Synthesis of carbazoles by dehydro Diels-Alder reactions of ynamides

Article abstract of DOI:10.1016/j.tet.2008.02.029

A new approach to carbazoles and benzannulated carbazoles by means of intramolecular dehydro Diels-Alder of ynamides is reported. N-(o-Ethynyl)aryl ynamides and N-(o-ethynyl) arylynamides were prepared in a few steps starting from o-iodoaniline. Thermal c

Full text of DOI:10.1016/j.tet.2008.02.029

Available online at www.sciencedirect.com
Tetrahedron 64 (2008) 3674e3686
www.elsevier.com/locate/tet
Synthesis of carbazoles by dehydro DielseAlder reactions of ynamides
*
´
´
´
´
M. Fernanda Martınez-Esperon, David Rodrıguez, Luis Castedo, Carlos Saa
Departamento de Qu´ımica Orga´nica, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
Received 28 September 2007; received in revised form 7 February 2008; accepted 8 February 2008
Available online 14 February 2008
Abstract
A new approach to carbazoles and benzannulated carbazoles by means of intramolecular dehydro DielseAlder of ynamides is reported.
N-(o-Ethynyl)aryl ynamides and N-(o-ethynyl) arylynamides were prepared in a few steps starting from o-iodoaniline. Thermal cycloaddition
of N-(o-ethynyl)aryl ynamides and N-(o-ethynyl) arylynamides affords carbazoles and benzannulated and heteroannulated carbazoles in
moderate-to-good yields.
Ó 2008 Elsevier Ltd. All rights reserved.
Kano's approach
1. Introduction
Me
Me
1. LDA, THF
methylenetriphenyl-
phosphorane
Carbazoles constitute an important class of alkaloids dis-
playing a wide variety of biological activities,1 and their deriv-
atives are also widely used as building blocks for new organic
materials.2 Accordingly, syntheses of carbazoles and modified
carbazoles have been extensively studied.3,4 One of the most
important and well-studied benzo[b]carbazoles is the interest-
ing antitumoral agent ellipticine,5 and the similarity of ben-
zo[b]carbazoles in general to this agent suggests their
potential for the development of novel antineoplastic agents.
Accordingly, several synthetic approaches to benzo[b]carb-
azoles have been developed over the past half century,6 includ-
ing benzannulation of indoles (Scheme 1),7 Fischer
indolization of phenylhydrazones (Scheme 2),8 modified Ne-
nitzescu reaction of p-benzoquinones with 2-aminomethy-
lene-1-indanones (Scheme 3),6 DielseAlder reactions of
pyrano[3,4-b]indol-3-ones,9 4H-furo[3,4-b]indoles10 and 2,4-
dihydropyrrolo[3,4-b]indoles (Scheme 4)11 and cycloaromati-
zation of N-[2-(1-alkynyl)phenyl]ketenimines (Scheme 5);12
yields have varied between 22% and 98%. The main failure
of these methods is their relative lack of flexibility, since
they almost exclusively allow the synthesis of the parent ben-
zo[b]carbazole nucleus but not that of benzo[b]annulated
analogues.
0 to rt to -78 °C
Ph
2. (PhCO)2O, THF
-78 °C to rt
THF, 0 °C to rt
N
N
O
SO2Ph
SO2Ph
Me
400 to 500 °C
26%
N
H
N
H
CH2
Me
Bergman's approach
Me
Me
O
1. cat. 10% Pd/C
HOAc, reflux
+
Me
N
2. 3 Å MS
N
H
H
Koomen's approach
1. BuLi, THF, -15 °C
2. phthalic anhydride
conc. HCl
reflux
THF, -78 °C to rt
(44% overall)
N
Me
N
COOLi
Me
O
Me
O
1. MeLi, THF
-100 to -78 °C
2. SnCl2, HCl
(83% overall)
N
Me
N
Me
Me
O
* Corresponding author.
E-mail address: qocsaa@usc.es (C. Saa).
´
Scheme 1. Benzannulation of indoles.
0040-4020/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.02.029

M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
3675
Kirsch's approach
2. Result
Cl
N
N
OMe
HCO2Et, NaOMe
toluene
2.1. Synthesis and intramolecular dehydro DielseAlder
reactions of N-(o-ethynyl)aryl ynamides 1
HOHC
NaOAc, MeOH
O
O
Ynamides 1aef were synthesized in three steps starting
from commercially available 2-iodoaniline (4). N-Tosylation
of 4 followed by Sonogashira coupling with the appropriate al-
kyne 5 gave alkynes 6aef, and N-ethynylation of these with
(trimethylsilyl)ethynyliodonium salt (7) gave the desired N-
(o-ethynyl)aryl ynamides 1aef, generally in reasonably good
overall yield (Scheme 7, Table 1).16 Using Cs2CO3 as the
base in the last step afforded desilylated ynamides 1
(R1¼H), using KHMDS retained the TMS group (1b0,c0,
R1¼TMS).4a
MeO
H
N
THF/ conc. HCl
(10:1)
N
reflux
O
N
H
MeO
OH
Scheme 2. Fischer indolization of phenylhydrazones.
Kuckländer's approach
O
AcO
1. HOAc, rt
2. Ac2O, reflux
+
The formation of carbazoles from ynamides 1 generally
proceeded best when the IDDA reaction was carried out by
heating the ynamides in a mixture of toluene and Et3N at
150 ꢀC (Table 2). Heating 1a under these conditions gave 2-
methylcarbazole 3a in only a moderate 40% yield (Table 2,
entry 1), but the interesting tetrahydro-5H-benzo[b]carbazole
nucleus 3b19 was obtained in 60% yield if Z¼Ts (43% yield
if Z¼CO2Me, entry 2). Exceptionally, preparation of the sily-
lated analogue 3b0 proceeded best in toluene/MeOH (entry
3).13 The benzannulated carbazole 3c was synthesized in low
N
Bn
BnHN
O
O
OAc
Scheme 3. Modified Nenitzescu reaction.
Here, we present a full account of the synthesis of carb-
azoles and benzannulated carbazoles 3, which are based on
intramolecular dehydro DielseAlder (IDDA) reactions13,14
of N-(o-ethynyl)aryl ynamides 115,16 and N-(o-ethynyl) aryl-
ynamides 2 (Scheme 6).17,18
Moody's approach
O
1,2-dichloroethane
+
O
reflux
44%
N
H
N
H
Me
Me
Gribble's approach
O
F
NaBH4
THF, Mg
O
+
CF3COOH
reflux
38%
N
Br
N
SO2Ph
SO2Ph
aq. MeOH/NaOH
O
+
THF, reflux
88%
N
H
N
N
SO2Ph
SO2Ph
CO2Me
Sha's approach
N
THF, reflux
NCO2Me
+
44%
N
N
SO2Ar
SO2Ar
DDQ, benzene
80%
Li / NH3 liq
95%
N
H
N
H
Scheme 4. DielseAlder reactions.

