3722-77-8Relevant academic research and scientific papers
Facile ring-closure cyclization of arenes by nucleophilic C-alkylation reaction in ionic liquid
Hong, Dong Jin,Kim, Dong Wook,Chi, Dae Yoon
, p. 54 - 56 (2010)
A novel synthetic method using an ionic liquid (IL) for a six-membered ring-closure cyclization is described. The ring-closure cyclization by nucleophilic C-alkylation was achieved with various halo- and alkanesulfonyloxyalkyl aromatic compounds in high yields with minimal byproducts using ILs as the reaction media in the absence of any catalyst. For example, the cyclization of 2-(3-methanesulfonyloxy-propoxy)naphthalene (1a) to 2,3-dihydro-1H-naphtho[2,1-b]pyran (2) in IL [bmim][PF6] proceeded selectively at 150 °C for 24 h in 85% yield.
Intramolecular hydroarylation of alkynes catalyzed by platinum or gold: Mechanism and endo selectivity
Nevado, Cristina,Echavarren, Antonio M.
, p. 3155 - 3164 (2007/10/03)
The cyclization of differently substituted aryl alkynes with Pt II or AuI catalysts proceeds by endo-dig pathways. When AgI was used to generate reactive cationic AuI catalysts, 2H-chromenes dimerize to form cyclobutane derivatives by a Ag I-catalyzed process. A DFT study on the cycliza-tion mechanism shows a kinetic and thermodynamic preference for 6-endodig versus 5-exo-dig cyclizations in PtII-catalyzed processes. Calculations indicate that although Friedel-Crafts and the cyclopropanation processes via metal cyclopropyl carbenes show very similar activation energies, platinum cyclopropyl carbenes are the stationary points with the lowest energy.
Reactions of γ-arylalkanols via aryl radical cation and alkoxyl radical intermediates. Part 3. Reactions of 3-arylprop-1-yl hydroperoxides with iron(II) in the presence of copper(II)
Goosen, Andre,Marais, Charles F.,McCleland, Cedric W.,Rinaldi, Fabrizio C.
, p. 1227 - 1236 (2007/10/02)
A strategy for comparing the 1,5- and 1,6-cyclisation reactions of 3-phenylpropan-1-oxyl radicals is described.Iron(II)-catalysed reduction of 3-(p-methylphenyl)prop-1-yl hydroperoxide and its para-chloro and para-methoxy-substituted analogues, carried out in the presence of copper(II), has been found to give in each case the appropriate para-substituted 3-phenylpropan-1-ol, 3-phenylpropanal and a low yield of a mixture of isomeric 6- and 7-substituted chromans.The alcohols are proposed to form via reduction of either the hydroperoxide or the resulting alkoxyl radical or its cyclised intermediates, and the aldehydes as a result of rearrangement of the alkoxyl radical to an α-hydroxy alkyl radical which subsequently undergoes oxidation.The 7-substituted chromans, which arise directly from 1,6-cyclisation of the alkoxyl radical, were found to dominate the 6-substituted isomers which result from rearrangement of 1,5-cyclised intermediates.This effect is attributed to inefficient interception of the 1,5-cyclised radical intermediate which permits equilibration to the thermodynamically more stable 1,6-cyclised radical isomer to occur.The effect of pH on the reactions has been investigated and although no products typical of the intermediacy of aryl radical cations were detected (even under highly acidic conditions), the formation of such intermediates cannot be excluded.Semiempirical MO calculations have been carried out (at the PM3 level of approximation) on a series of model compounds, yielding results which have clarified our understanding of the effect of substituents on the stabilities of the various intermediates arising from the cyclisation reactions of 3-phenylpropan-1-oxyl radicals.Furthermore, these calculations have supported our assumptions regarding the probability and specificity of rearrangements of the spirodienyl intermediates.
