- Aromatic substituent effect on the stereoselectivity of the condensed- and gas-Phase Acid-Induced methanolysis in 2-Aryloxiranes derived from 3,4-dihydronaphthalene and trans-1,2,3,4,4a,10a-Hexahydrophenanthrene bearing a tertiary benzylic oxirane nucleophilic centre
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The ring-opening reactions with MeOH of the title benzocondensed 2-aryl oxiranes 6 and 7a,b both in the condensed (methanolysis) and in the gas phase were examined, obtaining in all cases a good Hammett-type linear correlation. Results indicate that the secondary or tertiary nature of the benzylic oxirane carbon is not responsible for the different stereochemical behavior so far encountered in different 2-aryl oxirane systems under the same operating conditions.
- Crotti, Paolo,Di Bussolo, Valeria,Favero, Lucilla,Pineschi, Mauro,Sergiampietri, Daniela,Renzi, Gabriele,Ricciutelli, Massimo,Roselli, Graziella
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Read Online
- Anodic oxidation triggered divergent 1,2- And 1,4-group transfer reactions of β-hydroxycarboxylic acids enabled by electrochemical regulation
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We report a set of electrochemically regulated protocols for the divergent synthesis of ketones and β-keto esters from the same β-hydroxycarboxylic acid starting materials. Enabled by electrochemical control, the anodic oxidation of carboxylic acids proceeded in either a one-electron or a two-electron pathway, leading to a 1,4-aryl transfer or a semipinacol-type 1,2-group transfer product with excellent chemoselectivity. The 1,4-aryl transfer represents an unprecedented example of carbon-to-oxygen group transfer proceeding via a radical mechanism. In contrast to previously reported radical group transfer reactions, this 1,4-group transfer process features the migration of electron-rich aryl substituents. Furthermore, with these chemoselective electrochemical oxidation protocols, a range of ketones and β-keto esters including those possessing a challenging-to-access medium-sized ring could be synthesized in excellent yields. This journal is
- Jiang, Yangye,Lu, Gang,Mo, Fanyang,Yang, Jianxin,Yang, Yang,Yin, Yunxing,Zeng, Chengchu,Zhang, Lei,Zhang, Xianhao,Zhang, Zhenxing
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p. 12021 - 12028
(2020/11/26)
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- Fluoride Anions in Self-Assembled Chiral Cage for the Enantioselective Protonation of Silyl Enol Ethers
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The potential of Song's chiral oligoethylene glycols (oligoEGs) as catalysts was explored in the enantioselective protonation of trimethylsilyl enol ethers in combination with alkali metal fluoride (KF and CsF) and in the presence of a proton source. Highly enantioselective protonations of various silyl enol ethers of α-substituted tetralones were achieved, producing chiral α-substituted tetralones in full conversion and with up to 99% ee. The established protocol was successfully extended to the synthesis of biologically relevant chiral α-substituted chromanone and thiochromanone derivatives.
- Paladhi, Sushovan,Liu, Yidong,Kumar, B. Senthil,Jung, Min-Jung,Park, Sang Yeon,Yan, Hailong,Song, Choong Eui
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supporting information
p. 3279 - 3282
(2017/06/23)
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- Anti-Markovnikov Oxidation of β-Alkyl Styrenes with H2O as the Terminal Oxidant
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Oxygenation of alkenes is one of the most straightforward routes for the construction of carbonyl compounds. Wacker oxidation provides a broadly useful strategy to convert the mineral oil into higher value-added carbonyl chemicals. However, the conventional Wacker chemistry remains problematic, such as the poor activity for internal alkenes, the lack of anti-Markovnikov regioselectivity, and the high cost and chemical waste resulted from noble metal catalysts and stoichiometric oxidant. Here, we describe an unprecedented dehydrogenative oxygenation of β-alkyl styrenes and their derivatives with water under external-oxidant-free conditions by utilizing the synergistic effect of photocatalysis and proton-reduction catalysis that can address these challenges. This dual catalytic system possesses the single anti-Markovnikov selectivity due to the property of the visible-light-induced alkene radical cation intermediate.
