8
V. MZOZOYANA AND F. R. VANHEERDEN
J ¼ 7.9, 1.3), 9.82 (1H, bs), 10.08 (2H, bs). 13C NMR (100 MHz, DMSO-d6): d 94.8
(2ꢂ), 106.0, 128.6 (2ꢂ), 128.9 (2ꢂ), 132.1, 140.2, 159.8 (2ꢂ), 162.3, 196.9; HRMS
(ESI–): Found [M – H]– 229.0497, Calc. for C13H9O4 229.0501; IR (neat) ꢀmax (cmꢀ1):
3621, 1625, 1598, 1543, 1319.
Phenyl[2,4,6-trihydroxy-3-(3-methyl-2-butenyl)phenyl] methanone (7a)
To a mixture of phenyl(2,4,6-trihydroxyphenyl)methanone (0.276 g, 1.2 mmol) and
DBU (0.183 g, 1.2 mmol) in dry THF (15 ml) was added a prenyl bromide (0.179 g,
1.2 mmol) in small increments. The mixture was stirred at room temperature for
24 h. After addition of 2 M HCl (30 ml), the mixture was stirred for a further 15 min
and extracted with EtOAc (4 ꢂ 20 ml), washed with brine (30 ml) and dried over
anhydrous MgSO4. The removal of the solvent in vavuo resulted in a light orange
product. After purification by the silica gel column chromatography (Hexanes:EtOAc,
4:1), 7a was obtained as a light orange semisolid (0.222 g, 0.744 mmol, 62%); TLC Rf
1
0.54 (Hexanes:EtOAc, 4:1); H NMR (400 MHz, CDCl3): d 1.76 (3H, d, J ¼ 1.1), 1.80
(3H, s), 3.36 (2H, d, J ¼ 7.0), 5.26 (1H, m), 5.93 (2H, s), 6.15 (1H, bs), 7.51 (2H,
dd, J ¼ 8.1, 7.5), 7.58 (1H, tt, J ¼ 7.5, 1.5), 7.64 (2H, dd, J ¼ 8.1,1.5), 10.29 (1H, bs).
13C NMR (100 MHz, CDCl3): d 17.9, 21.7, 25.8, 96.2, 104.6, 106.6, 121.6, 127.8
(2ꢂ), 129.2 (2ꢂ), 132.2, 135.4, 140.0, 159.4, 160.8, 162.6, 197.7; HRMS (ESI–):
Found [M – H]– 297.1130, Calc. for C18H17O4 297.1127; IR (neat) ꢀmax (cmꢀ1):
3523, 3023, 2953, 1652, 1594, 1577, 1420, 1111.
Phenyl[2,4,6-trihydroxy-3-(3-methyl-2-butenyl)phenyl]methanone (9a)
To a mixture of phenyl(2,4,6-trihydroxyphenyl)methanone (0.276 g, 1.2 mmol) and DBU
(0.366 g, 2.4 mmol) in dry THF (15 ml) was added a prenyl bromide (0.358 g, 2.4 mmol)
in small increments. The temperature of the reaction mixture was increased to 45 ꢁC
and stirred for 24 h. After the temperature of the mixture was reduced to room tem-
perature, a 2 M HCl (20 mL) was added to the mixture, it was stirred for a further
15 min and extracted with EtOAc (4 ꢂ 20 mL), washed with brine (20 mL) and dried
over anhydrous MgSO4. The removal of the solvent in vacuo resulted in a light orange
product. After purification by silica gel column chromatography (Hexanes:EtOAc, 4:1),
9a was obtained as a light orange semisolid (48%); TLC Rf 0.85 (Hexanes:EtOAc, 4:1);
1H NMR (400 MHz, CDCl3): d 1.74 (6H, d, J ¼ 1.1), 1.79 (6H, s), 3.34 (4H, d, J ¼ 7.1),
5.22 (2H, m), 6.35 (1H, bs), 7.50 (2H, dd, J ¼ 8.0, 7.7), 7.57 (1H, tt, J ¼ 7.7, 1.5), 7.64
(2H, dd, J ¼ 8.0, 1.5), 8.91 (2H, bs). 13C NMR (100 MHz, CDCl3): d 17.6 (2ꢂ), 21.8
(2ꢂ), 26.0 (2ꢂ), 104.6, 106.3 (2ꢂ), 121.9 (2ꢂ),127.8 (2ꢂ), 129.2 (2ꢂ), 132.2, 135.4
(2ꢂ), 140.0, 157.5 (2ꢂ), 161.0, 198.0; HRMS (ESIþ): Found [M þ Na]þ 389.1723, Calc.
for C23H26NaO4 389.1729; IR (neat) ꢀmax (cmꢀ1): 3512, 3023, 2942, 1632, 1586, 1566,
1443, 1121.
Full experimental detail, characterization data for all compounds and 1H and 13C
this article’s webpage.