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Can. J. Chem. Vol. 86, 2008
1.27 g (0.008 mol) of 3-methoxy-4-hydroxybenzaldehyde.
On work-up, the resulting yellow oil was twice eluted
through a silica gel column (CH2Cl2), which afforded 10 as
m-Benzylphenol (24)
A THF solution of 2.0 g of 5 was shaken under H2 (2 atm,
1 atm = 101.325 kPa) for 30 h. The product mixture was
eluted by CH2Cl2 in a silica column, which gave the initial
crude product. Colorless 24 was obtained by distillation un-
der reduced pressure. 1H NMR (300 MHz, acetone-d6) δ: 3.9
(d, 2H), 6.6–6.8 (m, 3H), 7.0–7.4 (m, 6H), 8.2 (s, 1H, D2O
exchangeable). MS (CI) m/z: 185 (M+ + 1).
1
a pure clear oil. H NMR (300 MHz, acetone-d6) δ: 3.4 (s,
3H), 4.6 (d, 1H, D2O exchangeable), 5.7 (d, 1H), 5.9 (d, 1H,
D2O exchangeable), 7.0–7.5 (m, 8H). MS (CI) m/z: 213 (M+
– 17), 231 (M+).
3,5-Dibutyl-4-hydroxybenzhydrol (11)
Following the general procedure for PhMgBr, 1 g of Mg
(0.042 mol) and 6.54 g (0.042 mol) of PhBr were used to
produce PhMgBr, which was subsequently reacted with
3.36 g (0.014 mol) of 3,5-di-t-butyl-4-hydroxybenzaldehyde.
The crude product was obtained as an orange solid which
was recrystallized in ligroin to give white crystals, mp 123
General photolysis procedure
All preparative photolysis were carried out in a Rayonet
RPR 100 photochemical reactor equipped with 254 lamps,
using quartz tubes (100–200 mL), which were cooled with
an internal cold finger (tap water, <15 °C). Solutions were
continuously purged with a stream of argon via a stainless
steel syringe needle for 10 min before and during the irradi-
ation to effect stirring and deoxygenation. The length of
photolysis varied from 3–60 min depending on the conver-
sion desired. After photolysis, work-up involved adding a
saturated aqueous solution of NaCl and extracting with 5 ×
75 mL portions of CH2Cl2. The organic extracts were then
combined and dried over MgSO4. Filtration of the MgSO4
and evaporation of CH2Cl2 under reduced pressure provided
crude photochemical products, which were then separated by
preparative TLC, if necessary, and characterized by 1H NMR
and mass spectroscopy. Control experiments were repeated
in the absence of light at RT (-22 °C). Possible thermal re-
actions in photomethanolysis were eliminated by the addi-
tion of a pinch of NaHCO3.
1
to 124 °C. H NMR (300 MHz, acetone-d6) δ: 1.4 (s, 18H),
4.6 (d, 1H, D2O exchangeable), 5.7 (d, 1H), 5.9 (d, 1H, D2O
exchangeable), 7.0–7.5 (m, 7H). MS (CI) m/z: 295 (M+ – 17,
base peak), 313 (M+ + 1).
p-Methoxybenzhydrol (17)
p-Methoxybenzophenone (2 g, 0.01 mol) was reduced us-
ing NaBH4 (4.29 g, 0.13 mol) according to the general pro-
cedure. The crude product was recrystallized from petroleum
1
ether to give a white crystalline solid, mp 59–62 °C. H
NMR (300 MHz, acetone-d6) δ: 3.7 (s, 1H), 4.7 (d, 1H, D2O
exchangeable), 5.8(d, 1H), 6.7–7.5 (m, 9H), 8.2 (s, 1H, D2O
exchangeable). MS (CI) m/z: 197 (M+ – 17, base peak), 215
(M+ + 1). (EI) 214 (M+).
