Synthesis of Phenylalanine Analogs
J. Chin. Chem. Soc., Vol. 52, No. 5, 2005 1065
136.51, 130.49 (2´), 128.74 (2´), 128.40 (2´), 128.30, 127.84,
114.28 (2´), 67.18, 55.43, 55.16, 52.51, 37.59.
m/z (%) = 309 (M+, 15); HRMS (EI, M+) calcd for C16H23NO5
1
309.1576, found 309.1577; H NMR (300 MHz, CDCl3) d
7.03 (d, J = 9.0 Hz, 2H), 6.82 (d, J = 9.0 Hz, 2H), 4.95 (br d, J
= 7.8 Hz, 1H), 4.59-4.49 (m, 1H), 3.78 (s, 3H), 3.71 (s, 3H),
3.10-2.94 (m, 2H), 1.41 (s, 9H); 13C NMR (75 MHz, CDCl3) d
172.66, 158.90, 155.32, 130.50 (2´), 128.15, 114.21 (2´),
80.11, 55.44, 54.76, 52.39, 37.70, 28.52 (3´).
Ethyl N-benzyloxycarbonyl-3,4-dimethoxyphenyl-
alaninate (1c1)
IR (CHCl3) 3333, 1738, 1703 cm-1; EI-MS: C21H25NO6
m/z (%) = 387 (M+, 4); HRMS (EI, M+) calcd for C21H25NO6
1
387.1682, found 387.1685; H NMR (300 MHz, CDCl3) d
7.35-7.30 (m, 5H), 6.75 (d, J = 9.0 Hz, 1H), 6.66-6.61 (m,
2H), 5.23 (br d, J = 7.5 Hz, 1H), 5.12-5.06 (m, 2H), 4.65-4.55
(m, 1H), 4.20-4.12 (m, 2H), 3.84 (s, 3H), 3.79 (s, 3H), 3.18-
3.08 (m, 2H), 1.25 (t, J = 7.2 Hz, 3H); 13C NMR (75 MHz,
CDCl3) d 172.23, 156.36, 149.37, 148.31, 136.85, 129.11
(2´), 128.83 (2´), 122.07 (2´), 113.16, 111.97 (2´), 67.56,
62.02, 56.63 (2´), 55.36, 38.53, 14.14.
Ethyl N-tert-butoxycarbonyl-3,4-dimethoxyphenyl-
alaninate (1c2)20c
IR (CHCl3) 3395, 1746, 1704 cm-1; EI-MS: C18H27NO6
m/z (%) = 353 (M+, 8); HRMS (EI, M+) calcd for C18H27NO6
1
353.1838, found 353.1840; H NMR (300 MHz, CDCl3) d
6.78 (d, J = 6.0 Hz, 1H), 6.68-6.62 (m, 2H), 4.97 (br d, J = 7.8
Hz, 1H), 4.54-4.48 (m, 1H), 4.16 (q, J = 6.0 Hz, 2H), 3.85 (s,
6H), 3.10-2.95 (m, 2H), 1.41 (s, 9H), 1.24 (t, J = 6.0 Hz, 3H);
13C NMR (75 MHz, CDCl3) d 172.17, 155.31, 149.08, 148.32,
128.74, 121.68, 112.70, 111.45, 80.07, 61.53, 56.11, 56.03,
54.74, 38.13, 28.54 (3´), 14.39.
Ethyl N-benzyloxycarbonyl-4-fluorophenylalaninate
(1d1)19c
IR (CHCl3) 3342, 1740, 1710 cm-1; EI-MS: C19H20FNO4
m/z (%) = 345 (M+, 1); HRMS (EI, M+) calcd for C19H20FNO4
1
345.1376, found 345.1375; H NMR (300 MHz, CDCl3) d
Ethyl N-tert-butoxycarbonyl-4-fluorophenylalaninate
(1d2)
7.36-7.26 (m, 5H), 7.08-7.03 (m, 2H), 6.98-6.91 (m, 2H),
5.25 (br d, J = 7.8 Hz, 1H), 5.12-5.08 (m, 2H), 4.63-4.58 (m,
1H), 4.19-4.13 (m, 2H), 3.16-3.04 (m, 2H), 1.23 (t, J = 7.2
Hz, 3H); 13C NMR (75 MHz, CDCl3) d 171.53, 163.87,
160.62, 155.78, 136.46, 131.12, 131.01, 128.76, 128.46 (2´),
128.34 (2´), 115.76, 115.47, 67.22, 61.82, 55.06, 37.79,
14.33.
