M. Alhaffar et al. / Catalysis Communications 11 (2010) 778–782
779
the separation of the compounds; precisely the initial temperature
2.3. Characterization of dihydronaphthalenes
was 50 °C, hold 2 min, then ramped at 10 °C/min to 140 °C (hold
time 0 min), then finally ramped at 20 °C/min to 250 °C (hold time
20 min). The detector was flame ionization detector (FID), with
hydrogen and air flow of 40.0 and 450.0 ml/min, respectively. Ma-
keup flow was on with 45.0 ml/min of helium. The products of
the reactions were also analyzed on GC–MS Varian Saturn 2000
equipped with 30 m capillary column (HP-5). Thin-layer chroma-
tography (TLC) analyses were performed on silica gel Merck 60
2.3.1. 3-Methoxy-5,6-dihydronaphthalen-2-ol (5a)
White solid, mp 108–109 °C; IR (KBr) v (cmꢀ1) 1576, 1613 (C@C),
3424 (OH); 1H NMR d (CDCl3): 2.26 (m, 2H, C6-2H), 2.70 (t, 2H,
J = 8.25 Hz, C5-2H), 3.87 (s, 3H, OMe), 5.44 (s, 1H, OH), 5.91 (dt,
1H, J = 9.50, 4.30 Hz, C7-H), 6.33 (dt, J = 9.75, 1.85 Hz, C8-H), 6.62
(s, 1H, C4-H), 6.63 (s, 1H, C2-H); 13C NMR d (CDCl3): 23.2, 27.3,
56.0, 110.6, 112.4, 126.6, 127.1, 127.2, 127.5, 143.8, 145.1; GC–
MS m/z 176 (M+). Analysis calculated for C11H12O2 (176.20): C,
74.98; H, 6.86; found: C, 74.86; H, 6.83.
F254 plates (250 lm layer thickness).
2.3.2. 5,6-Dihydronaphtho[2,3-d][1,3]dioxole (5c)
2.2. General procedure for the hydroformylation of allylbenzene
derivatives
Oil; IR (neat) v (cmꢀ1) 1575, 1614 (C@C); 1H NMR d (CDCl3):
2.27 (m, 2H, C6-2H), 2.71 (t, 2H, J = 8.25 Hz, C5-2H), 5.90 (s, 2H,
OCH2O), 5.94 (dt, 1H, J = 9.45, 4.43 Hz, C7-H), 6.35 (dt, J = 9.45,
1.75 Hz, C8-H), 6.57 (s, 1H, C4-H), 6.64 (s, 1H, C2-H); 13C NMR d
(CDCl3): 23.0, 27.7, 100.6, 106.7, 108.4, 108.5, 126.5, 127.4, 127.9,
129.2, 145.9; GC–MS m/z 174 (M+). Analysis calculated for
C11H10O2 (174.18): C, 75.85; H, 5.79; found: C, 75.72; H, 5.88.
To a Parr autoclave fitted with a glass liner and stirring bar,
Rh(CO)2(acac) (0.005 mmol), ligand (0.030 mmol), allylbenzene
derivative (5.0 mmol), H3PO4 (85%) (0.14 mmol), anisole
(3.76 mmol) and CH2Cl2 (5.0 ml) are added. The autoclave is vented
three times with CO and then pressurized with CO and H2. The
mixture is stirred and heated for the required time. At the end of
the reaction, the autoclave is cooled down, and the pressure is re-
leased under fume hood. The reaction mixture is filtered and the
products are separated on silica gel column using ethyl acetate/
petroleum ether (2:8) as eluent and identified by GC, NMR, FT-IR,
GC–MS, and elemental analysis.
2.3.3. 1,3-Dimethoxy-5,6-dihydronaphthalen-2-ol (5d)
Oil; IR (neat) v (cmꢀ1) 1575, 1612 (C@C), 3424 (OH); 1H NMR d
(CDCl3): 2.24 (m, 2H, C6-2H), 2.66 (t, 2H, J = 8.25 Hz, C5-2H), 3.82
(s, 3H, OMe), 3.85 (s, 3H, OMe), 5.40 (s, 1H, OH), 5.94 (dt, 1H,
J = 9.75, 4.67 Hz, C7-H), 6.44 (s, 1H, C4-H), 6.66 (dt, J = 9.75,
R1
R1
R1
R2
R1
R2
R2
Rh(CO)2acac, Ligand
R2
CHO
+
+
Solvent, T (oC), Time (h)
CO/H2 (1: 2) (300 psi)
R3
R3
CHO
R3
R3
CHO
1
2
4
3
a: R1= H, R2= OH, R3= OCH3
b: R1= H, R2=R3= OCH3
R1
R1
R2
R3
R2
+
c: R1 = H, R2,R3 = -OCH2O-
R3
d:
R1=R3= OCH3, R2= OH
e: R1=R3= H, R2= OCH3
f:
1'
5
R1=R2=R3= H
Scheme 1.
Table 1
Hydroformylation–cyclization of eugenol 1a by Rh(CO)2acac. Effect of the type of ligand.a
Entry
Ligand
Conversion (%)b
Yield of 10a (%)b
Yield of 5a (%)b
Yield of aldehydes (%)c
Aldehydes distribution (%)d
2a
3a
28
96
19
86
95
4a
1e
2
PPh3
PPh3
Ultranox626
Ultranox626
(PhO)3P
dppp
99
98
99
98
97
3
3
21
3
4
16
1
0
55
0
65
52
0
96
22
96
29
29
2
1
4
0
4
5
0
0
71
0
81
10
0
3e
4
5
6
100
45
0
55
7
dppb
9
1
3
5
a
Reaction conditions: Rh(CO)2acac (0.005 mmol), ligand (0.03 mmol, except for PPh3 and (PhO)3P 0.06 mmol), eugenol (1a) (5.0 mmol), H3PO4 (85%) (0.14 mmol), CH2Cl2
(5.0 ml), CO/H2 (100/200 psi), 2 h, 110 °C.
b
Determined by GC using anisole as internal standard.
c
Calculated yield = conversion ꢀ (10a + 5a).
d
Determined by GC and 1H NMR.
No acid.
e