122
J. Koch et al./Carbohydrate Research 313 (1998) 117±123
11.08 (CH3), 25.87 (CH2±CH3), 59.16 (N±CH2),
60.43 (CH2OH), 129.77 (C-5), 135.43 (C-4), 136.28
(C-2), 138.45 (C-3), 168.67 (C-6); MS-CI: m/z 168
(100%, M+1+). Anal. Calcd for C9H13NO2: C,
64.65; H, 7.84; N, 8.38. Found: C, 64.22; H, 8.27;
N, 8.34.
NMR (CDCl3): ꢂ 1.05 (t, 3 H, CH3), 2.18 (m, 2 H,
CH2CH3), 5.04 (s, 2 H, OCH2), 7.33 (m, 5 H,
C6H5), 7.43 (t, 1 H, CHN); 13C NMR (COSY,
CDCl3): 11.04 (CH3), 23.06 (CH2CH3), 75.50
(CH2O), 128.22 (C-2), 128.33 (C-4), 128.34 (C-3),
138.18 (C-1), 152.28 (CHN); (b) 1H NMR
(CDCl3): ꢂ 1.02 (t, 3 H, CH3),2.36 (m, 2H,
CH2CH3), 5.09 (s, 2 H, OCH2), 6.64 (t, 1 H,
CHN), 7.27 (m, 5 H, C6H5); 13C NMR (COSY,
CDCl3):10.61 (CH3), 19.28 (CH2CH3), 75.67
(CH2O), 127.68 (C-4), 127.76 (C-3), 127.86 (C-2),
137.78 (C-1), 153.50 (CHN); MS-CI: m/z 164
(100%, M+1+); GC±MS data: tret 17.3 min; m/z
(rel. intensity) 163 (1%, M+), 146 (2),133 (4),105
(2),92 (8),91 (100),77 (12),65 (9),51 (8). Anal. Calcd
for C9H11NO: C, 73.57; H, 8.03; N, 8.59. Found:
C, 73.19; H, 8.08; N, 8.49.
Isolation of 6-formyl-l-propylpyridinium-3-olate
(5b).Ð1-Propylamine (9 g, 152.2 mmol) and
KH2PO4, (40 g, 296 mmol) were dissolved in
150 mL of water and the pH adjusted to 4.8 with
phosphoric acid. Glucose (27 g, 150 mmol) was
added and the mixture was re¯uxed for 100 min.
After cooling, the solution was extracted with
EtOAc several times. The pH was then adjusted
to 7.5 and the solution again extracted with
EtOAc. The latter organic layers were subjected
to solid-phase extraction on silica and eluted with
MeOH. The eluate was evaporated, dissolved in
water and puri®ed by preparative HPLC. Collected
fractions were evaporated, lyophilized and crystal-
lized, giving ꢁ40 mg (0.24 mmol, 0.16%) of 5b as
crystals. The structure was determined by X-ray
crystallography (Fig. 1). Spectral data were
identical to those of the synthesized reference
compound.
6-Formyl-1-propylpyridinium-3-olate (5b).Ð6-
hydroxymethyl-1-propylpyridinium-3-olate (1.67 g,
10 mmol) was dissolved in 50 mL, of MeOH, acti-
vated MnO2 (5 g, 57.5 mmol, Fluka, Neu-Ulm,
Germany) was added and the mixture was heated
at re¯ux for 3 h. Subsequent to ®ltration and eva-
poration, the residue was puri®ed by ¯ash chro-
matography on silica gel, eluting with MeOH and
crystallisation (Et2O THF) to give 1.16 g (7 mmol,
ꢀ
70%) of 5b as yellow crystals: mp 121 C; tret
(HPLC) 12.6 min; UVmax 238, 291, 343 nm; 1H
NMR (Me2SO-d6): ꢂ 0.91 (t, 3 H, CH3), 1.81 (m,
2H, CH2CH3), 4.62 (t, 2 H, NCH2), 6.88 (dd, 1 H,
H-4), 7.77 (d, 1 H, H-2), 7.89 (d, 1 H, H-5), 9.61 (s,
1 H, CHO); MS-CI: m/z 166 (100%, M+1+).
Anal. Calcd for C9H11NO2: C, 65.44; H, 6.71; N,
8.48. Found: C, 65.13; H, 7.17; N, 8.28. Spectral
data were identical to those of the isolated com-
pound.
6-(N-Propyl)-carbimino-1-methylpyridinium-3-
olate (7b).Ð6-Formyl-1-methylpyridinium-3-olate
(137 mg, 1 mmol) was dissolved in 1-propylamine
(2.36 g, 40 mmol) and the excess of amine was eva-
porated in vacuo at room temperature and in high
vacuo to give 176 mg (99%) of 8b as a yellow solid:
mp 126 ꢀC; tret (HPLC) 13.2 min; UVmax 236,
337 nm; 1H NMR (CDCl3): ꢂ 0.90 (t, 3 H,
CH2CH3), 1.65 (m, 2 H, CH2CH3), 3.52 (t, 2 H,
NCH2), 4.19 (s, 3 H, NCH3), 7.14 (dd, 1 H, H-4),
7.32 (d, 1 H, H-2), 7.56 (d, 1 H, H-6), 8.17 (s, 1 H,
CHN); 13C NMR (COSY, CDCl3): 11.70
(CH2CH3), 23.98 (CH2CH3), 46.43 (NCH3), 64.09
(NCH2), 126.60 (C-3), 130.03 (C-5), 133.28 (C-4),
137.79 (C-2) 152.20 (CHN), 170.39 (C-6); MS-CI:
m/z 179 (100%, M+1+).
Formation of 5b,c under acidic conditions.ÐGlu-
cose (90 mg, 0.5 mmol) or fructose (90 mg,
0.5 mmol) and 1-propylamine (59 mg, 1 mmol) or
N6-acetyl-l-lysine (188 mg, 1 mmol) were dissolved
in 1 mL of water and KH2PO4 (136 mg, 1 mmol)
was added. The pH was adjusted to 5.0 with phos-
phoric acid or NaOH, respectively. The mixture
was heated at 100 ꢀC in a sealed vessel. The sample
was diluted and analyzed by HPLC±DAD.
Propanal-O-benzyloxime (syn and anti iso-
mers).ÐPropanal (58 mg, 1 mmol) was added to a
solution of O-benzylhydroxylamine hydrochloride
(160 mg, 1 mmol) and Na2CO3 (53 mg, 0.5 mmol)
in 10 mL of water. After shaking the mixture, the
product was extracted with diethyl ether and the
organic layer dried over anhydrous Na2SO4, fol-
lowed by evaporation in vacuo. Subsequent pur-
i®cation on silica gel, eluting with EtOAc, gave
130 mg (80%) of colourless liquid. NMR data are
Formation of 5b under physiological condi-
tions.ÐGlucose (90 mg, 0.5 mmol) and 1-propyla-
mine (59 mg, 1 mmol) were heated in 5 mL of 1 M
ꢀ
phosphate buer (pH 7.4) at 38 C. The mixture
was analyzed daily by HPLC±DAD.
Degradation of the Amadori compound.Ð1-
Deoxy-1-(1-propylammonium)fructose, oxalate salt
1
given for the anti (a) and syn (b) isomers. (a) H