(3aR*,15dR*)-2,2-dimethyl-3a,11,12,13,14,15d-hexahydroazuleno[1',2':1,2]phenanthro[9,10-
d][1,3]dioxole (3arom)
H
H
Bu Sn
3
Pd(CH CN) Cl
2
3
2
O
+
OTf
LiCl, DMF, rt
O
O
O
O
O
6
3
3arom
rt
A solution of the enoltriflate 6 (0.500 g, 0.627 mmol, 1 equiv), Pd(CH CN) Cl (0.008 g, 0.031 mmol,
3
2
2
0
.05 equiv) and LiCl (0.053 g, 1.254 mmol, 2 equiv) in anhydrous DMF (15 mL) was carefully degassed
and placed under argon. The mixture was stirred at r.t. until the disapearance of the starting material
monitored by TLC, 1 h). Then the reaction was quenched with water (5 mL) and extracted with Et O (3
(
2
x 10mL). The combined organic extracts were dried over MgSO and concentrated in vacuo. The residue
4
was purified by Et N pretreated silica gel flash column chromatography (hexane) to afford the cyclized
3
and inseparable products 3 and 3arom. (which resulted from the aromatisation of 3) as a yellow oil for a
global yield around 50 %. We noticed that after 5 days the isolated mixture only contained 3arom.
Data for 3:
1
TLC: R 0.54 (ether/hexane 2/8). H NMR (300 MHz, CDCl ): δ 1.70 (s, 3H), 1.71 (s, 3H), 1.59-1.75
f
3
(
m, 2H), 1.87-1.91 (m, 2H), 2.58-2.66 (m, 2H), 2.75-2.95 (m, 2H), 3.90 (d br, 1H, J = 10.6), 4.06 (d br,
1
H, J = 9), 4.20 (d br, 1H, J = 11.2), 4.97 (d, 1H, J = 8.7), 5.82 (s br, 1H), 6.20 (d br, 1H, J = 10), 6.44
1
3
(
(
d br, 1H, J = 10), 6.89 (t br, 1H, J = 5.9), 7.40 (s br, 1H), 7.52 (m, 2H), 7.66 (d, 1H, J = 7.5). C NMR
75 MHz, CDCl ): δ 25.97, 26.91, 28.24, 28.28, 30.25, 30.48, 39.31, 46.30, 77.48, 78.56, 111.70,
3
1
1
19.00, 120.88, 124.20, 127.32, 128.55, 129.66, 130.20, 135.19, 135.67, 136.90, 139.00, 139.71, 142.07,
+
+
46.42. MS (EI, 70 eV) (intensity): calc'd for (C H O ) 358.2; found: 358.5 (5) [M] , 300.5 (5) [M-
2
5 26 2
+
+
(CH ) CO] , 284.4 (3) [M-(CH ) CO ] , 272.4 (2), 254.3 (13), 241.3 (28).
3
2
3 2
2
Data for 3arom.:
TLC: R 0.54 (ether/hexane 2/8). H NMR (200 MHz, CDCl ): δ 1.60-1.78 (m, 2H), 1.62 (s, 3H), 1.66
1
f
3
(
s, 3H), 1.87-1.95 (m, 2H), 1.90-1.99 (m, 2H), 2.50-2.67 (m, 2H), 4.88 (syst AB, 2H, JAB = 10.5, ∆ν =
3
7
2
1
2.6 Hz), 6.57 (s br, 1H), 7.22 (d, 1H, J = 7.8), 7.36 (td, 2H, J = 6.7, 1.8), 7.49 (m, 1H), 7.59 (d, 1H, J =
1
3
.8), 7.64 (dd, 1H, J = 7.6, 1.7), 7.76 (td, 1H, J = 5.9, J = 1.5). C NMR (75 MHz, CDCl ): δ 25.71,
3
7.33, 27.33, 27.74, 29.70, 30.65, 79.29, 79.69, 112.11, 119.06, 121.93, 124.08, 124.88, 126.97, 127.12,
27.40, 127.68, 130.26, 133.77, 134.10, 134.49, 141.19, 141.63, 143.53, 145.67. MS (EI, 70 eV): m/z
(
%) 357 [M+H], (11), 356 [M], (57), 298 [(M-(CH ) CO]. IR (CHCl ): ν 3019, 2929, 2855, 1718, 1632,
3
2
3
1
522, 1480, 1418, 1376, 1262, 1216, 1088, 1059, 1028, 758. MS (EI, 70 eV) (intensity): calc'd for
2
5