8
D. Singh et al. / Tetrahedron xxx (2014) 1e9
(22d). Rf (30% EtOAc/hexane) 0.58. Mp 140 ꢀC. IR (KBr) nmax: 1267,
1672, 1734, 3024 cmꢁ1
1H NMR (300 MHz, CDCl3):
120.73, 126.38, 141.20, 145.58, 150.86 (12C, aromatic), 171.28
.
(2C, CO).
d
1.15 (3H, s, 2CH3),1.45 (6H, s, 2CH3),
HRMS (ESI) m/z [MþNa]þ calculated for C22H26O6: 409.1622;
1.88 (6H, s, 2CH3), 2.09 (6H, s, 2CH3), 5.95 (2H, s, olefinic), 6.58 (2H,
s, olefinic).
found 409.1617.
13C NMR (75 MHz CDCl3):
d
15.44 (2C, CH3), 20.55 (2C, CH3),
4.2.21. 6-[1-(2-Acetoxy-4-hydroxy-3,5-dimethyl-phenyl)-ethyl]-3-
24.05 (2C, CH3), 25.77 (2C, CH3), 41.25 (1C, Cq), 78.43 (2C, carbon
attached to OCOCH3), 145.41, 145.65, 138.09, 138.75 (8C, olefinic),
169.19, 198.84 (4C, CO).
hydroxy-2,4-dimethyl-phenyl ester (35a). Rf (30% EtOAc/hexane)
0.65. IR (KBr) nmax: 1190, 1480, 1760, 2860, 3542 cmꢁ1
.
1H NMR (400 MHz, CDCl3):
d
1.45 (3H, d, J¼7.2 Hz, CH3),1.86 (3H,
Anal. Calcd for C23H28O6: C, 68.98; H, 7.05; found: 68.89; H, 7.6.
s, CH3), 2.02 (3H, s, CH3), 2.21 (6H, s, 2CH3), 2.34 (3H, s, CH3), 3.78
(1H, q, J¼7.2 Hz, CH), 4.71 (2H, s, exchangeable OH), 6.78 (3H, s,
aromatic).
4.2.16. 3-[1-(3-Acetoxy-3,5-dimethyl-4-oxo-cyclohexa-1,5-dienyl)-
cyclopentyl]-1,5-di methyl-6-oxo-cyclohexa-2,4-dienylester (22e). Rf
13C NMR (100 MHz CDCl3):
d 9.83 (1C, CH3), 15.26 (2C, CH3),
(30% EtOAc/hexane) 0.54. IR (KBr) nmax: 1240, 1674, 1730, 3010 cmꢁ1
16.07, 20.60, 41.72 (3C, CH3), 37.54 (1C, CH), 116.48, 122.73, 126.68,
127.55, 132.70, 145.43, 140.46, 146.11, 150.45, 151.47 (10C, aromatic),
169.41 (1C, CO).
.
1H NMR (300 MHz, CDCl3):
d 1.38 (6H, s, 2CH3), 1.66 (4H, m,
2CH2), 1.81 (4H, m, 2CH2), 1.90 (6H, s, 2CH3), 2.10 (6H, s, 2CH3), 5.97
(2H, s, olefinic), 6.58 (2H, s, olefinic).
Anal. Calcd for C20H24O4: C, 72.15; H, 7.37; found: 72.02;
H, 7.21.
13C NMR (75 MHz CDCl3):
d 15.50 (2C, CH3), 20.63 (2C, CH3),
22.78, 24.21 (4C, CH2), 34.01 (2C, CH3), 54.21 (1C, Cq), 78.50 (2C,
carbon attached to OCOCH3), 145.68, 136.30, 138.56, 138.66 (8C,
olefinic), 169.45, 198.97 (4C, CO).
4.2.22. 6-[1-(2-Acetoxy-4-hydroxy-3,5-dimethyl-phenyl)-propyl]-3-
hydroxy-2,4-dimethyl-phenyl ester (34b). Rf (30% EtOAc/hexane)
Anal. Calcd for C25H30O6: C, 70.40; H, 7.09; found: 70.20; H, 7.16.
0.44. Mp 190 ꢀC. IR (KBr) nmax: 1226, 1482, 1745, 3445 cmꢁ1
.
