Diastereotopic synthesis of 1- and 1,1-substituted 4-phenyl-2,3,4,9- tetrahydro-1H-β-carbolines

Article abstract of DOI:10.1007/s10600-005-0043-9

A diastereotopic Pictet-Spengler reaction was performed to form previously unknown 1- and 1,1-substituted 4-phenyl-β-carbolines based on β-phenyltryptamine, aldehydes of various structure, and isatins. It has been demonstrated that the predominant diaster

Full text of DOI:10.1007/s10600-005-0043-9

Chemistry of Natural Compounds, Vol. 40, No. 6, 2004
DIASTEREOTOPIC SYNTHESIS OF 1- AND 1,1-SUBSTITUTED
4-PHENYL-2,3,4,9-TETRAHYDRO-1H-β-CARBOLINES
B. B. Semenov,1 K. A. Novikov,1 A. N. Spitsin,1
V. N. Azev,2 and V. V. Kachala3
UDC 547.759.3
A diastereotopic Pictet—Spengler reaction was performed to form previously unknown1-and 1,1-substituted
4-phenyl-β-carbolines based on β-phenyltryptamine, aldehydes of various structure, and isatins. It has been
demonstrated that the predominant diastereomers of the prepared β-carbolines have the (R*,R*)
configuration. The diasteroselectivity (de) of the reaction varies from 44 to 88%.
Key words: β-carbolines, β-phenyltryptamine, Pictet—Spengler reaction, diastereoselective synthesis, eleagnine,
harmane alkaloids.
The Pictet—Spengler reaction, which occurs in plants and in humans, leads to the formation of various derivatives
including isoquinoline and β-carboline.
Some verysimple alkaloids containing theβ-carboline structural moietyand belonging tothe harmane group are found
in medicinal plants such as Passiflora fluidum [1], P. edulis, P. incarnata, Bansteriopsis caapi [2], and Peganum harmala [3],
Zygophylaceae. Theyare used in traditional medicine to treat asthma, jaundice, and other diseases [3, 4]. Harmaline is a known
MAO inhibitor and powerful serotonin antagonist [5]. Harmane alkaloids have been detected in food plants [2] such as soy,
rye, wheat, rice, barley, mushrooms, grape juice, wine [6], charredinsects, and cigarette smoke. It has been reported that alcohol
increases the harmane content in the brain and urine [7].
Cytotoxic effects of harmane alkaloids have also been found [8]. These alkaloids are reported to affect the
cardiovascular system [9, 10] and to have a hypotensive effect [10].
The harmane alkaloids include also eleagnine [(1R)-1-methyl-2,3,4,9-tetrahydro-1H-β-carboline].
A synthesis of the racemate of eleagnine (1a) using the Pictet—Spengler reaction based on tryptamine (1) and
acetaldehyde was previously proposed [11].
Much later eleagnine was biosynthesized [12] and synthesized enantioselectively [13, 14] and (1S)-1-methyl-2,3,4,9-
tetrahydro-1H-β-carboline was synthesized enantioselectively (ee > 98%) [15]. The reaction proceeded through the formation
of two diastereomers with subsequent fractional crystallization of one of them and removal of a sulfamide, which was known
to be chiral.
Recently the solid-phase chemistryofindole is rapidlydeveloping with the Pictet—Spengler reaction being carried out
on apolymericsupport tosynthesize1,3-disubstitutedβ-carbolines. Diastereoselectivities(de)of8-52%havebeen obtainedfrom
tryptophan [16-25]. It depended on the presence of a substituted nitrogen in the indole ring [20].
Based on this, we carried out diastereotopic syntheses of previously unknown 4-phenyl-1- and 1,1-substituted
β-carboline derivatives using thePictet—Spengler reaction. Thestartingmaterialswereβ-phenyltryptamine(1)asthe racemate
and aliphatic, aromatic, and heterocyclic aldehydes.
1) D. I. Mendeleev Russian Chemical Engineering University, 125047, Moscow, Miusskaya pl. 9, fax (7095) 200 42
04, e-mail: semenovb@mail.ru; 2) Tufts University, Medford, 02155, USA, e-mail: vazev02@tufts.edu; 3) Institute of Organic
Chemistry, Russia, Moscow, e-amil: kachala@ioc.ac.ru. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 481-485,
November-December, 2004. Original article submitted July 26, 2004.
0009-3130/04/4006-0585 ©2004 Springer Science + Business Media, Inc.
585

