Palladium-catalyzed chemoselective intramolecular cyclization of bromoanilinoalkenenitriles

Article abstract of DOI:10.1039/a702710i

α-(o-Bromoanilino)alkenenitriIes 1a-f and 2a-e and α-(N-alkenylamino)-β-(o-bromophenyl)-propanenitriles 7a-c and 8a-c undergo palladium-catalyzed conversion into o-(methylamino)benzonitrile 12, o-[(alkenylamino)ethenyl]benzonitriles 24a-c, N-alkenylanilines 26b, 26c, 3-benzazepines 29a, 29c, 31a and 32a, γ-carbolines 36 and pyrrolo[3,2-b]indole 45. The reactions involve intramolecular additions of arylpalladium to the cyano group and subsequent processes such as cyano group transposition, hydrolysis, electrocyclization, ethyl group transfer and oxidative aromatization. A general mechanism for the palladium-catalyzed arylation of a cyano group is proposed.

Full text of DOI:10.1039/a702710i

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Palladium-catalyzed chemoselective intramolecular cyclization of
bromoanilinoalkenenitriles
Chau-Chen Yang,* Huo-Mu Tai and Pei-J iun Sun
Department of Cosmetic Science, Chia Nan College of Pharmacy and Science, Tainan 717,
Taiwan, Republic of China
á-(o-Bromoanilino)alkenenitriles 1a–f and 2a–e and á-(N-alkenylamino)-â-(o-bromophenyl)-
propanenitriles 7a–c and 8a–c undergo palladium-catalyzed conversion into o-(methylamino)benzonitrile
12, o-[(alkenylamino)ethenyl]benzonitriles 24a–c, N-alkenylanilines 26b, 26c, 3-benzazepines 29a, 29c, 31a
and 32a, ã-carbolines 36 and pyrrolo[3,2-b]indole 45. The reactions involve intramolecular additions of
arylpalladium to the cyano group and subsequent processes such as cyano group transposition, hydrolysis,
electrocyclization, ethyl group transfer and oxidative aromatization. A general mechanism for the
palladium-catalyzed arylation of a cyano group is proposed.
CN
Introduction
R
NHMe
1a R = MeCH=CH
1b R = PrCH=CH
1c R = Me2C=CH
1d R = PhCH=CH
1e R = MeCH=CHCH=CH
1f R = (CH2)2CH
O
H
NMe
Heck reactions are important palladium-catalyzed reactions for
carbon–carbon bond formation such as the well documented
arylation of olefins;1 the corresponding arylation of a cyano
group is, however, unprecedented except for a previous report
from our group.2 A series of N-methyl-(o-bromoanilino)alk-3-
enenitriles 1a–e, 2-anilino-2-cyclopropylacetonitrile 1f, N-
12 N HCl
KCN(aq.)
Br
R
+
Br
ButOH/THF
0 oC, 2 h
ButOK
methyl-(o-bromoanilino)alk-2-enenitriles
2a–e
and
N-
alkenylamino-3-(o-bromophenyl)propanenitriles 7a–c, 8a–c
have been prepared, and their intramolecular palladium-
catalyzed cyclizations studied.2 Most of these compounds have
olefin and cyano groups oriented in similar proximity to the
arylpalladium complex. The palladium-catalyzed cyclization
may occur by two competitive pathways: namely by attack on
the olefinic function or on the cyano group. This study indicates
that the palladium-catalyzed arylation occurs in most cases
selectively at the cyano group to afford o-(methylamino)-
benzonitrile 12, o-[(alkenylamino)ethenyl]benzonitriles 24, N-
alkenylanilines 26, γ-carbolines 36 and pyrrolo[3,2-b]indole 45.
CN
R1
NMe
Br
(1)
2a R1 = Et
2b R1 = Bu
2c R1 = Pri
2d R1 = Bn
2e R1 = EtCH=CH
Results and discussion
Br
R1
R2
Non-conjugated α-(o-bromoanilino)alkenenitriles 1a–e were
prepared [eqn. (1)] by condensation of equimolar amounts of
an appropriate unsaturated aldehyde, potassium cyanide and
N-methyl-o-bromoaniline3 in the presence of hydrochloric acid
(12 ).4 α-Amino(cyclopropyl)acetonitrile 1f was similarly pre-
pared from cyclopropanecarbaldehyde. Treatment of 1a–e with
a strong base But-OK in ButOH–THF at 0 ЊC for 2 h gave the
thermodynamically favoured conjugated α-aminoalkenenitriles
2a–e predominantly as the 2E-isomer (E :Z > 10).5 2-(Alkenyl-
amino)acetonitriles 5a–c, 6a–c, prepared from N-alkyl-
ations of α-aminonitriles 3 and 4,6 were treated with lithium
diisopropylamide (LDA) and o-bromobenzyl bromide to give
2-(alkenylamino)-3-(o-bromophenyl)propanenitriles 7a–c and
8a–c [eqn. (2)].7
CN
CN
Cl
CN
Et3N
CH2Cl2
R2
Et3N/CH2Cl2
40 o
+ RNH2
N
R
R1
NH
R
40 o
C
C
3 R = Ph
4 R = Bn
5a R = Ph, R1 = R2 = H
5b R = Ph, R1 = R2 = Me
5c R = R1 = Ph, R2= H
6a R= Bn, R1 = R2 = H
6b R = Bn, R1 = R2 = Me
6c R = Bn, R1 = Ph, R2 = H
1 LDA/THF
R
N
Br
Br
R1
2
CN
R2
Br
In
a
typical procedure8 (Table 1), α-(o-bromo-
7a R = Ph, R1 = R2 = H
anilino)alkenenitrile 1d (1 mmol) in DMF (15 ml) was treated
with Pd(OAc)2 (0.1 mmol), PPh3 (0.2 mmol) and Et3N (1.2
mmol) for 6 h at 100 ЊC under an argon atmosphere to give 2-
(methylamino)benzonitrile 12 and γ-carboline 17 in 38 and 36%
yields, respectively. The reactions of 1a–c, e, f gave the benzo-
nitrile 12 (60–85%) and aldehydes RCHO.
(2)
7b R = Ph, R2 = R2 = Me
7c R = R1 = Ph, R2 = H
8a R= Bn, R1 = R2 = H
8b R = Bn, R1 = R2 = Me
8c R = Bn, R1 = Ph, R2 = H
A possible mechanism for the palladium-catalyzed reactions9
is illustrated by the formation of the benzonitrile 12 (Scheme 1).
The reactions were presumably initiated by oxidative insertion
of Pd 0 into the bromophenyl groups. The organopalladium 9
undergoing cyclisation by attack on the cyano group, giving 10,
but not the olefinic double bonds. The iminoindoline 10 might
J. Chem. Soc., Perkin Trans. 1, 1997
2843

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PdII(OAc)2
Et3N
Br
CN
PPh3/DMF
CN
N
R
Pd0L2
Me
+
N
R
(L = PPh3)
1a-f
Br–
Me
11
NPdBr
R
PdBr
H2O
CN
N
N
R
CN
Me
Me
10
9
NHMe
12
PdBr
N+
For 10d
PdBr
NH
Ph
+
R = PhCH=CH
H-shift
+ PhCH=CHCHO
RCHO
N
Ph
N
Ph
Me
Me
14
13
electrocyclization
PdBr
PdBr
H
N
Ph
H
N+
Ph
N
Ph
Et3N
H-shift
–Pd0, –HBr
N
Ph
N
Ph
H
N
Ph
Me
Me
Me
15
17
16
Scheme 1
Table 1 Palladium-catalyzed chemoselective intramolecular cyclization of bromoanilinoalkenenitrilesa
Products (yield, %)b
Reaction
Entry
Substrate
Base
time (h)
Addition to CN
Addition to C᎐C
᎐
1
2
3
4
5
1a
1b
1c
1d
1e
1f
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
6
6
6
6
6
12 (81)
12 (60)
12 (85)
12 (38) ϩ 17 (36)
12 (72)
—
—
—
—
—
—
6
6
12 (80)
7
8
9
7a
7b
7c
8a
8b
8c
2a
2b
2c
2d
2e
2a
2b
2c
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Na2CO3
Na2CO3
Na2CO3
8
8
8
8
8
8
6
6
6
6
6
12
12
12
—
29a (60) ϩ 31a (18)
—
29c (16)
32a (77)
—
—
—
—
—
—
—
—
—
26b (76)
26c (66)
24a (9)
10
11
12
13
14
15
16
17
18
19
20
24b (78)
24c (72)
36a (88)
36b (73)
36c (85)
36d (63)
36e (75)
45 (52)
36e (51)
48 (73)
—
a
The reactions were run under an argon atmosphere with 1 equiv. of bromoanilinoalkenenitrile, 1.2 equiv of base, 20 mol% of PH3P, and 10 mol%
of Pd(OAc)2 in DMF at 100 ЊC. b Isolated yields after purification.
yield an iminium ion 11, which is subsequently hydrolyzed to
give 2-(methylamino)benzonitrile 12 and aldehydes RCHO.
When R is a styryl group, the palladium amide 10d reacted
further with cinnamaldehyde to give γ-carboline 17.10 This
process might involve electrocyclization, H-shift and elimin-
ation of palladium and HBr.
