European Journal of Organic Chemistry
10.1002/ejoc.201700515
FULL PAPER
layer was washed with saturated aqueous potassium carbonate. The
aqueous layer was extracted twice with diethyl ether, the combined
Hz, 2 H), 5.35–5.38 (m, 1 H), 6.78 (s, 1 H), 6.92 (d, J = 7.9 Hz, 1 H), 7.47
13
(d, J = 7.9 Hz, 1 H), 7.61 (br s, 1 H), 7.70 ppm (s, 1 H); C NMR (125
MHz, CDCl ): δ = 13.14 (3 CH), 14.05 (3 CH), 17.60 (CH ), 17.88 (CH ),
18.06 (6 CH ), 18.12 (6 CH ), 25.77 (CH ), 28.41 (CH ), 99.92 (CH),
organic layers were dried (MgSO
4
), and the solvent was evaporated.
3
3
3
Purification of the crude product by column chromatography (silica gel,
3
3
3
2
isohexane/ethyl acetate, 25:1) provided the [1,4]oxazepino[2,3,4-
112.53 (CH), 117.93 (C), 121.04 (CH), 121.26 (C), 121.38 (CH), 123.42
(CH), 123.59 (C), 126.77 (C), 132.25 (C), 132.28 (C), 138.78 (C), 138.85
(C), 153.18 ppm (C); IR (ATR): ν = 3482, 2943, 2889, 2866, 2053, 2030,
2007, 1967, 1630, 1570, 1500, 1471, 1419, 1394, 1364, 1347, 1291,
1226, 1170, 1147, 1070, 1001, 948, 919, 879, 865, 823, 795, 768, 733,
1
jk]carbazole 15c (122 mg, 0.254 mmol, 52%) as bright yellow oil.
NMR (500 MHz, CDCl
H
3
): δ = 1.16 (d, J = 7.5 Hz, 18 H), 1.34–1.41 (m,
3
6
H), 1.52 (s, 6 H), 3.92 (s, 3 H), 5.52 (d, J = 9.3 Hz, 1 H), 6.87 (s, 1 H),
.92 (d, J = 9.4 Hz, 1 H), 7.03 (dd, J = 7.8, 0.8 Hz, 1 H), 7.20 (t, J = 7.8
13
−1
Hz, 1 H), 7.66 (dd, J = 7.7, 0.8 Hz, 1 H), 8.49 ppm (s, 1 H); C NMR
714, 680 cm ; UV (MeOH): λ = 216, 242, 254, 303, 320, 332 nm;
(
(
1
1
125 MHz, CDCl
CH ), 79.87 (C), 100.07 (CH), 113.66 (CH), 116.62 (C), 117.44 (C),
17.76 (CH), 118.65 (CH), 121.83 (CH), 122.54 (CH), 124.67 (CH),
26.09 (C), 131.06 (C), 141.78 (C), 143.36 (C), 155.43 (C), 167.49 ppm
3
): δ = 13.18 (3 CH), 18.01 (6 CH
3
), 29.45 (2 CH
3
), 51.82
fluorescence (MeOH): λex = 303 nm, λem = 345, 358 nm; MS (EI): m/z (%)
= 593 (100) [M] , 550 (8), 494 (6), 438 (5), 436 (4), 392 (4); elemental
+
3
2 2
analysis calcd for C36H59NO Si : C 72.79, H 10.01, N 2.36; found: C
72.92, H 10.18, N 2.47.
(C); IR (ATR): ν = 2944, 2892, 2866, 1726, 1700, 1655, 1625, 1589,
1
1
=
4
565, 1498, 1470, 1459, 1426, 1396, 1362, 1238, 1211, 1138, 1114,
090, 1065, 908, 881, 831, 776, 736, 715, 682, 652 cm ; UV (MeOH): λ
1
,7-Dihydroxy-6-methyl-2-(3-methylbut-2-en-1-yl)carbazole
(27):
−
1
TBAF (1 M in THF, 0.83 mL, 0.83 mmol) was added at 0 °C to a solution
of carbazole 24 (244 mg, 0.557 mmol) in THF (10 mL) and the mixture
was stirred at 0 °C for 10 min. Water and ethyl acetate were added, the
layers were separated, and the organic layer was washed with water.
The aqueous layer was extracted with ethyl acetate, the combined
220, 257, 269 (sh), 296 nm; fluorescence (MeOH): λex = 296 nm, λex
=
+
+
26 nm; MS (ESI, +50 V): m/z = 480.4 [M+H] , 448.5 [M−OCH
3
] ;
elemental analysis calcd for C28
found: C 70.33, H 8.08, N 3.05.
