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For reviews on gold-catalyzed reactions, see: a
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For reviews on gold-catalyzed reactions, see: a) G. Dyker, Angew. Chem. 2000, 112, 4407;
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For selected papers on gold-catalyzed intramolecular cyclization of monopropargyl esters [reports on substrates of bis(propargyl ester) type are quite rare], see: a) X. Shi, D. J. Gorin, F. D. Toste, J. Am. Chem. Soc. 2005, 127, 5802;
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For selected papers on gold-catalyzed intramolecular cyclization of monopropargyl esters [reports on substrates of bis(propargyl ester) type are quite rare], see: a) X. Shi, D. J. Gorin, F. D. Toste, J. Am. Chem. Soc. 2005, 127, 5802;
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33747272412
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For related gold-catalyzed reactions carried out in our group, see: a
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For related gold-catalyzed reactions carried out in our group, see: a) Y. Liu, M. Liu, S. Guo, H. Tu, Y. Zhou, H. Gao. Org. Lett. 2006, 8, 3445;
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28844445185
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b) Y. Liu, F. Song, Z. Song, M. Liu, B. Yan, Org. Lett. 2005, 7, 5409;
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34
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53849104455
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Alkynyl-substituted indenyl ketones such as 3a are somewhat unstable after evaporation of the solvent, a small amount of colored matter will appear. However, it becomes stable in the solid state. In these cases, the desired products were further purified by recrystallization or by washing with the organic solvents.
-
Alkynyl-substituted indenyl ketones such as 3a are somewhat unstable after evaporation of the solvent, a small amount of colored matter will appear. However, it becomes stable in the solid state. In these cases, the desired products were further purified by recrystallization or by washing with the organic solvents.
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35
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53849121090
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We have also tried TfOH-catalyzed reaction of 1a in the presence of water as suggested by one reviewer. It was found that addition of 1 equiv. of H2O could afford 3a in 96% NMR yield, however, in the presence of 5 equiv. of H2O, only a trace amount of indene was observed
-
2O, only a trace amount of indene was observed.
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36
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53849113804
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Interestingly, the isomerization between 4 and its double bond isomer the 2,3-disubstituted indene could be observed through heating a sample loaded on silica gel (200-300 mesh). For example, a double bond isomer was isolated in 72% yield with >99% isomeric purity upon heating 4i for 20 h. (Chemical Equation Presented)
-
Interestingly, the isomerization between 4 and its double bond isomer the 2,3-disubstituted indene could be observed through heating a sample loaded on silica gel (200-300 mesh). For example, a double bond isomer was isolated in 72% yield with >99% isomeric purity upon heating 4i for 20 h. (Chemical Equation Presented)
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37
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53849105940
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Crystallographic data for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC 668960 (3f, CCDC 668961 (4l, These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via or on application to CCDC, 12Union Road, Cambridge CB21EZ, UK [Fax: int. code +44-1223-336-033; e-mail: deposit@ccdc.cam.ac.uk
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Crystallographic data for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC 668960 (3f), CCDC 668961 (4l). These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif or on application to CCDC, 12Union Road, Cambridge CB21EZ, UK [Fax: int. code +44-(1223-336-033; e-mail: deposit@ccdc.cam.ac.uk].
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38
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53849113482
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See Supporting Information
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See Supporting Information.
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39
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53849090081
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To understand the possible formation of benzylic cation, we tried the reaction of acetic acid benzhydryl ester with mesitylene catalyzed by 8% TfOH; the desired substitution product of 2-diphenylmethyl-1,3,5-trimethylbenzene was obtained in 99% yield;
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a) To understand the possible formation of benzylic cation, we tried the reaction of acetic acid benzhydryl ester with mesitylene catalyzed by 8% TfOH; the desired substitution product of 2-diphenylmethyl-1,3,5-trimethylbenzene was obtained in 99% yield;
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40
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33645801996
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for the (Chemical Equation Presented) Brønsted acid-catalyzed condensation of furans with acetone through a benzylic cation intermediate, see: A. S. K. Hashmi, L. Schwarz, P. Rubenbauer, M. C. Blanco, Adv. Synth. Catal. 2006, 348, 705.
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b) for the (Chemical Equation Presented) Brønsted acid-catalyzed condensation of furans with acetone through a benzylic cation intermediate, see: A. S. K. Hashmi, L. Schwarz, P. Rubenbauer, M. C. Blanco, Adv. Synth. Catal. 2006, 348, 705.
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41
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0000859695
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For reviews on theoretical and experimental studies on benzyl cations, see: a, Eds, G. A. Olah, P. v. R. Schleyer, Wiley-Interscience, New York, Chapter 28;
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For reviews on theoretical and experimental studies on benzyl cations, see: a) H. H. Freedman, in: Carbonium Ions, (Eds.: G. A. Olah, P. v. R. Schleyer), Wiley-Interscience, New York, 1973, Vol. 4, Chapter 28;
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Freedman, H.H.1
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0004194826
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0025269877
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33748356712
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Angle, S.R.1
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50
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53849148044
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3 solution (the detailed procedure is shown in the Supporting Information).
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3 solution (the detailed procedure is shown in the Supporting Information).
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