Under similar reaction conditions, the palladium-catalyzed
reactions of 2-(alkenylamino)-3-(o-bromophenyl)propane-
nitrile 7b afforded the alkenylamine 26b (76%). This result was
explained in terms of the organopalladium compound (18
and 19) attacking the cyano group selectively (Scheme 2). Thus,
the benzonitrile iminium salts (22 and 23) generated from the
2844
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PdBr
R1
PdBr
R2
Pd(OAc)2–PPh3
Et3N–DMF 100 o
CN
R2 = H
7a-c
8a-c
C
N
R
N
R
R1
for 18a, c
and 19a
CN
18a R = Ph, R1 = R2 = H
18b R = Ph, R1 = R2 = Me
18c R = R1 = Ph, R2 = H
19a R = Bn, R1 = R2 =H
19b R = Bn, R1 = R2 = Me
19c R = Bn, R1 = Ph, R2 = H
27a R = Ph, R1 = H
27c R = R1 = Ph
28a R = Bn, R1 = H
–Pd0
–HBr
for 18b, c and19a-c
R1
CN
R2
NPdBr
R2
+
–Pd0
–Br–
N
R1
N
R
N
R
R1
R
CN
22 R = Ph
23 R = Bn
20 R = Ph
21 R = Bn
29a R = Ph, R1 = H
29c R = R1 = Ph
[30a R= Bn, R1 = H]
–H+
Et3N
(–Pd0, –HBr)
H2O
–HCN
CN
R1
R2
R2
CN
R1
+
N
R
HN
R1
CHO
N
R
R
26b R = Ph, R1 = R2 = Me
26c R = R1 =Ph, R2 = H
24a R = Bn, R1 = R2 = H
31a R = Ph, R1 = H
32a R = Bn, R1 = H
25
24b R = Bn, R1 = R2 = Me
24c R = Bn, R1 = Ph, R2 = H
Scheme 2
iminoindoline intermediates (20 and 21) upon elimination of
HBr would give the aminovinylbenzonitriles 24 or undergo
hydrolysis to give the alkenylamines 26b, c. On the other hand,
analogous organopalladium compounds (18a, c) might attack
the less hindered double bonds as shown in the transformation
of 7a and 7c to 3-benzazepine derivatives 29a (60%) and 29c
(16%). The reactions of 8a–c followed similar pathways, the
organopalladium intermediate attacking either the cyano group
or the olefinic double bond depending on the nature of the
substrates. At elevated reaction temperatures, elimination of
HCN from 29a and 30a occurred to give the benzazepines 31a
and 32a.
[3,2-b]indole 45 (52%), γ-carbolines 36e (51%) and 48 (73%),
respectively. The γ-H of the organopalladium compound 42a
was removed by Na2CO3 to give an anion 43a, which yielded the
pyrrolo[3,2-b]indole 45 as the result of a nucleophilic reaction
and hydrogen shift (Scheme 4). For 2b and 2c (R = Pri or Bu),
the intermediates 43b and 43c might undergo the palladium
transfer, giving the π-allylpalladium complex as 46d and 46c.
Elimination of palladium and HBr followed by electrocycliz-
ation and oxidative aromatization would furnish the γ-
carbolines 36e and 48.
Conclusions
The palladium-catalyzed reactions of the conjugated bromo-
anilinoalkenenitriles 2a–e (as E/Z-mixtures) afforded γ-
carbolines 36a–e (63–88% entries 13–17). The organopalladium
compound 34e (R1 = butenyl) had the potential to undergo 6π
electrocyclization and subsequent elimination of palladium and
HBr to produce the γ-carboline 36e (Scheme 3). Although the
intermediates 34a, b, d derived from 2a, b, d (R = Et, Bu, Bn)
could not undergo electrocyclization, capture of an ethyl group
from Et3NHϩ would give 38a, b, d. Subsequent elimination of
palladium and HBr, followed by electrocyclization and oxida-
tive aromatization would furnish the γ-carbolines 36a, b, d. The
intermediate 34c derived from 2c (R = Pri) underwent electrocy-
clization in a different way, via 40, to furnish the 4-isopropyl-γ-
carboline 36c.
Our study of the palladium-catalyzed reactions shows three
common features: (i) the organopalladium compounds 9
undergo cyclization by preferential attack on the cyano group
rather than at the olefinic double bonds; (ii) the iminopal-
ladium compounds 18 and 19 undergo either the transposition
of cyano groups or cyclization at the olefinic double bonds;
(iii) since Et3NHϩ may transfer an ethyl group to the imino-
palladium compounds 34a–d, the palladium-catalyzed reac-
tions of 2a–d proceeded differently on replacement of Et3N by
Na2CO3.
Experimental
In order to determine whether the ethyl group was trans-
ferred from Et3N in the conversion of 2a–c into γ-carbolines
36a–c, we replaced Et3N with Na2CO3 (1.2 equiv.) as the base in
the palladium-catalyzed reactions (entries 18–20).11 Under such
conditions, compounds 2a, 2b and 2c yielded to the pyrrolo-
Melting points are uncorrected. 1H NMR spectra were
recorded at 200 or 300 MHz; 13C NMR spectra were recorded
at 50 or 75 MHz, TMS was used as an internal standard
(J values in Hz). Mass spectra were recorded at an ionizing
voltage of 70 eV. Merck silica gel 60F sheets were used for
J. Chem. Soc., Perkin Trans. 1, 1997
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2a-e
Pd0
PdBr
NH
PdBr
NPdBr
R1
CN
H-shift
R2
R1
N
N
N
R3
Me
Me
Me
34a-e
33a-e
37a R2 = H, R3 = Me
37b R2 = H, R3= Pr
37c R2 = H, R3 = Ph
37d R2 = R3= Me
electrocyclization for 34e
1 = EtCH=CH
R
ethyl transfer
from Et3NH+
for 34a-d
H
N
Et
R
1 = Et, Bu, Bn, Pri
N
PdBr
Me
PdBr
N
Me
N
Et3N
–Pd0, –HBr
35
R2
N
for 38c and
H-shift
–Pd0
–HBr
Et3N
Me
N
R3
Me
Me
Me
40
38a R2 = H, R3 = Me
38b R2 = H, R3= Pr
38c R2 = H, R3 = Ph
38d R2 = R3= Me
N
Et
electrocyclization
N
N
Me
N
–Pd0
Et3N
36e
–HBr
Me
Me
Me
41
N
Me
R4
N
Me
R4
electrocyclization and
oxidative aromatization
oxidative aromatization
N
N
N
Me
Me
N
39a R4 = Me
39b R4 = Pr
39d R4 = Ph
36a R4 = Me
36b R4 = Pr
36d R4 = Ph
Me
Me
Me
36c
Scheme 3
analytical thin-layer chromatography. Column chromatography
was performed on SiO2 (70–230 mesh); gradients of EtOAc and
hexane were used as eluents. DMF, Et3N and CH2Cl2 were
distilled over CaH2, whilst THF was distilled from sodium
benzophenone ketyl under N2.
1.5, ArH); δC(CDCl3) 17.4 (q, C-5), 35.0 (q, NCH3),
58.3 (d, C-2), 115.4 (s, CN), 120.3 (s), 123.2 (d), 123.6 (d), 126.1
(d), 128.4 (d), 131.8 (d), 133.7 (d) and 147.9 (s); m/z 266
([M ϩ 2]ϩ, 28%), 264 (Mϩ, 32), 185 (68), 157 (100), 105 (52)
and 77 (74) (Found: M, 266.0238. C12H13N2Br requires M,
266.0242).
Preparation of 2-(N-methyl-o-bromoanilino)alk-3-enenitriles
1a–f
2-(N-Methyl-o-bromoanilino)hept-3-enenitrile 1b. Yield 78%;
oil; TLC [EtOAc–hexane (2:98)] Rf 0.25; νmax(neat)/cmϪ1 2960,
2800, 2240 (CN), 1590, 1490, 970 and 760; δH (CDCl3) 0.90 (3 H,
t, J 7, H-7), 1.35–1.50 (2 H, m, H-6), 2.08 (2 H, dt, J 7, 7, H-5),
2.72 (3 H, s, NCH3), 4.89 (1 H, br dd, J 2, 1, NCH), 5.57 (1 H,
dd, J 16, 2, 3-H), 6.10 (1 H, dtd, J 16, 7, 1, 4-H), 6.93–7.02 (1 H,
m, ArH), 7.23–7.34 (2 H, m, ArH) and 7.55 (1 H, dd, J 8, 1,
ArH); δC(CDCl3) 13.5 (q, C-7), 21.8 (t, C-6), 33.9 (t, C-4), 35.0
(q, NCH3), 58.3 (d, C-2), 115.4 (s, CN), 120.3 (s), 122.5 (d),
123.2 (d), 126.1 (d), 128.4 (d), 133.6 (d), 136.9 (d) and 147.9 (s);
m/z 294 ([M ϩ 2]ϩ, 9%), 292 (Mϩ, 11), 185 (64), 157 (100), 105
(50) and 77 (76) (Found: M, 292.0574. C14H17N2Br requires M,
292.0575).
To a mixture of N-methyl-o-bromoaniline (15.0 mmol) and aq.
