4172
S. V. Kini, M. M. V. Ramana / Tetrahedron Letters 45 (2004) 4171–4173
Table 1
Compound
R1
R2
R3
R2R3
Mpa (ꢁC)
Yieldb (%)
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
4a
4b
4c
4d
4e
H
H
H
222
217
122
120
129
112
94
93
94
92
93
97
90
92
89
95
88
33
36
34
36
31
H
OCH3
OCH3
OCH3
H
H
H
–OCH2O–
OCH3
H
OCH3
H
OCH3
H
H
OCH3
OCH3
OCH3
H
H
85
H
–OCH2O–
–OCH2O–
118
134
199
118
78
OCH3
H
OCH3
H
OCH3
H
H
OCH3
OCH3
OCH3
H
H
H
OCH3
126
156
OCH3
OCH3
a Melting points are uncorrected.
b Yields refer to purified product.
yl}ethyl-N,N-dimethylamine 3a, as a white crystalline
solid (90%), mp 111–112 ꢁC.
References and notes
IR (KBr): [m 1620, Ar (C@C)]; 1H NMR (CDCl3,
60 MHz): d ¼ 2:3 [s, 6H, N–(CH3)2], 2.45–3.55 (m, 4H,
–CH2–CH2), 3.95 (s, 6H, –OCH3), 7.6–6.5 [m, 9H, (ArH
and CH@CH)]; UV (methanol) kmax nm (log e): 207 (4.16),
294 (4.15), 322 (4.16); GC–MS m=z: 311 (Mþ) (54), 296
(22), 80 (17), 267 (15), 222 (35),178 (12), 152 (29), 91 (33),
58 (100); Analysis C20H25NO2 requires: C, 77.14; H, 8.09;
N, 4.50. Found: C, 77.21; H, 8.19; N, 4.46.
1. Castedo, L.; Tojo, G. In The Alkaloids; Brossi, A., Ed.;
Academic: New York, 1990; Vol. 39, pp 99–138.
2. Wu, W. N.; Beal, J. L.; Doskotch, R. W. J. Nat. Prod.
1980, 43, 143–148.
3. Gupta, R. S.; Skrepinsky, J. L.; Shiminovitch, L. J. Mol.
Pharmacol. 1980, 18, 136–138.
4. Bhattacharya, S. K.; Bose, R.; Ghosh, P.; Tripati, V. J.;
Ray, A. B.; Dasgupta, B. PsychoPharmacol. (Berlin)
1978, 59, 29–41.
5. Blaschke, G. Arch. Pharm. 1968, 301, 432–435.
6. Mndzhoyan, A. L.; Mnatsakanyan, V. A.; Arutyunyan, L.
S. Arm. Khim. Zh. 1969, 22, 842–847;
Compounds 3b–e were synthesized in a similar manner.
(E)-N-2{2-[2-(4,5-Dimethoxyphenyl)ethenyl]-4,5-dimeth-
oxyphenyl}ethyl-N,N-dimethylamine 3b, white crystals
(92%), mp 94 ꢁC, (lit.,6 mp 94 ꢁC).
(E)-N-2{2-[2-(4-Methoxyphenyl)ethenyl]-4,5-dimethoxy-
phenyl}ethyl-N,N-dimethylamine 3c, white crystals (89%),
mp 85 ꢁC, (lit.,6 mp 85 ꢁC).
Chem. Abstr. 1970, 72, 21808w.
7. Estevez, J. C.; Vellavarde, M. C.; Estevez, R. J.; Seuas, J.
A.; Castedo, L. Can. J. Chem. 1990, 68, 964–968.
8. Robinson, R. A. J. Org. Chem. 1951, 16, 1911–1920.
9. Tsatsas, G. Ann. Pharma Frang. 1952, 10, 61–71;
Chem. Abstr. 1952, 46, 11209b.
10. Kundo, H.; Kundo, T. J. Pharm. Soc. Jpn. 1928, 48, 324–
337; Chem. Abstr. 1928, 22, 3414.
11. Dyke, S. F.; Sainsbury, M. Tetrahedron 1965, 21, 1907–
1915.
