K. Iida et al.
water. Aluminum oxide (20 g) was added to the extract, and the 5.29 (d, 2H, 3J1H13C 5 3.0 Hz, C-3-13COOCH2–), 5.31 (d, 2H,
mixture was evaporated. The residue was divided into six portions, 3J1H13C 5 3.3 Hz, C-5-13COOCH2–), 7.40 (10H, m, phenyl-H), 8.94
and to each was added 1-bromooctane (2.1 ml, 12.2 mmol; total (1H, brs, –NH–); 13C-NMR (CDCl3) d: 131.6 (C-4), 139.2 (C-2), 161.0
12.6 ml, total 73.2 mmol), followed by microwave irradiation for 5 min. (C-3-13CO–), 165.0 (C-5-13CO–); IR (KBr) cmꢀ1: 3309, 1660, 1625,
Chromatography of the combined six reaction mixtures absorbed 1416, 1259, 1178, 1074; EI-MS m/z (rel. int.%): 367 (M1, 53), 276
on aluminum oxide on silica gel with hexane:ethyl acetate (40:1–20:1) (36), 260 (15), 231 (7), 152 (5), 141 (4), 91 (100), 65 (4).
gave n-octyl [1-13C]acetate (2b) (6.91 g, 82%), 1H-NMR (CDCl3) d:
0.88 (t, 3H, J56.8 Hz, –(CH2)7CH3), 1.23 (br, 12H, –CH2(CH2)6CH3), [2,4-13C2]Hymecromone (6) (7-Hydroxy-4-methyl[2,4-13C2]cou-
2.05 (d, 3H, 2J1H13C 56.9 Hz, CH133CO–), 4.05 (dt, 2H, J53.0 Hz,
marin)
3J1H13C 53.3 Hz, –13COOCH2–); 13C-NMR (CDCl3) d: 171.1 (C-1); IR
To a mixture of n-octyl [1,3-13C2]acetoacetate (3b) (2.93 g,
(neat) cm-1: 2957, 2929, 2858, 1701, 1468, 1365, 1211, 1039.
13.5 mmol) and 1,3-benzenediol (5) (1.49 g, 13.5 mmol) was
added dropwise conc. H2SO4 (12 ml) at 01C under an N2
n-Octyl [1,3-13C2]acetoacetate (3b)
atmosphere, and the mixture was stirred at room temperature
n-Octyl [1-13C]acetate (2b) (6.91 g, 39.9 mmol) was added
dropwise to potassium tert-butoxide (3.15 g, 28.1 mmol) at 01C
under an N2 atmosphere, and the reaction mixture was heated
at 1001C for 1.5 h. The reaction was quenched with 10% HCl at
01C. The organic layer was separated and the water layer was
extracted with Et2O. The combined extract was washed with sat.
NaHCO3 aq. and brine, dried over anhydrous MgSO4 and
evaporated. Chromatography of the crude product on silica
gel with hexane:ethyl acetate (15:1) gave n-octyl [1,3–13C2]
acetoacetate (3b) (2.93 g, 68%), 1H-NMR (CDCl3) d: 0.88 (t, 3H,
J 5 6.3 Hz, –(CH2)7CH3), 1.23 (br, 12H, –CH2(CH2)6CH3), 2.27 (d,
3H, 2J1H13C 5 6.0 Hz, CH313CO–), 3.45 (t, 2H, 2J1H13C 5 6.6 Hz,
–13COCH123COO–), 4.14 (dt, 2H, J 5 3.0 Hz, 3J1H13C 5 3.8 Hz,
–13COOCH2–); 13C-NMR (CDCl3) d: 167.1 (C-1), 200.3 (C-3); IR
(neat) cmꢀ1: 2957, 2928, 2858, 1700, 1679, 1617, 1457, 1406,
1359, 1309, 1221, 1134, 1029, 788; EI-MS m/z (rel. int.%): 216 (M1,
0.8), 105 (100), 87 (39), 70 (19), 57 (20), 44 (34), 43 (16).
