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1
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0003955355
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CRC, Boca Raton
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M. Santelli, J.-M. Pons, Lewis Acids and Selectivity in Organic Chemistry, CRC, Boca Raton, 1996, p. 334;
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(1996)
Lewis Acids and Selectivity in Organic Chemistry
, pp. 334
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Santelli, M.1
Pons, J.-M.2
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3
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1942521170
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For a discussion of the basic concepts of this approach, see: a
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For a discussion of the basic concepts of this approach, see: a) S. S. Minegishi, S. Kobayashi, H. Mayr, J. Am. Chem. Soc. 2004, 126, 5174;
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(2004)
J. Am. Chem. Soc
, vol.126
, pp. 5174
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Minegishi, S.S.1
Kobayashi, S.2
Mayr, H.3
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4
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7244247089
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b) B. Denegri, S. Minegishi, O. Kronja, H. Mayr, Angew. Chem. 2004, 116, 2353;
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(2004)
Angew. Chem
, vol.116
, pp. 2353
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Denegri, B.1
Minegishi, S.2
Kronja, O.3
Mayr, H.4
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6
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0037241494
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c) H. Mayr, B. Kempf, A. F. Ofial, Acc. Chem. Res. 2003, 36, 66.
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(2003)
Acc. Chem. Res
, vol.36
, pp. 66
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Mayr, H.1
Kempf, B.2
Ofial, A.F.3
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7
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28544443880
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a) M. Hofmann, N. Hampel, T. Kanzian, H. Mayr, Angew. Chem. 2004, 116, 5518;
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(2004)
Angew. Chem
, vol.116
, pp. 5518
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Hofmann, M.1
Hampel, N.2
Kanzian, T.3
Mayr, H.4
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10
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57049130223
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Preliminary results of this study were presented at ESOC-2007, Dublin, Ireland (Book of Abstracts, 342).
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Preliminary results of this study were presented at ESOC-2007, Dublin, Ireland (Book of Abstracts, 342).
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11
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0035541760
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a) W. A. Smit, M. I. Lazareva, I. P. Smolyakova, R. Caple, Russ. Chem. Bull. Int. Ed. 2001, 50, 1949;
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(2001)
Russ. Chem. Bull. Int. Ed
, vol.50
, pp. 1949
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Smit, W.A.1
Lazareva, M.I.2
Smolyakova, I.P.3
Caple, R.4
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20
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0346970844
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For a review, see: a
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For a review, see: a) J.-P. Bégué, D. Bonnet-Delpon, B. Crousse, Synlett 2004, 18;
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(2004)
Synlett
, pp. 18
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Bégué, J.-P.1
Bonnet-Delpon, D.2
Crousse, B.3
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22
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5844252510
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T=1 (for water), see: C. Reichardt, Chem. Rev. 1994, 94, 2319.
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T=1 (for water), see: C. Reichardt, Chem. Rev. 1994, 94, 2319.
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23
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33847797449
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From the data of solvolytic studies, the ionizing power Y for HFIP is 3.61 (cf. Y=3.04 for HCOOH), see: F. L. Schadt, T. W. Bentley, P. von R. Schleyer, J. Am. Chem. Soc. 1976, 98, 7667.
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From the data of solvolytic studies, the ionizing power Y for HFIP is 3.61 (cf. Y=3.04 for HCOOH), see: F. L. Schadt, T. W. Bentley, P. von R. Schleyer, J. Am. Chem. Soc. 1976, 98, 7667.
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24
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57049164070
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According to recent estimates by Mayr and co-workers, the magnitude of the nucleophilicity parameter N≈-2.4 for HFIP, which is much lower than N values for the majority of other polar solvents and synthetically useful π donors (see Refs. [2a, 3a]).
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According to recent estimates by Mayr and co-workers, the magnitude of the nucleophilicity parameter N≈-2.4 for HFIP, which is much lower than N values for the majority of other polar solvents and synthetically useful π donors (see Refs. [2a, 3a]).
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25
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0000956882
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M. A. Matesich, J. Knoefel, H. Feldman, D. F. Evans, J. Phys. Chem. 1973, 77, 366.
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(1973)
J. Phys. Chem
, vol.77
, pp. 366
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Matesich, M.A.1
Knoefel, J.2
Feldman, H.3
Evans, D.F.4
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26
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84987028552
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G. W. Caldwell, J. A. Massuchi, M. G. Ikonomou, Org. Mass Spectrom. 1989, 24, 8.
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(1989)
Org. Mass Spectrom
, vol.24
, pp. 8
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Caldwell, G.W.1
Massuchi, J.A.2
Ikonomou, M.G.3
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27
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0001745182
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HFIP was shown to be a much stronger hydrogen-bond donor than phenol towards various acceptors, regardless of the experimental parameters used to measure this property (calorimetric data, shift in O-H-stretching frequency, hydrogen-bond chemical shifts; see K. F. Purcell, J. A. Stikeleather, S. D. Brunk, J. Am. Chem. Soc. 1969, 91, 4019).