3676
M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
Shi and Wang's approach
R
Ph
R
R
Ph3PBr2
diphenylketene
Et2O, 0 °C to rt.
71-90%
Et3N, benzene
C
Ph
PPh3
reflux
74-91%
N
N
R
NH2
R
R
N
11
benzene
reflux
33-98%
N
Ph
H
N
Ph
Ph
Scheme 5. Cycloaromatization of ketenimines.
EWG
R1
N
R2
3
EWG
N
EWG
N
R1
R1
R2
R2
Δ
Δ
EWG
N
EWG
N
R1
R2
1
2
EWG = Ts, Ms, CO2Me
R1 = H, TMS
R2 = H, TMS, Ph
Scheme 6. Synthesis of carbazoles by intramolecular dehydro DielseAlder of ynamides.
R
Rh(I)-catalyzed [2þ2þ2] cycloaddition of ynamides to al-
kynes, which is not convenient for these targets.21 Unlike
silylated enyne 1b0, silylated arenyne 1c0 underwent decompo-
sition during all attempted IDDA reactions (entry 5).
I
1) TsCl, Py, THF
(5)
2)
R
NH2
NH
Ts
CuI (5%), PdCl2(PPh)2 (3%),
THF/Et3N, rt.
4
6a-f
Gratifyingly, unlike the methods mentioned above, the yna-
mide IDDA approach allowed the uneventful preparation of
benz[b]annulated carbazoles with additional benzene rings:
heating ynamides 1def gave the known naphtho[1,2-b]carb-
azole 3d (90% yield, entry 6),22 the hitherto unknown naph-
tho[2,1-b]carbazole 3e (30% yield, entry 7) and the likewise
unknown dibenzo[a,c]carbazole 3f (60% yield, entry 8).
We next examined the regioselectivity of the dehydro
DielseAlder reaction by installing a second aryl ring in the
starting ynamide 1 (R1¼Ar). Heating 1g23 gave the 2-nitro-
11-phenylbenzo[b]carbazole 3g (though in rather poor yield)
by selective cycloaddition to the conjugated arenynamide moi-
ety (Scheme 8), but with the 2-pyrimidinyl ynamide 1h23 the
cycloaddition occurred regioselectively at the arenyne moiety,
R
R1
1) Cs2CO3 or KHMDS
OTf
TMS
I
N
Ts
2)
Ph
CH2Cl2, rt
(7)
1a-f, R1 = H
1b',c', R1 = TMS
Scheme 7. Synthesis of N-(o-ethynyl)aryl ynamides 1aef and silylated
ynamides 1b0,c0.
yield20 when protected as a tosylate (Z¼Ts) but protection as
a carbamate (Z¼CO2Me) gave a more satisfactory 50% yield
(entry 4). This metal-free IDDA approach to benzannulated
carbazoles nicely complements the efficient intermolecular

M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
3677
Table 1
Synthesis of N-(o-ethynyl)aryl ynamides 1aef and silylated ynamides 1b0,c0
Table 2
Results of intramolecular dehydro DielseAlder reactions of ynamides 1aef
and silylated ynamides 1b0,c0
Entry
R
R1
Ynamide
Yielda (%)
Entry Ynamide 1
Carbazole 3
Yielda (%)
1
H
1a
45b
Me
1
1a
40
N
2
3
4
5
6
H
1b
1b0
1c
35
38
74
58
20
Ts
60
43
TMS
H
Z = Ts
2
3
1b
N
Z
Z = CO2Me
TMS
H
1c0
1d
1b0
85b
N
TMS
Ts
12 (15)b
50
Z = Ts
4
5
1c
N
Z
7
H
H
1e
1f
16
38
Z = CO2Me
1c0
d
8
N
Ts
TMS
a
Yield for three steps.
Yield for four steps.
b
6
7
1d
1e
90
N
Ts
giving 6-pyrimidinylbenzo[b]carbazole 3h (again in poor
yield). Interestingly, when the cyclohexenylynamide 1b was
subjected to Sonogashira conditions in the presence of
iodobenzene,24 two carbazoles were isolated, 11-cyclohexe-
nylbenzo[b]carbazole 3i in 8% yield and 6-phenyltetrahy-
drobenzo[b]carbazole 3j in 16% yield, suggesting that the
initial phenylation of 1b had been followed by the two possi-
ble cycloadditions in roughly 1:2 ratio (Scheme 8).
30
60
N
Ts
8
1f
N
Ts
2.2. Synthesis and intramolecular dehydro DielseAlder
reactions of N-(o-ethynyl) arylynamides 2
a
Conditions: 1 (0.01 M in toluene, typically 6 mL) and 0.5 mL of Et3N,
sealed tube, 150 ꢀC.
Given the above results and Danheiser’s17 observation that
conjugated enynamides (in our case 2) give better results than
ynamides lacking such conjugation (in our case 1), we decided
to explore in more detail the IDDA reactions of N-(o-ethynyl)
arylynamides 2. Like ynamides 1, these were prepared from o-
iodoaniline (4) (Scheme 4). Sonogashira coupling between 4
and alkyne 5i (R¼TIPS), followed by N-tosylation gave the al-
kyne 6i, and N-ethynylation of the latter with (trimethylsilyl)
ethynyliodonium salt 7 gave the N-(o-ethynyl)aryl ynamide 1i
in good overall yield. Sonogashira cross-coupling of 1i with
aryl iodides 8 then led to the desired TIPS-substituted arylyna-
mides 20 in relatively good yields (Table 3).24
All attempts to cyclize the silylated compounds 20aei led to
complex mixtures, probably owing to steric hindrance by the
triisopropylsilyl group. Therefore, deprotection was carried
out before the IDDA reaction, treatment of alkynes 20aei
with TBAF giving the corresponding arylynamides 2aei in
rather good yields (Scheme 9 and Table 3).
b
MeOH instead Et3N.
