96
S. Chakraborty, G. Chattopadhyay, and C. Saha
Vol 50
Tosylhydrazone of 6-methoxy-3,7,8-trimethyl-1-keto-1,2,3,
C7-H), 7.414 (m, 2H, C1 and C8-H), 7.662 (s, 1H, C4-H), 7.900 (s,
1H, C5-H), 10.12 (br s, 1H, NH). 13C-NMR (CDCl3, 125MHz): d
21.36 (+), 55.32 (+), 99.04 (ꢂ), 110.41 (+), 112.51 (+) ꢃ 2C, 119.67
(+), 119.77 (ꢂ), 123.89 (+), 124.48 (ꢂ), 127.35 (+), 128.24 (ꢂ),
133.59 (ꢂ), 150.51 (ꢂ). HRMS: m/z calcd for C14H13NONa
[M + Na]+ 234.0894; found 234.0890.
4-tetrahydrocarbazole (2z). UV (MeOH): 314 nm. 1H-NMR
(DMSO-d6, 500 MHz): d 1.21 (d, J= 6.20 Hz, 3H, C3-CH3), 2.230
(s, 3H, Ar-CH3), 2.245 (s, 3H, Ar-CH3), 2.27 (s, 3H, Ar-CH3),
2.49–2.65 (m, 3H, C2-H and C3-H), 3.10 (d, J= 12.90 Hz, 2H, C4-
H), 3.86 (s, 3H, Ar-OCH3), 6.82 (s, 1H, C5-H), 7.489
(d, J= 8.55 Hz, 2H, ortho-Ar-CH3), 8.021 (d, J=7.25Hz, 2H,
ortho-Ar-SO2NH-), 10.380 (s, 1H, -NHSO2-), 11.4042 (s, 1H,
N-H). 13C-NMR (DMSO-d6, 125 MHz): d 12.46 (+), 13.58 (+),
21.47 (+), 21.76 (+), 33.05 (+), 46.41 (ꢂ), 55.79 (+), 97.36 (+),
110.68 (ꢂ), 114.47 (ꢂ), 120.60 (ꢂ), 122.84 (ꢂ), 126.92 (ꢂ),
128.54 ꢃ 2 (+), 129.53 (ꢂ), 129.81 ꢃ 2 (+), 135.54 (ꢂ), 138.87
(ꢂ), 141.55 (ꢂ), 143.14 (ꢂ), 153.27 (ꢂ).
1-Methoxy-6-methyl-9H-carbazole (3r), glycozolicine. IR
1
(KBr): 3485 cmꢂ1 (–NH). H-NMR (CDCl3, 500 MHz): d 2.422
(s, 3H, C6-CH3), 3.852 (s, 3H, C1-OCH3), 7.201 (m, 2H, C2
and C3-H), 7.271 (dd, J1 = 8.15 Hz, J2 = 0.77 Hz, 1H, C7-H),
7.484 (d, J = 8.18 Hz, 1H, C8-H), 7.662 (d, J = 8.12 Hz, 1H, C4-
H), 7.941 (s, 1H, C5-H), 10.01 (br s, 1H, NH). 13C-NMR
(CDCl3, 125 MHz): d 21.30 (+), 55.36 (+), 99.15 (ꢂ), 110.38
(+), 112.48 (+) ꢃ 2C, 119.47 (+), 119.87 (ꢂ), 123.78 (+),
124.58 (ꢂ), 127.40 (+), 128.32 (ꢂ), 135.49 (ꢂ), 149.81 (ꢂ).
HRMS: m/z calcd for C14H13NONa [M + Na]+ 234.0894; found
234.0892.
General experimental procedure for tandem reduction–
oxidation of tosylhydrazone (2) using the combination of
NaBH4 and Pd–C on MgSO4ꢀ7H2O support under microwave
irradiation.
A solution of tosylhydrazone (2) (1 mmol) in
2,3-Dimethoxy-6-methyl-9H-carbazole (3u). 1H-NMR (CDCl3,
500 MHz): d 2.511 (s, 3H, C6-CH3), 3.952 (s, 3H, Ar-OCH3),
3.990 (s, 3H, Ar-OCH3), 6.813 (s, 1H, C1-H), 6.901(d, J=7.88Hz,
1H, C7-H), 7.149 (d, J= 7.90 Hz, 1H, C8-H), 7.495 (s, 1H, C4-H),
7.74 (s, 1H, C5-H), 10.18 (br s, 1H, NH). 13C-NMR (CDCl3,
125 MHz): d 21.44 (+), 56.42 (+), 56.47 (+), 94.34 (+), 102.74 (+),
109.47 (ꢂ), 110.18 (+), 119.24 (+), 120.59 (ꢂ), 125.54 (+), 128.58
(ꢂ), 134.65 (ꢂ), 137.70 (ꢂ), 144.32 (ꢂ), 149.35 (ꢂ). HRMS: m/z
calcd for C15H15NO2Na [M + Na]+ 264.1000; found 264.1000.