for 12 h. The reaction was quenched with ice–water at 01C. The
resultant solid was collected by filtration and dissolved in EtOH
(100 ml). To this solution was added silica gel (10 g) and the
mixture was evaporated. Chromatography of the residue on
silica gel with hexane:ethyl acetate (3:2–1:1) gave [2,4-13C2]hy-
1
mecromone (6) (1.75 g, 73%), H-NMR (DMSO-d6) d: 2.37 (d, 3H,
2J1H13C 5 6.0 Hz, C-4-CH3), 6.13 (d, 1H, 2J1H13C 5 4.9 Hz, C-3-H),
6.71 (d, 1H, J 5 2.3 Hz, C-8-H), 6.81 (dd, 1H, J 5 2.3, 8.7 Hz, C-6-H),
7.60 (dd, 1H, J 5 8.7 Hz, 3J1H13C 5 3.8 Hz, C-5-H); 13C-NMR (DMSO-
d6) d: 153.7 (C-4), 160.4 (C-2); IR (neat) cmꢀ1: 3147, 1655, 1593,
1556, 1451, 1379, 1359, 1319, 1267, 1244, 1200, 1132, 1063,
1016, 981, 896, 845, 805, 762, 740, 693, 640, 581, 533; EI-MS m/z
(rel. int.%): 178 (M1, 100), 149 (100), 148 (56), 121 (13), 92 (13), 78
(4), 66 (5).
References
Dibenzyl 2,4-dimethyl[2,4-13C2]pyrrole-3,5-di[13C]carboxy-
late (4)
[1] K. Iida, K. Ohtaka, M. Kajiwara, FEBS J. 2007, 274, 3475–3481. DOI:
10.1111/j.1742-4658.2007.05880.
[2] K. Iida, M. Kajiwara, FEBS J. 2007, 274, 5090–5095. DOI: 10.1111/
j.1742-4658.2007.06028.
[3] M. Kajiwara, T. Okazaki, K. Iida, S. Narumi, M. Hirose, M. Ijichi,
T. Abei, S. Hirano, M. Iinuma, Chem. Pharm. Bull. 1996, 44,
1258–1260.
[4] K. Iida, T. Chiyoda, R. Hirasawa, A. Iwata, M. Kajiwara, J. Label.
Compd. Radiopharm. 1996, 39, 69–77.
[5] S. M. McElvain, J. Am. Chem. Soc. 1929, 51, 3124–3130.
[6] J. K. H. Inglis, K. C. Roberts, Org. Synth. 1941, Coll. Vol. 1,
235–236.
A solution of sodium nitrite (0.58 g, 8.41 mmol) in water (0.8 ml)
was added dropwise to a solution of benzyl [1,3-13C2]acetoace-
tate (3a) (1.56 g, 8.03 mmol) in acetic acid (4.7 ml) at 01C for
10 min, and the mixture was stirred at room temperature. The
reaction was complete after 2 h, and at that time, benzyl
[1,3-13C2]acetoacetate (3a) (1.56 g, 8.03 mmol) and zinc powder
(1.27 g, 19.42 mmol) were added, and the mixture was heated
under reflux for 1 h. The reaction mixture was added to water
(20 ml) at 01C, and the mixture was left to stand for 6 h and then
filtered. The residue was dried and dissolved in CHCl3. The
solution was filtered, and the filtrate was evaporated to give
dibenzyl 2,4-dimethyl[2,4-13C2]pyrrole-3,5-di[13C]carboxylate (4)
[7] K. Yoshizawa, S. Toyota, F. Toda, Tetrahedron Lett. 2001, 42,
7983–7985.
[8] H. D. Durst, M. Milano, E. J. Kikta Jr, S. A. Connelly, E. Grushka, Anal.
Chem. 1975, 47, 1797–1801.
[9] R. L. Patience, J. D. Thomas, J. Chromatogr. 1982, 234, 225–230.
[10] H. Fischer, Org. Synth. 1943, Coll. Vol. 2, 202–204.
(1.59 g, 54%), m.p. 136.01C; 1H-NMR (CDCl3) d: 2.48 (d, 3H,
2J1H13C 5 6.9 Hz, C-4-CH3), 2.58 (d, 3H, J1H13C 5 6.9 Hz, C-2-CH3), [11] A. Russell, J. R. Frye, Org. Synth. 1955, Coll. Vol. 3, 281–285.
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J. Label Compd. Radiopharm 2008, 51 167–169
Copyright r 2008 John Wiley & Sons, Ltd.