- Zhang, Guoting,Hu, Xia,Chiang, Chien-Wei,Yi, Hong,Pei, Pengkun,Singh, Atul K.,Lei, Aiwen
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supporting information
p. 12037 - 12040
(2016/09/28)
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- Synthesis of 2-tetralone derivatives by Bi(OTf)3-catalyzed intramolecular hydroarylation/isomerization of propargyl alcohols
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Compared to 1-tetralones, 2-tetralones are expensive, less stable, and difficult to synthesize. A concise Bi-catalyzed method was developed for the synthesis of 2-tetralones from 5-phenylpent-1-yn-3-ol derivatives. Diverse 2-tetralones were obtained in moderate to good yields under mild conditions.
- Yun, Jihee,Park, Jungmin,Kim, Jaehyun,Lee, Kooyeon
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p. 1045 - 1048
(2015/02/19)
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- PREPARATION METHOD OF 2-TETRALONE DERIVATIVES CATALYZED BY BISMUTH/SILVER MIXED SALTS
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The present invention relates to a method for preparing a 2-tetralone derivative using a bismuth/silver mixed catalyst in a simple and efficient manner. According to the method, a target material can be obtained within short time as the bismuth/silver mixed catalyst is used. The 2-tetralone derivative, prepared by the method, can be used to synthesize pharmaceutical products and intermediates of natural materials. The 2-tetralone derivative is represented by Chemical formula 1.COPYRIGHT KIPO 2015
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Paragraph 0063; 0064; 0065; 0066; 0067
(2016/10/17)
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- Oxone-acetone mediated Wacker-type oxidation of benzo-fused olefins
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Herein we disclose a novel application of the oxone-acetone combination for the Wacker-type oxidation of indenes and dihydronaphthalenes leading, respectively, to indan-2-ones and 2-tetralones. The amount of the base employed in the reaction seems to switch the reaction path from dioxygenation to Wacker-type oxidation. Control experiments suggest that the reaction is not proceeding via the epoxide route and also that there is no role of trace amounts of metals present in the reagents on the current oxidation.
- Phatake, Ravindra S.,Ramana, Chepuri V.
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supporting information
p. 3868 - 3871
(2015/06/08)
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- Oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III)
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A novel protocol for the oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III) was developed. This approach uses inexpensive, readily available, and stable chemicals (PhI, mCPBA, and TsOH) giving rearrangement products in yields comparable to those obtained using the more expensive commercially available [hydroxy(tosyloxy)iodo]benzene [HTIB or Koser's reagent]. Additionally, an alternative protocol for the synthesis of 1-methyl-2-tetralone through the one-step epoxidation/rearrangement of 4-methyl-1,2-dihydronaphthalene using mCPBA and TsOH was developed.
- Ahmad, Anees,Scarassati, Paulo,Jalalian, Nazli,Olofsson, Berit,Silva Jr., Luiz F.
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supporting information
p. 5818 - 5820
(2013/10/01)
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- Cyclization and ring-expansion processes involving samarium diiodide promoted reductive formation and subsequent oxidative ring opening of cyclopropanol derivatives
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Samarium diiodide promoted reaction of various α-bromornethyl cycloalkanones, followed by subsequent treatment with trimethylsilyl chloride, leads to the production of cyclopropyl silyl ethers embedded in bicyclo[m.l.0]alkane frameworks. Treatment of the ethers with oxidative electron-transfer reagents, such as Fe(III), Ce(IV), and Mn(III) salts, generates ring-expanded ketones that convert to cyclic conjugated enones in moderate to good yields. In addition, the reduction-oxidation reaction sequences can be successfully performed in one pot. The regioselectivities of cyclopropane ring opening in the bicyclic substrates depend on the oxidizing agents used. For example, reactions promoted by FeCl3 with pyridine lead to the expected ring-expansion process involving internal-bond cleavage of bicycloalkane and yielding cyclic enones as final products. In contrast, reactions with Ce(NH4)I(NO3)6 or Mn(OAc) 3 as oxidizing agents proceed by way of external-bond cleavage to give α-iodomethyl cycloalkanones.