5H-[1,3]-dioxolo[4,5-b]carbazole (3v). IR (KBr): 3402 cmꢂ1
(-NH). 1H-NMR (CDCl3, 500 MHz): d 6.008 (s, 2H, O-CH2-
O), 6.898 (s, 1H, C1-H), 7.180 (m, 1H, C6-H), 7.312 (m, 1H,
C7-H), 7.372 (d, J = 8.07 Hz, C8-H), 7.437 (s, 1H, C4-H), 7.909
(d, J = 7.81 Hz, 1H, C5-H), 10.28 (1H, NH). 13C-NMR (CDCl3,
125 MHz): d 92.08 (+), 99.52 (+), 102.56 (ꢂ), 110.55 (+),
116.54 (ꢂ), 119.29 (+), 119.33 (+), 123.69 (ꢂ), 124.28 (+),
134.90 (ꢂ), 139.47 (ꢂ), 142.52 (ꢂ), 147.34 (ꢂ). HRMS: m/z
calcd for C13H9NO2Na [M + Na]+ 234.0530; found 234.0527.
8-Methyl-5H-[1,3]-dioxolo[4,5-b]carbazole (3w), clausenalene.
IR (KBr): 3410cmꢂ1 (-NH). 1H-NMR (CDCl3, 500MHz): d
2.410 (s, 3H, Ar-CH3), 6.102 (s, 2H, O-CH2-O), 6.902 (s, 1H, C1-
H), 7.282 (m, 1H, C7-H), 7.363 (d, J = 8.07Hz, C8-H), 7.434 (s,
1H, C4-H), 7.912 (s, 1H, C5-H), 10.26 (br s, 1H, NH). 13C-NMR
(CDCl3, 125 MHz): d 21.28 (+), 92.13 (+), 99.57 (+), 102.59 (ꢂ),
110.61 (+), 117.64 (ꢂ), 119.22 (+), 119.87 (+), 124.20 (ꢂ),
125.47(ꢂ), 135.12 (ꢂ), 139.87 (ꢂ), 143.32 (ꢂ), 147.87 (ꢂ).
HRMS: m/z calcd for C14H11NO2Na [M + Na]+ 248.0687; found
248.0683.
dichloromethane–methanol mixture (2:1, 20 mL) was poured in
MgSO4ꢀ7H2O (1.5 g) in a porcelain basin. Solvent was then
evaporated at room temperature to obtain a dry mass, which
was further dried in vacuum. To this mixture Pd–C (10%,
100 mg) was added and mixed intimately. After that, NaBH4
(20 mmol) was added, mixed thoroughly, and dried in vacuum.
This reaction mixture in four equal parts was then irradiated
under microwave at 100 W power, 100ꢁC, and 50 psi (max) for
2–5 min. During the reaction, pressure inside the reaction tube
raised up to 30 psi. After completion, the whole reaction
mixture was extracted with dry dichloromethane, the solvent
was then evaporated to dryness, and the residue so obtained
was chromatographed over silica gel (15 g) column using a
mixture of n-hexane and dichloromethane as eluent to afford 3
as colorless solid. It was crystallized from n-hexane–
dichloromethane mixture. In the case of methoxy carbazoles,
particularly for the entry nos. 16, 17, 18, 19, 23, and 24, often
isolation and purification was carried out through vacuum
(0.5 mm of Hg) sublimation.
Spectral data of the unknown carbazoles and natural
carbazole alkaloids.
3-Methyl-9H-carbazole (3b).
IR (KBr): 3307 cmꢂ1 (-NH).