To our delight, heating 2a in a mixture of toluene and Et3N
afforded 3c in 50% yield (Table 4, entry 1) instead of the 12%
obtained with 1c (Table 2, entry 4), in keeping with the trend
observed by Danheiser.17 However, naphthylynamide 2b gave
a lower yield of naphthocarbazole 3d than did 1d, 73% (Table
4, entry 2) as against 90% (Table 2, entry 6). Surprisingly, the
yields of the IDDA reactions of arylynamides 2 did not seem
to be influenced by the electronic characteristics of the aryl-
ynamide moiety (Table 4, entries 3 and 4), best yields were ob-
tained with halogenated arylynamides (entries 5 and 6). When
heteroarylynamides were tried, the 2-pyridylynamide 2g failed
to respond to IDDA conditions (entry 7), and 2h and 2j gave
low yields of the corresponding heteroarylcarbazoles (entries 8
and 9).25 Halogen substitution in the non-reactive aryl ring of
the ynamide was well tolerated (2k, Fig. 1), as was the use of

3678
M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
Table 3
Synthesis of N-[o-(triisopropylsilyl)ethynyl] arylynamides 20 and N-(o-ethy-
nyl) arylynamides 2
NO2
Ph
Ph
NO2
Toluene
150 °C
16%
N
Ts
Entry
1
Ar
Arylynamide 20 Yield (%) Arylynamide 2 Yield (%)
N
Ts
20a
20b
20c
85
70
90
2a
2b
2c
71
81
81
1g
3g
Ph
N
2
3
Toluene
N
N
Ts
150 °C
10%
N
Ts
1h
N
N
3h
NO2
4
5
6
7
8
9
20d
20e
20f
60
63
67
47
64
95
2d
2e
2f
72
95
OMe
Cl
N
Ts
80
3i (8%)
F
PhI (1.1 equiv)
Pd(PPh3)4 (5%), CuI (2%)
N
+
a
20g
20h
20i
2g
2h
2i
Et3N, toluene
60 °C
N
Ts
N
N
70
1b
N
Ph
Ts
a
3j (16%)
Scheme 8. Regioselectivity of the IDDA reactions of ynamides 1g, 1h and the
Sonogashira product of 1b and iodobenzene.
S
10
20j
80
2j
70
a
Not isolated.
a mesyl nitrogen-protecting group (2l and 2m),26 since the cor-
responding carbazoles have been obtained in good-to-excel-
lent yields (entries 10e12).27 Interestingly, the 11-silylated
benzo[b]carbazole 3u was obtained in 31% yield from silyl-
ynamide 200a (Table 4, entry 13), whereas reaction of 1c0 had
failed to afford its 6-silylated isomer 3c0 (Table 2, entry 5) and
20a had given a complex mixture.
nicely complements the efficient intermolecular [2þ2þ2] cy-
cloaddition of ynamides to alkynes. Application to the synthe-
sis of demethylated ellipticine, an interesting antitumoral
agent, has also been shown. These results open new perspec-
tives for the application of ynamides in the field of poly-
and heterocyclic aromatics with pharmacological interest.
Gratifyingly, we have also been successful with the applica-
tion of our methodology to the synthesis of the interesting
demethylated derivative of the alkaloid ellipticine (5,11-di-
methyl-6H-pyrido[4,3-b]carbazole),5 which posseses extraor-
dinary anticancer activity. Owing to the instability of the
isolated ynamide 2i we performed the intramolecular dehydro
DielseAlder reaction with the in situ prepared ynamide. To
our delight, TIPS-substituted ynamide 20i was subjected to de-
silylation conditions and then heated at 150 ꢀC to give the pyr-
ido[4,3-b]carbazole 3v in 21% yield (Scheme 10). This result
could be considered as one of the most direct approaches to
this biological interesting pyridocarbazole nucleus.
5i
1)
TIPS
CuI (5%)
Ts
NH
PdCl2(PPh3)2 (3%)
97%
NH2
I
2) TsCl, Py, 80%
TIPS
4
6i
ArI 8
Ts
N
Pd(PPh3)4 (5%)
1) Cs2CO3, DMF
CuI (3%)
Et3N,Tol, 60 °C
37-85%
OTf
TMS
2)
I
Ph
7
TIPS
CH2Cl2, 85%
1i
Ts
N
3. Conclusions
Ts
N
TBAF
Ar
Intramolecular dehydro DielseAlder reactions of N-(o-
ethynyl)aryl ynamides and N-(o-ethynyl) arylynamides afford
carbazoles and benzannulated and heteroannulated carbazoles
in yields that range from poor to excellent but generally ex-
ceed 50%. This metal-free IDDA approach to carbazoles
Ar
TIPS
2'
2
Scheme 9. Synthesis of N-(o-ethynyl) arylynamides 2 and TIPS-substituted
arylynamides 20.

M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
3679
Table 4
Results of intramolecular dehydro DielseAlder reactions of arylynamides 2
Me
R
Entry
Arylynamide 2
Carbazole 3
Yield (%)
N
Cl
N
Ms
Ts
2l, R = Me
2m, R = OMe
1
2a
3c
50
2k
N
Ts
Figure 1. Halogen- and mesyl-substituted arylynamides 2kem.
2
3
2b
2c
3d
73
60
4. Experimental
4.1. General
N
Ts
NO2
OMe
Cl
3k
3l
All reactions were carried out under argon atmosphere with
magnetic stirring. The solvents were purified and dried using
standard procedures. All reagents were purchased and used
without further purification. 1H NMR at 250.13 MHz and
13C NMR spectra at 62.89 MHz were determined using
CDCl3 as solvent with tetramethylsilane as internal standard.
Mass spectra were measured by ionizing the sample at
70 eV. Column chromatographies were made on silica gel
230e240 mesh (flash).
N
Ts
4
5
6
2d
2e
2f
50
82
73
N
Ts
3m
3n
N
Ts
4.1.1. General procedure for the synthesis of N-(o-ethynyl)-
aryl ynamides 1
F
To a stirred solution of N-tosylaniline 5 (1 mmol) in dry
DMF (20 mL) was added Cs2CO3 (1.3 equiv) at rt. After
30 min, a solution of 6 (1.3 mmol) in dry CH2Cl2 (8 mL)
was added dropwise. Stirring was continued until starting ma-
terials disappeared (TLC monitoring, typically 5 h). Then,
ether was added (10 mL) and the combined organic layers
were extracted with water and brine, dried over anhydrous
Na2SO4 and concentrated to dryness. Purification of the resi-
due by flash chromatography on silica gel using a gradient
mixture of EtOAc/hexanes as eluent afforded ynamides 1 in
good yields.
N
Ts
da
21b
34b
N
N
7
8
9
2g
2h
2j
3o
3p
3q
N
Ts
N
Ts
S
N
Ts
4.1.1.1. N-Ethynyl-2-((Z)-pent-3-en-1-ynyl)-N-tosylbenzenamine
1
Me
(1a). H NMR (CDCl3) d: 7.71 (d, J¼8.3 Hz, 2H, ArH),
7.47e7.44 (m, 1H, ArH), 7.35e7.21 (m, 5H, ArH), 6.07e
5.94 (m, 1H, C]CH), 5.47 (dd, J¼10.7, 1.6 Hz, 1H, C]CH),
3.83 (s, 1H, C^CH), 2.41 (s, 3H, CH3), 1.90 (dd, J¼6.9,
1.6 Hz, 3H, CH3).
10
2k
3r
57
Cl
N
Ts
Me
4.1.1.2. 2-(2-Cyclohexenylethynyl)-N-ethynyl-N-tosylbenzen-
amine (1b). 1H NMR (CDCl3) d: 7.55 (d, J¼8.2 Hz, 2H,
ArH), 7.28e7.24 (m, 1H, ArH), 7.14e7.11 (m, 5H, ArH),
5.92 (m, 1H, C]CH), 2.70 (s, 1H, CCH), 2.27 (s, 3H,
CH3), 1.95e1.89 (m, 4H, CH2), 1.46e1.44 (m, 4H, CH2).