- Tsuchida, Hiroyuki,Tamura, Mutsuko,Hasegawa, Eietsu
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supporting information; experimental part
p. 2467 - 2475
(2009/07/18)
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- Ring contraction of 1,2-dihydronaphthalenes promoted by thallium(III) in acetonitrile: A diastereoselective approach to indanes
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Trans-1,3-Disubstituted indanes are conveniently accessed by a stereoselective ring contraction of 1,2-dihydronaphthalenes upon treatment with thallium(III) nitrate (TTN) in acetonitrile. Under these conditions, the oxidative rearrangement of either di- or trisubstituted double bonds is possible. Georg Thieme Verlag Stuttgart.
- Ferraz, Helena M. C.,Carneiro, Vania M. T.,Silva Jr., Luiz F.
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experimental part
p. 385 - 388
(2009/06/18)
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- Application of [hydroxy(tosyloxy)iodo]benzene in the wittig-ring expansion sequence for the synthesis of β-benzocycloalkenones from α-benzocycloalkenones
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The conversion of α-benzocycloalkenones to homologous β-benzocycloalkenones containing six, seven and eight-membered rings is reported. This was accomplished via a Wittig olefination-oxidative rearrangement sequence using [hydroxy(tosyloxy)iodo]-benzene (HTIB) is the oxidant, that enables the synthesis of regioisomeric pairs of methyl-substituted β-benzocycloalkenones. The incorporation of carbon-13 at C-1 of the β-tetralone nucleus was also demonstrated. The Wittig-HTIB approach is a useful alternative to analogous sequences in which Tl(NO3) 3·3H2O or the Prevost combination (AgNO 3/I2) are employed in the oxidation step.
- Justik, Michael W.,Koser, Gerald F.
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p. 217 - 225
(2007/10/03)
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- Biomimetic reactions in organic synthesis: Semi-pinacol rearrangements of some spirocyclic epoxyalcohols derived from Julia-Colonna asymmetric epoxidations
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Epoxy tert-alcohols have been prepared from (E)-enones in a two-step approach consisting of Julia-Colonna asymmetric epoxidation followed by Grignard alkylation of the epoxyketone. On treatment with sub-stoichiometric amounts of Yb(OTf)3 these trans-epoxyalcohols underwent efficient stereoselective semi-pinacol rearrangement to afford anti-α-phenyl-β-hydroxy-ketones (aldols). Under the same conditions, spirocyclic epoxyalcohols derived from 1-tetralone and 1-benzosuberone undergo either ring contraction (via semi-pinacol rearrangement) or fragmentation. A mechanistic rationale is presented to explain the formation of the various products.
- Hauer, Bernhard,Bickley, Jamie F.,Massue, Julien,Pena, Paula C. A.,Roberts, Stanley M.,Skidmore, John
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p. 546 - 550
(2007/10/03)
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- The semi-pinacol rearrangement of homochiral epoxyalcohols catalysed by rare earth triflates
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α,β-Epoxy ketones, prepared using the polyleucine catalysed asymmetric epoxidation of enones, can be converted into α-substituted β-hydroxy ketones via carbonyl alkylation with Grignard reagents followed by ytterbium triflate catalysed semi-pinacol rearrangement of the resulting epoxyalcohols.
- Bickley,Hauer,Pena,Roberts,Skidmore
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p. 1253 - 1255
(2007/10/03)
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- A concise synthesis of 1-substituted-2-tetralones by selective diol dehydration leading to ketone transposition
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Dehydration of 1-substituted-1,2-tetralindiols with zinc iodide afforded the corresponding 2-tetralones in excellent yields. This procedure was found to be superior to the more conventional BF3-catalyzed rearrangement of 1-substituted-1,2-epoxytetralins. (C) 2000 Elsevier Science Ltd.
- Jensen,Slobodzian
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p. 6029 - 6033
(2007/10/03)
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- Indium(III) chloride-promoted rearrangement of epoxides: A selective synthesis of substituted benzylic aldehydes and ketones
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A simple and efficient procedure for the rearrangement of substituted epoxides catalyzed by InCl3 has been developed. Aryl-substituted epoxides isomerize with complete regioselectivity to form a single carbonyl compound via cleavage of the benzylic C-O bond. The reactions are simple, fast, and high yielding. This procedure is very mild compared to those catalyzed with BF3 and other Lewis acids and compatible with several acid-sensitive functionalities. This protocol provides a highly selective synthesis of substituted benzylic aldehydes and ketones. However, rearrangement of alkyl- substituted epoxides is not very selective.