4
H37NO Si: C 70.11, H 7.77, N 2.92;
4
organic layers were dried (MgSO ), and the solvent was evaporated.
1-Hydroxy-6-methyl-2-(3-methylbut-2-en-1-yl)-7-
Purification by column chromatography (silica gel, isohexane/ethyl
(
triisopropylsilyloxy)carbazole (24): Silicon tetrachloride (0.76 mL, 6.6
acetate, 2:1) provided the 1,7-dihydroxycarbazole 27 (139 mg, 0.494
mmol, 89%) as brown solid. M.p. 153–156 °C; H NMR (500 MHz,
1
mmol) and then diisobutylaluminum hydride (1 M in toluene, 6.6 mL, 6.6
mmol) were added slowly at −78 °C to a solution of pyrano[2,3-
a]carbazole 6a (720 mg, 1.65 mmol) in toluene (35 mL). The mixture was
stirred for 5 min at −78 °C, the external cooling was removed, and the
mixture was stirred for further 105 min. The reaction mixture was diluted
with diethyl ether. The organic layer was separated and washed with
saturated aqueous sodium bicarbonate. The aqueous layer was
extracted with diethyl ether and the combined organic layers were dried
CDCl
3
): δ = 1.81 (d, J = 1.0 Hz, 3 H), 1.86 (s, 3 H), 2.39 (s, 3 H), 3.53 (d,
J = 7.0 Hz, 2 H), 5.41–5.44 (m, 1 H), 6.84 (s, 1 H), 6.90 (d, J = 7.9 Hz,
13
1 H), 7.44 (d, J = 7.9 Hz, 1 H), 7.71 (s, 1 H), 8.04 ppm (br s, 1 H);
NMR (125 MHz, CDCl ): δ = 16.18 (CH ), 18.01 (CH ), 25.80 (CH
30.33 (CH ), 96.73 (CH), 111.49 (CH), 116.11 (C), 117.73 (C), 121.08
C
3
3
3
3
),
2
(C), 121.16 (CH), 121.69 (CH), 122.61 (CH), 123.82 (C), 129.61 (C),
1
134.86 (C), 139.33 (C), 139.89 (C), 152.86 ppm (C); H NMR (500 MHz,
(MgSO
4
). Evaporation of the solvent and purification of the crude material
6
acetone-d ): δ = 1.72 (d, J = 0.8 Hz, 3 H), 1.75 (s, 3 H), 2.32 (s, 3 H),
by column chromatography (silica gel, isohexane/ethyl acetate, 15:1)
provided the prenylcarbazole 24 (522 mg, 1.19 mmol, 72%) as brown oil.
3.49 (d, J = 7.3 Hz, 2 H), 5.35–5.39 (m, 1 H), 6.85 (d, J = 7.9 Hz, 1 H),
13
6.97 (s, 1 H), 7.40 (d, J = 7.9 Hz, 1 H), 7.68 ppm (s, 1 H); C NMR (125
MHz, acetone-d ): δ = 16.68 (CH ), 17.83 (CH ), 25.86 (CH ), 28.94
(CH ), 97.18 (CH), 111.77 (CH), 117.33 (C), 117.55 (C), 121.24 (CH),
1
H NMR (500 MHz, CDCl
H), 1.81 (d, J = 1.0 Hz, 3 H), 1.86 (s, 3 H), 2.37 (s, 3 H), 3.52 (d, J = 7.2
Hz, 2 H), 5.40–5.43 (m, 1 H), 6.85 (s, 1 H), 6.89 (d, J = 7.9 Hz, 1 H), 7.43
3
): δ = 1.14 (d, J = 7.5 Hz, 18 H), 1.31–1.40 (m,
6
3
3
3
3
2
121.90 (CH), 123.43 (C), 124.32 (C), 124.60 (CH), 131.02 (C), 131.87
13
1
(
d, J = 7.9 Hz, 1 H), 7.71 (s, 1 H), 7.89 ppm (br s, 1 H); C NMR (125
MHz, CDCl ): δ = 13.09 (3 CH), 17.58 (CH ), 17.97 (CH ), 18.09 (6 CH ),
5.79 (CH ), 30.56 (CH ), 99.99 (CH), 111.64 (CH), 117.51 (C), 120.59
C), 121.12 (CH), 121.15 (C), 121.46 (CH), 122.49 (CH), 124.00 (C),
29.57 (C), 135.23 (C), 139.09 (C), 139.93 (C), 153.35 ppm (C); IR
ATR): ν = 3416, 2942, 2865, 1697, 1628, 1573, 1504, 1471, 1434, 1374,
(C), 140.07 (C), 140.65 (C), 155.05 ppm (C); H NMR (500 MHz, DMSO-
3
3
3
3
6
d ): δ = 1.69 (s, 3 H), 1.72 (s, 3 H), 2.22 (s, 3 H), 3.40 (d, J = 7.7 Hz, 2 H),
