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M. S. Azevedo et al.
PAPER
Benzo[b]furan-2-yl(2¢-bromophenyl) Carbinol (9a); General
Procedure
Benzo[b]furan-2-yl(2-bromophenyl)methyl Diethylcarbamate
(4a); General Procedure
To a solution of 2-(2-bromo)-benzoylbenzofuran (8a) (1.99 mmol)
in MeOH (8 mL) was added a solution of NaBH4 (0.77 mmol) in
10% aq NaOH (0.5 mL) and water (1.3 mL). The resulting mixture
was stirred vigorously at r.t. for 15 min and under agitation over a 5
min period. The mixture was extracted with CH2Cl2 (3 × 70 mL) and
washed with brine (3 × 60 mL). The organic phase was dried
(Na2SO4), filtered and evaporated. The material was filtered using
silica gel (EtOAc–hexanes, 10:90). The substance 9a was obtained
as a yellow oil; yield: 0.589 g (98%).
To a suspension of 60% NaH (6.22 mmol) in THF (10 mL) was add-
ed a solution of alcohol 9a (6.22 mmol) in THF (20 mL). The reac-
tion mixture was stirred at 0 °C (ice-water bath) and allowed to
warm to r.t. (2 h) under argon. After this period, diethylcarbamoyl
chloride (6.22 mmol) was added and the reaction was stirred for an
additional 1 h. The reaction was then treated with 10% KOH (10
mL) and extracted with CH2Cl2 (3 × 20 mL). The organic layer was
washed with 5% HCl (5 mL) and water (20 mL). The organic phase
was dried (Na2SO4) and evaporated to afford 4a as a yellow solid;25
yield: 0.843 g (96%); mp 78–79 °C (hexanes).
IR (KBr): 3341 (OH) cm–1.
IR (KBr): 1699 (C=O) cm–1.
1H NMR (200 MHz, CDCl3): d = 7.70 (dd, J = 1.6, 7.9 Hz, 1 H),
7.59 (dd, J = 1.6, 7.9 Hz, 1 H), 7.58 (dd, J = 1.0, 8.9 Hz, 1 H), 7.47
(dd, J = 1.6, 8.9 Hz, 1 H), 7.29 (dd, J = 1.0, 1.6 Hz, 1 H), 7.18 (s, 1
H), 7.20 (m, 3 H), 6.33 (d, J = 3.6 Hz, 1 H), 6.31 (s, 1 H, CHOH).
13C NMR (50 MHz, CDCl3): d = 157.1, 156.8, 141.3, 133.1, 130.2,
129.0, 128.7, 127.6, 126.7, 123.8, 123.6, 120.4, 118.9 (CBr), 103.9,
72.6 (COH).
1H NMR (300 MHz, CDCl3): d = 7.65 (dd, J = 1.6, 7.7 Hz, 1 H),
7.57 (dd, J = 1.0, 7.9 Hz, 1 H), 7.54–7.35 (m, 3 H), 7.28 (s, 1 H),
7.27–7.15 (m, 3 H), 6.54 (s, 1 H, CHOR), 3.34 (m, 4 H, NCH2R),
1.12 (m, 6 H, NRCH3).
13C NMR (75 MHz, CDCl3): d = 155.42, 154.52, 137.49, 133.15,
129.87, 128.73, 128.02, 127.74, 126.72, 124.66, 123.05, 122.94,
121.42, 111.59, 106.39, 71.01 (CHOR), 42.29 (NCH2R), 41.63
(NCH2R), 14.36 (NRCH3), 13.58 (NRCH3).
MS (EI): m/z (%) = 303 (46) [M+], 285 (32), 205 (92), 147(100).
Anal. Calcd for C15H11BrO2: C; 59.43; H, 3.66; Br, 26.36; O, 10.56.
Found: C, 59.45; H, 3.70.
MS (EI): m/z (%) = 401 (10) [M+], 285 (100), 205 (92).
Anal. Calcd for C20H20BrNO3: C, 59.71; H, 5.01; Br, 19.86; N, 3.48;
O, 11.93. Found: C, 59.30; H, 5.10; N, 3.33.
Benzo[b]furan-2-yl(3,4-dimethoxyphenyl) Carbinol (9b)
The procedure described above was adapted using the following
quantities of reagents: 2-(3,4-dimethoxy)-benzoylbenzofuran (8b,
1.99 mmol), MeOH (8 mL), NaBH4 (0.77 mmol), 10% NaOH (0.5
mL) and H2O (1.3 mL). Compound 9b was obtained as a viscous
oil; yield: 0.453 g (85%).
Benzo[b]furan-2-yl(3,4-dimethoxyphenyl)methyl Diethylcar-
bamate (4b)
The procedure described above was adapted using the following
quantities of reagents: alcohol 9b (6.22 mmol), NaH 60% (6.22
mmol), THF (20 mL), and N,N-diethylcarbamoyl chloride (6.22
mmol). Compound 4b was obtained as a viscous yellow oil; yield:
1.91 g (83%).
IR (KBr): 3363 (OH) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.52 (m, 2 H), 7.44 (m, 1 H), 7.28
(dd, J = 1.7, 7.2 Hz, 1 H), 7.22 (dd, J = 1.5, 7.3 Hz, 1 H), 6.99 (ddd,
J = 0.4, 1.5, 8.1 Hz, 1 H), 6.88 (s, 1 H), 6.94 (s, 1 H), 6.53 (t, J = 0.9
Hz, 1 H), 5.90 (s, 1 H, OCHOH), 3.90 (s, 6 H, OCH3).