11
12
2l
3s
3t
95
63
N
Ms
OMe
2m
N
Ms
TMS
4.1.1.3. Methyl 2-(2-cyclohexenylethynyl) phenylethynylcarba-
mate (1b, Z¼CO2Me). 1H NMR (CDCl3) d: 7.45 (dd, J¼6.5,
2.4 Hz, 1H, ArH), 7.41e7.24 (m, 3H, ArH), 6.22 (m, 1H,
C]CH), 3.82 (s, 3H, CH3), 2.82 (s, 1H, CCH), 2.21e2.18
(m, 4H, CH2), 1.71e1.60 (m, 4H, CH2).
13
200ac
3u
31b
N
Ts
a
Not isolated.
Partial decomposition of starting material occurred.
Same structure as 20a but with TMS instead of TIPS.
b
c
4.1.1.4. 2-(2-Cyclohexenylethynyl)-N-(2-(trimethylsilyl)ethynyl)-
N-tosylbenzenamine (1b0). 1H NMR (CDCl3) d: 7.71 (d,

3680
M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
Me
N
N
Me
H
Ellipticine
TIPS
N
N
N
Tol/Et3N
150 °C
TBAF
N
Ts
N
Ts
N
Ts
2'i
2i
3v
Scheme 10. Synthesis of demethylated ellipticine derivative 3v by intramolecular dehydro DielseAlder of arylynamide 2i.
J¼8.4 Hz, 2H, ArH), 7.42e7.40 (m, 1H, ArH), 7.31e7.27 (m,
5H, ArH), 2.43 (s, 3H, CH3), 2.09e2.08 (m, 2H, CH2), 2.02e
2.01 (m, 2H, CH2), 1.62e1.58 (m, 4H, CH2), 0.13 (s, 3H,
Si(CH3)3).
(m, 2H, ArH), 7.46e7.41 (m, 4H, ArH), 7.28e7.10 (m, 7H,
ArH), 2.18 (s, 3H, CH3).
4.1.1.12. 2-(2-Phenylethynyl)-N-(2-(pyrimidin-2-yl)ethynyl)-N-
tosylbenzenamine (1h). 1H NMR (CDCl3) d: 8.59 (d,
J¼5.0 Hz, 2H, ArH), 7.78 (d, J¼8.4 Hz, 2H, ArH), 7.49 (dd,
J¼5.7, 3.5 Hz, 1H, ArH), 7.46 (dd, J¼5.9, 3.3 Hz, 1H,
ArH), 7.37 (d, J¼3.5 Hz, 1H, ArH), 7.36 (d, J¼3.5 Hz, 1H,
ArH), 7.26e7.21 (m, 3H, ArH), 7.19e7.15 (m, 2H, ArH),
7.10e7.07 (m, 3H, ArH), 2.14 (s, 3H, CH3).
4.1.1.5. N-Ethynyl-2-(2-phenylethynyl)-N-tosylbenzenamine (1c,
Z¼Ts). 1H NMR (CDCl3) d: 7.68 (d, J¼7.8 Hz, 2H, ArH),
7.51e7.30 (m, 9H, ArH), 7.07 (d, J¼7.8 Hz, 2H, ArH), 2.94
(s, 1H, CCH), 2.15 (s, 3H, CH3).
4.1.1.6. Methyl ethynyl-2-(2-phenylethynyl)phenylcarbamate (1c,
Z¼CO2Me). 1H NMR (CDCl3) d: 7.61 (dd, J¼7.6, 1.7 Hz, 1H,
ArH), 7.57e7.54 (m, 2H, ArH), 7.44e7.39 (m, 2H, ArH),
7.38e7.34 (m, 4H, ArH), 3.85 (s, 3H, CH3), 2.88 (s, 1H,
CCH).
4.1.2. General procedure for the synthesis of N-(o-ethynyl)
arylynamides 20
To a reaction flask was added 1 mmol ynamide 1i,
1.1 mmol of aryl iodide, 0.05 mmol of Pd(PPh3)4, 7.5 mL of
Et3N and 3.7 mL of toluene. The solution was stirred at rt for
10 min, and 0.02 mmol of CuI was then added. After heating
the reaction mixture at 60 ꢀC until starting material disap-
peared (TLC monitoring, 4e8 h), the mixture was diluted
with EtOAc, filtered through silica, and concentrated in vacuo.
Purification of the residue by flash chromatography on silica
gel using a gradient mixture of EtOAc/hexanes as eluent
afforded ynamides 20 in good yields.
4.1.1.7.
N-(2-(Trimethylsilyl)ethynyl)-2-(2-phenylethynyl)-N-
1
tosylbenzenamine (1c0). H NMR (CDCl3) d: 7.85 (d, J¼
8.2 Hz, 2H, ArH), 7.66e7.61 (m, 9H, ArH), 7.24 (d, J¼8.2 Hz,
2H, ArH), 2.32 (s, 3H, CH3), 0.24 (s, 9H, Si(CH3)3).
4.1.1.8. N-Ethynyl-2-(2-(naphthalen-3-yl)ethynyl)-N-tosylbenz-
enamine (1d). 1H NMR (CDCl3) d: 7.80e7.71 (m, 6H,
ArH), 7.54e7.37 (m, 7H, ArH), 7.05 (d, J¼8.2 Hz, 2H, ArH),
2.98 (s, 1H, CCH), 2.01 (s, 3H, CH3).
4.1.2.1. 2-(2-(Triisopropylsilyl)ethynyl)-N-(2-phenylethynyl)-
N-tosylbenzenamine (20a). Following the procedure described
above and starting with 1i (300 mg, 0.67 mmol), iodobenzene
(82 mg, 0.73 mmol), Pd(PPh3)4 (38 mg), CuI (2.5 mg) in Et3N
(5 mL) and toluene (2.5 mL), 20a was isolated as a clear oil
4.1.1.9. N-Ethynyl-2-(2-(naphthalen-1-yl)ethynyl)-N-tosylbenz-
enamine (1e). 1H NMR (CDCl3) d: 8.35e8.31 (m, 1H, ArH),
7.84 (d, J¼7.9 Hz, 2H, ArH), 7.69e7.39 (m, 10H, ArH),
6.87 (d, J¼7.9 Hz, 2H, ArH), 3.02 (s, 1H, C^CH), 1.83 (s,
3H, CH3).
