1586
P. S. Maley, R. M. Anderson, and D. E. Lewis
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pellets using a Nicolet 5DXC FT-IR spectrometer. H NMR spectra were
recorded as CDCl3 solutions using a JEOL Eclipse NMR spectrometer
operating at 400 MHz; peak positions are reported as d (ppm) downfield
from internal Me4Si. 13C NMR spectra were recorded as CDCl3 solutions at
100 MHz; peak positions are reported in ppm relative to the center peak of
CDCl3 (77.1 ppm). Vanillin was used as obtained from Fisher Chemical
Company; all other reagents and solvents were used as obtained from
Aldrich Chemical Company. Microanalyses were performed by Robertson–
Microlit Laboratories, Rahway, NJ.
General Procedure
To a stirred solution of the a,v-dibromide (1.0 eq.) and vanillin (ꢀ2.05 eq.)
in acetone (ꢁ20 mL per mmol dihalide) was added potassium carbonate
(ꢀ2.1 eq.). The reaction mixture was heated under reflux for 18–24 h, after
which time the solids were collected by vacuum filtration. The solids were
boiled with approximately 2–3 times their volume of toluene, and the
mixture was filtered hot. The 4,40-(a,v-alkylenedioxy)-bis(3-methoxybenzal-
dehyde) was obtained as colorless crystals upon cooling the filtrate.
4,40-(1,4-butylenedioxy)-bis(3-methoxybenzaldehyde) was prepared by
procedure A from vanillin (15.7 g, 0.102 mol), 1,4-dibromobutane (9.01 g,
0.042 mol), and potassium carbonate (14.2 g, 0.103 mol) in acetone
(ꢁ100 mL). The product (7.10 g, 47%) was obtained as white crystalline
plates, mp 160–1638C. nmax (cm21): 2956 (w), 2936 (w), 2839 (w), 2831
(w), 2763 (w), 2736 (w), 1693 (m), 1674 (s), 1596 (m), 1584 (s), 1508 (s),
1
1276 (s), 1261 (s), 1133 (s), 1001 (m), 812 (m), 731 (m). H NMR (d ppm):
9.85 (2H, s, CH55O), 7.43 (2H, d J ¼ 1.8 Hz of d J ¼ 8.1 Hz, C50 –H), 7.41
(2H, d J ¼ 1.8 Hz, C20 –H), 6.99 (2H, d J ¼ 8.1 Hz, C60 –H), 4.22 (4H, br.
t, O–CH2), 3.90 (6H, s, OCH3), 2.12 (4H, br. t, O–CH2CH2). 13C NMR (d
ppm): 191.0 (C55O), 154.0, 149.9, 130.0, 126.8, 111.4, 109.3, 68.7, 56.0,
25.8. Found C, 66.78; H 6.15%. C20H22O6 requires C, 67.03; H, 6.19%.
4,40-(1,6-hexylenedioxy)-bis(3-methoxybenzaldehyde) was prepared by
procedure A from vanillin (15.4 g, 0.101 mol), 1,6-dibromohexane (11.7 g,
0.048 mol), and potassium carbonate (14.4 g, 0.103 mol) in acetone
(ꢁ100 mL). The product (10.4 g, 57%) was obtained as white crystalline
plates, mp 162.5–1648C. nmax (cm21): 2951 (w), 2934 (w), 2874 (w), 2829
(w), 2760 (w), 2731 (w), 1696 (m), 1681 (s), 1593 (s), 1585 (s), 1507
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(s), 1277 (s), 1262 (s), 1134 (s), 1011 (s), 733 (m). H NMR (d ppm): 9.85
(2H, s, CH55O), 7.43 (2H, dd J ¼ 1.8, 8.1 Hz, C50 –H), 7.41 (2H,
d J ¼ 1.8 Hz, C20 –H), 6.96 (2H, d J ¼ 8.1 Hz, C60 –H), 4.12 (4H, t
J ¼ 6.6 Hz, O–CH2), 3.92 (6H, s, OCH3), 1.93 (4H, br. pentet J ¼ 6.9 Hz,
O–CH2CH2), 1.59 (4H, br. m, O–CH2CH2CH2). 13C NMR (d ppm): 191.0,
154.2, 149.9, 130.0, 126.8, 111.4, 109.4, 69.0, 56.1, 28.9, 25.8. Found
C, 68.31; H, 6.94%. C22H26O6 requires C, 68.38; H, 6.78%.