5.31–5.34 (m, 1 H), 6.74 (d, J = 7.9 Hz, 1 H), 6.87 (s, 1 H), 7.30 (d, J =
2
(
1
(
3
2
7.9 Hz, 1 H), 7.60 (s, 1 H), 8.59 (s, 1 H), 9.24 (s, 1 H), 10.25 ppm (s,
13
1 H); C NMR (125 MHz, DMSO-d
6 3 3
): δ = 16.52 (CH ), 17.70 (CH ),
25.58 (CH ), 27.91 (CH ), 96.33 (CH), 110.49 (CH), 115.54 (C), 115.95
3
2
1
331, 1299, 1227, 1170, 1145, 1100, 1067, 999, 923, 879, 852, 800, 715,
(C), 119.92 (CH), 120.84 (CH), 122.35 (C), 122.62 (C), 123.88 (CH),
130.17 (C), 130.47 (C), 139.15 (C), 139.37 (C), 154.12 ppm (C); IR
(ATR): ν = 3416, 3375, 3329, 2968, 2912, 2853, 1625, 1581, 1507, 1469,
1445, 1372, 1341, 1294, 1266, 1221, 1159, 1135, 1062, 1000, 908, 878,
−
1
683, 613 cm
; UV (MeOH): λ = 238, 254, 302, 321, 334 nm;
fluorescence (MeOH): λex = 302 nm, λem = 361 nm; MS (EI): m/z (%) =
+
437 (100) [M] , 394 (23), 382 (17), 338 (24), 326 (25), 325 (17), 310 (15),
−
1
280 (14), 224 (15), 180 (11), 59 (17), 43 (14); elemental analysis calcd
846, 802, 788, 737, 673, 662, 621 cm ; UV (MeOH): λ = 235, 251 (sh),
300, 315, 330 nm; fluorescence (MeOH): λex = 300 nm, λem = 360 nm;
for C27
2
H39NO Si: C 74.09, H 8.98, N 3.20; found: C 73.77, H 9.02, N 3.33.
+
MS (EI): m/z (%) = 281 (77) [M] , 264 (10), 251 (11), 225 (100), 196 (21),
1
C
83 (11), 168 (12), 167 (11), 55 (20), 39 (19); HRMS (ESI): m/z calcd for
H20NO [M+H] : 282.149; found: found: 282.147.
18 2
6
-Methyl-2-(3-methylbut-2-en-1-yl)-1,7-bis(triisopropylsilyloxy)carba-
+
+
zole (25): DBU (0.20 mL, 1.3 mmol) and TIPSCl (0.15 mL, 0.70 mmol)
were added sequentially to a solution of the 1-hydroxycarbazole 24 (238
mg, 0.544 mmol) in dichloromethane (8 mL) and the mixture was stirred
at room temperature for 1 h. Diethyl ether was added and the solution
was washed with a saturated aqueous solution of ammonium chloride.
The aqueous layer was extracted with diethyl ether and the combined
organic layers were dried (MgSO ). Evaporation of the solvent and
4
purification of the residue by column chromatography (silica gel,
isohexane/ethyl acetate, 40:1) provided the bis(silyloxy)carbazole 25
6-Methyl-1-((2-methylbut-3-en-2-yl)oxy)-7-
(triisopropylsilyloxy)carbazole (28): solution of 1,1-dimethylallyl
methyl carbonate (585 mg, 4.06 mmol) in THF (7.5 mL) was added to a
mixture of the 8-hydroxycarbazole 8a (500 mg, 1.35 mmol) and
tetrakistriphenylphosphinepalladium (15.6 mg, 13.5 µmol) and the
mixture was stirred at room temperature for 1 h. The mixture was filtered
A
®
over a short pad of Celite (dichloromethane) and the solvent was
1
(305 mg, 0.513 mmol, 94%) as colorless oil. H NMR (500 MHz, CDCl
3
):
evaporated. Purification of the residue by column chromatography (silica
gel, isohexane/ethyl acetate, 30:1) and drying in high vacuum for 15 min
provided the tert-prenyl ether 28 (602 mg) as yellow solid which was
δ = 1.15 (d, J = 7.5 Hz, 18 H), 1.16 (d, J = 7.5 Hz, 18 H), 1.33–1.43 (m, 6
H), 1.74 (s, 3 H), 1.77 (d, J = 0.7 Hz, 3 H), 2.37 (s, 3 H), 3.49 (d, J = 7.1
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