3a f
4a f
TABLE 1. PMR Chemical Shifts for - and - , ppm
Compound
Proton
3a
4a
3b
4b
3c
4c
3d
4d
3e
4e
3f
4f
(1R*,4R*) (1S*, 4R*) (1R*, 4R*) (1S*, 4R*) (1R*, 4R*) (1S*, 4R*) (1R*, 4R*) (1S*, 4R*) (1R*, 4R*) (1S*, 4R*) (1R*, 4R*) (1S*, 4R*)
1-H
2-H
3-H
4.91
-
4.75
-
5.89
-
5.76
-
5.75
-
5.58
-
5.76
-
5.60
-
5.89
-
5.70
-
3.40
2.81
4.37
a
a
a
5.92
-
5.75
-
3.40
2.82
4.39
a
a
a
3.79
3.20
4.55
6.53
6.76
7.04
7.40
11.33
7.28
7.35
7.35
1.61
-
3.56
3.22
4.41
6.58
6.78
7.08
7.40
11.29
7.31
7.35
7.35
1.64
-
3.67
3.38
4.60
6.58
6.74
6.99
7.27
10.76
7.29
7.35
7.31
-
3.41
2.85
4.46
6.69
6.80
7.03
7.32
11.02
7.35
a
a
-
7.44
a
a
3.59
3.16
4.51
6.59
6.74
6.98
7.25
10.71
7.30
7.32
7.32
-
3.37
2.82
4.36
6.69
6.79
7.01
7.30
10.94
7.32
7.32
7.32
-
3.60
3.19
4.61
6.59
6.74
6.97
7.31
10.67
7.30
7.30
7.26
-
3.39
2.89
4.42
6.72
6.80
7.00
7.36
10.94
7.30
7.30
7.26
-
3.60
3.17
4.51
6.64
6.78
6.99
7.26
10.74
7.31
7.33
7.37
-
3.65
3.20
4.56
6.61
6.76
6.99
7.25
10.77
7.29
7.33
7.29
-
4-H
7-H
8-H
9-H
10-H
11-H
14-H
15-H
16-H
17-H
18-H
19-H
20-H
21-H
a
a
10.99
a
a
a
-
8.06
8.39
-
11.02
a
a
a
-
a
-
7.43
7.49
7.44
-
7.45
7.56
-
7.45
7.51
-
7.38
7.00
-
7.30
7.02
-
7.68
8.30
-
8.30
-
8.31
-
-
-
-
-
-
-
a
-
-
-
-
3.78
3.76
-
-
______
aSignal not assigned.
15
13
3
_
4
_
7
5
NH
2
NH
H SO
2
4
HSO
HSO
4
+
+
+
R
1
10a
NH
NH
1
9
2
2
N
H
R
2
11N
N
N
H
H
R
2
R
R
2
R
1
1
1
R*, R*
R*, S*
2
3
4
17
17
17
3a: R = CH , R = H; 3b: R =
, R = H; 3c: R =
, R = H; 3d: R =
, R = H;
2
1
3
2
1
2
1
2
1
19
19
19
OCH
3
Cl
O
17
17
21
19
O
3e: R =
, R = H;
3f: R =
, R = H;
3h: R =
, R = H;
2
1
2
1
2
1
19
19
HN
N
NO
2
NO
2
NO
Br
2
Br
19
21
19
21
19
21
19
21
3i: R R =
3k: R R =
;
3l: R R =
1 2
;
3j: R R =
;
1
2
1
2
1
2
23
Br
23
23
23
18 NH
18 NH
18 NH
18 NH
17
17
17
17
O
O
O
O
Scheme 1
586