1
(300 mg, 85%). H NMR (CDCl3) d: 7.79 (d, J¼8.2 Hz, 2H,
ArH), 7.60 (d, J¼7.4 Hz, 1H, ArH), 7.34e7.25 (m, 9H,
ArH), 7.12 (d, J¼7.5 Hz, 1H, ArH), 2.45 (s, 3H, CH3), 1.10
(s, 21H, Si(CH(CH3)2)3); 13C NMR/DEPT (CDCl3) d: 144.7
(C), 139.4 (C), 134.6 (C), 134.5 (CH), 131.1 (2ꢁCH), 129.5
(2ꢁCH), 128.8 (2ꢁCH), 128.3 (2ꢁCH), 128.0 (CH), 127.9
(2ꢁCH), 127.4 (CH), 124.1 (C), 123.0 (C), 102.0 (C), 97.9
(C), 83.0 (C), 70.0 (C), 21.7 (CH3), 18.6 (Si(CH(CH3)2)3),
11.3 (Si(CH(CH3)2)3); MS FAB m/z (%): 528 (Mþþ1, 2),
231 (43), 137 (100); HRMS: (C32H38NO2SSi) calcd:
528.2392; found: 528.2390.
4.1.1.10. N-Ethynyl-2-(2-(phenanthren-9-yl)ethynyl)-N-tosyl-
benzenamine (1f). 1H NMR (CDCl3) d: 8.71e8.67 (m, 3H,
ArH), 8.44 (d, J¼7.5 Hz, 1H, ArH), 7.87e7.85 (m, 2H, ArH),
7.72e7.63 (m, 6H, ArH), 7.47e7.43 (m, 3H, ArH), 6.86 (d,
J¼8.0 Hz, 2H, ArH), 3.05 (s, 1H, C^CH), 1.74 (s, 3H, CH3).
4.1.1.11. N-(2-(4-Nitrophenyl)ethynyl)-2-(2-phenylethynyl)-N-
tosylbenzenamine (1g). 1H NMR (CDCl3) d: 8.10 (d,
J¼8.5 Hz, 2H, ArH), 7.73 (d, J¼8.5 Hz, 2H, ArH), 7.57e7.52

M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
3681
4.1.2.2. 2-(2-(Triisopropylsilyl)ethynyl)-N-(2-(naphthalen-1-
yl)ethynyl)-N-tosylbenzenamine (20b). Following the proce-
dure described above and starting with 1i (100 mg,
0.22 mmol), iodonaphthalene (36 mL, 0.24 mmol), Pd(PPh3)4
(13 mg), CuI (1 mg) in Et3N (1.5 mL) and toluene (0.7 mL),
20b was isolated as a clear oil (89 mg, 70%). 1H NMR
(CDCl3) d: 8.26 (d, J¼8.0 Hz, 1H, ArH), 7.86e7.17 (m,
14H, ArH), 2.45 (s, 3H, CH3), 1.09 (s, 21H, Si(CH(CH3)2)3);
13C NMR/DEPT (CDCl3) d: 144.8 (C), 144.7 (C), 139.5 (C),
136.6 (C), 134.7 (C), 134.6 (CH), 13.10 (C), 133.06 (C),
129.7 (2ꢁCH), 129.5 (CH), 129.2 (CH), 12.1 (CH), 129.0
(CH), 128.9 (CH), 128.4 (2ꢁCH), 128.0 (CH), 127.8 (CH),
126.4 (CH), 126.2 (CH), 125.0 (CH), 102.0 (C), 98.1 (C),
87.7 (C), 68.5 (C), 21.6 (CH3), 18.6 (Si(CH(CH3)2)3), 11.3
Si(CH(CH3)2)3.
(CDCl3) d: 7.75 (d, J¼8.3 Hz, 2H, ArH), 7.58 (dd, J¼7.0,
2.2 Hz, 1H, ArH), 7.33e7.23 (m, 8H, ArH), 7.11 (dd,
J¼7.1, 2.0 Hz, 1H, ArH), 2.44 (s, 3H, CH3), 1.08 (m, 21H,
Si(CH(CH3)2)3); 13C NMR/DEPT (CDCl3) d: 144.8 (C),
139.1 (C), 134.6 (CH), 133.3 (C), 132.2 (2ꢁCH), 129.6
(2ꢁCH), 128.9 (CH), 128.3 (2ꢁCH), 128.2 (CH), 124.0 (C),
121.6 (C), 101.9 (C), 98.0 (C), 83.8 (C), 69.1 (C), 21.7
(CH3), 18.6 (CH3), 11.2 (CH). MS ESI-TOF m/z (%): 580
(MþþH2O, 100), 562 (Mþ, 3), 428 (29); HRMS:
(C32H37ClNO2SSi) calcd: 562.1997; found: 562.1992.
4.1.2.6. N-(2-(4-Fluorophenyl)ethynyl)-2-(2-(triisopropylsilyl)-
ethynyl)-N-tosylbenzenamine (20f). Following the procedure
described above and starting with 1i (190 mg, 0.55 mmol),
1-iodo-4-fluorbenzene (128 mg, 0.60 mmol), Pd(PPh3)4
(31 mg), CuI (2 mg) in Et3N (4 mL) and toluene (2 mL), 20f
1
4.1.2.3. 2-(2-(Triisopropylsilyl)ethynyl)-N-(2-(4-nitrophenyl)-
ethynyl)-N-tosylbenzenamine (20c). Following the procedure
described above and starting with 1i (100 mg, 0.22 mmol),
4-iodonitrobencene (61 mg, 0.24 mmol), Pd(PPh3)4 (13 mg),
CuI (1 mg) in Et3N (1.5 mL) and toluene (0.7 mL), 20c was
was isolated as a clear oil (145 mg, 62%). H NMR (CDCl3)
d: 7.76 (d, J¼8.3 Hz, 2H, ArH), 7.58 (dd, J¼7.1, 2.2 Hz,
1H, ArH), 7.33e7.24 (m, 6H, ArH), 7.10 (d, J¼7.3 Hz, 1H,
ArH), 6.94 (t, J¼8.7 Hz, 1H, ArH), 2.44 (s, 3H, CH3), 1.09
(s, 21H, Si(CH(CH3)2)3); 13C NMR/DEPT (CDCl3) d: 164.0
(C), 160.1 (C), 144.7 (C), 139.3 (C), 134.5 (CH), 133.2
(CH), 133.0 (CH), 129.6 (2ꢁCH), 128.9 (2ꢁCH), 128.3
(2ꢁCH), 128.1 (CH), 124.0 (C), 119.1 (C), 115.4 (CH),
115.1 (CH), 102.0 (C), 97.9 (C), 82.5 (C), 68.9 (C), 21.6
(CH3), 18.6 (Si(CH(CH3)2)3), 11.2 (Si(CH(CH3)2)3); MS
ESI-TOF m/z (%): 546 (Mþþ1, 100), 348 (33); HRMS:
(C32H37FNO2SSi) calcd: 546.2293; found: 546.2289.