1H NMR (400 MHz, CDCl3):
d
1.28 (3H, t, J¼7.2 Hz, CH3), 1.87 (2H,
4.2.17. Typical experimental procedure for photoreaction of bis-
cyclohexadienones (6, 22aee). A solution of bis-acetoxy cyclo-
hexadienone (3.0 mmol) in acetone (600 ml) was irradiated with
a mercury vapour lamp (125 W) in a quartz immersion well. After
completion of the reaction solvent was evaporated under vacuo to
give crude product, which was purified by flash chromatography
over a column of silica gel. Elution of the column with EtOAc/hex-
ane afforded two different products for each substrate (Scheme 8,
Table 3). The structures of the products were then confirmed by
their mp, FTIR, 1H and 13C NMR and HRMS spectral analysis.
m, CH2), 1.99 (6H, s, 2CH3), 2.20 (6H, s, 2 CH3), 2.45 (6H, s, 2CH3),
4.13 (1H, t, J¼7.2 Hz, CH), 4.65 (2H, s, exchangeable OH), 6.82 (2H, s,
aromatic).
13C NMR (100 MHz CDCl3):
d 9.87 (1C, CH3), 13.08 (2C, CH3), 14.17
(2C, CH3), 16.10 (2C, CH3), 20.58 (1C, CH2), 31.62 (1C, CH), 116.48,
120.59,124.69,126.83,146.26,150.79 (12C, aromatic),169.56 (2C, CO).
HRMS (ESI) m/z [MþNa]þ calculated for C23H28O6: 423.1778;
found 423.1776.
4.2.23. 3-Hydroxy-6-[1-(4-hydroxy-3,5-dimethyl-phenyl)-propyl]-
2,4-dimethyl-phenyl ester (35b). Rf (30% EtOAc/hexane) 0.62. IR
4.2.18. 3-Hydroxy-6-(4-hydroxy-3,5-dimethyl-benzyl)-2,4-dimethyl-
(KBr) nmax: 1200, 1750, 2870, 4740 cmꢁ1
.
phenyl ester (32). Rf (30% EtOAc/hexane) 0.44. Mp 172 ꢀC. IR (KBr)
1H NMR (400 MHz, CDCl3):
d
0.89 (3H, t, J¼7.2 Hz, CH3), 1.27 (2H,
nmax: 1432, 1482, 1740, 3410 cmꢁ1
.
m, CH2), 2.00 (3H, s, CH3), 2.22 (9H, superimposed s, 3CH3), 2.45
(3H, s, CH3), 3.54 (1H, t, J¼7.2 Hz, CH), 4.50 (2H, s, exchangeable
OH), 6.81 (1H, s, aromatic), 6.83 (2H, s, aromatic).
1H NMR (400 MHz, CDCl3):
d 2.04 (6H, s, 2CH3), 2.15 (6H, s,
2CH3), 2.28 (6H, s, 2CH3), 3.53 (2H, s, CH2), 4.72 (2H, exchangeable
OH), 6.67 (2H, s, aromatic).
13C NMR (100 MHz CDCl3):
d 9.28 (1C, CH), 12.98 (2C, CH3), 15.10,
13C NMR (100 MHz CDCl3):
d
9.66 (2C, CH3), 15.77 (2C, CH3),
16.11, 20.83 (3C, CH3), 28.92 (1C, CH2), 41.72 (1C, CH), 113.67, 120.64,
122.69, 127.78, 127.83, 128.09, 136.10, 137.42, 147.12, 150.24 (10C,
aromatic), 170.44 (1C, CO).
Anal. Calcd for C21H26O4: C, 73.66; H, 7.65; found: 72.58;
H, 7.61.
20.51 (2C, CH3), 41.81 (1C, CH2), 116.40, 120.79, 123.61, 141.14,
146.20, 151.07 (12C, aromatic), 169.41 (2C, CO).
HRMS (ESI) m/z [MþNa]þ calculated for C21H24O6: 395.1465;
found 395.1462.