1H-NMR (CDCl3, 500 MHz): d 2.453 (s, 3H, C3-CH3), 7.181 (dd,
J1 =8.17Hz, J2 =0.78Hz, 1H, C6-H), 7.281 (dd, J1 =8.07Hz,
J2 = 0.67 Hz, 1H, C2-H), 7.314 (m, 2H, C1-H and C7-H), 7.521 (d,
J= 8.18 Hz, 1H, C8-H), 7.862 (s, 1H, C4-H), 8.100 (d, J=8.00Hz,
1H, C4-H), 10.01 (br s, 1H, NH). 13C-NMR (CDCl3, 125 MHz): d
21.46 (+), 100.04 (ꢂ), 111.41 (+) x 2C, 119.02 (+), 119.65 (+),
120.07 (+), 123.09 (ꢂ), 124.45 (+), 126.35 (+), 128.24 (ꢂ), 129.25
(ꢂ), 145.51 (ꢂ). HRMS: m/z calcd for C13H11NNa [M + Na]+
204.0788; found 204.0785.
3-Methoxy-1,2-dimethyl-9H-carbazole (3y), deoxycarbazomycin B.
1
IR (KBr): 3428 cmꢂ1 (-NH). H-NMR (CDCl3, 500MHz): d 2.343
(s, 3H, C2-CH3), 2.423 (s, 3H, C1-CH3), 3.947 (s, 3H, C3-OCH3),
7.181–7.582 (m, 1H, C6-H, C7-H and C8-H), 7.358 (s, 1H, C4-H),
7.904 (s, 1H, C5-H). 13C-NMR (CDCl3, 125 MHz): d 12.17 (+),
14.01 (+), 57.12 (+), 99.04 (+), 110.41 (+), 119.02(+), 119.87 (+),
120.07 (ꢂ), 124.09 (ꢂ), 124.38 (ꢂ), 126.35 (+), 128.24 (ꢂ), 134.59
(ꢂ), 137.96 (ꢂ), 152.51 (ꢂ). HRMS: m/z calcd for C15H15NONa
[M + Na]+ 248.1051; found 248.1053.
3-Methoxy-1,2,6-trimethyl-9H-carbazole (3z). IR (KBr):
3425 cmꢂ1 (-NH). 1H-NMR (CDCl3, 500 MHz): d 2.343 (s, 3H, C2-
CH3), 2.453 (s, 3H, C6-CH3), 2.523 (s, 3H, C1-CH3), 3.943 (s, 3H,
C3-OCH3), 7.181 (dd, J1 =8.17Hz, J2 = 0.78 Hz, 1H, C7-H), 7.314
(d, J=8.18Hz, 1H, C8-H), 7.362 (s, 1H, C4-H), 7.800 (s, 1H, C5-H).
13C-NMR (CDCl3, 125 MHz): d 12.27 (+), 13.88 (+), 21.46 (+),
56.32 (+), 99.04 (+), 110.41 (+), 119.02 (ꢂ), 119.87 (+), 120.07
(ꢂ), 124.09 (ꢂ), 124.38 (ꢂ), 126.35 (+), 128.24 (ꢂ), 134.59 (ꢂ),
1,3,6-Trimethyl-9H-carbazole (3k). IR (KBr): 3310 cmꢂ1
(-NH). 1H-NMR (CDCl3, 500MHz): d 2.493 (s, 3H, C1-CH3),
2.516 (s, 6H, C3-CH3 and C6-CH3), 7.194 (s, 1H, C2-H), 7.210 (d,
J= 7.19 Hz, 1H, C7-H), 7.323 (d, J= 8.18 Hz, 1H, C8-H), 7.684 (s,
1H, C4-H), 7.817 (s, 1H, C5-H), 10.10 (br s, 1H, NH). 13C-NMR
(CDCl3, 125 MHz): d 16.83 (+), 21.38 (+), 21.46 (+), 110.35 (+),
117.73 (+), 119.35 (ꢂ), 120.35 (+), 122.97 (ꢂ), 123.97 (ꢂ), 126.86
(+), 127.79 (+), 128.55 (ꢂ), 128.68 (ꢂ), 137.49 (ꢂ), 138.05 (ꢂ).
HRMS: m/z calcd for C15H15NNa [M + Na]+ 232.1101; found
232.1100.
3-Methoxy-6-methyl-9H-carbazole (3m), glycozoline. IR
1
(KBr): 3435 cmꢂ1 (-NH). H-NMR (CDCl3, 500 MHz): d 2.432 (s,
3H, C6-CH3), 3.843 (s, 3H, C3-OCH3), 7.171 (dd, J1 =8.10Hz,
J2 =0.76Hz, 1H, C2-H), 7.281 (dd, J1 =8.15Hz, J2 = 0.77 Hz, 1H,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet