2780
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 12, December, 2004
Volkonskii et al.
achieved only after 3 days at 20 °C and one day at 30 °C
(4a : 2a : 6 : 13a = 1.0 : 0.14 : 0.59 : 0.64) (NMR, GLC).
Nꢀ[1,2,2ꢀTrifluoroꢀ1ꢀ(1ꢀhydrohexafluoroisobutenylꢀ
oxy)ethyl]diethylamine (14a). 1H NMR, δ: 1.2 (br.t, 6 H, H(4),
1.35 (m, 4 H, H(5)); 1.60 (m, 4 H, H(4)); 2.90 (m, 4 H, H(3));
2
3
5.94 (td, 1 H, H(1), JH(1),F(1) = 55 Hz, JH(1),F(2) = 2.4 Hz);
7.70 (br.s, 1 H, H(2)). 19F NMR, δ: –56.0 and –54.74 (both ddd,
AB system, 2 F, F(1), 2JF(1A),F(1B) = 300 Hz, 2JF(1),H(1) = 55 Hz,
3JF(1),F(2) = 8.8 Hz); –28.3 (br.s, 1 F, F(2)); 14.96 (q, 3 F, F(3),
4JF(3),F(4) = 6.4 Hz); 17.77 (q, 3 F, F(4), 4JF(4),F(3) = 6.4 Hz).
(N,NꢀDibutyl)difluoroacetamide di(1ꢀhydrohexafluoroisoꢀ
butenyl)acetal (15b). 1H NMR, δ: 0.98 (m, 6 H, H(6)); 1.35 (m,
4 H, H(5)); 1.60 (m, 4 H, H(4)); 2.90 (m, 4 H, H(3)); 6.11 (t,
1 H, H(1), 2JH(1),F(1) = 50 Hz); 7.70 (br.s, 2 H, H(2)). 19F NMR,
δ: –55.08 (d, 2 F, F(1), 2JF(1),H(1) = 50 Hz); 14.87 (q, 6 F, F(2),
4JF(2),F(3) = 6.4 Hz); 17.53 (q, 6 F, F(3), 4JF(3),F(2) = 6.4 Hz).
Reaction of silane 2a with Nꢀ(2ꢀchloroꢀ1,1,2ꢀtrifluoroethyl)diꢀ
ethylamine (12c). Freshly distilled amine 12c (0.3883 g,
2.048 mmol) was added with cooling (–78 °C) to freshly disꢀ
tilled silyl ether 2a (1.0104 g, 4.006 mmol) and the mixture was
allowed to stand at 20 °C. After one day, the starting compounds
were completely consumed, and the reaction mixture contained
Me3SiF (4a), divinyl ether 6, chlorodiethylfluoroacetamide
(13c), aldehyde 1, chlorofluoroketene aminoacetal 16a, and
isobutenyl isobutyl ether 17 (1.0 : 0.65 : 0.73 : 0.03 : 0.07 : 0.04)
(NMR, GLC). Distillation of the reaction mixture did not afꢀ
ford fractions containing more than 88.5% of divinyl ether 6.
Reaction of silane 2a with Nꢀ(2ꢀchloroꢀ1,1,2ꢀtrifluoroethyl)diꢀ
butylamine (12d). Freshly distilled amine 12d (21.4 g, 87.1 mmol)
was added dropwise with stirring and cooling (–20 °C) to freshly
distilled silyl ether 2a (46.5 g, 184.4 mmol). The reaction mixꢀ
ture was allowed to slowly warm to room temperature. After one
day (at 20 °C), the starting compounds and intermediates were
absent in the reaction mixture (GLC and NMR), and the mixꢀ
ture contained Me3SiF (4a), divinyl ether 6, dibutylchloroꢀ
fluoroacetamide (13d), aldehyde 1, and chlorofluoroketene
aminoacetal 16b (1.0 : 0.40 : 0.44 : 0.08 : 0.08). Distillation
afforded 22.54 g (75%) of divinyl ether 6 with a purity of >98%
(NMR, GLC), b.p. 48—50 °C (8 Torr).
3
3JH(4),H(3) ≈ 7 Hz); 3.0 (br.q, 4 H, H(3), JH(3),H(4) ≈ 7 Hz); 6.0
2
(br.t, 1 H, H(1), JH(1),F(1) ≈ 53 Hz); 7.7 (br.s, 1 H, H(2)).
19F NMR, δ: –56.7 and –55.0 (both br.dd, AB system, 2 F,
2
2
F(1), JF(1A),F(1B) = 293.5 Hz, JF(1),H(1) ≈ 53 Hz); –27.3 (br.s,
1 F, F(2)); 14.70 (q, 3 F, F(3), 4JF(3),F(4) ≈ 6 Hz); 17.57 (q, 3 F,
4
F(4), JF(4),F(3) ≈ 6 Hz).
(N,NꢀDiethyl)difluoroacetamide di(1ꢀhydrohexafluoroꢀ
isobutenyl)acetal (15a). 1H NMR, δ: 1.2 (br.t, 6 H, H(4),
3
3JH(4),H(3) ≈ 7 Hz); 3.0 (br.q, 4 H, H(3), JH(3),H(4) ≈ 7 Hz); 6.2
2
(t, 1 H, H(1), JH(1),F(1) = 52.8 Hz); 7.7 (br.s, 2 H, H(2)).
