R. Röhrkasten et al. • Synthesis of the Caffeine Metabolites
1531
(q, N CH 3); 95.50 (s, C-5); 142.94 (s, C-2); 149.67
of formic acid/acetic formic anhydride (1:1) and
(s, C-6); 160.67 (s, C-4). - MS (70 eV, 215 °C): m / stirred for 7 d at 20 °C with exclusion of moisture;
0.5 ml of acetic formic anhydride were added ev-
ery day (after 2 d 8 was almost dissolved and gen-
erally a colorless solid precipitates). The solvents
were removed and the solid (-2.4 g; >100%) was
suspended in 247 ml of dioxane/water (97:3), re-
fluxed for 10 min and insoluble 8 was removed by
filtration. A fter the filtrate was cooled to 20 °C the
precipitate was filtered off; concentration of the
filtrate to 20 ml under reduced pressure (T <
40 °C) gives another fraction. The residues (1.6-
2.0 g) were suspended in 40 ml of acetone (30 min/
4 °C) and than washed three times with 5 ml of
ice-cold trichlorom ethane/m ethanol (9:1) and
dried over P20 5; yield: 1.35-1.80 g (60-80% ) col-
orless 9, mp. 227-229 °C (dec), R F = 0.20 (silica
z
(% ) = 156 (100) (M +-0.5 •H20 ); 71 (43); 44
(61). - IR (KBr): v (cm -1) = 3490 (m); 3390 (s);
3205 (s); 1700-1610 (s); 1590-1510 (s); 1456 (s);
1385 (m); 1366 (m); 1284 (m); 1258 (m); 1181 (m);
1109 (m); 755 (m); 723 (m); 702 (m); 655 (m). -
UV (methanol): Amax(nm) (lg e) = 219 (sh, 3.32);
260 (3.88); 285 (2.96).
5-Acetylam ino-6-am ino-3-m ethyluracil-hydrate
(A A M U ) (8)
16.52 g (100 mmol) of 5,6-diamino-3-methylura-
cil-semihydrate (7) in 150 ml of glacial acetic acid
were refluxed for 3 h with a m ixture of 9.02 g
(110 mmol) of dry sodium acetate and 11.23 g
(110 mmol) of absol. acetic anhydride. The mix-
ture was cooled to 20 °C, and the solid was filtered
off and washed three times with 50 ml of water
and dried in vacuo\ yield: 19.24 g (89% ) of 8 as
colorless microcrystals. The filtrate was evapo-
rated to dryness in vacuo and the yellow residue
recrystallized from 100 ml of water and dried over
P20 5; further 1.70 g (8% ) of colorless 8 is ob-
tained. Overall yield: 20.94 g (97% ), subl.-p.
276 °C; m.p. >350 °C (ref. [1]; m.p. >350 °C); R F =
0.16 (alumina; m ethanol).- R F = 0.12 (silica gel;
ethyl acetate/acetic acid (9:1)); tHPLC = 4.52 min.
gel; ethyl acetate/acetic acid (9:1)); tHPLC
=
6.70 min. - HPLC-purity: -9 1 -9 5 % 9, -3 -7 % 8,
-1 -3 % 12.
C8H 10N4O4 (226.19)
Calcd
Found C 41.4
C 42.48 H 4.46 N 24.77%,
H 4.2 N 24.1% .
*H NM R ([D6]-DMSO, 300 MHz): <3 (ppm) =
1.96 (s, 3H, COCH3); 3.12 (s, 3H, N CH3); 8.35
(s(broad), 1H, CHO); 8.83 (s, 1H, NH); 10.53;
11.03 (s(broad), 2 •1H, 2 •NH). - 13C NM R ([D6]-
DMSO, 75.5 MHz): (3 (ppm) = 22.87 (q, C O C H 3);
27.25 (q, N CH3); 96.15 (s, C-5); 142.64 (s, C-2);
149.23 (s, C-6); 161.26 (s, C-4); 162.79 (d, CHO);
170.10 (s, CO CH 3). - MS (70 eV, 170 °C): m /z
(% ) = 226 (10) (M+); 184 (33); 156 (29); 71 (27);
44 (24); 43 (100); 42 (18). - IR (KBr): v (cm “1) =
3425 (m); 3245 (s); 3065 (m); 2935 (m); 1739 (s);
1715 (s); 1678 (s); 1641 (vs); 1561 (m); 1524 (m);
1508 (m); 1301 (m); 1204 (m); 752 (m). - UV
(methanol, <5 min after preparation of the solu-
tion): Amax(nm) (lg e) = 210 (4.32); 286 (4.13). -
UV (water): Amax(nm) (lg e) = 207.5 (4.24); 285
(4.15).
C7H 10N4O r H ,O (216.20)
Calcd
C 38.89 H 5.59 N 25.92%,
Found C 39.13 H 5.85 N 26.21%.
NM R ([D6]-DMSO, 300 MHz): (3 (ppm) =
I.91 (s, 3H, CO CH 3); 3.04 (s, 3H, N C H 3); 6.06
(s(broad), 2H, NH 2); 8.37 (s, 1H, N H CO ); 10.22-
II.03 (s(broad), 1H, H -l).
-
13C NM R (5%
N a0 D /D 20 /[D 6]-D M S0 as int. standard, 75.5
MHz): <3 (ppm) = 19.21 (q, C O C H 3); 25.09 (q,
N CH3); 85.60 (s, C-5); 156.79 (s, C-2); 158.33 (s, C-
6); 161.30 (s, C-4); 172.40 (s, CO CH 3). - MS (70
eV, 170 °C): m /z (% ) = 198 (26) (M +-H20 ); 157
(11); 156 (100) ([M+- H 70 ]-C 0 C H 2); 155 (20); 71
(34); 70 (16); 44 (15); 43 (66). - IR (KBr): v (cm-1) =
3545 (s); 3435 (m); 3365 (m); 3165 (s); 3055 (m);
1711 (s); 1667 (s); 1640 (s); 1580-1530 (s); 1470
(s); 1377 (m); 1318 (m); 969 (m); 778 (m); 750 (m);
713 (m); 638 (m). - UV (methanol): 2max(nrn) (lg
5,6-Diacetylamino-3-methyluracil ( DAMU) (12)
DAMU 12 was separated by semi-preparative
HPLC; subl.-p. 160 °C (needles developed) and
m.p. 257 °C .- R f - 0.61 (alumina; methanol);
^hplc —11-20 min.
e)
=
218 (3.82); 264 (4.25).
-
UV (water):
C9H 12N40 4 (240.22)
l mas(nm) (lg e) = 223.5 (3.84); 264 (4.27).
'H NMR ([D6]-DMSO, 300 MHz): (3 (ppm) =
1.97 (s, 3H, 5-COCH3); 2.14 (s, 3H, 4-COCH3);
3.12 (s, 3H, NCH3); 8.75; 10.06; 11.32 (s, 3-1H,
3-N H ). - 13C NMR ([D6]-DMSO, 75.5 MHz): (3
(ppm) = 23.04; 24.20 (q, 2 C O C H 3); 27.30 (q,
N C H 3); 96.16 (s, C-5); 143.34 (s, C-2); 148.91 (s, C-
5-Acetylam ino-6-form ylam ino-3-m ethyluracil
(AFM U) (9)
2.16 g (10.0 mmol) of 5-acetylamino-6-amino-3-
methyluracil-hydrate (8) were suspended in 6 ml
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 7/27/15 3:22 PM