12. Becker, D.; Hughes, L. R.; Raphael, R. A. J. Chem. Soc.,
Perkin Trans. 1 1977, 1674–1681.
13. Albonico, S. M.; Kuck, A. M.; Dealofeu, V. Ann. Chem.
1965, 685, 200–206; Chem. Abstr. 1965, 63, 11634f.
14. Kitasato, Z. Acta Phytochim. 1927, 3, 175–258;
Chem. Abstr. 1928, 22, 1779.
(E)-N-2{2-[2-(4,5-Methylenedioxyphenyl)ethenyl]-4,5-di-
methoxyphenyl}ethyl-N,N-dimethylamine 3d, white crys-
tals (95%), mp 118–120 ꢁC.
IR (KBr): [m 1620, Ar (C@C)]; 1H NMR (CDCl3,
60 MHz): d ¼ 2:4 [s, 6H, N–(CH3)2], 2.6–3.8 (m, 4H,
–CH2–CH2), 4.0 (s, 6H, –OCH3), 5.7 (s, 2H, –O–CH2–O),
6.25–7.35 [m, 7H, (Ar and CH@CH)]; UV (methanol) kmax
nm (log e): 223 (3.96), 295 (3.73), 35 (3.88); Analysis
C21H25NO4 requires: C, 70.96; H, 7.09; N, 3.94. Found: C,
70.92; H, 7.13; N, 3.99.
(E)-N-2{2-[2-(3,4,5-Trimethoxyphenyl)ethenyl]-4,5-dimeth-
oxyphenyl}ethyl-N,N-dimethylamine 3e, white crystals
(88%), mp 132–134 ꢁC.
IR (KBr): [m 1610, Ar (C@C)]; 1H NMR (CDCl3,
60 MHz): d ¼ 2:45 [s, 6H, N–(CH3)2], 2.6–3.7 (m, 4H,
–CH2–CH2), 4.0 (s, 9H, –OCH3), 3.8 (s, 6H, –OCH3), 6.4–
6.8 [s, 6H, (ArH and CH@CH)]; UV (methanol) kmax nm
(log e): 221 (4.04), 328 (4.08); GC–MS m=z: 401 (Mþ) (23),
385 (24), 356 (20), 342 (26), 221 (28), 180 (33), 163 (23), 87
(25), 74 (21), 58 (100); Analysis C23H31NO5 requires: C,
68.80; H, 7.78; N, 3.49. Found: C, 68.86; H, 7.76; N, 3.42.
17. General procedure for the photochemical electrocycliza-
tion of stilbene derivatives 3a–e.
15. El-Sayed, H. A.; Swaringen, R. A.; David, A.; Yeowell;
Crouch, R. C.; Hurlbort, S. J. Chem. Soc., Perkin Trans. 1
1982, 2067–2077.
16. General procedure for the Hofmann degradation
of 1-arylmethyl-1,2,3,4-tetrahydro-6,7-dimethoxy-2,2-di-
methylisoquinolinium iodides 2a–e.
A stirred solution of 2a (2.2 g, 0.005 mol) and 20%
methanolic KOH (25 mL) was refluxed for 4 h. After
removal of the solvent under reduced pressure, the residue
was decomposed with chilled water (50 mL) and extracted
with chloroform (3 · 25 mL). The combined chloroform
extract was washed with water (2 · 50 mL) and dried over
anhydrous sodium sulfate. After removal of the solvent,
the residue obtained was purified by column chromatog-
raphy [neutral alumina, petroleum ether–CHCl3, 95:5] to
afford (E)-N-2{2-[2-(phenyl)ethenyl]-4,5-dimethoxyphen-
A stirred solution of 3a (200 mg, 0.00064 mol), cyclohex-
ane (300 mL) and iodine (10 mg) was irradiated using a
high pressure mercury lamp [USHIO-UM-452 (450 W)] at
20 ꢁC for 5 h. The reaction mass was washed with 1%
aqueous sodium thiosulfate solution (100 mL) followed by
water (100 mL). The cyclohexane solution was dried over