2177-47-1Relevant academic research and scientific papers
Cycloaddition Reactions of Indenes. 2. Reactions with Dimethyl Acetylenedicarboxylate and Maleic Anhydride
Noland, Wayland E.,Kameswaran, Venkataraman,Landucci, Lawrence L.
, p. 4564 - 4572 (1980)
1H-Indenes (1) react with dimethyl acetylenedicarboxylate (DMAD), unlike maleic anhydride and other ethylenic dienophiles, without prior isomerization to 2H-indenes (2), giving a 1:1 Diels-Alder adduct (6) formed with destruction of the aromaticity of the benzene ring. This intermediate, not isolated in the present work, appears to serve as the precursor for all further adducts. Thus, 1H-indene (1a) and 1-methyl-1H-indene (1b), but not the more sterically hindered 1-ethyl-1H-indene, react with DMAD in refluxing benzene (with 1a) or toluene (with 1b) via a 1,2-cycloaddition to 6 to give solid 1:2 adducts (7a, 34percent; 7b, 30percent). In refluxing xylene the reaction goes further to give a 1:3 adduct (11a; 40percent from 1a, 71percent from 7a) formed by a Diels-Alder addition of a third molecule of DMAD across the remaining diene system of 7a. Reaction of 2-methyl-1H-indene (1c) with DMAD in refluxing xylene gave the corresponding 1:3 adduct (11c, 5-6percent), but an attempt in refluxing toluene to isolate a solid 1:2 adduct (7c) was unsuccessful.A 3-substituent in the 1H-indene, which becomes a 4-substituent in 6, blocks the 1,2-cycloaddition (to give 7) and diverts the DMAD to the cyclohexadiene system of 6, where a Diels-Alder reaction occurs in refluxing xylene to give another type of 1:2 adduct (8). The following 3-substituted 1H-indenes (1) gave 1:2 adducts of type 8: 3-methyl- (8d, 41percent), 3-ethyl- (8e, 40percent), 1,3-dimethyl- (8f, 31percent), 2,3-dimethyl- (8g, 19percent), 3-carboxy- (8l, 74percent), 3-(methoxycarbonyl)-(8m, 66percent), and 3-cyano-1H-indene (8n, 63percent). Alkaline hydrolysis of 8l and acidification to pH 2 gave the monosodium salt (91percent) of the corresponding pentacarboxylic acid (13l). Hydrogenation of 8l over PtO2 gave a tetrahydro derivative (14l, 100percent). That maleic anhydride can take the place of the second (but not the first) molecule of DMAD in 8 is shown by the formation of a 1:1:1 mixed adduct (10l, 17percent) along with the 1:2 adduct (8l, 18percent) from reaction of 1l, DMAD, and maleic anhydride in a 1:2:2 molar ratio in refluxing xylene. A similar 1:1:1 mixed adduct (10n, 59percent), but no 1:2 adduct (8n), was isolated from the corresponding reaction of 1n, DMAD, and maleic anhydride in a 1:1:1 molar ratio. Similarly, maleic anhydride can take the place of the third molecule of DMAD in the 1:3 adduct 11. Thus, reaction of 7a and 7b with maleic anhydride in refluxing xylene gave the corresponding 1:2:1 mixed adducts (12a, 69percent; 12b, 32percent), formed by Diels-Alder addition across the cyclohexadiene system of 7a and 7b. Reaction of 1-methyl-1H-indene (1b), DMAD, and maleic anhydride in a 1:2:1 molar ratio in refluxing xylene also gave 12b (31percent) but no 1:3 adduct (11b). Methyl esterification of 12a gave the corresponding hexamethyl ester (15a, 52percent). On the basis of the shielding effects of neighboring ethylene groups on the methylene bridge protons, an NMR rationale has been developed for assignment of stereochemistry to the adducts 8-12.
