70063-93-3Relevant academic research and scientific papers
Palladium-Catalyzed Methylation of Aryl and Vinyl Halides by Stabilized Methylaluminum and Methylgallium Complexes
Blum, Jochanan,Gelman, Dmitri,Baidossi, Wael,Shakh, Eduard,Rosenfeld, Ayelet,Aizenshtat, Zeev,Wassermann, Birgit C.,Frick, Michael,Heymer, Bernd,Schutte, Stefan,Wernik, Sonja,Schumann, Herbert
, p. 8681 - 8686 (1997)
The intramolecularly stabilized mono- and dialkylaluminum complexes 1a, 2, 3, 4a, 5a, 5c, 6a, 6c, 7, 8, and 9 in the presence of palladium catalysts, cross-alkylate aryl, vinyl, and benzyl bromides and iodides under mild standard laboratory conditions. Aryl bromides with carbonyl substituents or benzylic halides are converted partially into dialkyl compounds. Under similar conditions, the analogous stabilized dimethylgallium complexes 1b, 4b, 5b, 6b, and 10 methylate aryl and vinyl bromides and iodides in a highly selective manner. Substituted bromobenzenes XC6H4Br, where X = CHO, COPh, CO2Et, CN, NO2, Cl, CH2Br, or CH=CHCOPh, are methylated by the organogallium reagents usually only at the aromatic ring halogen atom to give substituted toluenes as single products. The methylation rates were shown to depend on the nature of the chelating ligands, on the solvent, and on the type of palladium catalyst employed.
The photochemistry of indenyl alcohols and esters: Substituent effects on the competition between ion- and radical-derived products
Pincock,Young
, p. 1083 - 1095 (2007/10/03)
The photochemistry of the indenyl acetates 1 and pivalates 2, substituted with X = H, 5-CH3O, and 6-CH3O, have been examined in both methanol and cyclohexane. The precursor alcohols 3 were also found to be photoreactive. Although only radical-derived products were obtained in cyclohexane, both ion- and radical-derived products were formed in methanol. The absence of significant fluorescence emission from any of the substrates 1, 2, and 3 indicates that the excited singlet states are highly reactive. A mechanism is proposed for the ion-derived products that proceeds through direct heterolytic cleavage to give an indenyl cation - carboxylate anion pair. The indenyl cations generated are anti-aromatic in the ground state and their efficient generation by this photochemical solvolysis is in sharp contrast to the very low reactivity of related ground-state substrates. For the pivalate esters 2, an excited-state migratory decarboxylation is proposed for the formation of tert-butyl derived products.
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.
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.
