Helvetica Chimica Acta – Vol. 89 (2006)
2017
[a]2D5 =+135.2 (c=0.85, CHCl3). IR (ATR): 3363w, 3172w (br.), 3058w, 3029w, 2863w, 1951w, 1876w,
1811w, 1656w, 1526m, 1495m, 1453m, 1392w, 1360m, 1326m, 1250w, 1205m, 1087s, 1067s, 909m, 847w,
820w. 1H-NMR (300 MHz, CDCl3): 8.42 (br. s, NH); 7.42–7.23 (m, 15 arom. H); 5.14 (d, J=11.2,
PhCH); 4.81 (d, J=11.5, PhCH); 4.62 (d, J=11.8, PhCH); 4.58 (d, J=11.5, PhCH); 4.49 (d, J=11.8,
PhCH); 4.47 (d, J=11.8, PhCH); 4.36 (d, J=5.0, irrad. at 3.83 ! s, HꢀC(2)); 3.83 (dt, J=6.0, 4.7,
irrad. at 4.36 ! dd, J=5.9, 4.4, HꢀC(3)); 3.79–3.71 (m, HꢀC(5)); 3.51 (t, J=9.3, HꢀC(6)); 3.45 (dd,
J=9.0, 4.4, H’ꢀC(6)); 2.26 (ddd, J=14.0, 6.5, 4.4, irrad. at 3.83 ! dd, J=14.0, 6.2, HeqꢀC(4)); 1.59
(td, J=14.0, 6.3, irrad. at 3.83 ! dd, J=14.9, 5.8, HaxꢀC(4)). 13C-NMR (75 MHz, CDCl3): 199.64 (s,
C=S); 137.66, 137.59, 137.06 (3s); 128.48–127.53 (several d); 81.00 (d, C(3)); 73.93 (d, C(2)); 73.73,
73.41, 72.69 (3t, 3 PhCH2); 71.58 (t, C(6)); 52.41 (d, C(5)); 26.57 (t, C(4)). HR-MALDI-MS: 470.1753
(100, [M+Na]+, C27
A
G
N
6.53, N 3.13, S 7.16; found: C 72.34, H 6.42, N 3.05, S 7.27.
Preparation of 29 and 30. A soln. of 28 (58 mg, 0.13 mmol) in THF (4 ml) was cooled to 08, treated
with Hg(OAc)2 (46 mg, 0.14 mmol) and H2NCH2CH(OMe)2 (71 ml, 0.64 mmol), stirred for 2 h, diluted
with Et
(3.1 ml) was treated with TsOH·H2O (100 mg, 0.52 mmol) and stirred at 758 for 24 h. The mixture
was diluted with AcOEt (50 ml) and washed with sat. K2CO3 soln. The aq. layer was extracted with
G
A
ACHTREUNG
AcOEt (250 ml). The combined org. layers were dried (Na2SO4), filtered, and evaporated. FC
(AcOEt/cyclohexane 1:4) afforded 30 (38 mg, 64%) and 29 (12 mg, 20%).
Data of (5R,7S,8S)-7,8-Bis(benzyloxy)-5-[(benzyloxy)methyl]-5,6,7,8-tetrahydroimidazo[1,2-a]pyri-
dine (30). Rf (AcOEt/cyclohexane 1:1) 0.34. [a]2D5 =+122.6 (c=0.66, CHCl3). IR (ATR): 3062w,
3029w, 2920w, 2863w, 1953w, 1876w, 1811w, 1724w, 1676w, 1604w, 1585w, 1495m, 1481w, 1453m, 1360m,
1327w, 1305w, 1254w, 1207w, 1175w, 1086s, 1063s, 1027s, 909m, 822w. 1H-NMR (300 MHz, CDCl3):
7.39–7.21 (m, 15 arom. H); 7.20, 7.11 (2d, J=1.2, HꢀC(2), HꢀC(3)); 4.95 (d, J=11.8, PhCH); 4.80
(d, J=12.1, PhCH); 4.69 (d, J=3.7, irrad. at 4.02 ! s, HꢀC(8)); 4.61 (d, J=11.8, PhCH); 4.54 (d,