- Ranu, Brindaban C.,Jana, Umasish
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p. 8212 - 8216
(2007/10/03)
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- Hydroborations: A new route for the preparation of 1-alkyl- (or aryl) 2-tetralones
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The hydroboration followed by chromic acid oxidation of 1-alkyl- and 1-aryl-3,4-dihydronaphthalenes leads to the corresponding 1-alkyl- (or aryl)2-tetralones (1-substituted 3,4-dihydronaphthalen-2(1H)-ones.
- Kirkiacharian,Koutsourakis
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p. 737 - 742
(2007/10/02)
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- A process for the preparation of nepinalone
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A process for the preparation of 1-methyl-1-[2-(1-N-piperidine)ethyl]-1,2,3,4-tetrahydronaphthalen-2-one hydrochloride (also named Nepinalone) which consists in reacting 2-phenylpropionic acid chloride with ethylene, obtaining 1-methyl-2-tetralone, which is subsequently reacted with 2-chloroethyl-1-N-piperidine, using heptane as the solvent; and subsequent salifying.
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- EFFECT OF THE 9-METHYL SUBSTITUENT ON THE CHEMICAL BEHAVIOUR UNDER ACID CONDITIONS OF THE DIASTEREOISOMERIC 9,10-OXIDES DERIVED FROM trans-1,2,3,4,4a,10a-HEXAHYDROPHENANTHRENE
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Significant differences are present in the chemical behaviour, under acidic ring-opening conditions, between the diastereoisomeric couples of 2-aryl substituted oxiranes 3a and 3e, and 4a and 4e.The results of the acid hydrolysis of the two types of epoxides (3 and 4) have been rationalized through two different mechanisms which cannot easily be reconciled.A substantial structural difference in the two systems is the presence of a tertiary benzylic oxirane carbon in epoxides 3 and of a secondary one in epoxides 4.Therefore, the 9-methyl substituted epoxides 5a and 5e, in which the benzylic oxirane carbon is tertiary, have been prepared and studied.The introduction of the methyl substituent in the 9-position does not modify, in the case of epoxide 5a, the complete anti diastereoselectivity originally observed in the hydrolysis of the unsubstituted epoxide 4a.By way of contrast, in the hydrolysis of epoxide 5e and in the trichloroacetolysis of both epoxides 5a and 5e, a considerable increase in the syn/anti ratio is observed when compared with the data obtained in the corresponding reactions of the non-methyl-substituted epoxides (4a and 4e).Furthermore, in the trichloroacetolysis reactions of both epoxides 5a and 5e, marked amounts of the corresponding non-addition products (ketone and unsaturated alcohol) are revealed.Apart from the increased syn diastereoselectivity in the hydrolysis of epoxide 5e and in the trichloroacetolysis of 5a and 5e, and from the incursion of non-addition products in the trichloroacetolysis of both 5a and 5e, the general trend of the reactions of epoxides 5a and 5e remains substantially unmodified with respect to the one observed with the parent compounds 4a and 4e.The formation of rearrangement products in the reactions of epoxides 5 was rationalized keeping into consideration either the steric or/and the elctronic effect of the 9-methyl substituent.The results obtained indicate that the secondary nature of the benzylic oxirane carbon of epoxides 4a,e is not responsible for the above-mentioned differences in chemical behaviour between epoxides of type 3 and 4.
