3374
Y. Hari et al.
PAPER
MS (EI): m/z = 234 (M+), 206 (M+ – N2), 73 (bp).
HRMS (EI): m/z calcd for C12H18OSi (M+ – N2): 206.1127; found:
1H NMR (CDCl3): d = 0.10 (9 H, s), 1.36 (3 H, t, J = 7.1 Hz), 4.35
(2 H, q, J = 7.1 Hz), 5.89 (1 H, s), 6.61 (1 H, s), 7.27–7.35 (5 H, m),
10.52 (1 H, br).
13C NMR (CDCl3): d = 0.1, 14.3, 61.1, 70.4, 105.9, 126.1, 127.7,
128.3, 142.2, 161.0.
206.1127.
1-Diazo-2-methyl-4-phenyl-1-(trimethylsilyl)butan-2-ol (2f)
Yield: >99%; yellow oil.
IR (neat): 3435, 2039 cm–1.
1H NMR (CD2Cl2): d = 0.25 (9 H, s), 1.47 (3 H, s), 1.62 (1 H, s),
1.91–1.98 (2 H, m), 2.69–2.77 (2 H, m), 7.18–7.28 (5 H, m).
MS (EI): m/z = 318 (M+), 303 (M+ – Me), 257 (bp).
HRMS (EI): m/z calcd for C16H22N2O3Si (M+): 318.1400; found:
318.1366.
Ethyl 3-[(4-Methoxyphenyl)(trimethylsilyloxy)methyl]-1H-
pyrazole-5-carboxylate (4c)
Yield: 78%; pale yellow oil.
IR (neat): 3281, 1717 cm–1.
MS (EI): m/z = 234 (M+ – N2), 73 (bp).
HRMS (EI): m/z calcd for C14H22OSi (M+ – N2): 234.1420; found:
234.1440.
Dimethyl 3-[(4-Chlorophenyl)(trimethylsilyloxy)methyl]-1H-
pyrazole-4,5-dicarboxylate (3a)
Yield: 80%; pale yellow oil.
1H NMR (CDCl3): d = 0.09 (9 H, s), 1.36 (3 H, t, J = 7.1 Hz), 3.79
(3 H, s), 4.35 (2 H, q, J = 7.1 Hz), 5.88 (1 H, s), 6.61 (1 H, s), 6.86
(2 H, d, J = 8.4 Hz), 7.28 (2 H, d, J = 8.4 Hz), 11.05 (1 H, br).
IR (neat): 3284, 1738, 1728 cm–1.
1H NMR (CDCl3): d = 0.08 (9 H, s), 3.78 (3 H, s), 3.92 (3 H, s), 6.58
(1 H, s), 7.28 (4 H, m), 11.21 (1 H, br).
13C NMR (CDCl3): d = 0.1, 14.3, 55.2, 61.0, 70.0, 105.7, 113.7,
127.5, 134.4, 140.2, 151.7, 159.0, 161.1.
MS (EI): m/z = 348 (M+), 333 (M+ – Me), 287 (bp).
13C NMR (CDCl3): d = –0.1, 51.8, 52.6, 58.6, 109.8, 118.2, 127.9,
128.5, 133.9, 139.3, 150.1, 162.1, 162.5.
HRMS (EI): m/z calcd for C17H24N2O4Si (M+): 348.1505; found:
348.1505.
MS (EI): m/z = 398 (M+), 396 (M+), 364 (bp).
Ethyl 3-[2,2-Dimethyl-1-(trimethylsilyloxy)propyl]-1H-pyr-
azole-5-carboxylate (4d)
Yield: 66%; colorless crystals (hexane–EtOAc); mp 133–134 °C.
IR (neat): 3177, 1730 cm–1.
HRMS (EI): m/z calcd for C17H2135ClN2O5Si (M+): 396.0879;
found: 396.0893; m/z calcd for C17H2137ClN2O5Si (M+): 398.0879;
found: 398.0895.
Dimethyl 3-[4-Phenyl-2-(trimethylsilyloxy)butan-2-yl]-1H-
pyrazole-4,5-dicarboxylate (3f)
1H NMR (CDCl3): d = 0.03 (9 H, s), 0.88 (9 H, s), 1.38 (3 H, t,
J = 7.1 Hz), 4.43 (2 H, q, J = 7.1 Hz), 6.65 (1 H, s), 10.70 (1 H, br).
Yield: 83%; pale yellow oil.
IR (neat): 3326, 1738, 1730 cm–1.
