aryllithium.functionalization

[ Pobierz całość w formacie PDF ]

20 1
75 77 �C/16 Torr; nD 1.4966; yield: 4.21 g (71%). H NMR: � H), 7.56 (t, J 7.4 Hz, 2 H), 6.95 (t, J 7.8 Hz, 1 H), 6.89 (dd,
13
7.22 (dd, J 8.1, 1.6 Hz, 1 H), 6.9 (m, 2 H) ppm. C NMR: � J 8.0, 1.3 Hz, 1 H), 6.79 (dm, J 7.9 Hz, 1 H), 4.11 (t, J
13
143.7, 131.0 (t, J 260 Hz), 127.1, 124.5, 108.5, 106.6, 101.4 ppm. 6.1 Hz, 2 H), 2.72 (t, J 7.6 Hz, 2 H), 2.0 (m, 2 H) ppm. C
C7H3BrF2O2 (237.01): calcd. C 35.47, H 1.28; found C 35.42, H 1.38. NMR: � 143.5, 142.0, 136.0, 133.9, 131.4 (t, J 258 Hz), 129.3
(2 C), 127.9 (2 C), 124.4, 123.6, 122.9, 107.7, 69.5, 28.4, 25.3 ppm.
4-(Bromomethyl)-2,2-difluoro-1,3-benzodioxole (12b): A solution of
triphenylphosphane (6.6 g, 25 mmol) in acetonitrile (50 mL) was 6. Azido Compounds, Phthalimides, Nitro Compounds, Carbox-
cooled in an ice bath and treated with bromine (1.3 mL, 4.0 g, amides, and Nitriles
25 mmol) before 4-(2,2-difluoro-1,3-benzodioxol-4-yl)methanol
4-Azido-2,2-difluoro-1,3-benzodioxole (14a): A solution of 2,2-di-
(2b; see Section 6; 4.7 g, 25 mmol) was added. The solution was
fluoro-1,3-benzodioxole (2.9 mL, 4.0 g, 25 mmol) and sec-butyl-
heated for 2 h at 50 �C. Immediate distillation afforded a color-
lithium (25 mmol) in tetrahydrofuran (50 mL) and cyclohexane
less liquid; m.p. 24 25 �C (from hexanes at 75 �C); b.p. 86 88
(20 mL) was kept for 2 h at 75 �C. After the addition of p-tolu-
1
�C/6 Torr; yield: 5.40 g (86%). H NMR: � 7.10 (dd, J 7.9,
enesulfonyl[38] azide (4.9 g, 25 mmol), the mixture was allowed to
1.7 Hz, 1 H), 7.06 (t, J 7.8 Hz, 1 H), 7.00 (dd, J 7.8, 1.7 Hz,
stand at 25 �C for 2 h. Immediate distillation afforded the prod-
13
1 H), 4.48 (s, 2 H) ppm. C NMR: � 143.7, 141.7, 131.5 (t, J
256 Hz), 124.7, 123.9, 120.4, 109.6, 24.4 ppm. C8H5BrF2O2 uct 14a as an orange-colored, solidifying oil; m.p. 20 22 �C (from
1
pentanes); b.p. 80 82 �C/10 Torr; yield: 4.74 g (94%). H NMR:
(251.03): calcd. C 38.28, H 2.01; found C 37.99, H 2.26. The same
� 7.06 (t, J 8.2 Hz, 1 H), 6.84 (dd, J 8.1, 1.0 Hz, 1 H), 6.80
compound 12b was prepared in 65% yield from 2,2-difluoro-4-
13
(dd, J 8.4, 1.0 Hz, 1 H) ppm. C NMR: � 144.9, 132.4, 131.6
methyl-1,3-benzodioxole (8; see Section 4; 4.3 g, 25 mmol) and
(t, J 258 Hz), 124.4, 123.8, 114.9, 105.9 ppm. C7H3F2N3O2
bromine (1.3 mL, 4.0 g, 25 mmol) in tetrachloromethane (50 mL).
(199.12): calcd. C 42.23, H 1.52; found C 42.40, H 1.68.
3-(2-Bromoethyl)-2,2-difluoro-1,3-benzodioxole (12c): Prepared and
4-(3-Azidopropyl)-2,2-difluoro-1,3-benzodioxole (14d): A mixture of
worked-up as its lower homolog 12b (see below; 5.0 g, 25 mmol);
3-(2,2-difluoro-1,3-benzodioxol-4-yl)propyl benzenesulfonate
colorless liquid; b.p. 131 133 �C/12 Torr; n20 1.5029; yield: 5.83 g
D
(3.6 g, 10 mmol) and sodium azide (0.65 g, 10 mmol) in ethanol
1
(89%). H NMR: � 7.03 (t, J 7.9 Hz, 1 H), 6.97 (dd, J 8.2,
(20 mL) was refluxed for 6 h. The reaction mixture was then
1.4 Hz, 1 H), 6.94 (d, J 8.6 Hz, 1 H), 3.61 (t, J 7.3 Hz, 2 H),
cooled, the ethanol was evaporated, the residue dissolved in diethyl
13
3.24 (t, J 7.3 Hz, 2 H) ppm. C NMR: � 143.6, 141.3, 130.6 (t,
J 252 Hz), 124.7, 123.6, 121.4, 108.3, 32.8, 30.3 ppm. C9H7BrF2O2 ether (20 mL) and washed with water (2 10 mL). After drying
with sodium sulfate, the solvents were evaporated from the ethereal
(265.05): calcd. C 40.78, H 2.66; found C 40.71, H 2.62.
phase and the product was distilled under reduced pressure as a
4-(3-Bromopropyl)-2,2-difluoro-1,3-benzodioxole (12d): As above, colorless liquid; b.p. 117 119 �C/12 Torr; n20 1.4877; yield:
D
1
from alcohol 2d (5.4 g, 25 mmol); colorless oil; b.p. 102 103 �C/ 2.07 g (85%). H NMR: � 7.01 (t, J 7.9 Hz, 1 H), 6.9 (m, 2
1
6Torr; n20 1.4988; yield: 6.12 g (88%). H NMR: � 6.9 (m, 3 H), 3.33 (t, J 6.7 Hz, 2 H), 2.76 (t, J 7.7 Hz, 2 H), 1.9 (symm.
D
13
H), 3.42 (t, J 6.5 Hz, 2 H), 2.84 (t, J 7.4 Hz, 2 H), 2.2 (m, 2 m, 2 H) ppm. C NMR: � 143.6, 142.1, 131.5 (t, J 253 Hz),
13
H) ppm. C NMR: � 143.6, 142.1, 131.4 (t, J 251 Hz), 124.5, 124.4, 123.6, 123.5, 107.6, 50.6, 28.6, 26.4 ppm. C10H9F2N3O2 [ Pobierz całość w formacie PDF ]

Pokrewne