TABLE 2. 13C NMR Chemical Shifts for 3a-f and 4a-f, ppm
Compound
C atom
3a
4a
3b
4b
3c
4c
3d
4d
3e
4e
3f
4f
(1R*, 4R*) (1S*, 4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*)
C-1
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C-10
C10a
C-12
C13
C-14
C-15
C-16
C-17
C-18
C-19
C-20
C-21
49.0
48.5
37.4
108.2
125.0
118.8
118.8
121.4
111.4
136.4
132.0
140.3
128.2
128.3
127.3
16.7
-
47.3
44.9
36.8
107.3
125.0
118.8
118.8
121.5
111.4
136.3
132.5
140.3
128.2
128.3
127.2
17.9
-
56.9
49.7
38.4
54.6
46.2
38.2
110.3
55.9
50.6
39.6
54.0
47.3
39.6
109.2
126.2
118.5
118.4
120.8
111.5
136.4
133.7
141.5
128.2
128.2
126.7
a
56.5
50.3
38.8
54.6
47.1
38.9
56.0
49.9
38.7
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
-
56.0
50.1
39.2
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
-
110.4
125.2
118.9
118.7
121.3
111.6
136.6
131.7
141.4
128.4
128.4
127.1
a
110.6
125.7
118.7
118.3
120.8
111.3
136.3
134.1
142.8
128.2
128.2
126.5
139.1
131.1
128.3
a
110.5
125.6
118.9
118.7
121.3
111.6
136.7
133.0
142.0
128.4
128.4
127.0
129.7
130.7
114.2
159.8
55.4
110.4
125.8
118.7
118.8
121.4
111.5
136.6
133.4
142.7
128.4
128.4
126.8
129.7
130.5
114.1
159.5
55.8
110.6
125.3
118.8
118.6
121.2
111.4
136.5
132.0
141.9
128.3
128.3
126.8
145.6
130.7
123.6
147.7
-
110.7
125.4
118.8
118.6
121.2
111.4
136.5
132.1
141.9
128.3
128.3
126.8
139.9
123.9
147.8
123.6
-
a
118.8
118.7
121.3
111.6
136.5
a
a
128.4
a
a
a
a
a
a
-
129.6
129.3
129.3
-
129.3
128.3
a
-
-
-
-
-
-
-
-
______
aSignal not assigned.
TABLE 3. PMR Chemical Shifts for 3h-l and 4h-l, ppm
Compound
Proton
3h
4h
3i
4i
3j
4j
3k
4k
3l
4l
(1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*)
1-H
3-H
5.78
3.41
2.80
4.24
6.70
6.75
6.94
7.28
10.51
7.28
7.28
7.21
7.51
-
5.70
3.22
2.78
4.19
6.61
6.79
7.01
7.35
10.78
7.28
7.28
7.20
7.47
-
-
-
-
-
-
-
-
-
3.79
4.13
4.80
6.58
6.77
7.03
7.25
10.97
7.41
7.40
7.33
11.31
7.45
7.13
7.52
7.16
3.44
3.98
4.68
6.70
6.82
7.08
7.28
11.08
7.40
7.40
7.34
11.28
7.43
7.15
7.46
7.20
3.97
3.88
4.57
6.59
6.76
7.01
7.23
10.88
7.38
7.38
7.31
11.14
7.47
-
3.16
3.63
4.40
6.83
6.83
7.04
7.23
10.91
7.38
7.38
7.31
11.02
7.36
-
3.37
3.63
4.37
6.62
6.73
6.97
7.20
10.76
7.33
7.32
7.25
11.08
7.33
-
3.03
4.02
4.29
6.93
6.82
7.03
7.21
10.81
7.33
7.32
7.25
10.99
7.28
-
3.41
3.71
4.45
6.60
6.75
6.98
7.18
10.76
7.35
7.35
7.28
11.41
8.06
-
3.06
4.03
4.34
6.95
6.85
7.03
7.20
10.81
7.35
7.35
7.26
11.25
7.91
-
4-H
7-H
8-H
9-H
10-H
11-H
14-H
15-H
16-H
17-H
19-H
20-H
21-H
22-H
-
-
4.34
1.30
4.28
1.32
7.62
7.04
7.54
6.98
7.75
-
7.73
-
8.33
7.21
8.29
7.18
587