HCl (12 ; 12.5 ml), the appropriate unsaturated aldehyde (18
mmol) was added dropwise at 0 ЊC, followed by aqueous KCN
(1.05 g, 16.2 mol, 5 ml). After being stirred for 12 h at room
temperature, the mixture was separated, the aqueous phase then
being extracted with EtOAc. The combined organic phase and
extracts were washed with aq. HCl (1 ) and brine, dried
(Na2SO4) and concentrated under reduced pressure to give the
title compound; compounds 1a–f decomposed to give aniline
and aldehydes if subjected to chromatography on a silica gel
column.
2-(N-Methyl-o-bromoanilino)pent-3-enenitrile 1a. Yield 59%;
oil; TLC [EtOAc–hexane (2:98)] Rf 0.28; νmax(neat)/cmϪ1
2960, 2801, 2240 (CN), 1590, 1476, 970 and 760; δH (CDCl3)
1.73 (3 H, ddd, J 6, 1, 1, CHCH3), 2.65 (3 H, s, NCH3),
4.80 (1 H, br s, NCH), 6.56 (1 H, ddq, J 15, 3, 1, 3-H),
6.06 (1 H, dqd, J 15, 6, 1, 4-H), 6.88–6.96 (1 H, m,
ArH), 7.20–7.23 (2 H, m, ArH) and 7.48 (1 H, dd, J 8,
4-Methyl-2-(N-methyl-o-bromoanilino)pent-3-enenitrile 1c.
Yield 83%; oil; TLC [EtOAc–hexane (2:98)] Rf 0.29; νmax(neat)/
cmϪ1 2920, 2220 (CN), 1600, 1490, 770, 740 and 670; δH (CDCl3)
1.68 [3 H, d, J 1, 1/2 × C(CH3)2], 1.81 [3 H, d, J 1, 1/
2 × C(CH3)2], 2.84 (3 H, s, NCH3), 4.91 (1 H, d, J 8, NCH), 5.34
(1 H, br d, J 8, 3-H), 6.95–7.06 (1 H, m, ArH), 7.26–7.35 (2 H,
m), ArH and 7.56 (1 H, d, J 8, ArH); δC(CDCl3) 18.6 (q, C-5),
2846
J. Chem. Soc., Perkin Trans. 1, 1997

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2a-c
m, ArH) and 7.57 (1 H, dd, J 8, ArH); δC(CDCl3) 18.1 (q, C-7),
35.2 (q, NCH3), 58.2 (d, C-2), 115.2 (s, CN), 120.3 (s), 121.8 (d),
123.2 (d), 126.1 (d), 128.4 (d), 129.4 (d), 132.9 (d), 133.7 (d),
135.2 (d) and 147.9 (s); m/z 292 ([M ϩ 2]ϩ, 26%), 290 (Mϩ, 29),
277 (21), 275 (20), 211 (51), 185 (74),157 (100), 106 (50) and 77
(60) (Found: M, 290.0417. C14H15N2Br requires M, 290.0419).
2-Cyclopropyl-2-(N-methyl-o-bromoanilino)ethanenitrile 1f.
Yield 78%; oil; TLC [EtOAc–hexane (5:95)] Rf 0.22; νmax(neat)/
cmϪ1 2960, 2210 (CN), 1590, 1480, 1280 and 760; δH (CDCl3)
0.61–0.83 [4 H, m, CH(CH2)2], 1.32–1.43 [1 H, m, CH(CH2)2],
2.91 (3 H, s, NCH3), 4.15 (1 H, d, J 9, NCH), 6.96–7.04 (1 H, m,
ArH), 7.30 (2 H, dd, J 8, 8, ArH) and 7.56 (1 H, dd, J 8, ArH);
δC(CDCl3) 2.1 (t), 4.1 (t), 11.8 (d, C-3), 36.1 (q, NCH3), 60.2 (d,
C-2), 115.4 (s, CN), 120.5 (s), 123.6 (d), 126.2 (d), 128.4 (d),
133.6 (d) and 147.9 (s); m/z 266 ([M ϩ 2]ϩ, 68%), 264 (Mϩ, 72),
240 (18), 238 (20), 225 (82), 223 (92), 186 (70), 184 (83),105 (68),
84 (7), 77 (68) and 49 (100) (Found: M, 264.0268. C12H13N2Br
requires M, 264.0262).
Pd0
NPdBr
NPdBr
R1
R
Na2CO3
R1
R
N
N
Me
Me
42a R = Me, R1 = H
42b R = Pr, R1 = H
42c R = R1 = Me
43b R = Pr, R1 = H
43c R = R1 = Me
Na2CO3
for 42a
–H+
N–
R2
R
NPdBr
N
N
Me
PdBr
Me
Me
Preparation of N-methyl-o-bromoanilinoalk-2-enenitriles 2a–e
The appropriate N-methyl-o-bromoanilinoalk-3-enenitrile was
treated with ButOK (1.1 equiv.) at 0 ЊC in a mixture of THF (10
ml) and ButOH (2 ml). After 2 h the reaction was quenched by
the addition of aqueous NH4Cl (5 ml) to the mixture which was
then extracted with ethyl acetate. The combined extracts were
washed with brine, dried (Na2SO4), concentrated and purified
by chromatography on a silica gel column with gradients of
EtOAc and hexane to afford the title compounds.
46b R2 = Et
46c R2 = H
43a
–Pd0, –Br–
–Pd0, –Br–
NH
R2
R
N
Me
N
N
2-(N-Methyl-o-bromoanilino)pent-2-enenitrile 2a. Yield 64%
(this compound was a mixture of two isomers, E :Z = 95:5).
(2E )-Isomer: oil; TLC [EtOAc–hexane (2:98)] Rf 0.23;
νmax(neat)/cmϪ1 2890, 2205 (CN),1603, 1585, 1470, 750 and 720;
δH (CDCl3) 1.07 (3 H, t, J 6, CH2CH3), 2.36 (2 H, dq, J 6, 6,
CHCH2), 3.03 (3 H, s, NCH3), 5.26 (1 H, t, J 6, 3-H), 7.09 (1 H,
ddd, J 8, 8, 1, ArH), 7.18 (1 H, dd, J 8, 1, ArH), 7.33 (1 H, ddd,
J 8, 8, 1, ArH) and 7.60 (1 H, dd, J 8, 1, ArH); δC(CDCl3) 14.4
(q, C-5), 22.8 (t, C-4), 39.4 (q, NCH3), 114.3 (s, CN), 121.9
(2 × s), 123.5 (d), 127.6 (d), 127.7 (d), 128.4 (d), 133.8 (d) and
144.8 (s); m/z 266 ([M ϩ 2]ϩ, 28%), 264 (Mϩ, 32), 251 (75), 249
(74), 199 (51), 169 (100), 157 (23) and 77 (70) (Found: C, 54.02;
H, 4.99; N, 10.58%; M, 266.0238. C12H13N2Br requires C, 54.54;
H, 4.96; N, 10.61%; M, 266.0242); (2Z)-isomer: δH (CDCl3) 0.85
(3 H, t, J 6, CH2CH3), 3.12 (3 H, s, NCH3) and 5.74 (1 H, t, J 6,
3-H).
Me
Me
44
47b R2 = Et
47c R2 = H
electrocyclization and
oxidative aromatization
H-shift
H
N
N
R2
R
Me
N
N
Me
Me
36e R = H, R2 = Et
48 R = Me, R2 = H
45
Scheme 4
2-(N-Methyl-o-bromoanilino)hept-2-enenitrile 2b. Yield 62%
(this compound was a mixture of two isomers, E :Z = 94:6).
(2E )-Isomer: oil; TLC [EtOAc–hexane (2:98)] Rf 0.24;
νmax(neat)/cmϪ1 2890, 2210 (CN), 1605, 1590, 1470, 745 and
720; δH (CDCl3) 0.93 (3 H, t, J 7, CH2CH3), 1.30–1.46 (4 H, m,
CH2CH2CH3), 2.35 (2 H, dt, J 7, 7, CHCH2), 3.04 (3 H, s,
NCH3), 5.25 (1 H, t, J 7, 3-H), 7.10 (1 H, ddd, J 8, 8, 1, ArH),
7.18 (1 H, dd, J 8, 1, ArH), 7.33 (1 H, ddd, J 8, 8, 1, ArH) and
7.60 (1 H, dd, J 8, 1, ArH); δC(CDCl3) 13.8 (q, C-7), 22.0 (t, C-
6), 29.1 (t, C-5), 31.9 (t, C-4), 39.5 (q, NCH3), 114.4 (s, CN),
121.9 (s), 122.2 (d), 122.3 (s), 127.6 (d), 127.7 (d), 128.4 (d),
133.9 (d) and 144.9 (s); m/z 294 ([M ϩ 2]ϩ, 11%), 292 (Mϩ, 11),
204 (100), 187 (59), 185 (61), 148 (18) and 77 (20) (Found: C,
57.13; H, 5.89; N, 9.57%; M, 292.0570. C14H17N2Br requires C,
57.52; H, 5.87; N, 9.59%; M, 292.0575); (2Z )-isomer:
δH (CDCl3) 3.11 (3 H, s, NCH3) and 5.79 (1 H, t, J 7, 3-H).
4-Methyl-2-(N-methyl-o-bromoanilino)pent-2-enenitrile 2c.