1
isolated as a clear oil (113 mg, 90%). H NMR (CDCl3) d:
8.13 (d, J¼8.6 Hz, 2H, ArH), 7.76 (d, J¼8.3 Hz, 2H, ArH),
7.60 (dd, J¼6.7, 2.5 Hz, 1H, ArH), 7.43e7.32 (m, 6H,
ArH), 7.22 (d, J¼7.2, 2.9 Hz, 1H, ArH), 2.46 (s, 3H, CH3),
1.03 (s, 21H, Si(CH(CH3)2)3); 13C NMR/DEPT (CDCl3) d:
146.0 (C), 145.2 (C), 138.3 (C), 134.8 (CH), 134.5 (C),
130.7 (C), 130.5 (2ꢁCH), 129.8 (2ꢁCH), 129.2 (CH), 129.0
(CH), 128.4 (CH), 128.3 (2ꢁCH), 123.6 (C), 123.4 (2ꢁCH),
101.5 (C), 98.5 (C), 88.9 (C), 70.3 (C), 21.7 (CH3), 18.5
(Si(CH(CH3)2)3), 11.2 (Si(CH(CH3)2)3).
4.1.2.7.
2-(2-(Triisopropylsilyl)ethynyl)-N-(2-(pyridin-2-yl)-
ethynyl)-N-tosylbenzenamine (20g). Following the procedure
described above and starting with 1i (100 mg, 0.22 mmol),
2-iodopyridine (36 mL, 0.24 mmol), Pd(PPh3)4 (13 mg), CuI
(1 mg) in Et3N (3.2 mL) and toluene (1.6 mL), 20g was iso-
4.1.2.4. 2-(2-(Triisopropylsilyl)ethynyl)-N-(2-(4-methoxyphe-
nyl)ethynyl)-N-tosylbenzenamine (20d). Following the proce-
dure described above and starting with 1i (150 mg,
0.33 mmol), 4-iodoanisole (86 mg, 0.37 mmol), Pd(PPh3)4
(19 mg), CuI (1 mg) in Et3N (2.5 mL) and toluene (1.2 mL),
20d was isolated as a clear oil (110 mg, 60%). 1H NMR
(CDCl3) d: 7.78 (d, J¼8.5 Hz, 2H, ArH), 7.59 (d, J¼7.5 Hz,
1H, ArH), 7.33e7.27 (m, 6H, ArH), 7.07 (d, J¼7.5 Hz, 1H,
ArH), 6.79 (d, J¼8.5 Hz, 2H, ArH), 3.79 (s, 3H, OCH3),
2.46 (s, 3H, CH3), 1.13 (s, 21H, Si(CH(CH3)2)3); 13C NMR/
DEPT (CDCl3) d: 159.3 (C), 144.5 (C), 139.8 (C), 134.7
(C), 134.5 (CH), 133.2 (2ꢁCH), 129.5 (2ꢁCH), 128.83
(CH), 128.77 (CH), 128.4 (2ꢁCH), 128.0 (CH), 124.2 (C),
115.0 (C), 113.7 (2ꢁCH), 102.2 (C), 97.7 (C), 81.6 (C),
69.5 (C), 55.2 (OCH3), 21.7 (CH3), 18.6 (Si(CH(CH3)2)3),
11.3 (Si(CH(CH3)2)3); MS FAB m/z (%): 558 (Mþþ1, 5),
384 (24), 154 (34), 121 (100); HRMS: (C33H40NO3SSi) calcd:
558.2498; found: 558.2504.
1
lated as a clear oil (55 mg, 47%). H NMR (CDCl3) d: 8.46
(br s, 1H, ArH), 7.77 (d, J¼8.3 Hz, 2H, ArH), 7.56 (dd,
J¼7.6, 1.4 Hz, 1H, ArH), 7.34e7.22 (m, 6H, ArH), 7.12 (t,
J¼5.2 Hz, 1H, ArH), 7.06 (d, J¼7.7 Hz, 1H, ArH), 2.42 (s,
3H, CH3), 1.06 (s, 21H, Si(CH(CH3)2)3); 13C NMR/DEPT
(CDCl3) d: 149.5 (CH), 144.9 (C), 143.6 (C), 138.7 (C),
135.7 (CH), 134.54 (CH), 134.5 (C), 129.7 (2ꢁCH), 129.1
(CH), 128.9 (CH), 128.4 (2ꢁCH), 128.2 (CH), 126.1 (CH),
124.2 (C), 121.7 (CH), 101.8 (C), 97.9 (C), 83.2 (C), 70.4
(C), 21.7 (CH3), 18.5 (Si(CH(CH3)2)3), 11.2 (Si(CH(CH3)2)3);
MS ESI-TOF m/z (%): 529 (Mþþ1, 22), 268 (45), 288 (100);
HRMS: (C31H37N2O2SSi) calcd: 529.2345; found: 529.2340.
4.1.2.8.
2-(2-(Triisopropylsilyl)ethynyl)-N-(2-(pyridin-3-yl)-
ethynyl)-N-tosylbenzenamine (20h). Following the procedure
described above and starting with 1i (100 mg, 0.22 mmol),
3-iodopyridine (50 mg, 0.24 mmol), Pd(PPh3)4 (13 mg), CuI
(1 mg) in Et3N (1.5 mL) and toluene (0.7 mL), 20h was iso-
4.1.2.5. N-(2-(4-Chlorophenyl)ethynyl)-2-(2-(triisopropylsilyl)-
ethynyl)-N-tosylbenzenamine (20e). Following the procedure
described above and starting with 1i (150 mg, 0.40 mmol),
1-chloro-4-iodobenzene (105 mg, 0.44 mmol), Pd(PPh3)4
(23 mg), CuI (2 mg) in Et3N (3 mL) and toluene (1.5 mL),
20e was isolated as a clear oil (122 mg, 63%). 1H NMR
1
lated as a clear oil (74 mg, 64%). H NMR (CDCl3) d: 8.55
(d, J¼1.5 Hz, 1H, ArH), 8.46 (dd, J¼4.6, 1.5 Hz, 1H, ArH),
7.78 (d, J¼8.3 Hz, 2H, ArH), 7.63e7.59 (m, 2H, ArH),
7.39e7.28 (m, 4H, ArH), 7.22e7.15 (m, 2H, ArH), 2.45 (s,
3H, CH3), 1.09 (s, 21H, Si(CH(CH3)2)3); 13C NMR/DEPT

3682
M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
(CDCl3) d: 151.6 (CH), 147.7(CH), 144.9 (C), 138.8 (C),
137.8 (CH), 134.7 (CH), 134.5 (C), 129.7 (2ꢁCH), 129.1
(CH), 128.9 (CH), 128.4 (2ꢁCH), 128.2 (CH), 123.9 (C),
122.7 (CH), 109.0 (C), 101.8 (C), 98.2 (C), 86.0 (C), 67.1
(C), 21.6 (CH3), 18.5 (Si(CH(CH3)2)3), 11.2 (Si(CH(CH3)2)3);
MS ESI-TOF m/z (%): 529 (Mþþ1, 100); HRMS:
(C31H37N2O2SSi) calcd: 529.2345; found: 529.2340.