TABLE 4. 13C NMR Chemical Shifts for 3h-l and 4h-l, ppm
Compound
3j 4j
(1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*) (1R*,4R*) (1S*,4R*)
C atom
3h
4h
3i
4i
3k
4k
3l
4l
C-1
C-3
47.8
49.7
46.1
45.0
59.7
45.2
60.3
46.8
60.2
46.2
61.3
47.3
61.9
47.8
62.2
47.4
60.4
47.5
60.9
47.5
C-4
38.7
38.6
37.1
37.2
38.3
38.3
39.8
38.5
39.4
38.1
C-5
C-6
C-7
C-8
108.9
125.3
118.4
118.0
120.2
111.2
136.9
131.7
144.4
128.2
128.1
126.1
133.5
130.4
-
108.5
125.2
118.6
118.3
120.6
111.4
136.5
131.6
140.9
128.2
128.2
126.3
133.4
130.4
-
112.0
125.0
119.2
119.0
122.2
111.7
136.8
127.5
140.7
128.7
128.5
127.5
-
172.6
124.9
126.2
122.8
131.7
111.2
143.1
111.9*
125.1*
119.1
119.0
122.2
111.7
136.8
127.6*
140.3
128.6
128.5
127.2
-
170.9*
126.6*
125.7
122.7
131.2
111.6
142.7
112.5
125.2
119.1
118.9
121.9
111.6
136.6
128.6
141.9
128.6
128.4
127.1
-
174.3
130.2
128.3
114.0
133.6
112.7
142.3
112.0
125.5
118.8
118.8
121.7
111.5
136.6
128.6
141.7
128.6
128.4
126.5
-
173.1*
132.4*
128.3
114.0
132.7
112.5
142.0
113.9
125.6
119.0
118.5
121.4
111.4
136.4
131.0
143.1
128.3
128.2
126.8
-
177.1
134.8
126.2
114.0
134.1
103.4
141.8
113.8
125.5
118.6
118.5
121.5
111.4
136.4
131.3
144.3
128.2
128.2
126.5
-
175.0
135.9*
126.1
113.9
133.9
103.5
141.8
113.3
125.5
119.0
118.5
121.4
111.3
136.4
132.2
142.8
128.2
128.2
126.5
-
177.3
131.4
120.6
142.3
126.9
110.4
149.3
112.4
125.8
118.6
118.5
121.4
111.3
136.4
130.6
144.2
128.1
128.2
126.1
-
178.4
133.1
119.8
142.2
126.5
110.3
149.3
C-9
C-10
C10a
C-12
C-13
C-14
C-15
C-16
C-17
C-18
C-18a
C-19
C-20
C-21
C-22
C-23
111.3
161.8
60.2
14.1
-
111.1
161.8
60.2
14.1
-
______
*Signal may be inaccurately assigned.
The diastereoselectivityis known tobe determinedeither byelectronic or steric factors [26]. Therefore, the substituents
in the 2- and 4-positions of the pyrrolidine ring in intermediate 2 should be as far from each other as possible, i.e., have the
trans-orientation. The Pictet—Spengler reaction was proved to proceed through spiro intermediate 2 using isotopic labeling
*
*
[27]. Primarily the (R ,R ) diastereomers 3 (Scheme 1) are formed during the rearrangement of 2 into the β-carboline system
apparently because of these same steric factors.
Compounds 3 and 4 are mixtures of two diastereomers with predominance of the R ,R diastereomer (a, de 44%; b,
70%; c, 62%; d, 63%; e, 62%; f, 56%; h, 66%; i, 88%; j, 72%; k, 72%; l, 66%).
*
*
The ratioofdiastereomers (de) was found bycomparing the integrated intensities ofH-3, H-3a, and H-4 in PMRspectra
of the prepared compounds. Their structures were studied using one- (1D) and two-dimensional (2D) NMR spectroscopy. Two
13
sets of signals of different intensity corresponding to two diastereomers were observed in 1D PMR and C NMR spectra. The
signals were assigned by analyzing 2D COSY, TOCSY, HSQC, and HMBC spectra. The three-dimensional structure of each
diastereomer was found using 2D H—H NOE (NOESY) spectroscopy to determine closely positioned protons. Tables 1-4 give
13
chemical shifts in PMR and C NMR spectra for 3 and 4.
The compounds were named using IUPAC rules and the program ACD Lab.
EXPERIMENTAL
NMR spectra were recorded on a DRX-500 (Bruker) instrument at working frequencies 500.13 and 125.76 MHz for
1
13
H and C, respectively, in DMSO-d at 30°C using standard Bruker methods. 2D HSQC and HMBC spectra were obtained
6
588

