Proline-Catalyzed Asymmetric Amination of Branched Aldehydes
FULL PAPER
–113.1 ppm. IR (KBr): ν = 3048 cm–1 (vw, ν[CHar]), 2934, 2860 (w,
w, ν[CH]), 2834 (w, ν[OCH3]), 1655, 1601, 1509 (w, w, m, ν[C–Car]),
1457, 1406 (w, vw, δ[CH]), 1377 (vw, δ[OCH3]), 1276, 1259, 1225 ether/pentane, 1:100). H NMR (400 MHz, CDCl3): δ = 1.85, 1.91
(w, w, m, ν[Car–O–C]), 1135 (w), 1101 (w), 1076 (w, ν[Car–O–C]), (2d, J = 1.3 Hz, 3 H, CR2CH3), 3.63, 3.67 (2s, 3 H, CHROCH3),
1011 (w), 981 (vw), 829 (w, δ[CHar]), 749, 720 (w, w, ν[CHal]) cm–1. 6.12, 6.43 (2q, J = 1.3 Hz, 1 H, CHROCH3), 7.32, 7.39 (2d, J =
as determined by comparison of the integrals of the methyl signals
˜
in the 1H NMR spectrum) as a colorless oil. Rf = 0.85 (diethyl
1
MS (EI = 70 eV): m/z (%) = 166 (100) [M+], 151 (44) [M+ – CH3],
123 (5). HRMS (EI) m/z calcd. for C10H11FO 166.0794; found
166.0797. C10H11FO (166.19): calcd. C 72.27, H 6.67; found
C 72.41, H 6.74.
8.2 Hz, 2 H, C3ЈHar), 7.63, 7.68 (2d, J = 8.1 Hz, 2 H, C2ЈHar) ppm.
13C NMR (100 MHz, CDCl3): δ = 12.3, 18.0 (CR2CH3), 60.1, 60.4
(RCHOCH3), 109.5, 113.3 (CR2CH3), 123.8, 123.9 (q,
J =
271.6 Hz, C4ЈarCF3), 125.8, 126.3 (q, J = 3.5 Hz, C3ЈarH), 126.7,
127.2 (C2ЈarH), 127.5 (q, J = 32.5 Hz, C4ЈarCF3), 133.7, 133.9
(C1ЈarCR2), 145.8, 146.7 (RCHOCH3) ppm. 19F NMR (376 MHz,
2-(4Ј-Chlorophenyl)-1-methoxypropene (2g): The product was syn-
thesized according to GP 1, Method B, employing 4-chloroaceto-
phenone (3.092 g, 20.00 mmol). Flash chromatography on silica
(diethyl ether/pentane, 1:80) delivered 3.123 g (17.10 mmol, 85%)
of a mixture of E- and Z-2g (E/Z ratio = 1.31:1, as determined by
CDCl ): δ = –62.6 ppm. IR (KBr): ν = 3078 cm–1 (w, ν[CHar]), 2938
˜
3
(w, ν[CH]), 2841 (w, ν[OCH3]), 1652, 1614, 1511, 1489 (w, w, w,
ν[C–Car]), 1459 (w, δ[CH]), 1411 (w, δ[OCH3]), 1327 (m), 1264,
1228, 1211 (w, w, w, w, ν[Car–O–C]), 1165, 1113, 1080, 1015 (w, w,
ν[Car–O–C]), 950 (vw), 835 (w, δ[CHar]), 764 (w, ν[CHal]) cm–1. MS
(EI = 70 eV): m/z (%) = 216 (83) [M+], 201 (19) [M+ – CH3], 173
(100) [C9H8F3+], 145 (34) [C7H4F3+], 103 (47), 77 (11) [C6H5+].
HRMS (EI) m/z calcd. for C11H11F3O 216.0762, found 216.0757.
C11H11F3O (216.20): calcd. C 72.27, H 6.67; found C 72.41, H 6.74.
1
comparison of the integrals of the methyl signals in the H NMR
spectrum) as a yellow oil. Rf = 0.73 (diethyl ether/pentane, 1:80).
