ORDER
REPRINTS
O-BENZYLATION OF POLYPHENOLICS
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4A (88%) and 4B (12%). On extraction of the combined aqueous washings
with 100 mlEtOAc further material(1.4 g) with simialr composition was
secured.
Boiling the combined raw materials (15.3 g) with heptane/EtOAc
(95/5) left a dark insoluble material (0.4 g) and gave a light tan solution.
Evaporating the solvent and removing the mineral oil (ca. 1 g) left a crystal-
line residue (12.2 g, 77% yield). Recrystallization once from hexane/toluene
(95/5) using active carbon furnished almost colourless 4A (10.8 g, 69% yield,
mp 79–80ꢀC). Alternatively, 4A and 4B could be separated by column chro-
matography (SiO2, EtOAc/heptane 1/6).
1,2,4-Tribenzyloxybenzene (4A). Mp 81–82ꢀC (lit 181–82ꢀC, 1480–
81ꢀC, 282ꢀC). TLC (SiO2, EtOAc/heptane 3:7) Rf ¼ 0.50. EIMS m/z (relative
%): 396 [Mþ](24), 305 [Mþ-benzyl](14), 181 (11), 91 [benzylþ](100). 1H
NMR (CDCl3, 400 MHz, d): 4.96, 5.09, and 5.12 (CH2, s), 6.46 (H5, dd,
J ¼ 8.7, 2.9 Hz), 6.66 (H3, d, J ¼ 2.9 Hz), 6.86 (H6, d, J¼ 8.7 Hz), 7.2–7.5 (15
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Ar-H, m), H NMR(DMSO-d6, 400 MHz, d): 5.01, 5.03, and 5.13 (CH2, s),
6.51 (H5, dd, J ¼ 8.7, 2.7 Hz), 6.79 (H3, d, J ¼ 2.8 Hz), 6.94 (H6, d,
J ¼ 8.8 Hz), 7.3–7.5 (15 Ar-H, m). 13C NMR (CDCl3, 100 MHz, d): 70.4,
71.0, and 72.5 (CH2), 103.7 (C3), 105.6 (C5), 116.9 (C6), 127.2–128.4
(16C), 136.9, 137.5, 143.1, 150.1, 154.0. IR (KBr, cmꢁ1): 1609 m, 1594 m,
and 1514 vs (aryl), 1227 vs (aryl-O), 1007 s (O-CH2). Anal. Calc. for
C27H24O3: C 81.79; H 6.10. Found: C 81.60; H 6.03.
2,4-Dibenzyloxy-5-benzylphenol (4B). Mp 107–108ꢀC. TLC (SiO2,
EtOAc/heptane 3:7) Rf ¼ 0.44. EIMS m/z (relative %): 396 [Mþ](9), 305
[Mþ-benzyl](4), 181 (8), 91 [benzylþ](100). 1H NMR (CDCl3, 400 MHz,
d): 4.71 and 5.04 (O-CH2, s), 4.93 (C-CH2, s), 6.57 (H3, s), 6.86 (H6, s),
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7.10–7.42 (15 Ar-H, m), 7.4 (OH). H NMR (DMSO-d6, 400 MHz, d): 5.16
(O-CH2, s), 4.95 and 4.93 (CH2, s), 6.92 and 6.94 (H3 and H6, s), 7.20–7.47
(15 Ar-H and OH, m) 13C NMR (CDCl3, 100 MHz, d): 71.6, 71.7, and 72.2
(CH2), 103.8 (C3), 119.5 (C6), 120.8, 127.0–128.4 (15C), 137.2, 137.4, 137.5,
143.0, 148.6, 150.8. IR (KBr, cmꢁ1): 1601 m and 1507 s (aryl), 1215 vs (aryl-
O), 1024 s (O-CH2). Anal. Calc. for C27H24O3: C 81.79; H 6.10. Found C
82.23; H 6.12. H3 and H6 in CDCl3 were assigned by comparison with 3B
and 4A. The regiochemistry could now be inferred from cross peaks in the
ROESY spectrum (CDCl3, mixing time 200 ms) between H3 and the O-
benzylic methylene protons (assigned to positions 2 and 4) in combination
with a cross peak between H6 and the C-benzylic methylene protons known
to be located at position 5.
2,5-Dibenzyloxyphenol (3A). TLC (SiO2, EtOAc/heptane 3:7) Rf ¼ 0.38.
1H NMR (DMSO-d6, 400 MHz, d): 4.96 and 5.00 (CH2, s), 6.34 (H4, dd,
J ¼ 8.7, 3.0 Hz), 6.50 (H6, d, J ¼ 3.0 Hz), 6.85 (H3, d, J ¼ 8.9 Hz), 7.25–7.50
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(Ar-H, m), 9.12 (OH, s). H NMR (CDCl3, 400 MHz, d): 3–5 (OH, very