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DOI: 10.1055/s-2002-32959
Synthesis of 1,1-Difluoroalkanes via Phase Transfer Catalysed Reaction of 1,1-bis-Triflates with KF in the Presence of Cocatalyst - Ph3SnF
Publikationsverlauf
Publikationsdatum:
25. Juli 2002 (online)
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Abstract
1,1-bis-Triflates treated with KF in the presence of triphenyltin fluoride and tetrabutylammonium hydrogen sulfate give 1,1-difluoroalkanes
Key words
phase transfer catalysis - tin compound - fluorination
-
1a
Fluorine-containing
Molecules. Structure, Reactivity, Synthesis and Applications
Liebman JF.Greenberg A.Dolbier WR. VCH; New York: 1988. -
1b
Filler R. Organofluorine Compounds in Medicinal Chemistry and Biomedical Applications, Studies in Organic Chemistry 48Filler R. Elsevier; New York: 1993. p.1-23 - 2
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Middleton WJ. J. Org. Chem. 1975, 40: 574 - 4
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References
Typical Procedure:
Dried powdered KF (3.094 g, 53.3 mmol), Ph3SnF (98 mg,
0.27 mmol) Bu4N+HSO4
- (91
mg, 0.27 mmol) and a freshly prepared solution of RCH(OTf)2 in CH2Cl2 (2.7
mmol in 4.5 mL) were vigorously stirred at r.t. till the reaction
was completed (16-48 h). The reaction mixture was diluted
with ether (25 mL), the solid was filtered off, washed with diethyl
ether (3 × 8 mL). The ether extracts
were combined and the solvent was distilled using a 20 cm Vigreux
column. The products were purified by chromatography (silica gel, n-pentane or n-pentane/CH2Cl2).
1,1-Difluorooctane: 1H
NMR (200 MHz, CDCl3): 0.89 (t, J [1H-1H] = 6.5
Hz, 3 H CH3), 1.25-1.50 (m, 10 H), 1.65-1.95 (m,
2 H), 5.79 (tt,
²
J [19F-1H] = 57
Hz; J [1H-1H] = 4.5
Hz, 1 H, CHF2). 19F NMR (178 MHz,
CDCl3): -116.2 (dt,
²
J [19F-1H] = 57
Hz;
³
J [19F-1H] = 17.5
Hz), MS (EI, 70 eV): 150 (M+, <1),
130 (M-HF, 1); 84(20), 81(17), 73(15), 71(21), 69(14),
68(12), 59(12), 57(60), 56(36), 55(37), 43(100), 42(23), 41(65).
1,1-Difluorodecane: 1H
NMR (200 MHz, CDCl3): 0.88 (t, J [1H-1H] = 6.5
Hz, 3 H CH3), 1,23-1,50 (m, 14 H), 1.65-1.95 (m,
2 H), 5.79 (tt,
²
J [19F-1H] = 57
Hz; J [1H-1H] = 4.5
Hz, 1 H, CHF2). 19F NMR (178 MHz,
CDCl3): -116.2 (dt;
²
J [19F-1H] = 57
Hz,
³
J [19F-1H] = 17.5
Hz). MS (EI, 70 eV): 178 (M+, 3), 107(13), 85(31),
84(16), 83(11), 82(15), 81(10), 73(16), 71(34), 70(21), 69(17),
57(80), 56(24), 55(34), 43(100), 42(15), 41(43).
1,1-Difluoro-2-phenyl-ethane: 1H
NMR (200 MHz, CDCl3): 3.07 (td,
³
J [19F-1H] = 17.3
Hz, J [1H-1H] = 4.6
Hz, 2 H; Ph-CH2-CHF2), 5.85 (tt,
²
J [19F-1H] = 56
Hz, J [1H-1H] = 4.6
Hz, 1 H, CHF2), 7.15-7,32 (m, 5 H, Ph). 19F
NMR (178 MHz, CDCl3): -115,5 (dt,
²
J [19F-1H] = 56.6
Hz,
3
J [19F-1H] = 17.3
Hz). MS (EI, 70 eV): 142 (M+, 33), 91(100), 65(14).
1,1-Difluoro-3-phenyl-propane: 1H
NMR (200 MHz, CDCl3): 2.01- 2.29 (m, 2 H, CH2-CHF2),
2.78 (t, J [1H-1H] = 7.9
Hz, 2 H, Ph-CH2), 5.80 (tt,
²
J [19F-1H] = 56.7
Hz, J [1H-1H] = 4.5
Hz, 1 H, CHF2), 7.16-7.36 (m, 5 H, Ph). 19F NMR
(178 MHz, CDCl3): -117.7 (dt,
²
J [19F-1H] = 56.8
Hz,
³
J [19F-1H] = 17.1
Hz). MS (EI, 70 eV): 156 (M+, 28), 92(11), 91(100),
65(11).
2-Ethyl-1,1-difluorohexane: 1H
NMR (200 MHz, CDCl3): 0.85-1.03 (m, 6 H), 1.25-1.55
(m, 8 H), 1.90-2.10 (1 H, CHCHF2), 5.71 (td,
²
J [19F-1H] = 58.0
Hz, J [1H-1H] = 4.0 Hz,
1 H, CHF2). 19F NMR (178 MHz, CDCl3): -123.43
(dd,
²
J [19F-1H] = 57.0
Hz,
³
J [19F-1H] = 15.7
Hz). MS (EI, 70 eV): 130 (M+ - HF,
1), 57(100), 56(11), 55(16), 43(49), 42(22), 41(48), 39(13).
Difluoromethylcyclohexane: 1H
NMR (200 MHz, CDCl3): 1.01-1.38 (m, 6 H), 1.61-1.84
(m, 5 H), 5.52 (td,
²
J [19F-1H] = 56.7
Hz, J [1H-1H] = 4.2
Hz, 1 H, CHF2). 19F NMR (178 MHz,
CDCl3): -123.82 (dd,
²
J [19F-1H] = 56.8
Hz,
³
J [19F-1H] = 14.1
Hz).