1H NMR (400 MHz, CDCl3): δ = 1.69, 1.76 (2d, J = 1.3 Hz, 3 H,
CR2CH3), 3.47, 3.55 (2s, 3 H, CHROCH3), 5.93, 6.18 (q, J =
1.3 Hz, 1 H, CHROCH3), 6.94, 7.16 (2d, J = 8.7, 2 H, C2ЈHar),
7.22, 7.29 (2d, J = 8.7 Hz, 2 H, C3ЈHar) ppm. 13C NMR (100 MHz,
CDCl3): δ = 12.2, 17.9 (CR2CH3), 59.7, 60.2 (RCHOCH3), 109.4,
113.3 (CR2CH3), 125.7, 128.2 (C3ЈarH), 131.3, 131.9 (C2ЈarH),
132.2, 134.5 (C4ЈarCl), 134.8, 135.2 (C1ЈarCR2), 137.1, 139.4
1-Methoxy-2-(4Ј-nitrophenyl)propene (2j): The product was synthe-
sized according to GP 1, Method B, employing 4-nitroacetophe-
none (0.826 g, 5.00 mmol). Flash chromatography on silica (diethyl
ether/pentane mixtures) delivered 0.175 g (0.906 mmol, 37%) of a
yellow oil. Rf = 0.44 (diethyl ether/pentane, 1:10). 1H NMR
(400 MHz, CDCl3): δ = 2.00 (d, J = 1.3 Hz, 3 H, CR2CH3), 3.8 (s,
3 H, CHROCH3), 6.66 (q, J = 1.3 Hz, 1 H, CHROCH3), 7.41 (ddd,
J = 9.3, 2.4, 2.3 Hz, 2 H, C2ЈHar), 8.13 (ddd, J = 9.3, 2.4, 2.3 Hz,
2 H, C3ЈHar) ppm. 13C NMR (100 MHz, CDCl3): δ = 12.2
(CR2CH3), 60.6 (RCHOCH3), 113.1 (CR2CH3), 123.9 (C3ЈarH),
124.8 (C2ЈarH), 145.8 (C1ЈarCR2), 147.7 (C4ЈarNO2), 148.7
(RCHOCH ) ppm. IR (KBr): ν = 3096, 3069 cm–1 (w, vw, ν[CHar]),
˜
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2981 (vw), 2935 (w, ν[CH]), 2841 (vw, ν[OCH3]), 1686, 1589, 1490
(m, m, w, ν[C–Car]), 1428 (w, δ[CH]), 1397 (w, δ[OCH3]), 1358 (w),
1261, 1176, 1094, (m, w, m, ν[Car–O–C]), 1013 (w), 959 (w), 829
(w, δ[CHar]), 762 (w, ν[CHal]) cm–1. MS (EI, II, 70 eV): m/z (%) =
184 (2) [M+], 169 (1), 167 (3) [M+-CH3], 156 (25), 154 (63)
[C9H10Cl+], 141 (60), 139 (100) [C8H8Cl+], 113 (24), 111 (60)
[C6H5Cl+], 77 (14), 75 (47) [C3H5Cl+]. HRMS m/z calcd. for
C10H1137ClO 184.0469, found: 184.0477. C10H11Cl (182.65): calcd.
C 65.76, H 6.07; found C 65.91, H 5.97.
(RCHOCH ) ppm. IR (KBr): ν = 3105, 3081, 3020 (vw, w, w,
˜
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ν[CHar]), 2967, 2938 (w, m, ν[CH]), 2841 (w, ν[OCH3]), 1744 (w),
1722 (w), 1639, 1589 (m, m, ν[C–Car]), 1507 (m, ν[NO2]), 1455 (w,
δ[CH]), 1416 (w, δ[OCH3]), 1392 (w, δ[CH]), 1349 (m, δ[NO2]),
1300, 1238 (m, m, ν[Car–O–C]), 1189 (w), 1146 (m), 1111 (m), 1074,
1036 (m, w, ν[Car–O–C]), 1004 (w), 945 (w), 847, 822 (m, w,
δ[CHar]), 780 (w), 752 (m) cm–1. MS (EI, II, 70 eV): m/z (%) = 193
2-(4Ј-Bromophenyl)-1-methoxypropene (2h): The product was syn-
thesized according to GP 1, Method B, employing 4-bromoace-
tophenone (1.990 g, 10.00 mmol). Flash chromatography on silica
(diethyl ether/pentane, 1:80) delivered 1.998 g (8.80 mmol, 88%) of
a mixture of E- and Z-2h (E/Z ratio = 1.25:1, as determined by
(100) [M+], 161 (9), 147 (5) [M+ – NO2], 132 (23) [M+ – CH3
–
1
NO2], 115 (10) [C9H7+], 103 (12) [C8H7+], 91 (7) [C7H7+], 77 (8)
[C6H5+]. HRMS m/z calcd. for C10H11NO3 193.0739, found:
193.0741. C10H11NO3 (193.20): calcd. C 62.17, H 5.74, N 7.25;
found C 62.28, H 5.85, N 7.31.
comparison of the integrals of the methyl signals in the H NMR
spectrum) as a yellow oil. Rf = 0.58 (diethyl ether/pentane, 1:100).
