2177-48-2Relevant academic research and scientific papers
1,3-disubstituted indene complexes
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, (2008/06/13)
The present invention relates to organometallic compounds of transition metals with an indenyl ligand bonded in the 2-position and substituted in the 1,3-position, a process for their production, and their use as catalysts for the (co)polymerization of ol
New indenyl titanium catalysts for syndiospecific styrene polymerizations
Ready, Thomas E.,Chien, James C.W.,Rausch, Marvin D.
, p. 11 - 27 (2007/10/03)
A series of multi-methyl-substituted indenes as well as allylindene, n-propylindene, n-but-1-enylindene, and n-butylindene 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 were synthesized in excellent yields from reactions of the trimethylsilyl derivatives with TiCl4. The titanium complexes were evaluated as styrene polymerization catalysts in toluene solution when activated by methylaluminoxane. In general, catalytic activities decreased with each additional methyl substituent. Syndiospecificities were very high (90-95%).
Photochemistry of Alkylindenes in the Gas Phase
Suarez, Marie L.,Duguid, Robert J.,Morrison, Harry
, p. 6384 - 6391 (2007/10/02)
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.
Radical Rearrangements of 1,3-Dimethylindene Derivatives: A Comparison with Rearrangement by 1,5-Sigmatropy
Jones, David W.,Renyard, Stephen J.
, p. 467 - 471 (2007/10/02)
Radical dissociation-recombination mechanisms are proposed for the following thermal reactions: (i) interconversion of the meso- and (+/-)-forms of the bi-indenyls (3) and (6), (ii) racemisation of the methyl ether (1; X=Ph2COMe), and (iii) diastereoisome
Photoinduced Skeletal Rearrangement of Alkylindenes
Morrison, Harry,Giacherio, David,Palensky, Frederick J.
, p. 1051 - 1058 (2007/10/02)
The indene phototransposition reaction, a skeletal rearrangement of certain alkylindenes involving an interchange of carbons 1 and 1 (eq 2), is described.The postulated mechnism (Scheme II) involves a closure followed by a sigmatropic shift, opening to an isoindene and 1,5 hydrogen shifts to re-form the indene system.Results of experiments with indenes containing different alkyl groups at C1 and C2 and with 1,1-dimethylindene lend support to the proposed scheme.Experiments with (+)-1,2-dimethylindene indicate that the net migration of C1 to C3,necessary for transposition, occurs with clean inversion at C1 (as would be expected for a ground-state, four-electron, electrocyclic reaction).The reaction derives from the excited singlet state, and partial movement along the initial reaction surface appears to provide an efficient path for S1 radiationless decay.
Cycloaddition Reactions of Indenes. 2. Reactions with Dimethyl Acetylenedicarboxylate and Maleic Anhydride
Noland, Wayland E.,Kameswaran, Venkataraman,Landucci, Lawrence L.
, p. 4564 - 4572 (2007/10/02)
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.
