2234 Bull. Chem. Soc. Jpn., 77, No. 12 (2004)
Synthesis of Methoxylated (E)-Arylalkenes
H-6, H-5, H-3, and H-2), 4.59 (1H, t, J ¼ 6:4 Hz, H-10), 3.82 (3H,
s, 4-OCH3), 1.72–1.65 (2H, m, H-20), 0.91 (3H, t, J ¼ 7:5 Hz, H-
30); 13C NMR (CDCl3) ꢂ 159.1 (C-4), 146.2 (C-1), 129.1 (C-6),
118.1 (C-5), 112.8 (C-2), 111.7 (C-3), 76.1 (C-10) 55.2 (4-OCH3),
31.7 (C-20), 10.2 (C-30). Compound 3h: 74% yield; liquid;
1H NMR (CDCl3) ꢂ 6.62 (1H, s, H-6), 6.34 (1H, s, H-3), 4.29
(1H, t, J ¼ 6:4 Hz, H-10), 3.82 (6H, s, 4-OCH3 and 5-OCH3),
3.61 (3H, s, 2-OCH3), 1.76–1.41 (2H, m, H-20), 1.26–1.21 (2H,
m, H-30), 0.86 (3H, t, J ¼ 7:0 Hz, H-40); 13C NMR (CDCl3) ꢂ
151.2 (C-4), 147.2 (C-5), 142.4 (C-2), 118.8 (C-1), 109.9 (C-6),
97.9 (C-3), 73.8 (C-10), 56.3 (4-OCH3), 56.8 (5-OCH3), 55.8
(2-OCH3), 28.1 (C-20), 23.2 (C-30), 14.4 (C-40). Compound 3i:
79% yield; liquid; 1H NMR (CDCl3) ꢂ 6.78–6.72 (3H, m, H-6,
H-5, and H-2), 4.29 (1H, t, J ¼ 6:6 Hz, H-10), 3.84 and 3.81 (each
3H, s, two –OCH3), 1.72–1.42 (2H, m, H-20), 1.28–1.21 (2H, m,
H-30), 0.88 (3H, t, J ¼ 7:0 Hz, H-40); 13C NMR (CDCl3) ꢂ
148.4 (C-3), 147.5 (C-4), 137.1 (C-1), 118.4 (C-6), 113.5 (C-5),
108.2 (C-2), 73.2 (C-10), 56.2 (4-OCH3), 56.0 (3-OCH3), 27.7
(C-20), 23.1 (C-30), 13.9 (C-40). Compound 3j: 54% yield; liquid;
1H NMR (CDCl3) ꢂ 6.86–6.74 (3H, m, H-6, H-2, and H-5), 5.58
(1H, s, 4-OH), 4.77 (1H, q, J ¼ 7:0 Hz, H-10), 3.83 (3-OCH3),
2.09 (1H, s, OH), 1.42 (3H, d, J ¼ 7:0 Hz, H-20); 13C NMR
(CDCl3) ꢂ 146.6 (C-4), 145.0 (C-3), 137.9 (C-1), 118.3 (C-5),
114.1 (C-6), 108.0 (C-2), 70.3 (C-10), 55.9 (3-OCH3), 25.1 (C-
20). Compound 3k: 73% yield; liquid; 1H NMR (CDCl3) ꢂ 6.85
(1H, s, H-6), 6.43 (1H, s, H-3), 4.98 (1H, q, J ¼ 7:1 Hz, H-10),
3.79 (6H, s, 4-OCH3 and 5-OCH3), 3.74 (3H, s, 2-OCH3), 2.52
(1H, br, OH), 1.38 (3H, d, J ¼ 7:1 Hz, H-20); 13C NMR (CDCl3)
ꢂ 150.9 (C-4), 149.0 (C-5), 143.5 (C-2), 125.7 (C-1), 110.8 (C-6),
97.9 (C-3), 66.1 (C-10), 56.6 (4-OCH3), 56.2 (5-OCH3), 55.1
(2-OCH3), 23.6 (C-20).