- Chini, Marco,Crotti, Paolo,Macchia, Franco
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p. 827 - 836
(2007/10/02)
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- Photochemical reactivities of cyclic α-phenyl-β,γ-enones. Singlet 1,3-acyl shift, decarboxylation and unquenchable oxa-di-?-methane reactions upon direct irradiation
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The photochemistry of the α-phenyl-β,γ-enones 3-6 has been studied under conditions of direct (λ 300 nm) and triplet-sensitized irradiation.Upon direct irradiation, 3 exhibits decarbonylation, a 1,3-acyl shift (1,3-AS) and an oxa-di-?-methane (ODPM) rearrangement.Under the same conditions, 4, on the other hand, affords only the ODPM product whereas 5 gives the decarboxylation, 1,3-AS and ODPM products.The formation of the ODPM product of 5 is efficiently quenched by triplet quenchers in contrast to the ODPM products of 3 and 4, the quantum yields of which are not reduced upon the addition of typical triplet quenchers.Triplet-sensitized irradiation of 5 leads to the ODPM rearrangement, whereas surprisingly 3 and 4 are unreactive.It is suggested that the ODPM rearrangement, upon direct irradiation of 3 and 4, proceeds from the S2(??*) state.The ODPM product formed upon direct irradiation of 5 is thought to be formed from the T1(??*) state populated by ISC from the S1(n?*) state.Upon direct irradiation, 6 exhibits a reversible 1,3-AS and in addition ketene formation via an intramolecular 1,5-H shift.Under conditions of triplet photosensitization, compound 6 appears to be stable.Given the apparently different photochemical behaviour of these constrained compounds, a general reactivity pattern for the direct and sensitized irradiation cannot be defined.
- Koppes, Margareth J. C. M.,Cerfontain, Hans
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p. 549 - 562
(2007/10/02)
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- PHOTOREARRANGEMENT OF SPIRO-OXAZIRIDINES - APPLICATIONS IN THE SYNTHESES OF HEXAHYDRO-5H-PYRROLO-BENZAZEPIN-5-ONES AND A TETRAHYDRO-1H,5H-PYRROLOISOQUINOLIN-5-ONE
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Regiospecific photorearrangements of spiro-oxaziridines derived from 2-methylindan-1-one, 2-methyltetral-1-one and 1-methyltetral-2-one afforded the title componds.
- Johnson, G.P.,Marples, B.A.
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p. 4115 - 4118
(2007/10/02)
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- Effect of Ring Size and Methyl Substituents on LiBr-Catalyzed Rearrangements of Aryloxiranes
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A series of indene 2,3-oxides and 3,4-dihydronaphthalene 1,2-oxides with methyl substituents on the oxirane ring was prepared, and the lithium bromide/acetonitrile catalyzed isomerization of these compounds to the corresponding 2-keto derivatives was examined.The presence of methyl substituents on the oxirane ring at the α carbon greatly enhanced the reactivity of the oxiranes relative to that of the unsubstituted compounds, while the presence of substituents at the β carbon reduced their reactivity.The effect of ring size was examined via a competition experiment involving indene 2,3-oxide and 3,4-dihydronaphthalene 1,2-oxide.The results of these studies suggest that the reagent can be used for selective transformation of aryloxiranes.
- Banks, Harold,Ziffer, Herman
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p. 3743 - 3747
(2007/10/02)
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- Photochemistry of Bichromophoric Molecules. Intramolecular Excited-State Interactions in the cis- and trans-Decalin-Connected Aryl Olefins: 7-Methylene-4bβ-methyl-4bβ,5,6,7,8,8aβ,9,10-octahydrophenanthrene and Its 8aα Isomer
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The photochemistry and photophysics of the title compounds (1,2) are reported.The trans-decalin 1 is relatively photoinert but the cis isomer (2) undergoes a singlet-derived, intramolecular, 1,3 photocycloaddition to give 13 (φ = 0.046).It is proposed that 13 is formed via an intramolecular exciplex (Scheme II) as in the acyclic analogue, 6-phenyl-2-hexene (3) , with a rate constant for complexation, kex, equal to 5.4*106 s-1.This is 185-fold slower than kex for 3 and corresponds to a ΔG298 (=8.2 kcal/mol) which can be equated with a requisite half-chair/chair to half-chair/boat isomerization (eq 3).Though neither 1 nor 2 is phosphorescent at 77 K, 2 sensitizes the isomerization of 1-methylcyclohexene to methylenecyclohexane at room temperature in solution.Thus, intermolecular triplet-energy transfer is competitive with intramolecular energy transfer.Compound 13 efficiently (φ = 0.51) photocycloeliminates to give a carbene-derived product, 15.
- Pallmer, Michael,Morrison, Harry
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p. 798 - 803
(2007/10/02)
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