4.2.19. 6-(2-Acetoxy-4-hydroxy-3,5-dimethyl-benzyl)-3-hydroxy-
4.2.24. 6-[1-(2-Acetoxy-4-hydroxy-3,5-dimethyl-phenyl)-butyl]-3-
2,4-dimethyl-phenylester (33). Rf (30% EtOAc/hexane) 0.65.
hydroxy-2,4-dimethyl-phenyl ester (34c). Rf (30% EtOAc/hexane)
Mp 167 ꢀC. IR (KBr) nmax: 1440, 1578, 1750, 3426 cmꢁ1
.
0.44. Mp 142 ꢀC. IR (KBr) nmax: 1205, 1483, 1747, 4176, 3440 cmꢁ1
.
1H NMR (400 MHz, CDCl3):
d
2.04 (3H, s, CH3), 2.16 (3H, s, CH3),
1H NMR (400 MHz, CDCl3):
d
0.92 (3H, t, J¼7.2 Hz, CH3), 1.27 (2H,
2.21 (6H, s, 2CH3), 2.28 (3H, s, CH3), 3.63 (2H, s, CH2), 4.84 (2H, s,
exchangeable OH), 6.77 (3H, s, aromatic).
m, CH2), 1.83 (2H, m, CH2), 1.99 (6H, s, 2CH3), 2.19 (6H, s, 2CH3), 2.45
(6H, s, 2CH3), 3.97 (1H, t, J¼7.2 Hz, CH), 4.72 (2H, s, phenolic OH),
6.82 (2H, s, aromatic).
13C NMR (100 MHz CDCl3):
d 9.70 (2C, CH3),15.80,15.96 (2C, CH3),
20.58 (1C, CH3), 47.23 (1C, CH2),116.53,120.84,122.90,125.13,128.91,
141.23, 131.84, 146.17, 150.44, 151.01 (10C, aromatic), 169.28 (1C, CO).
Anal. Calcd for C19H24O4: calculated C, 72.13; H, 7.65; found:
72.02; H, 7.61.
13C NMR (100 MHz CDCl3):
d 9.87 (1C, CH3), 17.45, 18.00, 19.46
(6C, CH3), 41.07, 31.67 (2C, CH2), 36.72 (1C, CH), 116.49, 120.65,
126.90, 145.98, 146.62, 150.79 (12C, aromatic), 169.16 (1C, CO).
HRMS (ESI) m/z [MþNa]þ calculated for C24H30O6: 437.1935;
found 437.1931.
4.2.20. 3-Hydroxy-6-[1-(4-hydroxy-3,5-dimethyl-phenyl)-ethyl]-
2,4-dimethyl-phenyl ester (34a). Rf (30% EtOAc/hexane) 0.44.
4.2.25. 3-Hydroxy-6-[1-(4-hydroxy-3,5-dimethyl-phenyl)-butyl]-
Mp 184 ꢀC. IR (KBr) nmax: 1234, 1482, 1740, 3407 cmꢁ1
.
2,4-dimethyl-phenyl ester (35c). Rf (30% EtOAc/hexane) 0.65. IR
1H NMR (400 MHz, CDCl3):
d
1.44 (3H, d, J¼7.2 Hz, CH3), 2.00
(KBr) nmax: 1204, 1480, 1760, 2880, 3432 cmꢁ1
.
(6H, s, 2CH3), 2.18e2.34 (12H, m, 4CH3), 4.15 (1H, q, J¼7.2 Hz, CH),
1H NMR (400 MHz, CDCl3):
m, CH2), 1.96 (2H, m, CH2), 2.11 (3H, s, CH3), 2.25 (9H, s, CH3), 2.45
(3H, s, CH3), 3.66 (1H, t, J¼7.2 Hz, CH), 4.61 (2H, s, phenolic OH),
6.81 (2H, s, aromatic), 6.83 (1H, s, aromatic).
d
0.90 (3H, t, J¼7.2 Hz, CH3), 1.26 (2H,
4.70 (2H, s, exchangeable OH), 6.80 (2H, s, aromatic).
13C NMR (50 MHz CDCl3):
d
9.74 (1C, CH3), 16.03 (2C,
CH3), 20.55 (2C, CH3), 20.82 (2C, CH3), 31.95 (1C, CH), 116.41,