Yield 71% (this compound was a mixture of two isomers,
E :Z = 91:9). (2E )-Isomer: oil; TLC [EtOAc–hexane (2:98)] Rf
0.24; νmax(neat)/cmϪ1 2960, 2220 (CN), 1600, 1500, 1470, 760,
750 and 730; δH (CDCl3) 1.08 [6 H, d, J 7, CH(CH3)2], 2.72–2.91
[1 H, m, CH(CH3)2] 3.03 (3 H, s, NCH3), 5.08 (1 H, d, J 10, 3-
H), 7.05–7.20 (2 H, m, ArH), 7.26–7.37 (1 H, m, ArH) and 7.60
(1 H, dd, J 8, 1, ArH); δC(CDCl3) 23.3 [2 × q, CH(CH3)2], 29.6
(d, C-4), 39.5 (q, NCH3), 114.4 (s, CN), 120.6 (s), 121.8 (s),
127.5 (d), 127.6 (d), 128.4 (d), 129.5 (d), 133.9 (d) and 144.9 (s);
25.8 (q, C-5Ј), 36.6 (q, NCH3), 54.0 (d, C-2), 116.0 (s, CN),
117.1 (s), 120.7 (s), 123.7 (d), 126.3 (d), 128.3 (d), 133.7 (d),
140.7 (s) and 148.0 (s); m/z 280 ([M ϩ 2]ϩ, 7%), 278 (Mϩ, 7), 265
(14), 263 (13), 185 (69), 157 (100) and 105 (51) (Found: M,
27.0421. C13H15N2Br requires M, 278.0419).
2-(N-Methyl-o-bromoanilino)-4-phenylpent-3-enenitrile
1d.
Yield 86%; white solid, mp 86–88 ЊC; TLC [EtOAc–hexane
(2:98)] Rf 0.20; νmax(KBr)/cmϪ1 3054, 2234 (CN), 1582,
1469, 968, 741 and 695; δH (CDCl3) 2.78 (3 H, s, NCH3),
5.11 (1 H, dd, J 4, 1, 2-H), 6.32 (1 H, dd, J 16, 4, 3-H), 6.97–7.08
(2 H, m, ArH), 7.26–7.30 (5 H, m, ArH), 7.45 (2 H, dd,
J 8, 1, ArH) and 7.59 (1 H, d, J 8, ArH); δC(CDCl3) 35.4
(q, NCH3), 58.6 (d, C-2), 115.1 (s, CN), 120.4 (s), 121.6 (d),
123.3 (d), 126.3 (d), 126.8 (2 × d), 128.5 (d), 128.6 (d), 128.7
(2 × d), 133.7 (d), 134.9 (d), 135.1 (s) and 147.8 (s); m/z 328
([M ϩ 2]ϩ, 7%), 326 (Mϩ, 8), 247 (28), 157 (82), 142 (100), 115
(55) and 77 (14) (Found: M, 326.0420. C17H15N2Br requires M,
326.0419).
2-(N-Methyl-o-bromoanilino)hepta-3,5-dienenitrile 1e. Yield
83%; white solid, mp 65–67 ЊC; TLC [EtOAc–hexane (2:98)] Rf
0.19; νmax(KBr)/cmϪ1 2955, 2811, 2230 (CN), 1595, 1508, 990
and 743; δH (CDCl3) 1.79 (3 H, d, J 7, CHCH3), 2.73 (3 H, s,
NCH3), 4.98 (1 H, d, J 4, NCH), 5.66 (1 H, dd, J 15, 4, 3-H),
5.87 (1 H, dq, J 15, 7, 6-H), 6.12 (1 H, dd, J 15, 10, 5-H), 6.59 (1
H, dd, J 15, 10, 4-H), 6.97–7.04 (1 H, m, ArH), 7.29–7.31 (2 H,
J. Chem. Soc., Perkin Trans. 1, 1997
2847

View Article Online
m/z 280 ([M ϩ 2]ϩ, 20%), 278 (Mϩ, 22), 265 (72), 263 (74), 199
(62), 169 (100) and 77 (24) (Found: C, 55.98; H, 5.42; N,
10.06%; M, 278.0421. C13H15N2Br requires C, 56.11; H, 5.44; N,
10.09%; M, 278.0419); (2Z )-isomer: δH (CDCl3) 3.10 (3 H, s,
NCH3) and 5.52 (1 H, t, J 7, 3-H).
3-(o-Bromophenyl)-2-[N-(3-methylbutenyl)anilino]propane-
nitrile 7b. Yield 75%; oil; TLC [EtOAc–hexane (5:95)] Rf 0.28;
νmax(neat)/cmϪ1 2930, 2210 (CN), 1600, 1500, 1030, 760 and
690; δH (CDCl3) 1.73 [3 H, d, J 1, 1/2 × C(CH3)2], 1.76 [3 H, s,
1/2 × C(CH3)2], 3.22 (1 H, dd, J 13, 9, 1/2 × NCHCH2), 3.38
(1 H, dd, J 13, 7, 1/2 × NCHCH2), 3.85 (1 H, dd, J 14, 6,
2-(N-Methyl-o-bromoanilino)-4-phenylpent-2-enenitrile
2d.
Yield 67% (this compound was a mixture of two isomers,
E :Z = 93:7). (2E )-Isomer: oil; TLC [EtOAc–hexane (2:98)] Rf
0.17; νmax(neat)/cmϪ1 3020, 2220 (CN), 1610, 1496, 1020 and 690;
δH (CDCl3) 3.04 (3 H, s, NCH3), 3.68 (2 H, d, J 8, PhCH2), 5.34 (1
H, t, J 8, 3-H), 7.10 (1 H, ddd, J 8, 8, 1, ArH), 7.18–7.34 (7 H, m,
ArH) and 7.59 (1 H, dd, J 8, 1, ArH); δC(CDCl3) 32.4 (t, PhCH2),
39.4 (q, NCH3), 114.2 (s, CN), 119.2 (d), 119.7 (s), 122.0 (s),
126.5 (d), 127.7 (d), 127.9 (3 C, d), 128.4 (2 C, d), 133.8 (2 C, d),
137.6 (s) and 144.7 (s); m/z 328 ([M ϩ 2]ϩ, 38%), 326 (Mϩ, 35),
247 (100), 169 (60), 155 (42), 91 (68) and 77 (30) (Found: M,
326.0410. C17H15N2Br requires M, 326.0419); (2Z )-isomer:
δH (CDCl3) 3.16 (3 H, s, NCH3) and 5.92 (1 H, t, J 7, 3-H).
2-(N-Methyl-o-bromoanilino)hepta-2,4-dienenitrile 2e. Yield
65% (this compound was a mixture of two isomers, 2E :2Z =
90:10). (2E )-Isomer: oil; TLC [EtOAc–hexane (2:98)] Rf 0.26;
νmax(neat)/cmϪ1 2960, 2221 (CN), 1575, 1476, 962, 764 and 725;
δH (CDCl3) 1.02 (3 H, t, J 7.5, CH2CH3), 2.16 (2 H, qdd, J 7.5,
7.5, 1, CH2CH3), 3.11 (3 H, s, NCH3), 5.80 (1 H, dq, J 16, 7.5, 5-
H), 5.82 (1 H, d, J 10, 3-H), 6.38 (1 H, ddq, J 16, 10, 1, 4-H),
7.12 (1 H, ddd, J 8, 8, 1, ArH), 7.20 (1 H, dd, J 8, 1), 7.34 (1 H,
ddd, J 8, 8, 1, ArH) and 7.62 (1 H, dd, J 8, 1, ArH); δC(CDCl3)
13.5 (q, CH2CH3), 26.0 (t, CH2CH3), 39.6 (q, NCH3), 114.4 (s,
CN), 119.8 (d), 120.1 (s), 122.5 (s), 125.1 (d), 128.3 (d), 128.6
(2 × d), 134.0 (d), 137.7 (d) and 144.5 (s); m/z 292 ([M ϩ 2]ϩ,
31%), 290 (Mϩ, 29), 211 (100), 182 (59) and 169 (21) (Found:
C, 57.82; H, 5.23; N, 9.64%; M, 290.0439. C14H15N2Br requires
C, 57.92; H, 5.21; N, 9.66%; M, 290.0419); (2Z,4E )-isomer:
δH (CDCl3) 3.15 (3 H, s, NCH3) and 6.18 (1 H, dd, J 9, 1, 3-H).
1/2 × NCH CH᎐C), 4.00 (1 H, dd, J 14, 7, 1/2 × NCH CH᎐C),
᎐ ᎐
2 2
4.79 (1 H, dd, J 9, 7, NCHCN), 5.16 (1 H, dd, J 7, 6, ArH),
6.99–7.06 (3 H, m, ArH), 7.10–7.35 (5 H, m, ArH) and 7.58 (1
H, d, J 8, ArH); δC(CDCl3) 18.1 (q), 25.8 (q), 38.6 (t), 48.6 (t),
52.9 (d, C-2), 117.9 (s, CN), 119.1 (2 × d), 120.9 (d), 121.7 (d),
124.5 (s), 127.7 (d), 129.2 (3 × d), 132.1 (d), 133.0 (d), 134.8 (s),
135.8 (s) and 147.3 (s); m/z 370 ([M ϩ 2]ϩ, 14%), 368 (Mϩ, 13),
344 (40), 342 (42), 199 (100), 131 (35) and 69 (81) (Found: M,
368.0893. C20H21N2Br requires M, 368.0888).
3-(o-Bromophenyl)-2-(N-cinnamylanilino)propanenitrile 7c.