J=11.8, PhCH); 4.51 (d, J=11.8, PhCH); 4.48 (d, J=11.8, PhCH); 4.39 (dddd, Jꢂ7.8, 6.5, 4.7, 3.7,
HꢀC(5)); 4.02 (ddd, J=5.6, 3.7, 2.8, irrad. at 4.69 ! dd, J=5.6, 2.8, HꢀC(7)); 3.80 (dd, J=9.6, 7.5,
HCꢀC(5)); 3.69 (dd, J=9.6, 4.7, H’CꢀC(5)); 2.49 (ddd, J=14.6, 6.8, 2.8, irrad. at 4.02 ! dd, J=14.3,
6.8, HeqꢀC(6)); 2.12 (ddd, J=14.6, 5.3, 3.7, irrad. at 4.02 ! dd, J=14.9, 3.4, HaxꢀC(6)). 13C-NMR (75
MHz, CDCl3): 142.39 (s, C=N); 138.18, 137.74, 137.58 (3s); 128.44–127.36 (several d, including C(2));
119.09 (d, C(3)); 75.00 (d, C(7)); 74.73, 73.43, 71.56 (2 C) (3t, 3 PhCH2, CH2ꢀC(5)); 71.00 (d, C(8));
53.28 (d, C(5)); 26.73 (t, C(6)). HR-MALDI-MS: 477.2147 (100, [M+Na]+, C29
477.2149), 455.2329 (76, [M+H]+, C29
H31N2
A
G
U
G
G
ACHTREUNG
76.63, H 6.65, N 6.16; found: C 76.46, H 6.95, N 6.06.
Data of (5R,7S,8R)-7,8-Bis(benzyloxy)-5-[(benzyloxy)methyl]-5,6,7,8-tetrahydroimidazo[1,2-a]pyri-
dine (29). Rf (AcOEt/cyclohexane 1:1) 0.30. 1H-NMR (300 MHz, CDCl3): 7.44–7.27 (m, 15 arom. H, Hꢀ
C(2)); 7.07 (d, J=1.2, HꢀC(3)); 4.83 (br. d, J=2.2, HꢀC(8)); 4.82 (d, Jꢂ12.7, PhCH); 4.77 (d, J=12.1,
PhCH); 4.59 (d, J=12.1, PhCH); 4.54 (d, J=14.3, PhCH); 4.53 (d, J=14.9, PhCH); 4.46 (d, J=12.1,
PhCH); 4.29–4.19 (m, HꢀC(5)); 3.78 (dt, J ꢂ 12.1, 3.4, irrad. at 4.83 ! dd, J=12.1, 3.7, HꢀC(7));
3.68 (dd, J=12.8, 10.0, HCꢀC(5)); 3.68–3.65 (hidden signal, H’CꢀC(5)); 2.41 (q, Jꢂ12.1, HaxꢀC(6));
2.15 (dddd, J=13.1, 5.9, 3.7, 1.2, irrad. at 4.83 ! ddd, J=12.9, 6.0, 3.8, HeqꢀC(6)).
(5R,7S,8S)-5-(Hydroxymethyl)-5,6,7,8-tetrahydroimidazo[1,2-a]pyridine-7,8-diol (14). A suspension
of 30 (18 mg, 0.04 mmol) and 10% Pd/C (10 mg) in MeOH/AcOH 2 :1 (3 ml) was hydrogenated (6
bar) for 24 h. The suspension was filtered through Celite, and the residue was washed with MeOH (10
ml). Evaporation of the filtrate and FC (RP-18, elution with MeOH) afforded 14 (7.2 mg, 98%). Rf
(AcOEt/MeOH/H2O 3 :1:1) 0.26. IR (KBr): 3390s (br.), 2925s, 2855m, 1575s, 1528m, 1489m, 1446s,
1413s, 1321m, 1257m, 1171m, 1119m, 1090s, 1070s, 1044s, 1013m, 938w, 882w, 835w. 1H-NMR (300
MHz, D2
A
3.97–3.90 (hidden signal, HꢀC(7)); 3.93 (dd, J=11.8, 4.0, HCꢀC(5)); 3.79 (dd, J=11.8, 5.3, H’Cꢀ
C(5)); 2.36 (ddd, J=13.9, 5.6, 3.1, HeqꢀC(6)); 1.99 (dt, J=14.3, 8.4, HaxꢀC(6)). 13C-NMR (75 MHz, CD3-
A
C(5)); 54.86 (d, C(5)); 30.36 (d, C(6)).