatalyzed formation of the tetrahedral intermediate.Homoconjugate bases (HA2(-)) of the weak acids show a similar curvature in their dilution plots, and the same limiting rate constant as for weak acids.Two independent and competitive pathways for cyclization are proposed.For strong acid catalysis, an intermediate acylium ion is considered on the basis of Broensted α = -0.79, kH/kD ca. 1, and acceleration of anhydride hydrolysis by methyl substituents.A value of ΔSexcit. = -23 eu suggests that cyclization, rather than acylium ion formation, is rate limiting.For weak acid catalysis, α = -0.17, kH/kD = 4.3, ΔSexcit. = -31 eu, and methyl groups retard anhydride hydrolysis by electron release; for this pathway, catalyzed breakdown of a tetrahedral intermediate is considered rate limiting.The composite Broensted plot is curved because the two pathways follow different rate laws.In contrast to rate enhancement results for phenolic lactone formation, the pentamethylhomophthalic acid is only sevenfold as reactive as α,α-dimethylhomophthalic acid.For the catalyst acids, pK(acetonitrile) is shown to be a linear function of pK(H2O) over the entire range of acids examined.