2
19F NMR, δ: –55.5 (d, 2 F, F(1), JF(1),H(1) = 52.8 Hz);
4
14.74 (q, 6 F, F(2), JF(2),F(3) = 6.2 Hz); 17.41 (q, 6 F, F(3),
4JF(3),F(2) = 6.2 Hz).
Reaction of silane 2a with Nꢀ(1,1,2,2ꢀtetrafluoroethyl)diꢀ
butylamine (12b). Freshly distilled silyl ether 2a (0.22675 g,
0.8989 mmol) was mixed with freshly distilled amine 12b
(0.0958 g, 0.39 mmol) with ~93% purity (~4% of dibutylꢀ
amide 13b) at –78 °C and sealed in a glass tube. After 10 min
(20 °C), the reaction mixture contained (NMR spectroscopic
data) Me3SiF (4a), silane 2a, amine 12b, αꢀfluoroaminoacetal
14b, amidoacetal 15b, and amide 13b (1.0 : 2.35 : 0.61 : 0.97 :
: 0.03 : 0.08). After 40 min (at 20 °C), the conversion of the
starting silane 2a was ~100%, and the 14b : 15b ratio was 4 : 3
(NMR). After 5 h (at 20 °C), αꢀfluoroaminoacetal 14b was also
absent in the reaction mixture, but divinyl ether 6 appeared
(4a : 2a : 6 : 15b : 13b = 1.0 : 0.11 : 0.04 : 0.54 : 0.08) (NMR).
The complete conversion of amidoacetal 15b was achieved only
after 40 h at 20 °C and 5 h at 40 °C (4a : 2a : 6 : 13b =
1.0 : 0.1 : 0.59 : 0.66) (NMR, GLC).
Silyl ether 2a (39.12 g, 155.1 mmol) was added dropwise
with stirring and cooling (–78 °C) to amine 12b (17.98 g,
73 mmol) with ~93% purity containing ~4% (~0.72 g) of
dibutylamide 13b. The reaction mixture was allowed to warm to
room temperature with stirring. After completion of the weakly
exothermic reaction, the mixture was heated at 40—45 °C for 9 h,
the gaseous compounds being collected into a trap (–78 °C). At
20 °C, volatile compounds were distilled in vacuo (20 Torr) into
the same trap (–78 °C). A mixture containing Me3SiF (4a)
(13.60 g, 101.2%) and aldehyde 1* (0.28 g) (NMR, GLC) was
obtained in a yield of 13.89 g. Distillation of the residue afforded
23.82 g (95.4%) of divinyl ether 6 with a purity of >98% (NMR,
GLC), b.p. 35—37 °C (3 Torr), and 14.67 g of dibutylamide 13b
with 96.5% purity (3.5% of ether 6 as an impurity) (NMR,
GLC) (the yield was ~90% taking into account the purity and
content of amide 13b in the starting amine 12b), b.p. 56—58 °C
(1 Torr) (cf. lit. data26: b.p. 95 °C (1.5 Torr)).
Reaction of Nꢀ(1,1,2,2ꢀtetrafluoroethyl)diethylamine (12a)
with trifluoroacetic anhydride. Trifluoroacetic anhydride (56.7 g,
0.270 mol) was added dropwise with stirring to freshly distilled
amine 12a (50.6 g, 0.292 mol) at 20 °C at such a rate that the
liquid did not virtually condense in a water reflux condenser,
and gaseous compounds were collected into a trap (–78 °C).
After completion of the addition of the anhydride, the reaction
mixture was warmed to 70 °C for a short period of time.
Trifluoroacetyl fluoride was obtained in the trap (–78 °C) in a
yield of 61.1 g (97.5%) with a purity of >97% (NMR), b.p.
–55.5—–55.0 °C (cf. lit. data26: b.p. –59 °C).
We thank V. M. Kotov for providing a sample of
chlorodimethylvinylsilane (7b).
This study was in part financially supported by the
Russian Scientific Center (Applied Chemistry), St.ꢀPeꢀ
tersburg (Contract No. 17/01).
(N,NꢀDibutyl)difluoroacetamide (13b). 1H NMR (without
a solvent), δ: 0.85 (m, 6 H, H(5)); 1.25 (m, 4 H, H(4)); 1.50 (m,
4 H, H(3)); 3.30 (m, 4 H, H(2)); 6.30** (t, 1 H, H(1), 2JH(1),F
50 Hz). 19F NMR, δ: –45.8 (d, CF2, 2JF,H(1) = 50 Hz).
=
Nꢀ[1,2,2ꢀTrifluoroꢀ1ꢀ(1ꢀhydrohexafluoroisobutenylꢀ
oxy)ethyl]dibutylamine (14b). 1H NMR, δ: 0.98 (m, 6 H, H(6));
References
* An overstated yield of Me3SiF (4a) and the formation of an
insignificant amount of aldehyde 1 are, apparently, attributable
to the presence of HF traces in amine 12b.
1. HoubenꢀWeyl, OrganoꢀFluorine Compounds, Eds B. Baasner,
H. Hagemann, and J. C. Tatlow, Thieme, Stuttgart—New
York, 2000, E10a, 24; E10b/2, 298.
** In the reaction mixture, δ 6.07.
2. W. B. Farnham, Chem. Rev., 1996, 96, 1633.