Yield 83%; oil; TLC [EtOAc–hexane (2:98)] Rf 0.18; νmax(neat)/
cmϪ1 3050, 2250 (CN), 1600, 1500, 980, 760 and 690; δH (CDCl3)
3.29 (1 H, dd, J 14, 9, 1/2 × NCHCH2), 3.48 (1 H, dd, J 14, 7,
1/2 × NCHCH ), 4.16 (2 H, d, J 5.6, NCH CH᎐CH), 4.90 (1 H,
᎐
2
2
dd, J 9, 7, NCHCN), 6.23 (1 H, dt, J 16, 5.6, CH᎐CHPh), 6.66
᎐
(1 H, d, J 16, CH᎐CHPh), 7.10 (1 H, dd, J 8, 8, ArH), 7.14–7.40
᎐
(12 H, m, ArH) and 7.57 (1 H, d, J 8, ArH) δC(CDCl3) 38.8 (t),
53.1 (d, C-2), 53.2 (t), 117.9 (s, CN), 118.8 (2 × d), 121.9 (d),
124.7 (s), 125.8 (d), 126.5 (2 × d), 127.8 (2 × d), 128.6 (2 × d),
129.5 (3 × d), 132.2 (d), 132.8 (d), 133.2 (d), 134.8 (s), 136.6 (s)
and 147.4 (s); m/z 418 (4, [M ϩ 2]ϩ, 4%), 416 (Mϩ, 4), 247 (12),
171 (13), 169 (13), 117 (100), 91 (22) and 77 (18) (Found: C,
68.99; H, 5.11; N, 6.70%; M, 416.0881. C24H21N2Br requires C,
69.22; H, 5.09; N, 6.73%; M, 416.0888).
2-(N-Allyl-N-benzylamino)-3-(o-bromophenyl)propanenitrile
8a. Yield 80%; oil; TLC [EtOAc–hexane (10:90)] Rf 0.39;
νmax(neat)/cmϪ1 3050, 2800, 2220 (CN), 1640, 1500, 740 and
690; δH (CDCl3) 2.98–3.22 (3 H, m, NCHCH2, 1/2 ×
NCH CH᎐CH ), 3.36–3.52 (2 H, m, 1/2 × NCH CH᎐CH ,
᎐
᎐
2
2
2
2
Preparation of 2-alkenylamino-3-(o-bromophenyl)propane-
nitriles 7a–c and 8a–c
1/2 × PhCH2), 4.04–4.16 (2 H, m, NCHCN, 1/2 × PhCH2), 5.22
(1 H, br d, J 10, 1/2 × NCH CH᎐CH ), 5.30 (1 H, br d, J 19.5,
᎐
2
2
Under an atmosphere of argon, a solution of diisopropylamine
(0.9 ml, 5.5 mmol) in THF (10 ml) was cooled to Ϫ15 ЊC and a
solution of BuLi (1.6  in hexane; 3.5 ml, 5.5 mmol) was added
dropwise to it. After 15 min, the LDA solution was cooled to
1/2 × NCH CH᎐CH ), 5.73–5.84 (1 H, m, NCH CH᎐CH ),
᎐ ᎐
2 2 2 2
7.10–7.26 (8 H, m, ArH) and 7.50 (1 H, dd, J 8, 1, ArH);
δC(CDCl3) 38.1 (t), 52.9 (d), 54.2 (t), 116.8 (s, CN), 118.6 (t,
NCH CH᎐CH ), 124.5 (s), 127.3 (2 × d), 128.3 (2 × d), 128.5
᎐
2
2
Ϫ78 ЊC, and
a
solution of the appropriate 2-(alkenyl-
(2 × d), 128.9 (d), 131.9 (d), 132.8 (d), 134.5 (d), 135.1 (s) and
137.5 (s); m/z 356 ([M ϩ 2]ϩ, 0.3%), 354 (Mϩ, 0.3),185 (79), 171
(18), 169 (19), 91 (100) and 65 (23) (Found: C, 64.12; H, 5.41; N,
7.87. C19H19BrN2 requires C, 64.23; H, 5.39; N, 7.89%).
3-(o-Bromophenyl)-2-[N-(3-methylbutenyl)-N-benzylamino]-
propanenitrile 8b. Yield 74%; oil; TLC [EtOAc–hexane (5:95)]
Rf 0.27; νmax(neat)/cmϪ1 2905, 2220 (CN), 1590, 1450, 750 and
690; δH (CDCl3) 1.67 [3 H, s, 1/2 × C(CH3)2], 1.75 [3 H, s,
amino)acetonitrile (5 mmol) in THF (5 ml) was added dropwise
to it. The resulting orange-coloured solution was stirred for 45
min after which a solution of o-bromobenzyl bromide (1.5 g, 6
mmol) in THF (5 ml) was added dropwise to it. The reaction
solution was warmed to room temperature and kept for an add-
itional 6 h before being quenched with saturated aqueous
NH4Cl. The mixture was concentrated under reduced pressure,
and the residue was taken up with EtOAc. The resulting solu-
tion was washed with brine, dried (Na2SO4) and concentrated
under reduced pressure. The crude product was purified by
chromatography on a silica gel column with gradients of EtOAc
and hexane to give the title compound.
2-(N-Allylanilino)-3-(o-bromophenyl)propanenitrile 7a. Yield
81%; oil; TLC [EtOAc–hexane (2:98)] Rf 0.27; νmax(neat)/cmϪ1
3050, 2230 (CN), 1640, 1600, 1590, 750 and 690; δH (CDCl3)
3.25 (1 H, dd, J 13, 9, 1/2 × NCHCH2), 3.41 (1 H, dd, J 13,
6.6, 1/2 × NCHCH ), 4.00 (2 H, d, J 6, NCH CH᎐CH ), 4.84
(1 H, dd, J 9, 6.6, NCHCN), 5.23 (1 H, dd, J 9, 1, 1/2 ×
1/2 × C(CH ) ], 3.04–3.27 (4 H, m, NCHCH , NCH CH᎐C),
᎐
3
2
2
2
3.39 (1 H, d, J 14, 1/2 × CH2Ph), 4.05 (1 H, d, J 14,
1/2 × CH2Ph), 4.14 (1 H, t, J 8, NCHCN), 5.08–5.18 (1 H, m,
NCH CH᎐C),7.14–7.36 (8 H, m, ArH) and 7.52 (1 H, d, J 8,
᎐
2
ArH); δC(CDCl3) 18.1 (q), 25.9 (q), 38.3 (t), 49.1 (t), 52.7 (d, C-
2), 55.4 (t), 117.1 (s, CN), 120.5 (d), 124.5 (s), 127.3 (d), 127.4
(d), 128.3 (2 × d), 128.6 (2 × d), 128.9 (d), 132.0 (d),132.9 (d),
135.3 (s), 137.2 (s) and 137.9 (s); m/z 384 ([M ϩ 2]ϩ, 0.3%), 382
(Mϩ, 0.2), 345 (21), 343 (20), 277 (50), 275 (45), 254 (65), 171
(52), 91 (100) and 69 (85) (Found: M, 382.1038. C21H23N2Br
requires M, 382.1044).
᎐
2
2
2
NCH CH᎐CH ), 5.33 (1 H, dd, J 17, 1, 1/2 × NCH CH᎐CH ),
3-(o-Bromophenyl)-2-(N-cinnamyl-N-benzylamino)propane-
nitrile 8c. Yield 79%; oil; TLC [EtOAc–hexane (2:98)] Rf 0.17;
νmax(neat)/cmϪ1 3050, 2250, 1620, 1500, 970, 750 and 690;
᎐
᎐
2
2
2
2
5.89 (1 H, ddt, J 17, 9, 6, NCH CH᎐CH ), 6.96–7.05 (3 H, m,
᎐
2
2
ArH), 7.12–7.36 (5 H, m, ArH) and 7.60 (1 H, d, J 8, ArH);
δC(CDCl3) 38.4 (t), 52.9 (t), 53.0 (d, C-2), 117.4 (s, CN), 117.5
δ (CDCl ) 3.15–3.40 (3 H, m, NCHCH , 1/2 × NCH CH᎐CH),
᎐
H
3
2
2
(t, C᎐CH ),118.2 (2 C, d), 121.4 (d), 124.4 (s), 127.6 (d), 129.1
3.52 (1 H, d, J 14, 1/2 × CH2Ph), 3.66 (1 H, dd, J 14, 4,
᎐
2
(2 × d), 129.2 (d), 131.9 (d), 132.9 (d), 134.0 (d), 134.4 (s) and
147.0 (s); m/z 342 ([M ϩ 2]ϩ, 4%), 340 (Mϩ, 4), 171 (98), 104
(100) and 77 (65) (Found: C, 63.41; H, 5.06; N, 8.19%; M,
340.0569. C18H17N2Br requires C, 63.52; H, 5.04; N, 8.24%; M,
340.0575).