␣,␣-Diphenyl-o-hydroxybenzyl alcohol (8)
Photolysis o-hydroxybenzhydrol (4)
Following the general procedure for PhMgBr, Mg (4.2 g,
0.17 mol) and PhBr (27 g, 0.17 mol) were used to make the
PhMgBr, which then reacted with o-hydroxybenzoic acid
methyl ester (4.5 g, 0.03 mol). The crude product was
recrystallized from toluene to afford a white crystalline
A solution of 40 mg 4 in 100 mL 1:1 H2O/MeOH
(NaHCO3 treated) was photolyzed at 254 nm. 1H NMR anal-
ysis showed that ether 12 was the only product in low con-
version runs and o-benzylphenol 18 was formed only in high
conversion runs. Preparative TLC separation afforded pure
1
1
solid, mp 148–150 °C. H NMR (360 MHz, acetone-d6) δ:
12. H NMR (300 MHz, acetone-d6) δ: 3.3 (s, 3H), 5.7 (s,
6.4 (s/b, 1H, D2O exchangeable), 6.4–7.5 (m, 14H), 9.1 (s/b,
1H, D2O exchangeable); (300 MHz, CDCl3) δ: 3.7 (s, 1H,
D2O exchangeable), 6.4–7.4 (m, 14H), 8.1 (s, 1H, D2O ex-
changeable). MS (CI) m/z: 259 (M+ – 17, base peak).
1H), 6.7–7.4 (m, 9H), 8.5 (s, 1H, D2O exchangeable). MS
(CI) m/z: 183 (M+ – 31, base peak). The identity of 18 was
confirmed by comparison with an authentic sample.
Photolysis p-hydroxybenzhydrol (6)
A solution of 40 mg of 6 in 100 mL 1:1 H2O/MeOH
(NaHCO3 treated) was photolyzed at 254 nm for 3 min.
Methyl ether 14 was the only product purified by preparative
␣,␣-Diphenyl-m-hydroxybenzy alcohol (9)
The methyl ester of m-hydroxybenzoic acid was prepared
by refluxing 20 g of m-hydroxybenzoic acid in 400 mL of
MeOH with 1 mL of concd. H2SO4 for 10 h. After cooling
to RT, 2–4 g of NaHCO3 was added with stirring and most
of the MeOH evaporated. To this was added 200 mL of
CH2Cl2 and the solution backwashed with water and satu-
rated aq. NaHCO3. Crude m-hydroxybenzoic methyl ester
was obtained after removal of the solvent and used without
further purification.
1
TLC. H NMR (300 MHz, acetone-d6) δ: 2.9 (s, 3H), 5.2 (s,
1H), 6.6–7.4 (m, 9H), 8.3 (b, 1H, D2O exchangeable). MS
(CI) m/z: 121 (M+ – 93, base peak), 183 (M+ – 31), 215
(M+ + 1).
Photolysis of 3-phenylisocoumaranone (7)
A solution of 40 mg of 7 in 100 mL 1:1 H2O/MeOH was
1
Using the Grignard reaction procedure, 2 g of m-
hydroxybenzoic methyl ester (0.013 mol) was reacted with
PhMgBr produced from 2 g of Mg (0.083 mol) and 13 g of
PhBr (0.084 mol) to generate a yellow gel as the crude prod-
uct. The product was recrystallized from CH3CN to give
photolyzed at 254 nm for 3 min. The H NMR of the prod-
uct mixture showed that -3% of 12 was formed, as indicated
by the characteristic methoxy singlet at δ 3.3 (s, 3H) and
methine singlet at δ 5.7 (s, 1H).
1
Photolysis of ␣,␣-diphenyl-o-hydroxybenzyl alcohol (8)
A solution of 55 mg of 8 in 100 mL 1:1 H2O/MeOH
(NaHCO3 treated) was photolyzed at 254 nm for 3 min. The
product was its corresponding methyl ether (28%), purified
white crystals, mp 151 to 152 °C. H NMR (300 MHz, ace-
tone-d6) δ: 5.2 (s, 1H, D2O exchangeable), 6.6–7.4 (m,
14H), 8.2 (s, 1H, D2O exchangeable). MS (CI) m/z: 199 (M+
– 77, base peak), 277 (M+ + 1).
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