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C. Malavašic et al. / Tetrahedron: Asymmetry 22 (2011) 1364–1371
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105–106 °C; 1H NMR (300 MHz, CDCl3): d 0.99 and 1.01 (6H, 2d,
References
1:1, J = 6.8 Hz, (CH3)2CH); 2.28 (1H, doublet of septet, J = 5.2,
6.8 Hz, (CH3)2CH); 3.78 (3H, s, OCH3); 4.77 (1H, dd, J = 4.9,
8.6 Hz, CHNH); 6.58 (1H, br d, J = 8.0 Hz, CHNH); 7.43 and 7.75
(4H, 2dt, 1:1, J = 8.7, 2.2 Hz, C6H4). 13C NMR (75.5 MHz, CDCl3):
d 18.2, 19.1, 31.8, 52.4, 57.7, 128.7, 129.0, 132.7, 138.2, 166.4,
172.8. m/z (ESI) = 270 (MH+). m/z (HRMS) Found: 270.0900
(MH+). C13H17ClNO3 requires: m/z = 270.0897. (Found: C, 57.72;
H, 5.77; N, 5.31. C13H16ClNO3 requires: C, 57.89; H, 5.98; N,
5.19.); mmax (KBr) 3330, 2973, 1719 (C@O), 1664 (C@O), 1597,
1529, 1488, 1446, 1373, 1321, 1244, 1218, 1174, 1162, 1091,
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4.5.5. (RS)-N-(tert-Butoxycarbonyl)valine methyl ester (RS)-2g
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in agreement with the literature data for the (S)-isomer.23
ˇ
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4.5.6. (RS)-N-Tosylvaline methyl ester (RS)-2h
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Yield: 0.713 g (50%) of white solid; mp 97–99 °C (from CH2Cl2/n-
hexane). Spectroscopic data were in agreement with the literature
data for the (S)-isomer.24
ˇ
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ature data for the (RS)-isomer25a and the (S)-isomer.25b
4.5.8. (RS)-N-Trifluoroacetylvaline methyl ester (RS)-2j
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(S)-isomer.26
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Acknowledgement
We thank the Slovenian Research Agency for the financial sup-
port through grants P1-0179 and J1-0972.