1/2 × NCH CH᎐CH), 4.05–4.28 (2 H, m, 1/2 × NCH CH᎐CH,
᎐
᎐
2
2
NCHCN), 6.19 (1 H, ddd, J 16, 8, 6.6, NCH CH᎐CH), 6.65 (1
᎐
2
H, d, J 16, NCH CH᎐CH ), 7.14–7.43 (13 H, m, ArH) and 7.54
᎐
2
(1 H, d, J 8, ArH); δC(CDCl3) 38.1 (t), 52.9 (d, C-2), 53.6 (t),
55.5 (t), 116.8 (s, CN), 124.5 (s), 125.8 (d), 126.2 (2 × d), 127.4
2848
J. Chem. Soc., Perkin Trans. 1, 1997

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(2 × d), 127.44 (d), 127.6 (d), 128.35 (d), 128.4 (2 × d), 128.5
(2 × d), 128.9 (d), 131.9 (d), 132.8 (d), 133.5 (d), 135.0 (s), 136.5
(s) and 137.4 (s); m/z 432 [M ϩ 2]ϩ, 2%), 430 (Mϩ, 2), 261 (42),
117 (100) and 91 (52) (Found: M, 430.1052. C25H23N2Br
requires M, 430.1044).
J 16, NCH CH᎐CH ), 6.94 (1 H, ddd, J 8, 8, 1, ArH) and 7.20–
᎐
2
7.53 (14 H, m, ArH); δC(CDCl3) 52.8 (t), 55.2 (t), 93.8 (d), 106.8
(s), 119.1 (s, CN), 121.5 (d), 122.4 (d), 123.9 (d), 126.3 (2 × d),
127.4 (3 × d), 127.6 (d), 128.4 (2 × d), 128.5 (2 × d), 132.1 (d),
132.7 (d), 133.1 (d), 136.2 (s), 137.1 (s), 141.6 (d) and 143.5 (s);
m/z 350 (Mϩ, 6%), 128 (9), 117 (84) and 91 (100) (Found: C,
85.41; H, 6.35; N, 8.02%; M, 350.1772. C25H22N2 requires C,
85.67; H, 6.33; N, 8.00%; M, 350.1783).
N-(3-Methylbut-2-enyl)aniline 26b. Oil; TLC [EtOAc–hexane
(1:99)] Rf 0.10; νmax(neat)/cmϪ1 3400 (NH), 2905, 1600, 1490,
760 and 695; δH (CDCl3) 1.87 [3 H, s, 1/2 × C(CH3)2], 1.91 [3 H,
s, 1/2 × C(CH3)2], 3.66 (1 H, br s, NH), 3.82 (2 H, d, J 6.6,
General procedure for the palladium-catalyzed reactions
To a stirred solution of 1 (1 mmol) in DMF (10 ml) were
sequentially added Et3N (0.167 ml), PPh3 (52 mg, 0.2 mmol),
and Pd(OAc)2 (22.5 mg, 0.1 mmol) at room temperature under
an argon atmosphere. The reaction mixture was stirred and
heated at 100 ЊC for 6–8 h and then cooled to room temper-
ature, diluted with EtOAc (50 ml), washed with water (3 × 15
ml), dried (Na2SO4), filtered and concentrated under reduced
pressure. The residue was separated by chromatography on a
silica gel column with gradients of EtOAc and hexane to give
the products shown in Table 1.
2-(Methylamino)benzonitrile 12. Solid, mp 62–64 ЊC; TLC
[EtOAc–hexane (5:95)] Rf 0.13; νmax(KBr)/cmϪ1 3280 (NH),
3020, 2250 (CN),1576, 1480, 1210 and 743; δH (CDCl3) 2.77 (3
H, d, J 7, NCH3), 4.65 (1 H, br s, NH), 6.52 (1 H, d, J 8, Ph),
6.56 (1 H, d, J 8, Ph) and 7.28 (2 H, ddd, J 8, 8, 1, Ph);
δC(CDCl3) 29.7 (q, NCH3), 95.2 (s), 109.9 (d), 116.0 (d), 117.8
(s, CN), 132.4 (d), 134.1 (d) and 151.0 (s); m/z 132 ([M ϩ 2]ϩ,
84%), 131 (100), 104 (48) and 77 (24).
NCH CH᎐C), 5.48 (1 H, t, J 6, NCH CH᎐C), 6.76 (2 H, d, J 8,
᎐
᎐
2
2
Ph), 6.86 (1 H, dd, J 8, 8, Ph) and 7.36 (2 H, dd, J 8, 8, Ph);
δC(CDCl3) 18.5 (q), 26.2 (q), 42.5 (t), 113.4 (2 × d), 117.8 (d),
122.3 (d), 129.7 (2 × d), 135.9 (s) and 149.0 (s); m/z 161 (Mϩ,
36%), 146 (23), 106 (37), 93 (100), 77 (52) and 69 (64) (Found:
M, 161.1213. C11H15N requires M, 161.1204).
N-Cinnamylaniline 26c. Oil; TLC [EtOAc–hexane (1:99)] Rf
0.07; νmax(neat)/cmϪ1 3400 (NH), 3020, 1625, 1590, 1500, 963,
760 and 695; δH (CDCl3) 3.57 (1 H, br s, NH), 3.96 (2 H, dd, J 6,
1.4, NCH CH᎐CH), 6.36 (1 H, dt, J 16, 6, NCH CH᎐CH), 6.66
᎐
᎐
2
2
(1 H, d, J 16, NCH CH᎐CH ), 6.70–6.74 (2 H, m, Ph), 6.77 (1
᎐
2
H, ddd, J 8, 8, 1, Ph) and 7.22–7.42 (7 H, m, Ph); δC(CDCl3)
46.1 (t), 113.0 (2 × d), 117.5 (d), 126.3 (2 × d), 127.0 (d), 127.4
(d), 128.5 (2 × d), 129.2 (2 × d), 131.4 (d), 136.8 (s) and 148.0
(s); m/z 209 (Mϩ, 78%), 117 (100), 91 (30), 65 (20) and 51 (14)
(Found: M, 209.1219. C15H15N requires M, 209.1204).
9-Methyl-2-phenyl-3-(2E-phenylethenyl)-ã-carboline
17.
White solid, mp 197–199 ЊC; TLC [EtOAc–hexane (5:95)] Rf
0.23; νmax(KBr)/cmϪ1 2960, 1630, 1496, 965, 815 and 750;
δH (CDCl3) 3.83 (3 H, s, NCH3),7.21–7.61 (15 H, m, ArH), 7.97
4-Cyano-1-methylene-3-phenyl-2,3,4,5-tetrahydro-1H-3-
(1 H, d, J 16, ArCH᎐CHPh) and 8.51 (1 H, d, J 8, ArH);
benzazepine 29a. Solid, mp 115–117 ЊC; TLC [EtOAc–hexane
(5:95)] Rf 0.28; νmax(KBr)/cmϪ1 3030, 2220 (CN), 1590, 1500,
760 and 695; δH (CDCl3) 3.18 (1 H, dd, J 14, 5, 1/2 × NCHCH2),
3.51 (1 H, dd, J 14, 12, 1/2 × NCHCH2), 4.35 (1 H, d, J 20,
1/2 × NCH2), 4.49 (1 H, dd, J 12, 5, NCHCH2), 4.61 (1 H, ddd,
᎐
δC(CDCl3) 29.1 (q, NCH3), 108.7 (d), 116.7 (d), 119.8 (d), 121.4
(d), 122.3 (s), 126.6 (d), 127.0 (2 C, d), 127.4 (2 × d), 127.8 (d),
128.3(2 × d), 128.5 (2 × d), 130.2 (2 × d), 131.0 (d),134.2 (s),
137.8 (s), 140.5 (s), 141.2 (s), 142.7 (s), 145.2 (s) and 151.0 (s);
m/z 360 (Mϩ, 100%), 359 (89), 283 (74), 268 (22), 91 (31) and
77 (75) (Found: C, 86.47; H, 5.57; N, 7.74%, M, 360.1634.
C26H20N2 requires C, 86.63; H, 5.60; N, 7.78%; M, 360.1626).
N-Allyl-N-benzyl-2-(o-cyanophenyl)ethenylamine 24a. Oil;
TLC [EtOAc–hexane (2:98)] Rf 0.09; νmax(neat)/cmϪ1 3026,
2214 (s, CN), 1622, 1588, 940, 753 and 698; δH (CDCl3) 3.78 (2
J 20, 2, 2, 1/2 × NCH ), 5.34 (1 H, dd, J 2, 2, 1/2 × C᎐CH ),
᎐
2
2
5.51 (1 H, dd, J 2, 2, 1/2 × C᎐CH ), 6.72–6.82 (3 H, m, ArH),
᎐
2
7.11–7.24 (5 H, m, ArH) and 7.45 (1 H, dd, J 8, 1, ArH);
δC(CDCl3) 38.6 (t), 51.05 (d), 51.10 (t), 113.1 (t), 113.8 (2 × d),
118.6 (s), 119.4 (d), 127.8 (d), 128.4 (2 × d), 129.3 (3 × d), 132.6
(s), 139.6 (s), 148.6 (s) and 148.8 (s); m/z 260 (Mϩ, 54%), 259
(35), 245 (34), 129 (71), 115 (85) and 77 (100) (Found: C, 82.95;
H, 6.23; N, 10.75. C18H16N2 requires C, 83.03; H, 6.20; N,
10.77%).