13C NMR (CDCl3) d = –0.2, 14.4, 25.6, 35.9, 61.0, 75.6, 106.3,
144.2, 145.3, 161.8.
1H NMR (CDCl3): d = 0.26 (9 H, s), 1.75 (3 H, s), 2.02–2.27 (2 H,
m), 2.45–2.63 (2 H, m), 3.85 (3 H, s), 3.93 (3 H, s), 7.06–7.26 (5 H,
m), 10.8 (1 H, br).
13C NMR (CDCl3): d = 2.5, 28.9, 30.5, 43.9, 52.2, 52.5, 109.9,
125.7, 128.1, 128.2, 141.3, 151.5, 162.1, 163.9.
MS (EI): m/z = 389 (M+ – Me), 282 (bp).
HRMS (EI): m/z calcd for C19H25N2O5Si (M+ – Me): 389.1529;
MS (EI): m/z = 298 (M+), 283 (M+ – Me), 241 (bp).
Anal. Calcd for C14H26N2O3Si: C, 56.34; H, 8.78; N, 9.39. Found:
C, 56.32; H, 8.90; N, 9.43.
Ethyl 3-[1-Phenyl-1-(trimethylsilyloxy)ethyl]-1H-pyrazole-5-
carboxylate (4e)
Yield: 77%; pale yellow oil.
IR (neat): 3274, 1724 cm–1.
1H NMR (CDCl3): d = 0.06 (9 H, s), 1.38 (3 H, t, J = 7.1 Hz), 1.99
(3 H, s), 4.37 (2 H, q, J = 7.1 Hz), 6.68 (1 H, s), 7.22–7.31 (3 H, m),
7.36–7.39 (2 H, m), 10.97 (1 H, br).
found: 389.1533.
Ethyl 3-[(4-Chlorophenyl)(trimethylsilyloxy)methyl]-1H-pyr-
azole-5-carboxylate (4a)
Yield: 81%; yellow oil.
IR (neat): 3287, 1728 cm–1.
13C NMR (CDCl3): d = 1.9, 14.3, 30.2, 61.1, 74.7, 105.8, 125.1,
127.1, 128.0, 140.8, 146.7, 154.3, 161.4.
1H NMR (CDCl3): d = 0.11 (9 H, s), 1.37 (3 H, t, J = 7.1 Hz), 4.36
(2 H, q, J = 7.1 Hz), 5.86 (1 H, s), 6.61 (1 H, s), 7.28 (4 H, m), 10.40
(1 H, br).
13C NMR (CDCl3): d = 0.1, 14.3, 61.2, 69.9, 106.0, 127.4, 127.4,
128.5, 128.5, 133.3, 141.0, 160.6.
MS (EI): m/z = 317 (M+ – Me, bp).
HRMS (EI): m/z calcd for C16H21N2O3Si (M+ – Me): 317.1324;
found: 317.1322.
Ethyl 3-[4-Phenyl-2-(trimethylsilyloxy)butan-2-yl]-1H-pyr-
azole-5-carboxylate (4f)
Yield: 92%; pale yellow oil.
IR (neat): 3291, 1728 cm–1.
1H NMR (CDCl3): d = 0.17 (9 H, s), 1.41 (3 H, t, J = 7.1 Hz), 1.69
(3 H, s), 2.09 (2 H, t, J = 8.7 Hz), 2.32–2.37 (1 H, m), 2.57–2.68 (1
H, m), 4.40 (2 H, q, J = 7.1 Hz), 6.66 (1 H, s), 7.07–7.26 (5 H, m).
13C NMR (CDCl3): d = 2.4, 14.4, 22.7, 30.5, 46.6, 61.1, 74.4, 104.2,
125.7, 128.1, 128.2, 141.6, 142.0, 153.4, 161.7.
MS (EI): m/z = 354 (M+), 352 (M+), 291 (bp).
HRMS (EI): m/z calcd for C16H2135ClN2O3Si (M+): 352.1010;
found: 352.1009; m/z calcd for C17H2137ClN2O3Si (M+): 354.0981;
found: 354.1001.
Ethyl 3-[Phenyl(trimethylsilyloxy)methyl]-1H-pyrazole-5-car-
boxylate (4b)
Yield: 65%; pale yellow oil.
IR (neat): 3277, 1725 cm–1.
MS (EI): m/z = 345 (M+ – Me), 317 (bp).
Synthesis 2007, No. 21, 3371–3375 © Thieme Stuttgart · New York