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Volumn 47, Issue 50, 2008, Pages 9739-9742

Lewis acid catalyst free electrophilic alkylation of silicon-capped π donors in 1,1,1,3,3,3-hexafluoro-2-propanol

Author keywords

Electrophilic addition; Hydrogen bonds; Lewis acids; Silanes; Solvent effects

Indexed keywords

ADDITION REACTIONS; CATALYSIS; CHEMICAL REACTIONS; HYDROCARBONS; HYDROGEN; HYDROGEN BONDS; SILANES; SILICON; SOLVENTS;

EID: 57049099775     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200803927     Document Type: Article
Times cited : (64)

References (34)
  • 3
    • 1942521170 scopus 로고    scopus 로고
    • For a discussion of the basic concepts of this approach, see: a
    • 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;
    • (2004) J. Am. Chem. Soc , vol.126 , pp. 5174
    • Minegishi, S.S.1    Kobayashi, S.2    Mayr, H.3
  • 10
    • 57049130223 scopus 로고    scopus 로고
    • Preliminary results of this study were presented at ESOC-2007, Dublin, Ireland (Book of Abstracts, 342).
    • Preliminary results of this study were presented at ESOC-2007, Dublin, Ireland (Book of Abstracts, 342).
  • 22
    • 5844252510 scopus 로고    scopus 로고
    • T=1 (for water), see: C. Reichardt, Chem. Rev. 1994, 94, 2319.
    • T=1 (for water), see: C. Reichardt, Chem. Rev. 1994, 94, 2319.
  • 23
    • 33847797449 scopus 로고    scopus 로고
    • 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.
    • 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.
  • 24
    • 57049164070 scopus 로고    scopus 로고
    • 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]).
    • 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]).
  • 27
    • 0001745182 scopus 로고    scopus 로고
    • 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).
    • 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).
  • 28
    • 0041573625 scopus 로고    scopus 로고
    • 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
    • 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.
  • 29
    • 33947482378 scopus 로고    scopus 로고
    • 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.
    • 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.
  • 32
    • 57049125974 scopus 로고    scopus 로고
    • A full account of the studies, dealing with elaboration of the preparative methods, will be published shortly
    • A full account of the studies, dealing with elaboration of the preparative methods, will be published shortly.
  • 33
    • 0000565741 scopus 로고    scopus 로고
    • 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
    • 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).
  • 34
    • 57049134984 scopus 로고    scopus 로고
    • 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
    • 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).


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.