13C NMR (50 MHz, CDCl3): d = 158.60, 154.95, 149.03, 132.83,
127.91, 127.90, 124.12, 122.69, 120.98, 119.16, 117.41, 111.16,
110.90, 109.84, 103.70, 70.36 (CHOH), 55.80.
IR (KBr): 1702 (C=O) cm–1.
1H NMR (200 MHz, CDCl3): d = 7.53 (dd, J = 2.0, 6.8 Hz, 1 H),
7.45 (d, J = 8.0 Hz, 1 H), 7.28 (ddd, J = 1.0, 1.2, 7.5 Hz, 1 H), 7.17
(ddd, J = 1.5, 1.7, 6.8 Hz, 1 H), 7.07 (dd, J = 1.9, 7.8 Hz, 1 H), 7.03
(s, 1 H), 6.90 (d, J = 1.9 Hz, 1 H), 6.86 (d, J = 8.3 Hz, 1 H), 6.56 (s,
1 H, CHOR), 3.93 (s, 3 H, OCH3), 3.91 (s, 3 H, OCH3), 3.31 (m,
4 H, NCH2R), 1.12 (m, 6 H, NRCH3).
13C NMR (50 MHz, CDCl3): d = 156.29, 155.33, 154.86, 149.24,
149.07, 149.07, 130.53, 128.04, 124.47, 122.90, 121.25, 120.48,
120.08, 111.54, 111.05, 105.41, 71.71 (CHOR), 56.03, 42.24
(NCH2R), 41.62 (NCH2R), 14.36 (NRCH3), 13.63 (NRCH3).
MS (EI): m/z (%) = 284 (96) [M+], 267 (93), 253 (18), 165(100), 145
(49).
Anal. Calcd for C17H16O4: C, 71.82; H, 5.67; O, 22.51. Found: C,
71.84; H, 5.66.
Benzo[b]furan-2-yl(3,4-methylenedioxyphenyl) Carbinol (9c)
The procedure described above was adapted using the following
quantities of reagents: 2-(3,4-methylenedioxy)-benzoylbenzofuran
(8c) (1.99 mmol), MeOH (8 mL), NaBH4 (0.77 mmol), NaOH 10%
(0.5 mL), and H2O (1.3 mL). Compound 9c was obtained as a yel-
low oil; yield: 0.542 g (96%).
MS (EI): m/z (%) = 383 (10) [M+], 267 (100).
Anal. Calcd for C22H25NO5: C, 68.91; H, 6.57; N, 3.65; O, 20.86.
Found: C, 69.37; H, 6.32; N, 3.34.
Benzo[b]furan-2-yl(3,4-methylenedioxyphenyl)methyl Diethyl-
carbamate (4c)
IR (KBr): 3384 (OH) cm–1.
The procedure described above was adapted using the following
quantities of reagents: alcohol 9c (6.22 mmol), NaH 60% (6.22
mmol), THF (20 mL), and diethylcarbamoyl chloride (6.22 mmol).
The compound 4c was obtained as a viscous yellow oil; yield: 2.00
g (88%).
1H NMR (300 MHz, CDCl3): d = 7.48 (dd, J = 1.7, 7.2 Hz, 2 H),
7.43 (d, J = 8.3 Hz, 1 H), 7.23 (ddd, J = 1.2, 1.5, 7.5 Hz, 1 H), 7.22
(ddd, J = 1.2, 1.5, 7.3 Hz, 1 H), 6.96 (dd, J = 1.6, 6.2 Hz, 1 H), 6.89
(dd, J = 1.7, 7.9 Hz, 1 H), 6.79 (d, J = 7.9 Hz, 1 H), 6.53 (s, 1 H),
5.93 (s, 2 H, OCH2O), 5.81 (s, 1 H, CHOH).
13C NMR (50 MHz, CDCl3): d = 158.63, 155.19, 148.01, 147.77,
134.45, 128.14, 124.44, 122.99, 121.28, 120.66, 111.47, 108.37,
107.57, 103.96, 101.36 (OCH2O), 70.63 (CHOH).
IR (KBr): 1702 (C=O) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.52 (m, 1 H), 7.44 (m, 1 H), 7.26
(m, 1 H), 7.24 (m, 1 H), 6.98 (d, J = 0.46 Hz, 1 H), 6.95 (dd, J = 0.5,
1.7 Hz, 1 H), 6.86 (s, 1 H), 6.80 (dd, J = 1.3, 7.2 Hz, 1 H), 6.60 (s,
1 H, CHOH), 5.90 (s, 2 H, OCH2O), 3.35 (dd, J = 6.9, 7.1 Hz, 4 H,
NCH2R),1.14 (m, 6 H, NRCH3).
MS (EI): m/z (%) = 268 (97) [M+], 251 (100), 221 (12), 147 (24),
122 (34).
13C NMR (75 MHz, CDCl3): d = 155.86 (C=O), 155.05, 154.51,
149.07, 147.55, 131.65, 127.79, 124.21, 122.65, 121.09, 120.99,
Anal. Calcd for C16H12O4: C; 71.64, H; 4.51; O, 23.86. Found: C,
71.67; H, 4.53.
Synthesis 2004, No. 8, 1262–1268 © Thieme Stuttgart · New York