2248
A. Tafelska-Kaczmarek et al. / Tetrahedron: Asymmetry 21 (2010) 2244–2248
d (ppm): 1.12 (s, 9H, CH3), 2.99 (dd, J = 12.0, 6.6 Hz, 1H, CH2), 3.05
(dd, J = 12.0, 4.5 Hz, 1H, CH2), 4.78 (ddd, J = 6.6, 4.5, 0.9 Hz, 1H,
CH), 6.67 (t, J = 0.9 Hz, 1H, CH), 7.21 (td, J = 7.2, 1.2 Hz, 1H, CH),
7.26 (td, J = 7.2, 1.5 Hz, 1H, CH), 7.46 (ddd, J = 7.5, 1.5, 0.6 Hz, 1H,
CH), 7.54 (ddd, J = 7.5, 2.1, 0.6 Hz, 1H, CH). 13C NMR (75 MHz, CDCl3)
d (ppm): 29.1 (3 ꢀ CH3), 46.2 (CH2), 50.6 (C), 66.4 (CH), 103.1 (CH),
111.2 (CH), 120.9 (CH), 122.7 (CH), 123.9 (CH), 128.2 (C), 154.8 (C),
158.5 (C). IR, KBr (cmꢂ1): 3086, 2964, 2921, 1454, 1224, 1090, 961,
808, 755.
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Prepared from 14 following the procedure described in Sec-
tion 4.9, 85%, mp 67–68 °C. 1H NMR (300 MHz, CDCl3) d (ppm):
1.36 (s, 9H, CH3), 1.362 (t, J = 7.5 Hz, 3H, CH3), 3.02 (q, J = 7.5 Hz,
2H, CH2), 7.24 (t, J = 7.5 Hz, 1H, CH), 7.32 (dm, J = 7.5 Hz, 1H, CH),
7.57 (dd, J = 7.5, 1.5 Hz, 1H, CH), 7.98 (s, 1H, CH), 8.15 (s, 1H,
CH). 13C NMR (75 MHz, CDCl3) d (ppm): 14.0 (CH3), 22.6 (CH2),
29.0 (3 ꢀ CH3), 59.3 (C), 119.8 (CH), 121.1 (CH), 124.0 (CH), 126.9
(C), 127.6 (CH), 129.0 (C), 150.0 (C), 154.0 (C), 154.6 (C), 180.6
(CO). IR, KBr (cmꢂ1): 3424, 2968, 1686, 1656, 1554, 1168, 1001,
848, 745. Anal. Calcd for C16H19NO2: C, 74.68; H, 7.44; N, 5.44.
Found: C, 74.57; H, 7.36; N, 5.38.
4.12. (R)-(+)-tert-Butylamino-1-(7-ethylbenzofuran-2-
yl)ethanol 30
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Prepared by transfer hydrogenation of 21 following the proce-
dure described in Section 4.4, 73%, mp 56–58 °C, ½a D20
¼ þ27:2 (c
ꢁ
1.93, EtOH), 98% ee determined by HPLC analysis, Daicel Chiracel
OD-H column 250 ꢀ 4.6 mm, 5
lm, n-hexane/isopropanol 95:5,
flow 0.7 mL/min, (R) 8.99 min, 99.09%, (S) 14.39 min, 0.91%. Identi-
fied by comparison with (R)-30 prepared earlier.25 The racemate
was also analyzed. 1H NMR (300 MHz, CDCl3) d (ppm): 1.12 (s, 9H,
CH3), 1.34 (t, J = 7.5 Hz, 3H, CH3), 2.93 (q, J = 7.5 Hz, 2H, CH2), 3.00
(dd, J = 12.0, 6.3 Hz, 1H, CH2N), 3.05 (dd, J = 12.0, 4.5 Hz, 1H,
CH2N), 4.81 (ddd, J = 6.3, 4.5, 0.9 Hz, 1H, CH), 6.66 (d, J = 0.9 Hz, 1H,
CH), 7.08 (ddd, J = 7.2, 1.5, 0.6 Hz, 1H, CH), 7.15 (t, J = 7.5 Hz, 1H,
CH), 7.37 (dd, J = 7.5, 1.5 Hz, 1H CH). 13C NMR (75 MHz, CDCl3) d
(ppm): 14.1 (CH3), 22.8 (CH2), 29.1 (3 ꢀ CH3), 46.2 (C), 50.3 (CH2),
66.5 (CH), 103.1 (CH), 118.4 (CH), 122.8 (CH), 123.0 (CH), 127.6
(C), 127.8 (C), 154.3 (C), 158.3 (C). X-ray crystal structure (hydro-
chloride):
C
16H24ClNO2, Mr = 297.83. Colourless 0.46 ꢀ 0.34 ꢀ
0.30 mm crystal from acetone solution, orthorhombic space group
P212121. Cell parameters: a = 7.795(2), b = 10.358(2), c =
21.086(4) Å, V = 1702.5(6) Å3, Dcalc = 1.162 mg/m3, Z = 4, F(000) =
´
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Asymmetry 2008, 19, 956–963.
640,
of 0.9360 and 0.9028. R1 = 0.0528, wR2 = 0.1489 for reflections
I > 2 (I). The absolute structure Flack parameter x = 0.00(8). The
l
= 0.226 mmꢂ1. The maximum and minimum transmissions
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r
structural data have been deposited at the Cambridge Crystallo-
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Acknowledgement
Financial support from the Ministry of Science and Higher Edu-
cation, Warsaw, Grant PBZ-KBN 126/T09/2004, is acknowledged.