H, dd, J 6, 1, NCH CH᎐CH ), 4.37 (2 H, s, CH Ph), 5.19 (1 H,
᎐
2
2
2
dt, J 9, 1, 1/2 × NCH CH᎐CH ), 5.26 (1 H, d, J 14, 1/2 NCH -
᎐
2
2
2
CH᎐CH), 5.61 (1 H, d, J 14, NCH᎐CH), 5.81 (1 H, ddt, J 14, 9,
᎐
᎐
6, NCH CH᎐CH ), 6.93 (1 H, ddd, J 8, 8, 1, ArH), 7.14 (1 H, d,
4-Cyano-1-phenylmethylene-3-phenyl-2,3,4,5-tetrahydro-1H-
3-benzazepine 29c. Oil; TLC [EtOAc–hexane (1:99)] Rf 0.04;
νmax(neat)/cmϪ1 3010, 2905, 2210 (CN), 1590, 1500, 760 and
690; δH (CDCl3) 3.23 (1 H, dd, J 14, 5.5, 1/2 × NCHCH2), 3.53
(1 H, dd, J 14, 12, 1/2 × NCHCH2), 4.53 (1 H, dd, J 12, 5.5,
NCHCH2), 4.73 (2 H, d, J 2, NCH2), 6.67 (1 H, dd, J 8,1, ArH),
᎐
2
2
J 14, NCH᎐CH), 7.25–7.38 (7 H, m, ArH) and 7.44 (1 H, d, J 8,
᎐
ArH); δC(CDCl3) 53.4 (t), 55.5 (t), 93.9 (d), 107.0 (s), 118.0 (t),
119.2 (s, CN), 121.7 (d), 122.6 (2 × d), 127.5 (2 × d), 128.9
(2 × d), 132.2 (d), 132.6 (d), 133.0 (d), 135.0 (s), 141.7 (d) and
143.8 (s); m/z 274 (Mϩ, 10%), 273 (7), 158 (7), 128 (9), 91 (100)
and 65 (21) (Found: C, 83.01; H, 6.64; N, 10.18. C19H18N2
requires C, 83.17; H, 6.62; N, 10.22%).
N-Benzyl-N-(3-methylbut-2-enyl)-2-(o-cyanophenyl)ethenyl-
amine 24b. Oil; TLC [EtOAc–hexane (2:98)] Rf 0.15; νmax(neat)/
cmϪ1 2910, 2205 (s, CN), 1620, 1590, 940, 760 and 697;
δH (CDCl3) 1.61 [3 H, d, J 1, 1/2 × C(CH3)2], 1.74 [3 H, d, J 1,
6.78 (1 H, ddd, J 8, 8, 1, ArH), 6.92 (1 H, d, J 2, C᎐CHPh),
᎐
7.14–7.31 (11 H, m, ArH) and 7.47 (1 H, dd, J 8, 1); δC(CDCl3)
38.4 (t), 49.5 (t), 51.4 (d), 114.2 (2 × d), 118.7 (s), 119.6
(d),127.3 (d), 127.6 (d), 128.0 (d), 128.4 (d), 128.6 (2 × d), 128.7
(d), 129.2 (4 × d), 129.8 (d), 132.9 (s), 136.5 (s), 141.5 (s), 142.0
(s), 148.6 (s); m/z 336 (Mϩ, 35%), 245 (52), 128 (30), 115 (32),
104 (50), 91 (100) and 77 (84) (Found: C, 85.50; H, 6.03; N,
8.37. C24H20N2 requires C, 85.67; H, 6.00; N, 8.33%).
1/2 × C(CH ) ], 3.75 (2 H, d, J 7, NCH CH᎐C), 4.33 (2 H, s,
᎐
3
2
2
CH Ph), 5.21 (1 H, br d, J 7, NCH CH᎐C), 5.58 (1 H, d, J 14,
᎐
2
2
NCH᎐CH ), 6.90 (1 H, ddd, J 8, 8, 1, ArH), 7.15 (1 H, d, J 14,
2,3-Dihydro-1-methylene-3-phenyl-1H-3-benzazepine
31a.
᎐
NCH᎐CH), 7.24–7.36 (7 H, m, ArH) and 7.42 (1 H, dd, J 8, 1,
Oil, TLC [EtOAc–hexane (10:90)] Rf 0.53; νmax(neat)/cmϪ1
2930, 1630, 1600, 1350, 760 and 690; δH (CDCl3) 4.34 (2 H, s,
᎐
ArH); δC(CDCl3) 17.8 (q), 25.6 (q), 48.3 (t), 55.3 (t), 93.2 (d),
106.7 (s), 119.2 (d), 121.4 (d), 122.2 (d), 127.3 (d), 127.32 (s),
127.4 (2 × d), 128.5 (2 × d), 132.1 (d), 132.9 (d), 136.5 (s), 137.5
(s), 141.9 (d) and 143.9 (s); m/z 302 (Mϩ, 16%), 233 (24), 106
(30), 91 (100) and 69 (57) (Found: M, 302.1786. C21H22N2
requires M, 302.1783).
NCH ), 4.96 (1 H, d, J 1, 1/2 × C᎐CH ), 5.42 (1 H, d, J 1,
᎐
2
2
1/2 × C᎐CH ), 5.62 (1 H, d, J 9.5, NCH᎐CH ), 6.54 (1 H, d, J
᎐
᎐
2
9.5, NCH᎐CH) and 6.99–7.42 (9 H, m, ArH); δ (CDCl ) 54.8
᎐
C
3
(t), 106.3 (d), 114.3 (t), 119.5 (2 × d), 122.1 (d), 124.1 (d), 127.5
(d), 127.6 (d), 129.3 (2 × d), 129.7 (d), 134.6 (d), 134.62 (s),
138.2 (s), 143.4 (s) and 146.0 (s); m/z 233 (Mϩ, 43%), 232 (32),
141 (17), 130 (23), 115 (31), 104 (62) and 77 (100) (Found: M,
233.1198. C17H15N requires M, 233.1204) (Found: C, 87.45; H,
6.50; N, 6.04. C17H15N requires C, 87.51; H, 6.48; N, 6.01%).
3-Benzyl-2,3-dihydro-1-methylene-1H-3-benzazepine 32a. Oil;
N-Benzyl-N-cinnamyl-2-(o-cyanophenyl)ethenylamine
24c.
Oil; TLC [EtOAc–hexane (5:95)] Rf 0.09; νmax(neat)/cmϪ1 3030,
2210 (s, CN), 1620, 1590, 750 and 697; δH (CDCl3) 3.96 (2 H, d,
J 6, NCH CH᎐CH), 4.44 (2 H, s, CH Ph), 5.73 (1 H, d, J 14,
᎐
2
2
NCH᎐CH ), 6.18 (1 H, dt, J 16, 6, NCH CH᎐CH), 6.55 (1 H, d,
᎐
᎐
2
J. Chem. Soc., Perkin Trans. 1, 1997
2849

View Article Online
TLC [EtOAc–hexane (2:98)] Rf 0.32; νmax(neat)/cmϪ1 3026,
1619, 1591, 1487, 765 and 697; δH (CDCl3) 3.58 (2 H, s, NCH2),
(q, NCH3), 108.5 (d), 115.8 (d), 118.6 (d), 119.3 (d), 120.8 (d),
121.8 (s), 127.2 (d), 132.7 (s), 141.0 (s), 141.6 (s) and 155.4 (s);
m/z 211 ([M ϩ 1]ϩ, 23%), 210 (Mϩ, 100), 209 (54) and 195 (25)
(Found: C, 79.80; H, 6.75; N, 13.37%; M, 210.1155. C14H14N2
requires C, 79.96; H, 6.72; N, 13.33%; M, 210.1157).
4.19 (2 H, s, NCH Ph),4.75 (1 H, s, 1/2 × C᎐CH ), 5.23 (1 H, d, J
᎐
2
2
9, NCH᎐CH ), 5.40 (1 H, s, 1/2 × C᎐CH ), 6.25 × (1 H, d, J 9,
᎐
᎐
2
NCH᎐CH), 6.95 (1 H, dd, J 8, 8, ArH), 7.07–7.15 (2 H, m,
᎐
ArH) and 7.24–7.34 (6 H, m, ArH); δC(CDCl3) 55.2 (t), 59.6 (t),
100.5 (d), 114.1 (t), 123.0 (d), 127.4 (d), 127.5 (2 × d), 128.0
(2 × d), 128.5 (2 × d), 128.9 (d), 135.7 (s), 137.6 (s), 138.0 (s),
138.1 (d) and 143.8 (s); m/z 247 (Mϩ, 36%), 156 (22), 91 (100),
77 (14) and 65 (25) (Found: C, 87.32; H, 6.97; N, 5.70%; M,
247.3385. C18H17N requires C, 87.41; H, 6.93; N, 5.66%; M,
247.3397).
