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with hexane–benzene (1/1) to give N,N-dibutyl-2-bromo-
3,3,3-trifluoropropanamide (6aBr) (87% yield).
3.6.2. N,N-Pentamethylene-2-bromo-3,3,3-trifluoroprop-
anamide (6cBr). Yield 78%; IR (neat) 3001, 2986, 2947,
2858, 1643, 1462, 1369, 1323, 1373, 1157, 1123, 1015, 964,
872, 853, 806, 783, 691, 656 (cmK1); 1H NMR d 1.53–1.68
(m, 6H), 3.34–3.67 (m, 4H), 4.84 (q, JZ6.2 Hz, 1H); 13C
NMR d 24.0, 25.1, 25.9, 37.2 (q, JZ32.6 Hz), 43.4, 47.6,
122.3 (q, JZ277.7 Hz), 160.3; 19F NMR d K70.7 (d, JZ
6.2 Hz, 3F).
On the other hand, after treating 2a with bromine at 0 8C for
1 h as described above, the reaction mixture was concen-
trated under reduced pressure. Hexane was added to the
resulting residue to precipitate a crude solid, which was too
labile to be purified. However, spectral analyses of this
crude solid made it possible to determine successfully the
structure of the product 5a.
3.6.3. N,N-Diisopropyl-2-bromo-3,3,3-trifluoropropan-
amide (6dBr). Yield 37%; IR (neat) 2974, 2939, 2882,
1655, 1477, 1450, 1377, 1362, 1335, 1273, 1200, 1150,
1126, 1045, 876, 799, 691, 640 (cmK1); 1H NMR d 1.29 (d,
JZ6.5 Hz, 3H), 1.27 (d, JZ7.0 Hz, 3H), 1.38 (d, JZ
6.5 Hz, 3H), 1.39 (d, JZ6.5 Hz, 3H), 3.54 (br s, 1H), 3.86
(sept, JZ6.5 Hz, 1H), 4.68 (q, JZ6.0 Hz, 1H); 13C NMR d
19.6, 20.2, 20.4, 21.1, 38.8 (q, JZ31.8 Hz), 46.9, 49.9,
122.4 (q, JZ277.8 Hz), 160.7; 19F NMR d K68.6 (d, JZ
6.0 Hz, 3F).
3.5.1. N,N-Dibutyl-2-bromo-3,3,3-trifluoropropanamide
(6aBr). Yield 87%; IR (neat) 2963, 2936, 2874, 1663, 1458,
1346, 1277, 1161, 1119, 876, 698, 671 (cmK1); 1H NMR d
0.93 (t, JZ7.5 Hz, 3H), 0.98 (t, JZ7.5 Hz, 3H) 1.26–1.73
(m, 8H), 3.19–3.54 (m, 4H), 4.77 (q, JZ6.0 Hz, 1H); 13C
NMR d 13.4, 13.5, 19.7, 19.7, 28.9, 31.1, 37.1 (q, JZ
33.1 Hz), 46.3, 48.2, 122.2 (q, JZ278.1 Hz), 161.6; 19F
NMR d K69.0 (d, JZ6.0 Hz, 3F); MS (CI) m/z (rel
intensity) 320 (MCHC2, 100), 318 (MCH, 100), 274 (38),
238 (100), 231 (52), 196 (50), 156 (55); HRMS (CI) calcd
for C11H20BrF3NO: 318.0680, found 318.0643. Anal. Calcd
for C11H19BrF3NO: C 41.52, H 6.02, N 4.40. Found: C
41.72, H 5.82, N 4.21.
3.7. Reaction of the ynamine 2a with iodine
˚
To a mixture of the ynamine 2a (1.0 mmol) and MS 4 A
(1.0 g) in anhydrous MeCN (3.0 mL) was gradually added
iodine (0.254 g, 1.0 mmol) at room temperature under argon
and the mixture was stirred for 1 h. A saturated NaHCO3
aqueous solution (20 mL) was added to the mixture at room
temperature, and the whole mixture was stirred for 0.5 h.
The solvent was removed in vacuo to leave the crude
product, whi0ch 0was recrystallized from diethyl ether to give
pure N,N,N ,N -tetrabutyl-4-iodo-2,4-bis(trifluoromethyl)-
1-cyclobutene cyanine iodide (7a) (51% yield). On standing
in contact with the atmosphere or treatin0g with water, this
salt was readily converted into N,N,N N0-tetrabutyl-2,4-
bis(trifluoromethyl)-2-cyclobutene cyanine iodide (8a).