IR (CHCl3) 3386, 1745, 1711 cm-1; EI-MS: C16H22FNO4
m/z (%) = 311 (M+, 5); HRMS (EI, M+) calcd for C16H22FNO4
1
311.1533, found 311.1533; H NMR (300 MHz, CDCl3) d
7.12-7.07 (m, 2H), 7.00-6.94 (m, 2H), 4.99 (br d, J = 6.0 Hz,
1H), 4.59-4.50 (m, 1H), 4.15 (q, J = 7.2 Hz, 2H), 3.14-3.00
(m, 2H), 1.41 (s, 9H), 1.22 (t, J = 7.2 Hz, 3H); 13C NMR (75
MHz, CDCl3) d 172.94, 163.83, 130.59, 155.24, 132.09,
131.02, 115.68, 115.40, 80.19, 61.64, 54.70, 37.91, 28.51
(3´), 14.35.
Ethyl N-benzyloxycarbonyl-4-boronophenylalaninate (1e)
1H NMR (300 MHz, CDCl3, CD3OD) d 7.76-7.72 (m,
2H), 7.36-7.26 (m, 5H), 7.14-7.08 (m, 2H), 5.26-5.22 (m,
1H), 5.10-5.07 (m, 2H), 4.48-4.40 (m, 3H), 3.09-2.98 (m,
2H), 1.39 (t, J = 7.0 Hz, 3H).
Ethyl N-9-fluorenylmethoxycarbonylphenylalaninate
(1a3)21
IR (CHCl3) 3420, 1734, 1717 cm-1; EI-MS: C26H25NO4
m/z (%) = 415 (M+, 2); HRMS (EI, M+) calcd for C26H25NO4
Ethyl N-tert-butoxycarbonylphenylalaninate (1a2)20a
IR (CHCl3) 3397, 1740, 1704 cm-1; EI-MS: C16H23NO4
m/z (%) = 293 (M+, 12); HRMS (EI, M+) calcd for C16H23NO4
1
415.1784, found 415.1786; H NMR (300 MHz, CDCl3) d
7.66 (d, J = 7.4 Hz, 2H), 7.50-7.45 (m, 2H), 7.34-7.14 (m,
7H), 7.03 (d, J = 5.9 Hz, 2H), 5.22 (d, J = 8.0 Hz, 1H), 4.57 (d,
J = 6.0 Hz, 1H), 4.39-4.02 (m, 5H), 3.04-3.00 (m, 2H), 1.14
(t, J = 7.2 Hz, 3H).
1
293.1627, found 293.1625; H NMR (300 MHz, CDCl3) d
7.31-7.12 (m, 5H), 4.98 (br d, J = 6.6 Hz, 1H), 4.59-4.53 (m,
1H), 4.15 (q, J = 7.2 Hz, 2H), 3.14-3.04 (m, 2H), 1.41 (s, 9H),
1.22 (t, J = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3) d 172.11,
155.32, 136.32, 129.59 (2´), 128.71 (2´), 127.20, 80.09,
61.54, 54.67, 38.64, 28.52 (3´), 14.33.
Methyl N-9-fluorenylmethoxycarbonyl-4-methoxyphenyl-
alaninate (1b3)
IR (CHCl3) 3422, 1733, 1715 cm-1; EI-MS: C26H25NO5
m/z (%) = 431 (M+, 5); HRMS (EI, M+) calcd for C26H25NO5
Methyl N-tert-butoxycarbonyl-4-methoxyphenylalaninate
(1b2)20b
1
431.1733, found 431.1735; H NMR (300 MHz, CDCl3) d
IR (CHCl3) 3389, 1744, 1706 cm-1; EI-MS: C16H23NO5
7.76 (d, J = 7.5 Hz, 2H), 7.59-7.56 (m, 2H), 7.35-7.31 (m,