described above and starting with N-ethynyl-2-(2-(triisopro-
pylsilyl)ethynyl)-N-mesylbenzenamine (163 mg, 0.46 mmol),
1-iodo-4-methylbenzene (111 mg, 0.51 mmol), Pd(PPh3)4
(27 mg), CuI (2 mg) in Et3N (3.4 mL) and toluene (1.7 mL),
20l was isolated as a clear oil (125 mg, 61%). 1H NMR
(CDCl3) d: 7.60 (d, J¼6.6 Hz, 1H, ArH), 7.50 (d, J¼6.6 Hz,
1H, ArH), 7.42e7.35 (m, 2H, ArH), 7.28 (d, J¼7.9 Hz, 2H,
ArH), 7.06 (d, J¼7.9 Hz, 2H, ArH), 3.33 (s, 3H, CH3), 2.31
(s, 3H, CH3), 1.11 (s, 21H, Si(CH(CH3)2)3); 13C NMR/DEPT
(CDCl3) d: 138.4 (C), 137.7 (C), 134.9 (CH), 131.3 (2ꢁCH),
130.0 (CH), 129.5 (CH), 129.2 (CH), 128.7 (2ꢁCH), 122.8
(C), 119.5 (C), 102.5 (C), 98.4 (C), 81.0 (C), 70.6 (C), 39.8
(CH3), 21.3 (CH3), 18.6 (CH3), 11.2 (Si(CH(CH3)2)3); MS
ESI-TOF m/z (%): 466 (Mþþ1, 100), 344 (60), 279 (35);
HRMS: (C27H36NO2SSi) calcd: 466.2231; found: 466.2231.
4.1.2.9.
2-(2-(Triisopropylsilyl)ethynyl)-N-(2-(pyridin-4-yl)-
ethynyl)-N-tosylbenzenamine (20i). Following the procedure
described above and starting with 1i (120 mg, 0.27 mmol),
4-iodopyridine (60 mg, 0.29 mmol), Pd(PPh3)4 (15 mg), CuI
(1 mg) in Et3N (2.6 mL) and toluene (1.3 mL), 20i was isolated
1
as a clear oil (136 mg, 95%). H NMR (CDCl3) d: 8.28 (br s,
2H, ArH), 7.55 (d, J¼8.3 Hz, 2H, ArH), 7.39 (dd, J¼5.9,
2.6 Hz, 1H, ArH), 7.16e7.10 (m, 4H, ArH), 7.01e6.94 (m,
3H, ArH), 2.23 (s, 3H, CH3), 0.84 (s, 21H, Si(CH(CH3)2)3);
13C NMR/DEPT (CDCl3) d: 149.1 (2ꢁCH), 145.0 (C),
138.2 (C), 134.6 (CH), 134.3 (C), 131.6 (C), 129.6 (2ꢁCH),
129.1 (CH), 128.9 (CH), 128.3 (2ꢁCH), 128.2 (2ꢁCH),
124.0 (CH), 123.5 (C), 101.4 (C), 98.3 (C), 88.0 (C), 69.1
(C), 21.5 (CH3), 18.4 (Si(CH(CH3)2)3), 11.0 (Si(CH(CH3)2)3).
4.1.2.13. N-(2-(4-Methoxyphenyl)ethynyl)-2-(2-(triethylsilyl)-
ethynyl)-N-mesylbenzenamine (20m). Following the procedure
described above and starting with N-ethynyl-2-(2-(triisopro-
pylsilyl)ethynyl)-N-mesylbenzenamine (270 mg, 0.81 mmol),
1-iodo-4-methoxybenzene (209 mg, 0.89 mmol), Pd(PPh3)4
(47 mg), CuI (3 mg) in Et3N (6 mL) and toluene (3 mL), 20m
1
was isolated as a clear oil (186 mg, 52%). H NMR (CDCl3)
4.1.2.10. 2-(2-(Triisopropylsilyl)ethynyl)-N-(2-(thiophen-2-yl)-
ethynyl)-N-tosylbenzenamine (20j). Following the procedure
described above and starting with 1i (120 mg, 0.27 mmol),
2-iodothiophene (41 mL, 0.37 mmol), Pd(PPh3)4 (19 mg),
CuI (1 mg) in Et3N (2.5 mL) and toluene (1.2 mL), 20j was
d: 7.59 (dd, J¼6.9, 2.3 Hz, 1H, ArH), 7.51 (dd, J¼7.0, 2.0 Hz,
1H, ArH), 7.41e7.33 (m, 4H, ArH), 6.81 (d, J¼8.9 Hz, 2H,
ArH), 3.79 (s, 3H, ArH), 3.33 (s, 3H, ArH), 1.03 (t, J¼7.8 Hz,
9H, Si(CH2CH3)3), 0.67 (c, 6H, Si(CH2CH3)3); 13C NMR/
DEPT (CDCl3) d: 159.4 (C), 138.8 (C), 134.6 (CH), 133.3
(2ꢁCH), 130.2 (CH), 129.6 (CH), 129.1 (CH), 122.4 (C),
114.6 (C), 113.7 (2ꢁCH), 101.8 (C), 99.4 (C), 80.2 (C), 70.3
(C), 55.2 (CH3), 39.9 (CH3), 7.5 Si(CH2CH3)3, 4.2
Si(CH2CH3)3.
1
isolated as a clear oil (140 mg, 80%). H NMR (CDCl3) d:
7.77 (d, J¼8.3 Hz, 2H, ArH), 7.58 (dd, J¼7.0, 2.0 Hz, 1H,
ArH), 7.34e7.22 (m, 5H, ArH), 7.13 (dd, J¼3.6, 1.1 Hz, 1H,
ArH), 7.04 (dd, J¼7.5, 1.7 Hz, 1H, ArH), 6.93 (dd, J¼5.2,
3.7 Hz, 1H, ArH), 2.46 (s, 3H, CH3), 1.16 (s, 21H,
Si(CH(CH3)2)3); 13C NMR/DEPT (CDCl3) d: 144.7 (C),
139.4 (C), 134.6 (C), 134.4 (CH), 132.8 (CH), 129.6 (2ꢁCH),
129.0 (CH), 128.9 (CH), 128.3 (2ꢁCH), 127.9 (CH), 127.6
(CH), 126.8 (CH), 124.2 (C), 123.0 (C), 102.0 (C), 97.8 (C),
86.3 (C), 63.2 (C), 21.7 (CH3), 18.7 (Si(CH(CH3)2)3), 11.3
(Si(CH(CH3)2)3).