2,8,9-Trimethyl-ã-carboline 36a. Solid, mp 97–98 ЊC; TLC
[EtOAc–hexane (5:95)] Rf 0.11; νmax(KBr)/cmϪ1 3050, 1615,
1598 and 1490; δH (CDCl3) 2.41 (3 H, s, ArCH3), 2.66 (3 H, s,
ArCH3), 3.66 (3 H, s, NCH3), 7.23–7.32 (3 H, m, ArH), 7.48 (1
H, dd, J 8, 8, ArH) and 8.37 (1 H, d, J 8, ArH); δC(CDCl3) 20.3
(q, ArCH3), 22.5 (q, ArCH3), 28.7 (q, NCH3), 108.4 (d), 116.5
(d), 119.2 (d), 120.3 (d), 121.7 (2 × s), 125.6 (d), 128.3 (s), 133.4
(s), 141.2 (s) and 148.8 (s); m/z 211 ([M ϩ 1]ϩ, 24%), 210 (100,
Mϩ), 209 (56) and 195 (75) (Found: C, 80.03; H, 6.69; N,
13.29%, M, 210.1156. C13H12N2 requires C, 79.96; H, 6.72; N,
13.33%; M, 210.1157).
3,9-Dimethyl-2-propyl-ã-carboline 36b. Solid, mp 71–73 ЊC;
TLC [EtOAc–hexane (5:95)] Rf 0.07; νmax(KBr)/cmϪ1 3050,
1610, 1600 and 1490; δH (CDCl3) 1.08 (3 H, t, J 7, CH2CH3),
1.66–1.84 (2 H, m, ArCH2CH2), 2.76 (3 H, s, NCH3), 2.79 (2 H,
d, J 7.6, ArCH2), 3.81 (3 H, s, NCH3), 7.33 (1 H, ddd, J 8, 8, 1,
ArH), 7.40–7.42 (2 H, m, ArH), 7.52 (1 H, ddd, J 8, 8, 1, ArH)
and 8.41 (1 H, dd, J 8, 1, ArH); δC(CDCl3) 14.0 (q, CH2CH3),
22.2 (q, ArCH3), 23.4 (t), 28.9 (q, NCH3), 35.8 (t, ArCH2),
108.5 (d), 115.9 (d), 119.3 (d), 120.5 (d), 121.8 (s), 126.7 (d),
132.8 (s), 133.5 (s), 138.8 (s), 141.5 (s) and 148.5 (s); m/z 238
(Mϩ, 46%), 209 (100), 193 (18) and 57 (42) (Found: C, 80.55;
H, 7.64; N, 11.73%; M, 238.1478. C16H18N2 requires C, 80.62;
H, 7.62; N, 11.76%; M, 238.1470).
3,8-Dihydro-2,8-dimethylpyrrolo[3,2-b]indole 45. Solid, mp
162–164 ЊC; TLC [EtOAc–hexane (5:95)] Rf 0.13; νmax(KBr)/
cmϪ1 3040 (NH), 3010, 1600, 1495 and 740; δH (CDCl3) 2.45
(3 H, d, J 0.6, ArCH3), 3.76 (3 H, s, NCH3), 5.91 (1 H, q, J 0.6,
ArH), 7.07–7.20 (2 H, m, ArH), 7.30 (1 H, dd, J 8, 1, ArH), 7.53
(1 H, dd, J 8, 1, ArH) and 7.85 (1 H, br s, NH); δC(CDCl3) 14.3
(q), 30.8 (q, NCH3), 89.1 (d), 108.8 (d), 115.3 (s), 115.6 (d), 117.6
(d), 118.0 (s), 119.3 (d), 132.2 (s), 136.1 (s) and 140.1 (s); m/z 184
(Mϩ, 100%), 183 (93), 169 (20), 168 (24), 102 (9) and 91 (13)
(Found: C, 78.28; H, 6.54; N, 15.18. C12H12N2 requires C, 78.22;
H, 6.57; N, 15.21%).
2,9-Dimethyl-ã-carboline 48. Solid, mp 84–86 ЊC; TLC
[EtOAc–hexane (5:95)] Rf 0.11; νmax(KBr)/cmϪ1 2960, 1610,
1580, 750 and 740; δH (CDCl3) 2.37 (3 H, s, ArCH3), 3.50
(3 H, s, NCH3), 7.13–7.22 (3 H, m, ArH), 7.38 (1 H, ddd, J 8, 8,
1, ArH), 8.22 (1 H, s, ArH) and 8.24 (1 H, dd, J 8, 1, ArH);
δC(CDCl3) 19.0 (q, ArCH3), 28.4 (q, NCH3), 108.5 (d), 115.3
(d), 119.4 (d), 120.2 (d), 121.7 (s), 126.8 (d), 129.5 (s), 134.2 (s),
139.3 (s), 141.4 (s) and 142.2 (d); m/z 197 ([M ϩ 1]ϩ, 35%), 196
(Mϩ, 99), 195 (100), 181 (31), 167 (15), 153 (12) and 98 (21)
(Found: C, 79.47; H, 6.20; N, 14.24%; M, 196.0989. C13H12N2
requires C, 79.55; H, 6.17; N, 14.28%; M, 196.1000).
Acknowledgements
We thank the National Science Council of the Republic of
China for financial support (Grant NSC 83-0208-M041-006)
and Prof. Jim-Min Fang (National Taiwan University) for
helpful discussions.
References
9-Methyl-1-isopropyl-ã-carboline 36c. Oil; TLC [EtOAC–
hexane (15:85)] Rf 0.23; νmax(neat)/cmϪ1 2967, 1612, 1572, 1479,
750 and 740; δH (CDCl3) 1.43 [6 H, d, J 7, CH(CH3)2] 3.73–3.90
[1 H, m, ArCH(CH3)2], 4.03 (3 H, s, NCH3), 7.20–7.31 (2 H, m,
ArH), 7.37 (1 H, d, J 8, ArH), 7.50 (1 H, ddd, J 8, 8, 1, ArH),
8.36 (1 H, dd, J 8, 1, ArH) and 8.45 (1 H, d, J 8, ArH);
δC(CDCl3) 23.5 [2 × q, 2 × CH(CH3)2], 27.7 (d, ArCH), 32.4 (q,
NCH3), 108.6 (d), 116.9 (d), 119.6 (d), 120.5 (d), 122.0 (s), 127.4
(d), 129.5 (s), 132.0 (s), 140.0 (s), 141.9 (d) and 142.3 (s); m/z 224
(Mϩ, 100%), 209 (97), 194 (73), 181 (13) and 104 (14) (Found:
C, 80.25; H, 7.22; N, 12.46%; M, 224.1324. C15H16N2 requires
C, 80.31; H, 7.19; N, 12.50%; M, 224.1313).
3,9-Dimethyl-2-phenyl-ã-carboline 36d. Solid, mp 132–
134 ЊC; TLC [EtOAc–hexane (2:98)] Rf 0.10; νmax(KBr)/cmϪ1
3048, 1620, 1593, 1487, 747 and 702; δH (CDCl3) 2.65 (3 H, s,
ArCH3), 3.55 (3 H, s, NCH3), 7.20 (1 H, dd, J 8, 1, ArH), 7.25 (1
H, dd, J 8,1, ArH), 7.33–7.46 (7 H, m, ArH) and 8.40 (1 H, d, J
8, ArH); δC(CDCl3) 23.3 (q, ArCH3), 28.6 (q, NCH3), 108.4 (d),
116.5 (d), 119.3 (d), 120.5 (d), 121.4 (s), 127.0 (2 × d), 128.1
(2 × d), 129.2 (2 × d), 132.7 (s), 133.7 (s), 139.9 (s), 141.2 (s),
141.7 (s) and 147.3 (s); m/z 272 (Mϩ, 100%), 271 (52), 256 (14)
and 128 (12) (Found: C, 83.66; H, 5.97; N, 10.34%; M,
272.1298. C19H16N2 requires C, 83.78; H, 5.93; N, 10.29%; M,
272.1313).
1 (a) R. F. Heck, Palladium Reagents in Organic Syntheses, Academic
Press, London, 1985; (b) R. F. Heck, Org. React. 1982, 27, 345;
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(d) R. F. Heck, Acc. Chem. Res., 1979, 12, 146.
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Synlett, 1997, in press.
3 S. B. Kadin, J. Org. Chem., 1973, 38, 1348.
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Tetrahedron, 1993, 49, 1431.
10 R. A. Abramovich, Can. J. Chem., 1960, 38, 2273.
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S. M. Weinreb, Tetrahedron Lett., 1994, 35, 4287.
3-Ethyl-9-methyl-ã-carboline 36e. Oil; TLC [EtOAc–hexane
(10:90)] Rf 0.25; νmax(neat)/cmϪ1 2961, 1620, 1475, 1410, 845,
817 and 749; δH (CDCl3) 1.40 (3 H, t, J 7.5, CH2CH3), 3.02 (2 H,
q, J 7.5, ArCH2), 3.75 (3 H, s, NCH3), 7.21 (1 H, d, J 8, ArH),
7.27 (1 H, dd, J 8, 8, ArH), 7.35 (1 H, d, J 8, ArH), 7.50 (1 H,
dd, J 8,1, ArH), 7.54 (1 H, dd, J 8, 1, ArH) and 8.41 (1 H, dd, J
8, 1, ArH); δC(CDCl3), 15.0 (q, CH2CH3), 28.8 (t, ArCH2), 31.4
Paper 7/02710I
Received 21st April 1997
Accepted 18th June 1997
2850
J. Chem. Soc., Perkin Trans. 1, 1997