1H NMR (400 MHz, CDCl3): δ = 1.72, 1.79 (2d, J = 1.3 Hz, 3 H,
CR2CH3), 3.52, 3.56 (2s, 3 H, CHROCH3), 5.97, 6.25 (q, J =
1.3 Hz, 1 H, CHROCH3), 7.00, 7.26 (2d, J = 8.6 and 8.7 Hz, 2 H,
C2ЈHar), 7.23, 7.32 (2d, J = 8.6 and 8.7 Hz, 2 H, C3ЈHar) ppm. 13C
NMR (100 MHz, CDCl3): δ = 12.4, 18.1 (CR2CH3), 60.0, 60.3
(RCHOCH3), 109.6, 113.4 (CR2CH3), 119.4, 119.6 (C4ЈarBr), 126.5,
129.1 (C3ЈarH), 130.9, 131.3 (C2ЈarH), 133.6, 133.8 (C1ЈarCR2),
2-(4Ј-Cyanophenyl)-1-methoxypropene (2k): The product was syn-
thesized according to GP 1, Method B, employing 4-cyanoace-
tophenone (2.468 g, 17.00 mmol). Flash chromatography on silica
(diethyl ether/pentane, 1:5) delivered 2.827 g (16.30 mmol, 96%) of
a mixture of E- and Z-2k (E/Z ratio = 1.17:1, as determined by
137.2, 139.6 (RCHOCH ) ppm. IR (KBr): ν = 3102 cm–1 (w,
˜
3
1
comparison of the integrals of the methyl signals in the H NMR
ν[CHar]), 2981 (w), 2934 (w, ν[CH]), 2831 (w, ν[OCH3]), 1687, 1588,
1489 (m, w, m, ν[C–Car]), 1454, 1428 (w, w, δ[CH]), 1396 (w,
δ[OCH3]), 1360 (w), 1265, 1186, 1076, (w, w, m, ν[Car–O–C]), 1010
(m), 980 (w), 823 (m, δ[CHar]), 748, 722 (w, w, ν[CHal]) cm–1. MS
(EI, II, 70 eV): m/z (%) = 229, 227 (3) [M+], 200, 198 (16)
[C9H10Br+], 185 (43), 183 (65) [C8H7Br+], 157, 155 (16) [C6H5Br+],
75 (100). HRMS m/z calcd. for C10H11Br 225.9993, found:
225.9991. C10H11Br (227.10): calcd. C 52.89, H 4.88; found
C 52.67, H 4.95.
spectrum) as a yellow oil. Rf = 0.42 (diethyl ether/pentane, 1:5). 1H
NMR (400 MHz, CDCl3): δ = 1.84, 1.90 (2d, J = 1.3 Hz, 3 H,
CR2CH3), 3.66, 3.70 (2s, 3 H, CHROCH3), 6.18, 6.51 (q, J =
1.3 Hz, 1 H, CHROCH3), 7.29, 7.50 (2d, J = 8.7, 2 H, C2ЈHar),
7.47, 7.64 (2d, J = 8.7 Hz, 2 H, C3ЈHar) ppm. 13C NMR (100 MHz,
CDCl3): δ = 12.0, 17.8 (CR2CH3), 60.4, 60.6 (RCHOCH3), 108.7,
108.8 (C4ЈarCN), 108.9, 113.0 (CR2CH3), 119.4, 119.5 (C4ЈarCN),
124.9, 127.8 (C3ЈarH), 131.6, 132.1 (C2ЈarH), 143.0, 145.4
(RCHOCH3), 147.6, 147.8 (C1ЈarCR2) ppm. IR (KBr): ν =
˜
Methoxy-2-(4Ј-trifluoromethylphenyl)propene (2i): The product was
synthesized according to GP 1, Method A, employing 4-trifluoro-
methylacetophenone (2.932 g, 15.50 mmol). Flash chromatography
on silica (diethyl ether/pentane, 1:100) delivered 3.131 g
(14.50 mmol, 93%) of a mixture of E- and Z-2i (E/Z ratio = 1.24:1,
3104 cm–1 (vw, ν[CHar]), 2935 (w, ν[CH]), 2839 (w, ν[OCH3]), 2223
(m, ν[CN]), 1647, 1601 (m, m, ν[C–Car]), 1506 (w), 1456 (w, δ[CH]),
1410 (w, δ[OCH3]), 1265, 1228, 1208 (w, m, m, ν[Car–O–C]), 1180
(w), 1138 (m), 1115 (m), 1074 (m, ν[Car–O–C]), 1008 (w), 982 (vw),
944 (vw), 855, 832 (w, m, δ[CHar]) cm–1. MS (EI, II, 70 eV): m/z (%)
Eur. J. Org. Chem. 2007, 266–282
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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