3.5.2. N,N-Dibutyl(1,2-dibromo-3,3,3-trifluoropropenyl)-
amine (5a). Yield 99%; IR (neat) 3506, 2963, 2936, 2874,
1651, 1601, 1578, 1466, 1346, 1250, 1192, 1119, 876 (cmK1);
1H NMR d 0.90 (t, JZ7.0 Hz, 6H), 1.25–1.35 (m, 4H), 1.41–
1.51 (m, 4H), 2.68 (t, JZ7.8 Hz, 4H) for the major isomer,
2.91 (t, JZ7.3 Hz, 4H) for the minor isomer; 13C NMR d 13.6,
20.2, 29.0, 55.4, 111.1 (q, JZ35.0 Hz), 120.6 (q, JZ
273.9 Hz), 151.1 for the major isomer; 13.6, 20.2, 29.4,
53.7, 97.0 (q, JZ37.6 Hz), 121.0 (q, JZ272.1 Hz), 139.3 (q,
JZ3.8 Hz) for the minor isomer; 19F NMR d K57.5 (s, 3F) for
the major isomer, K55.3 (s, 3F) for the minor isomer.
3.7.1. N,N,N0,N0-Tetrabutyl-4-iodo-2,4-bis(trifluoro-
methyl)-2-cyclobutene cyanine iodide (7a). Yield 51%;
mp 133–1350 8C; IR (KBr) 2963, 2905, 2878, 1589, 1462,
3.6. Typical procedure for the one-pot synthesis of N,N-
dialkyl-2-bromo-3,3,3-trifluoropropanamides (6aBr–
dBr) from the tertiary amines 1
1
1315, 1250, 1153, 1126, 1080, 1061, 941, 737 (cmK1); H
NMR d 0.96 (t, JZ7.5 Hz, 6H), 0.99 (t, JZ7.5 Hz, 6H),
1.33–1.45 (m, 8H), 1.49–1.89 (m, 8H), 3.43–3.58 (m, 4H),
3.63–3.69 (m, 2H), 3.77–3.83 (m, 2H); 13C NMR d 13.3,
13.6, 19.4, 19.5, 28.6, 29.5, 43.1 (q, JZ31.2 Hz), 52.0 (q,
JZ4.1 Hz), 53.3 (q, JZ2.0 Hz), 95.7 (q, JZ41.8 Hz), 117.9
(q, JZ268.6 Hz), 121.8 (q, JZ279.2 Hz), 160.4; 19F NMR
d K52.2 (s, 3F), K63.5 (s, 3F); MS (FAB) m/z (rel
intensity) 1265 (2MKI, 100); HRMS (FAB) calcd for
C44H72F12I3N4 (2MKI): 1265.2699, found 1265.2708.
To a solution of LDA (2.2 mmol) in anhydrous THF
(2.0 mL) was dropwise added a solution of 1a (0.261 g,
1.0 mmol) in THF (1.0 mL) and DMPU (0.282 g, 2.2 mmol)
at 0 8C and the mixture was stirred at room temperature for
2 h. After addition of bromine (0.320 g, 2.0 mmol) at 0 8C,
the mixture was stirred at room temperature for 1 h. A
saturated NaHCO3 aqueous solution (30 mL) was then
added to the reaction mixture at room temperature and the
mixture was stirred for 0.5 h. This mixture was treated in the
same manner as described above to give 6aBr (75% yield).
3.7.2. N,N,N0,N0-Tetrabutyl-2,4-bis(trifluoromethyl)-2-
cyclobutene cyanine iodide (8a). Yield 49%; mp 136.5–
137.0 8C; IR (KBr) 2963, 2936, 2874, 1728, 1620, 1466,
1373, 1331, 1258, 1234, 1215, 1173, 1119, 1080, 1053, 983,
The similar reactions of other amines 1b–d provided the
corresponding 2-bromo propanamides 6bBr–dBr.
1
937, 864, 733, 652 (cmK1); H NMR d 0.93 (t, JZ7.0 Hz,
6H), 0.94 (t, JZ6.5 Hz, 6H), 1.31–1.43 (m, 8H), 1.49–1.58
(m, 2H), 1.68–1.84 (m, 4H), 1.88–1.97 (m, 2H), 3.44–3.66
(m, 8H), 6.72–6.74 (m, 1H); 13C NMR d 13.3, 13.5, 19.7,
19.7, 28.9, 29.7, 51.5 (q, JZ3.9 Hz), 54.7, 58.0 (q, JZ
30.2 Hz), 100.3 (q, JZ42.0 Hz), 117.8 (q, JZ267.7 Hz),
122.4 (q, JZ282.0 Hz), 155.8; 19F NMR d K54.5 (s, 3F),
K65.4 (d, JZ4.4 Hz, 3F); MS (FAB) m/z (rel intensity)
1013 (2MKI, 100); HRMS (FAB) calcd for C44H74F12IN4
3.6.1. N,N-Dimethyl-2-bromo-3,3,3-trifluoropropan-
amide (6bBr). Yield 64%; IR (neat) 2993, 1659, 1501,
1458, 1420, 1358, 1281, 1258, 1204, 1165, 1115, 1065, 876,
841, 691, 656 (cmK1); 1H NMR d 2.97 (s, 3H), 3.08 (s, 3H),
4.82 (q, JZ6.0 Hz, 1H); 13C NMR d 36.2, 37.2 (q, JZ
32.9 Hz), 37.7, 122.2 (q, JZ277.7 Hz), 162.1; 19F NMR d
K69.0 (d, JZ6.0 Hz, 3F).