UV-vis and IR spectral characterization of persistent carbenium ions, generated upon incorporation of cinnamyl alcohols in the acid zeolites HZSM-5 and HMor
Adam,Casades,Fornes,Garcia,Weichold
, p. 3947 - 3951 (2000)
Cinnamyl alcohol (1) and two derivatives 2 and 3 have been incorporated in dehydrated HMor and HZSM-5 zeolites with the aim to characterize spectroscopically the corresponding carbocations generated within the solids. Product studies of the supernatant liquid phase combined with diffuse reflectance UV-vis and IR spectroscopy provide unequivocal evidence for the carbocations. Thus, cinnamyl alcohol (1) affords the 1,5-diphenylpentadienyl cation in HMor and HZSM-5 as a persistent species. In the case of HMor with larger pore dimensions the bulkier 1-(2′-cinnamyl)-3-phenylpropenyl cation was also spectroscopically detected. No persistent carbocation was observed when the α-methylcinnamyl alcohol (2) was incorporated in the acid zeolites, wherein a complete cyclization to 2-methylindene takes place. Finally, incorporation of 2-methyl-4-tolyl-3-buten-2-ol (3) in HZSM-5 allowed detection of the gem-dimethyl-subsituted p-methylcinnamyl cation, with a lifetime of hours. This cation is not persistent enough in HMor to be characterized. The present study illustrates how structurally related allylic substrates may give distinct carbenium ions whose persistence depends on the host-guest fit in the interior of the acid zeolites.
Palladium-Catalyzed Cyclization of Benzyl Halides and Related Electrophiles Containing Alkenes and Alkynes as a Novel Route to Carbocycles
Wu, Guang-zhong,Lamaty, Frederic,Negishi, Ei-ichi
, p. 2507 - 2508 (1989)
Treatment of benzyl halides and related electrophiles containing alkene and alkyne groups with a catalytic amount of Pd complexes, such as Pd(PPh3)4, provides the corresponding cyclization products containing five- through seven-membered rings often with retention of the alkene regiochemistry.
Photochemistry of Alkylindenes in the Gas Phase
Suarez, Marie L.,Duguid, Robert J.,Morrison, Harry
, p. 6384 - 6391 (1989)
The photochemistry of indene and several alkylindenes has been studied in the gas phase using excitation (254 nm) which populates the S2 state.Reactions observed in the gas phase involve rearrangements different from those observed in solution, as evidenced by the formation of photoproducts explicable in terms of net hydrogen and alkyl migrations.Photodealkylation is also observed at low pressures.In a typical example, gas-phase irradiation of 1-methylindene produces 3-methylindene as the major product, in addition to 2-methylindene, while irradiation in solution leads only to the 2-methyl isomer.The reaction mechanism has been investigated via deuterium-labeling studies, the use of added potential triplet sensitizer and quencher gases, and collisional deactivation by added inert gases.Irradiation of selectively deuterated indenes results in nearly statistical scrambling in the five-membered ring of the indene skeleton, and multiple 1,5 hydrogen or alkyl migrations are proposed.The lack of triplet sensitization, quenching, or enhancement indicates that the photochemistry is derived from a single state.Collisional deactivation results in net quenching of all the photoproducts, with those exclusive to the gas phase quenched at a faster rate than the products observed in solution.Collisional deactivation concomitantly results in an enhancement in fluorescence emission, with little emission observed upon excitation into S2 in the absence of a quencher gas.A reaction scheme is proposed which involves the generation of photoproducts from S2 and S1vib.
Alkyl-substituted indenyl titanium precursors for syndiospecific ziegler-natta polymerization of styrene
Ready, Thomas E.,Chien, James C.W.,Rausch, Marvin D.
, p. 21 - 28 (1996)
A variety of 1- and 3-substituted alkylindenes (R = H, Me, Et, tert-butyl, Me3Si) as well as 2-methylindene and 3-(methylthio)indene have been prepared in good yields. The substituted indenes were converted into trimethylsilyl derivatives via reactions of intermediate organolithium complexes with chlorotrimethylsilane. The corresponding titanium complexes, (R-Ind)TiCl3, were synthesized in excellent yield from reactions of the trimethylsilyl derivatives with TiCl4. The titanium complexes were evaluated as styrene polymerization catalysts in toluene solution when activated by methylaluminoxane. Activities increased in the order: Cp 4 Ind 3Si, corresponding to an increase in the steric bulk of the substituent in the catalyst precursor. 1-(MeS)IndTiCl3 was found to be ineffective as a styrene polymerization catalyst. Syndiospecificities of the titanium complexes were generally very good (65-98%).
