M. D. Rozwadowska / Tetrahedron: Asymmetry 9 (1998) 1615–1618
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3. Conclusion
In conclusion, a highly efficient procedure is described for the transformation of (1S,2S)-2-amino-1-
aryl-1,3-propanediols into unnatural (R)-(+)-phenylalaninol and may serve as another example of the
practical use of industrial waste products.
4. Experimental
4.1. General procedure
Melting points: determined on a Koffler block and not corrected. IR spectra: Perkin–Elmer 180 in
KBr pellets. NMR spectra: Varian Gemini 300, TMS as internal standard. Mass spectra (EI): Jeol-D-100,
75 eV. Specific rotation: Perkin–Elmer polarimeter 243B at 20°C. Merck Kieselgel 60 (70–230 mesh)
was used for column chromatography and Merck DC-Alufolien Kieselgel 60254 for TLC. (1S,2S)-(+)-2-
Amino-1-phenyl-1,3-propanediol and (+)-thiomicamine were purchased from the Aldrich Chemical Co.
and used as received.
4.2. (4S,5S)-5-Hydroxymethyl-4-[4-(methylthio)phenyl]-2-phenyl-2-oxazoline 3
To (1S,2S)-(+)-thiomicamine 1 (10 g, 47 mmol) and potassium carbonate (1 g) in a mixture of ethylene
glycol (15 ml) and glycerol (8.2 ml) benzonitrile (8 ml, 78.4 mmol) was added and the resultant mixture
was heated at 110°C with stirring under an argon atmosphere until no more starting material was present
by TLC (ca. 20 h). After cooling to r.t., water was added and the product was collected by filtration,
washed with water and hexane, and dried to yield pure oxazoline 3 (13 g, 93%); m.p. 173.5–175°C, [α]D
+65.8 (c=0.5, MeOH) after recrystallization from methylene chloride (lit.5 for (−)-3: m.p. 171–173°C,
1
[α]D −64.4). IR (KBr) cm−1: 3195 (OH), 1648 (C_N); H-NMR (CDCl3) δ: 2.48 (s, 3H, SCH3), 3.4
(m, br, 1H, exchanges with D2O, OH), 3.76 (dd, J=3.8, 11.8 Hz, 1H, CHHOH), 4.08 (dd, J=3.5, 11.8
Hz, 1H, CHHOH), 4.22 (td, J=3.9, 3.6, 7.9 Hz, 1H, CHN), 5.51 (d, J=7.9 Hz, 1H, CHPh), 7.26–7.50 (m,
7H, ArH), 7.91 (d, J=7.1 Hz, 2H, ArH); CI-MS m/z (%): 299 (M+, 37), 268 (20), 194 (5), 165 (34), 147
(100), 130 (66), 105 (96), 77 (42). Found: C 68.27; H 5.61; N 4.63. C17H17NO2S (299.38) requires C
68.20; H 5.73; N 4.68%.
4.3. (4S,5S)-2,4-Diphenyl-5-hydroxymethyl-2-oxazoline 4
Oxazoline 4 was prepared from (1S,2S)-(+)-2-amino-1-phenyl-1,3-propanediol 2 (5 g, 29.9 mmol),
benzonitrile (5.1 ml, 49.9 mmol), potassium carbonate (0.66 g) in a mixture of ethylene glycol (10.5
ml) and glycerol (5.2 ml) according to the above procedure, in 92% yield. After recrystallization from
methylene chloride (74.7%): m.p. 186–187°C (sublimes from ca. 160°C), [α]D +51.0 (c=0.54, CHCl3),
[α]D +70.2 (c=0.5, MeOH); (lit.7 m.p. 127–129°C, [α]D −44.6, c=5.4, CHCl3). IR (KBr) cm−1: 3182
1
(OH), 1648 (C_N); H-NMR (CDCl3) δ: 3.76 (dd, J=3.8, 11.9 Hz, 1H, CHHOH), ca. 3.76 (s, broad,
1H, OH), 4.10 (dd, J=3.5, 11.9 Hz, 1H, CHHOH), 4.24 (dt, J=3.6, 8.0 Hz, 1H, CHN), 5.58 (d, J=8.2
Hz, 1H, CHPh), 7.26–7.48 (m, 8H, ArH), 7.89 (d, J=7.1 Hz, 2H, ArH); 13C-NMR (DMSO-d6) δ: 62.96
(CH2OH), 76.91 (CHN), 82.42 (CHPh), 125.33, 127.95, 128.60, 128.69, 131.56 (ArCH), 127.31, 141.38
(ArC), 162.17 (C_N); CI-MS m/z (%): 253 (M+, 2), 223 (22), 222 (100), 146 (25), 130 (33), 119 (50),