¨
658 G. HEINKELE AND T. E. MURDTER
Table 1 H/D exchange of sulfamethoxazole in 5% 2H2SO4 in 95% 2H2O (v/v)
Time (h)
Isotope distribution (%)
d2
Isolated yield (%)
d0
d1
d3
d4
48
72
96
60 mina
0.00
0.00
0.00
0.00
0.83
0.09
0.00
0.61
30.2
6.45
3.1
69.0
93.32
96.7
73.4
0.06
0.10
0.23
0.2
62
38
13
45
25.8
Note: Reactions were performed as given in text but terminated at the times indicated in the table.a Microwave.
precipitated. The reaction mixture was extracted three
times with 100 ml ethyl acetate in which the precipitate
dissolved immediately. The organic phase was dried
over sodium sulfate and evaporated to dryness to
obtain 753 mg (38%) of (2) as a white amorphous solid.
Recrystallization from ethanol gave colorless cubic
crystals. Yield: 659 mg (33% of theory). For isotope
distribution see Table 1. Anal.: Calculated for
chloric acid and water and dried to obtain 250 mg (84%
of theory) of (3) as a slightly brown solid of a purity
>99% (HPLC-UV at 254 nm). Anal.: Calculated for
C12H210H3N3O4S: C, 48.31; Hþ2H, 4.40; N, 14.09; O,
21.45; S, 10.75. Found: C, 48.34; Hþ2H, 4.41; N,
14.10; S, 10.94. Isotope distribution: d0: 0.00, d1: 0.07,
d2: 7.03, d3: 93.1, d4: 0.2. 13C-NMR (in 2H6-DMSO):
170.2 (C-50); 169.1 (C-100); 157.5 (C-30); 143.4 (C-4);
132.8 (C-1); 127.9 (C-2, C-6); 118.4 (low intensity)
(C-3, C-5); 95.3 (low intensity) (C-40); 24.1 (C-200); 12.0
C
10H82H3N3O3S: C, 46.86; Hþ2H 4.33; N, 16.40; O,
18.73; S, 12.51. Found: C, 46.83; Hþ2H 4.36; N, 16.43;
13
2
S, 12.68. C-NMR (in C2H3O2H): 171.7 (C-50); 159.6
(C-60). 1H-NMR (in H6-DMSO): 7.79 2H (C-2, C-6); 6.1
(C-30); 154.7 (C-4); 130.2 (C-2, C-6); 126.4 (C-1);
113.6–114.4 (m, low intensity, C-3, C-5); 95.8–96.7
(m, low intensity, C-40); 12.3 (C-60). 1H-NMR (in
C2H3O2H): 7.58 (s 2H, C-2, C-6); 6.13 (s 0.04H, C-40);
2.32 (s 3H, C-60). (Assignment was done according
to COSY experiments and in agreement with Saito
et al.8)
0.05H (C-40); 2.30 s 3H (C-60); 2.10 s 3H (C-200).
(4-amino-N-(b-D-glucopyranuronosyl)-N-(5-methy-
loxazol-3-yl)-benzenesulfonamide) (5)
To a hot solution of 550 mg of (2) in 7.5 ml methanol,
90.2 mg of LiOH and 854 mg of (4) were added and
stirred under reflux for 90 min. After the reaction
mixture was cooled in an ice bath, 496 mg of LiOH in
7.5 ml water was added and the solution was stirred for
additional 30 min at room temperature. The pH of the
reaction mixture was adjusted to pH 4 by the addition
of glacial acetic acid and unchanged (2) was extracted
three times with 15 ml chloroform. The organic phase
was dried over sodium sulfate and evaporated to
dryness to obtain 377 mg (68.5%) of (2) as a yellow
solid which was identified as pure (2) by TLC and
HPLC. The aqueous phase was evaporated to dryness
under reduced pressure. The foamy residue was stored
over potassium hydroxide under reduced pressure to
remove traces of acetic acid. The majority of hydrophilic
by-products were removed by a column chromatogra-
phy on silica gel 60 with acetone:methanol 50:50 (v/v).
Final purification was carried out by chromatography
on a Lobar B column packed with Lichroprep RP 18
(40–64 mm) (Merck, Darmstadt, Germany) with a two
step gradient. Firstly, some brown by-products were
eluted with water:methanol 85:15 (v/v) then (5) was
separated from an unidentified glucuronide with
water:methanol 2:1 (v/v). Freeze drying of the pooled
fractions containing (5) resulted in 123 mg (13.2% of
theory) of a white solid. Isotope distribution: d0: 0.00,
3,5,40-[2H3]-sulfamethoxazole (2) microwave assisted
In a closed PTFE-reaction vessel equipped with a
pressure control valve (approximately 7 bar) 500 mg of
(1) was dissolved in 1.5 ml 2H2SO4 and 28.5 ml 2H2O.
The reaction vessel was irradiated in a domestic
microwave oven at a nominal energy of 80 W (1/10 of
time with a fixed energy of 800 W) for 60 min. After
cooling down to room temperature, the reaction vessel
was opened, cooled in an ice bath and the product was
separated as described above, to obtain 224 mg (45% of
theory) as a white solid.
3,5,40-[2H3]-N4-acetyl-sulfamethoxazole (3)
To a solution of 256 mg (1 mmol) (2) in 5 ml dry
pyridine, 142 ml (2 mmol) acetyl chloride was added.
Spontaneously, a white solid precipitated. This pre-
cipitate re-dissolved while the reaction mixture was
stirred at 1008C. After 30 min the yellow solution was
cooled in an ice bath and diluted with 25 ml of ice-cold
1 M NaOH. Acidifying of the reaction mixture with
chilled 10% hydrochloric acid resulted in precipitation
of (3). The precipitate was washed with diluted hydro-
Copyright # 2007 John Wiley & Sons, Ltd.
J Label Compd Radiopharm 2007; 50: 656–659
DOI: 10.1002.jlcr