using a gradient method. TMS was used as an internal standard. Mass spectra were recorded in an SSQ-710 (Finnigan MAT)
spectrometer at 70 eV ionizing-electron energy. Elemental analyses agreed with those calculated.
β-Phenyltryptamine (1). A mixture of 3-(2-nitro-1-phenylethyl)indole (26.6 g, 0.1 mol) [28] in alcohol (94%,
100 mL) and freshly prepared Raney nickel (1 g) was treated over 60 h with hydrazine hydate (50 mL) in alcohol (100 mL).
If the boiling stopped, then a new portion of catalyst was added. The mixture was filtered. The filtered catalyst was washed
with hot alcohol (3 × 10 mL). The filtrate was evaporated. The solid was dissolved in anhydrous ether and treated with ether
saturated with HCl. The resulting hydrochloride was filtered off, suspended in ether, and shaken with aqueous base. The ether
solution was dried over MgSO and evaporated.
4
Yield 21 g (90%), mp 131-132°C (lit. mp 131-132 C [28]) (from ethylacetate).
General Method for Preparing 3 and 4. A mixture of 1 (1 g, 0.005 mol) in water (40 mL) and aldehyde or isatin
(0.72 g, 0.0043 mol) was treated with conc. H SO (1 g) and boiled for 60 h. The solid sulfates of 3 and 4 were filtered off and
2
4
crystallized from aqueous alcohol. The base was obtained by slurrying the sulfates with an excess of aqueous potash.
This method produced:
3a and 4a based on acetaldehyde and 1-methyl-4-phenyl-2,3,4,9-tetrahydro-β-carboline 1-sulfate.
+
Yield 50%, mp 218°C (sulfate), m/z (I , %): 262 (10) [M] .
rel
3b and 4b based on benzaldehyde and 1,4-diphenyl-2,3,4,9-tetrahydro-β-carboline 1-sulfate.
+
Yield 60%, mp 228°C (sulfate), m/z (I , %): 324 (14) [M] .
rel
3c and 4c based on p-chlorobenzaldehyde and 4-phenyl-1-(4-chlorophenyl)-2,3,4,9-tetrahydro-β-carboline 1-sulfate.
+
Yield 63%, mp 255°C (sulfate), m/z (I , %): 358 (14) [M] .
rel
3d and 4d based on p-methoxybenzaldehyde and 1-(4-methoxyphenyl)-4-phenyl-2,3,4,9-tetrahydro-β-carboline
1-sulfate.
+
Yield 55%, mp 225°C (sulfate), m/z (I , %): 354 (20) [M] .
rel
3e and 4e based on p-nitrobenzaldehyde and 1-(4-nitrophenyl)-4-phenyl-2,3,4,9-tetrahydro-β-carboline 1-sulfate.
+
Yield 80%, mp >260°C (sulfate), m/z (I , %): 369 (30) [M] .
rel
3f and 4f based on m-nitrobenzaldehyde and 1-(3-nitrophenyl)-4-phenyl-2,3,4,9-tetrahydro-β-carboline 1-sulfate.
+
Yield 76%, mp >260°C (sulfate), m/z (I , %): 369 (27) [M] .
rel
3h and 4h based on ethyl 4-formyl-1H-pyrazol-3(5)-carboxylate [32] and ethyl 4-(4-phenyl-2,3,4,9-tetrahydro-1H-β-
carbolin-1-yl)-1H-pyrazol-3(5)-carboxylate 1-sulfate.
+
Yield 87%, mp 255°C (sulfate), m/z (I , %): 386 (10) [M] .
rel
3i and 4i based on 1 H-indole-2,3-dione and 4-phenyl-2,3,4,9-tetrahydrospiro[β-carboline-1,3′-indole]-2 (1 H)-one
1-sulfate.
+
Yield 46%, mp >300°C. Mass spectrum (EI, 70 eV) m/z (I , %): 365 (10) [M] .
rel
3jand4jbasedon 5-bromo-1H-indole-2,3-dione[33]and5′-bromo-4-phenyl-2,3,4,9-tetrahydrospiro[β-carboline-1,3′-
indole]-2′(1′H)-one 1-sulfate.
+
Yield 60%, mp 263°C (dec.). Mass spectrum (EI, 70 eV) m/z (I , %): 444 (15) [M] .
rel
5,7-Dibromo-1H-indole-2,3-dione. A mixture of isatin (30 g) and conc. H SO (80 mL) was treated with bromine
2
4
(40 g) at <0°C with vigorous stirring, held at that temperature for 1 h, left overnight allowing the temperature to rise to ambient,
treated with glacial acetic acid (300 mL) and bromine (40 g), boiled until the bromine disappeared, poured onto ice, and filtered.
The solid was suspended with aqueous potash and washed with water until the washings were neutral to afford the product, yield
59 g, 95%, mp 253°C (lit. mp 252°C [30a]).
3k and 4k based on 5,7-dibromo-1H-indole-2,3-dione [33] and 5′,7′-dibromo-4-phenyl-2,3,4,9-tetrahydrospiro[β-
carboline-1,3′-indole]-2′(1′H)-one 1-sulfate.
+
Yield 76%, mp >300°C. Mass spectrum (EI, 70 eV) m/z (I , %): 523 (15) [M] .
rel
3l and 4l based on 5-nitro-1H-indole-2,3-dione [30b] and 5′-nitro-4-phenyl-2,3,4,9-tetrahydrospiro[β-carboline-1,3′-
indole]-2′(1′H)-one 1-sulfate.
+
Yield 39%, mp 246°C. Mass spectrum (EI, 70 eV) m/z (I , %): 410 (15) [M] .
rel
589

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590