OCH3), 1.88 (3H, d, J ¼ 1:7 Hz, H-30); 13C NMR (CDCl3) ꢂ
152.9 (C-3), 151.3 (C-2), 142.7 (C-4), 125.5 (C-1), 125.4 (C-10),
124.7 (C-20), 120.8 (C-5), 108.1 (C-6), 61.4 (3-OCH3), 61.2 (2-
OCH3), 56.4 (4-OCH3), 19.2 (C-30). Compound 1d: 64% yield;
mp 71–72 ꢂC (lit.7c mp 72–73 ꢂC); 1H NMR (CDCl3) ꢂ 6.57
(1H, d, J ¼ 16:1 Hz, H-10), 6.50 (1H, dq, J ¼ 5:5, 16.1 Hz, H-
20), 6.14 (2H, s, H-3 and H-5), 3.81 (6H, s, 2-OCH3 and 6-OCH3),
3.70 (3H, s, 4-OCH3), 1.89 (3H, d, J ¼ 5:5 Hz, H-30); 13C NMR
(CDCl3) ꢂ 160.1 (C-4), 158.3 (C-2 and C-6), 128.7 (C-10),
121.5 (C-20), 112.5 (C-1), 90.9 (C-3 and C-5), 55.1 (2-OCH3
and 6-OCH3), 53.4 (4-OCH3), 19.8 (C-30). Compound 1e: 72%
yield; liquid; 1H NMR (300 MHz, CDCl3) ꢂ 6.90–6.78 (3H, m,
H-6, H-5, and H-2), 6.35 (1H, d, J ¼ 16:2 Hz, H-10), 6.11 (1H,
m, H-20), 3.87, 3.83 (each 3H, s, two OCH3), 1.87 (3H, d, J ¼
6:2 Hz, H-30); 13C NMR (CDCl3) ꢂ 149.3 (C-4), 148.5 (C-3),
131.5 (C-10), 131.0 (C-20), 124.0 (C-1), 119.0 (C-5), 111.4 (C-
6), 108.7 (C-2), 56.0 (3-OCH3), 56.0 (4-OCH3), 18.8 (C-30). Com-
1
pound 1f: 69% yield; liquid; H NMR (CDCl3) ꢂ 6.92 (1H, s, H-
2), 6.77 (2H, d, H-5 and H-6), 6.35 (1H, d, J ¼ 16:2 Hz, H-10),
6.11 (1H, m, H-20), 5.95 (2H, s, –OCH2O–), 1.95 (3H, d, J ¼
6:2 Hz, H-30); 13C NMR (CDCl3) ꢂ 147.9 (C-4), 146.5 (C-3),
132.5 (C-10), 130.6 (C-20), 123.8 (C-1), 120.0 (C-5), 108.1 (C-
6), 105.3 (C-2), 100.6 (–OCH2O–), 18.3 (C-30). Compound 1g:
1
67% yield; liquid; H NMR (CDCl3) ꢂ 6.96 (2H, d, H-2 and H-
6), 6.88 (1H, d, J ¼ 16:2 Hz, H-10), 6.45 (2H, d, H-3 and H-5),
6.31 (1H, m, H-20), 3.83 (3H, s, OCH3), 1.87 (3H, d, J ¼ 6:2
Hz, H-30); 13C NMR (CDCl3) ꢂ 155.3 (C-4), 131.5 (C-10), 128.5
(C-3), 127.8 (C-5), 127.6 (C-20), 126.0 (C-1), 110.4 (C-6), 108.7
(C-2), 56.0 (4-OCH3), 18.8 (C-30). Compound 1h: 67% yield;
mp 40–41 ꢂC (reported as a liquid in literature5); 1H NMR
(CDCl3) ꢂ 6.82 (1H, s, H-6), 6.54 (1H, d, J ¼ 16:2 Hz, H-10),
6.29 (1H, s, H-3), 5.96 (1H, m, H-20), 3.66 (6H, s, 4-OCH3 and
5-OCH3), 3.60 (3H, s, 2-OCH3), 2.08 (2H, m, H-30), 0.93 (3H,
t, J ¼ 7:1 Hz, H-40); 13C NMR (CDCl3) ꢂ 151.5 (C-4), 148.8
(C-5), 143.3 (C-2), 130.6 (C-10), 123.2 (C-20), 118.8 (C-1),
109.9 (C-6), 97.9 (C-3), 56.3 (4-OCH3), 56.8 (5-OCH3), 55.8
(2-OCH3), 26.3 (C-30), 14.3 (C-40). Compound 1i: 66% yield; liq-
uid; 1H NMR (CDCl3) 6.90–6.79 (3H, m, H-6, H-5, and H-2), 6.51
(1H, d, J ¼ 16:1 Hz, H-10), 5.42 (1H, m, H-20), 3.84, 3.81 (each
3H, s, two OCH3), 2.21 (2H, m, H-30), 1.02 (3H, t, J ¼ 7:0 Hz,
H-40); 13C NMR (CDCl3) ꢂ 149.4 (C-4), 148.3 (C-3), 130.2 (C-
10), 128.2 (C-20), 123.8 (C-1), 118.7 (C-5), 108.5 (C-6), 97.9
(C-2), 56.2 (3-OCH3) 55.9 (4-OCH3), 25.7 (C-30), 14.9 (C-40).
General Procedure for Dehydration of Arylalkanols 3a–3k
into (E)-Arylalkenes 1a–1k under Microwave-Irradiation:
Arylalkanols (3a–3k) (0.01 mol), anhydrous silica gel (4.0 g) in
dioxane (6–8 mL) were suspended in a 100 mL Erlenmeyer flask,
and the mixture was irradiated under microwave radiation for 3–
12 min in parts until the disappearance of the starting material
based upon a TLC analysis. Upon cooling, the mixture was wash-
ed with ethyl acetate (3 ꢁ 10 mL) and filtered. The combined or-
ganic layer was washed with water and dried over anhydrous
Na2SO4. The solvent was evaporated, and the obtained liquid
was chromatographed on a silica-gel column using a hexane–ethyl
acetate mixture with increasing proportion of ethyl acetate up to
20% followed by recrystallisation to afford (E)-arylalkenes (1a–
1k). Compound 1a: 68% yield; white solid; mp 44–45 ꢂC (lit.7c
1
Compound 1j: 43% yield; liquid; H NMR (CDCl3) ꢂ 6.96 (3H,
m, H-6, H-2, and H-5), 6.70 (1H, d, J ¼ 16:2 Hz, H-10), 5.93
(1H, s, OH), 5.66 (1H, d, J ¼ 17:6 Hz, H-20a), 5.19 (1H, d, J ¼
10:9 Hz, H-20b), 3.90 (3H, s, 3-OMe); 13C NMR (CDCl3) ꢂ
147.1 (C-4), 146.07 (C-3), 137.1 (C-10), 130.3 (C-1), 120.1 (C-
5), 114.5 (C-6), 111.4 (C-20), 108.2 (C-2), 56.8 (3-OCH3). Com-
pound 1k: 48% yield; liquid; 1H NMR (CDCl3) ꢂ 7.03 (1H, s,
H-6), 6.94 (1H, d, J ¼ 16:5 Hz, H-10), 6.49 (1H, s, H-3), 5.62
(1H, d, J ¼ 17:6 Hz, H-20a), 5.18 (1H, d, J ¼ 10:8 Hz, H-20b),
3.88, 3.86, and 3.81 (each 3H, s, three OCH3); 13C NMR (CDCl3)
ꢂ 151.4 (C-4), 149.7 (C-5), 143.4 (C-2), 130.9 (C-10), 118.6 (C-1),
112.0 (C-20), 109.9 (C-6), 97.8 (C-3), 56.7 (4-OCH3), 56.5 (5-
OCH3), 56.0 (2-OCH3).
ꢂ
1
mp 44–45 C); H NMR (CDCl3) ꢂ 6.91 (1H, s, H-6), 6.64 (1H,
dd, J ¼ 1:5, 16.0 Hz, H-10), 6.45 (1H, s, H-3), 6.02 (1H, dq,
J ¼ 6:2, 16.0 Hz, H-20), 3.84, 3.81, and 3.77 (each 3H, s, three
OCH3), 1.87 (3H, dd, J ¼ 6:2, 1.5 Hz, H-30); 13C NMR (CDCl3)
ꢂ 149.9 (C-2), 148.0 (C-4), 142.6 (C-5), 124.4 (C-10), 123.4 (C-
20), 118.3 (C-1), 109.2 (C-6), 97.3 (C-3), 56.1 (4-OCH3), 55.7
(5-OCH3), 55.1 (2-OCH3), 18.7 (C-30). Compound 1b: 74% yield;
1
liquid; H NMR (CDCl3) ꢂ 6.50 (2H, s, H-2 and H-6), 6.31 (1H,
dq, J ¼ 1:4, 15.7 Hz, H-10), 6.12 (1H, dq, J ¼ 6:3, 15.7 Hz, H-
20), 3.81 (3H, s, 4-OCH3), 3.78 (6H, s, 3-OCH3 and 5-OCH3),
1.82 (3H, d, J ¼ 6:3 Hz, H-30); 13C NMR (CDCl3) ꢂ 153.3 (C-
4), 137.5 (C-3 and C-5), 134.1 (C-10), 131.3 (C-1), 125.6 (C-20),
103.1 (C-2 and C-6), 61.1 (4-OCH3), 56.4 (3-OCH3 and 5-OCH3),
18.6 (C-30). Compound 1c: 71% yield; liquid; 1H NMR (CDCl3) ꢂ
7.10 (1H, d, J ¼ 8:7 Hz, H-5), 6.64 (1H, s, H-6), 6.58 (1H, dq,
J ¼ 1:7, 15.9 Hz, H-10), 6.12 (1H, dq, J ¼ 6:6, 15.9 Hz, H-20),
3.89 (3H, s, 2-OCH3), 3.86 (3H, s, 4-OCH3), 3.84 (3H, s, 3-
Two of us (BPJ and AS) are indebted to CSIR, Delhi for the
award of SRF, respectively. The authors gratefully acknowl-
edge the Director of I.H.B.T., Palampur for his kind coopera-
tion and encouragement.