Intramolecular substitution reaction of alkylidene-lithium carbenoids: Regioselective synthesis of indenes
Yanagisawa, Hideyuki,Miura, Kasei,Kitamura, Mitsuru,Narasaka, Koichi,Ando, Kaori
, p. 3130 - 3135 (2002)
Intramolecular substitution reaction of geminal dibromo alkenes proceeds to afford indenes, dihydronaphthalenes, dihydrofurans, and dihydropyran via in sint generated lithium alkylidene carbenoids, which have a carbon or oxygen nucleophilic moiety. This reaction provides a regioselective method for the preparation of polysubstituted indenes.
Radical condensation between benzylic alcohols and acetamides to form 3-arylpropanamides
Azizi, Kobra,Madsen, Robert
, p. 7800 - 7806 (2020/08/14)
A new radical condensation reaction is developed where benzylic alcohols and acetamides are coupled to generate 3-arylpropanamides with water as the only byproduct. The transformation is performed with potassium tert-butoxide as the only additive and gives rise to a variety of 3-arylpropanamides in good yields. The mechanism has been investigated experimentally with labelled substrates, trapping experiments and spectroscopic measurements. The findings indicate a radical pathway where potassium tert-butoxide is believed to serve a dual role as both base and radical initiator. The radical anion of the benzylic alcohol is proposed as the key intermediate, which undergoes coupling with the enolate of the amide to form the new C-C bond. Subsequent elimination to the corresponding cinnamamide and olefin reduction then affords the 3-arylpropanamides.
CO extrusion in homogeneous gold catalysis: Reactivity of gold acyl species generated through water addition to gold vinylidenes
Bucher, Janina,St?sser, Tim,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
supporting information, p. 1666 - 1670 (2015/01/30)
Herein, we describe a new gold-catalyzed decarbonylative indene synthesis. Synergistic σ,π-activation of diyne substrates leads to gold vinylidene intermediates, which upon addition of water are transformed into gold acyl species, a type of organogold compound hitherto only scarcely reported. The latter are shown to undergo extrusion of CO, an elementary step completely unknown for homogeneous gold catalysis. By tuning the electronic and steric properties of the starting diyne systems, this new reactivity could be exploited for the synthesis of indene derivatives in high yields.
Nickel-catalyzed Kumada reaction of tosylalkanes with Grignard reagents to produce alkenes and modified arylketones
Wu, Ji-Cheng,Gong, Lu-Bing,Xia, Yuanzhi,Song, Ren-Jie,Xie, Ye-Xiang,Li, Jin-Heng
supporting information, p. 9909 - 9913 (2012/10/30)
Open a new door: The first example of alkene synthesis from alkyl electrophiles with Grignard reagents using the Kumada cross-coupling reaction strategy is reported. This method opens a new door for the Kumada cross-coupling reaction, allowing alkenes to be prepared from the reaction of tosylalkanes with Grignard reagents. Copyright
Acid catalysed reaction of indanones, tetralones and benzosuberone with neopentyl glycol and other alkanediols under forced conditions
Imai, Masao,Morais, Goreti Ribeiro,Al-Hindawi, Bassam,Al-Sulaibi, Mazen A.M.,Meetani, Mohammad,Thiemann, Thies
experimental part, p. 325 - 329 (2010/10/19)
Upon reaction with an excess of 2,2-dimethylpropane-1,3-diol (neopentyl glycol, NPG) under acid catalysis, indanones and tetralones yield indenes and dihydronaphthalenes, respectively. The reaction can also be carried out with butane-1,3-diol.