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HFIP was shown to be a much stronger hydrogen-bond donor than phenol towards various acceptors, regardless of the experimental parameters used to measure this property (calorimetric data, shift in O-H-stretching frequency, hydrogen-bond chemical shifts; see K. F. Purcell, J. A. Stikeleather, S. D. Brunk, J. Am. Chem. Soc. 1969, 91, 4019).
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28
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0041573625
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Calculations based upon the Kamlet-Taft generalized solvatochromic equation point to the much higher hydrogen-bond-donor ability of HFIP (α=1.96) than such proton donors as methanol (α=0.93) or acetic acid α=1.09, see: M. J. Kamlet, J.-L. Abboud, M. H. Abrham, R. W. Taft, J. Org. Chem. 1983, 48, 2877
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Calculations based upon the Kamlet-Taft generalized solvatochromic equation point to the much higher hydrogen-bond-donor ability of HFIP (α=1.96) than such proton donors as methanol (α=0.93) or acetic acid (α=1.09); see: M. J. Kamlet, J.-L. Abboud, M. H. Abrham, R. W. Taft, J. Org. Chem. 1983, 48, 2877.
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29
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33947482378
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For example, a 1:1 complex of HFIP with THF was stable enough to tolerate distillation at 100°C; recovery of the alcohol from this complex required its treatment with 20% oleum; see: W. J. Middleton, R. V. Lindsey, Jr., J. Am. Chem. Soc. 1964, 86, 4948.
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For example, a 1:1 complex of HFIP with THF was stable enough to tolerate distillation at 100°C; recovery of the alcohol from this complex required its treatment with 20% oleum; see: W. J. Middleton, R. V. Lindsey, Jr., J. Am. Chem. Soc. 1964, 86, 4948.
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30
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1542392557
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and references therein
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L. Eberson, M. P. Hartshorn, O. Persson, F. Radner, Chem. Commun. 1996, 2105, and references therein.
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(1996)
Chem. Commun
, pp. 2105
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Eberson, L.1
Hartshorn, M.P.2
Persson, O.3
Radner, F.4
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32
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57049125974
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A full account of the studies, dealing with elaboration of the preparative methods, will be published shortly
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A full account of the studies, dealing with elaboration of the preparative methods, will be published shortly.
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33
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0000565741
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Studies were carried out, aimed at the evaluation of the effects of HFIP on the parameters of UV/Vis and/or NMR spectroscopy of benzaldehyde acetal 5, p-methoxybenzaldehyde 16, or cyclopentenone 23. UV/Vis spectroscopy of solutions of 5 or 16 in HFIP did not disclose any substantial changes indicative of the formation of ionized species. There was a very small shift of the maximum, as compared to the basic spectra in CH2Cl2 (Δλmax=8-9 nm, whereas the appearance of an intense red-shifted maximum (Δλmax= 54-60 nm) was detected for the methoxycarbenium ion derived from 5 following treatment with boron trihalide or a structurally similar cationic complex of 16 with boron trihalide c.f. data in H. Mayr, G. Gorath, J. Am. Chem. Soc. 1995, 117, 7862
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max= 54-60 nm) was detected for the methoxycarbenium ion derived from 5 following treatment with boron trihalide or a structurally similar cationic complex of 16 with boron trihalide (c.f. data in H. Mayr, G. Gorath, J. Am. Chem. Soc. 1995, 117, 7862).
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34
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57049134984
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The results of the comparative studies of 1H and 13C NMR spectra for the solutions of 5 or 16 in neat CD2Cl2 and a CD2Cl2/HFIP (1:10) mixture revealed deshielding effects both for 1H (Δδ=0.2- 0.4 ppm for all protons of 5 and 16, except CHO in 16, which underwent an upfield shift, Δδ=0.15 ppm) and 13C signals (Δδ=3.0 ppm for CH(OMe)2 in 5 and 4.8 ppm for CHO in 16, Although the cause of these effects is far from clear, it is noteworthy that the transformation of 5 or 16 into the respective cationic derivatives resulted in much more dramatic changes in the NMR spectra (see the data in the reference cited above, A noticeable trend was observed upon the comparison of 13C NMR spectra of 23 in neat CD2Cl2 and a CD2Cl2/HFIP 1:5
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2/HFIP (1:5) mixture. The addition of HFIP resulted in a substantial downfield shift of C1 and C3 signals (Δδ=7.0 and 5.7 ppm, respectively) and an upfield shift for the C2 signal (Δδ=1.1 ppm). Similar, but substantially more strongly expressed, effects were observed earlier for the complexes of conjugated carbonyl compounds with various Lewis acids (for example, Δδ=8.3, -3.3, and 26.1 ppm for C1, C2, and C3, respectively, for the crotonaldehyde-boron trifluoride complex, see: R. F. Childs, D. L. Mulholland, A. Nixon, Can. J. Chem. 1982, 60, 801).
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