4.1.3. General procedure for the synthesis of N-(o-ethynyl)
arylynamides 2
Excess of tetrabutylammonium fluoride (1.0 M solution in
THF) was added to a solution of TIPS-protected arylynamides
20aek (0.1 mmol) in THF (10 mL), and the resulting mixture
was stirred at rt for 10 min. After solvent removal, the residue
was dissolved in EtOAc, washed with brine, dried over anhy-
drous Na2SO4 and concentrated to dryness. The residue was
purified by flash chromatography on silica gel using a gradient
mixture of EtOAc/hexanes as eluent giving arylynamides
2aek in good yields.
4.1.2.11. 5-Chloro-2-(2-(triisopropylsilyl)ethynyl)-N-(2-p-tolyl-
ethynyl)-N-tosylbenzenamine (20k). Following the procedure
described above and starting with 5-chloro-N-ethynyl-2-
(2-(triisopropylsilyl)ethynyl)-N-tosylbenzenamine (140 mg,
0.29 mmol), 1-iodo-4-methylbenzene (69 mg, 0.32 mmol),
Pd(PPh3)4 (17 mg), CuI (1 mg) in Et3N (2 mL) and toluene
(1 mL), 20k was isolated as a clear oil (90 mg, 54%). 1H
NMR (CDCl3) d: 7.60 (d, J¼8.3 Hz, 2H, ArH), 7.52 (d, J¼
8.4 Hz, 1H, ArH), 7.34 (d, J¼8.4 Hz, 1H, ArH), 7.17 (d,
J¼8.0 Hz, 2H, ArH), 7.08e7.04 (m, 3H, ArH), 6.90 (d,
J¼8.0 Hz, 2H, ArH), 2.30 (s, 3H, CH3), 2.15 (s, 3H,CH3),
0.93 (s, 21H, Si(CH(CH3)2)3); MS ESI-TOF m/z (%): 576
(Mþþ1, 100), 378 (16); HRMS: (C33H39ClNO2SSi) calcd:
576.2154; found: 576.2152.
4.1.3.1. N-2-Ethynylphenyl-N-2-phenylethynyl tosylamide
(2a). 1H NMR (CDCl3) d: 7.77 (d, J¼8.3 Hz, 2H, ArH),
7.53 (dd, J¼6.3, 3.3 Hz, 1H, ArH), 7.41e7.26 (m, 10H, ArH),
3.09 (s, 1H, C^CH), 2.44 (s, 3H, CH3).
4.1.3.2. 2-Ethynyl-N-(2-(naphthalen-1-yl)ethynyl)-N-tosylbenz-
enamine (2b). 1H NMR (CDCl3) d: 8.29e8.26 (m, 2H, ArH),
7.83e7.30 (m, 13H, ArH), 3.05 (s, 1H, CCH), 2.45 (s, 3H,
CH3).
4.1.2.12. N-(2-(4-Methylphenyl)ethynyl)-2-(2-(triisopropylsilyl)-
ethynyl)-N-mesylbenzenamine (20l). Following the procedure
4.1.3.3. N-2-Ethynylphenyl-N-2-(4-nitrophenyl)ethynyl tosyl-
amide (2c). 1H NMR (CDCl3) d: 8.14 (d, J¼8.9 Hz, 2H,

M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
3683
ArH), 7.75 (d, J¼8.3 Hz, 2H, ArH), 7.55 (dd, J¼6.6, 2.7 Hz,
1H, ArH), 7.48e7.34 (m, 7H, ArH), 3.05 (s, 1H, C^CH),
2.47 (s, 3H, CH3).
of arylynamide 20m (0.1 mmol) in THF, MeOH and H2O
(5þ2þ2 mL), and the resulting mixture was stirred at rt for
30 min. After solvent removal, the residue was dissolved in
EtOAc, washed with brine, dried over anhydrous Na2SO4
and concentrated to dryness. The residue was purified by flash
chromatography on silica gel using a gradient mixture of
EtOAc/hexanes 70:30 as eluent giving 2m as clear oil in
58% yield. 1H NMR (CDCl3) d: 7.59 (dd, J¼7.4, 1.9 Hz,
1H, ArH), 7.53 (dd, J¼7.9, 1.3 Hz, 1H, ArH), 7.43e7.33
(m, 4H, ArH), 6.80 (d, J¼8.9 Hz, 2H, ArH), 3.78 (s, 3H,
CH3), 3.48 (s, 1H, CCH), 3.32 (s, 3H, CH3); 13C NMR/
DEPT (CDCl3) d: 159.6 (C), 139.5 (C), 134.4 (CH), 133.7
(2ꢁCH), 130.0 (CH), 129.8 (CH), 129.1 (CH), 121.1 (C),
114.3 (C), 113.8 (2ꢁCH), 83.9 (CH), 80.1 (C), 79.7 (C),
70.3 (C), 55.2 (CH3), 39.4 (CH3).
4.1.3.4. N-2-Ethynylphenyl-N-2-(4-methoxyphenyl)ethynyl to-
sylamide (2d). 1H NMR (CDCl3) d: 7.75 (d, J¼8.4 Hz, 2H,
ArH), 7.52 (dd, J¼6.9, 2.4 Hz, 1H, ArH), 7.39e7.27 (m,
7H, ArH), 6.81 (d, J¼8.9 Hz, 2H, ArH), 3.79 (s, 3H,
OCH3), 3.06 (s, 1H, C^CH), 2.46 (s, 3H, CH3).
4.1.3.5. N-(2-(4-Chlorophenyl)ethynyl)-2-ethynyl-N-tosylbenz-
enamine (2e). 1H NMR (CDCl3) d: 7.73 (d, J¼8.3 Hz, 2H,
ArH), 7.54e7.50 (m, 1H, ArH), 7.38e7.21 (m, 9H, ArH),
3.04 (s, 1H, CCH), 2.45 (s, 3H, CH3); 13C NMR/DEPT
(CDCl3) d: 145.1 (C), 139.6 (C), 134.2 (CH), 133.9 (C),
133.7 (C), 132.6 (2ꢁCH), 129.6 (CHþ2ꢁCH), 129.1 (CH),
129.0 (CH), 128.5 (2ꢁCH), 122.1 (C), 121.3 (C), 83.4 (C),
83.1 (CH), 78.7 (C), 69.3 (C), 21.7 (CH3).
4.1.3.11. N-2-(2-Trimethylsilylethynyl)phenyl-N-2-phenylethynyl
1
tosylamide (200a). H NMR (CDCl3) d: 7.75 (d, J¼8.3 Hz, 2H,
ArH), 7.52e7.50 (m, 1H, ArH), 7.36e7.24 (m, 10H, ArH), 2.45
(s, 3H, CH3), 0.08 (s, 9H, Si(CH3)3).
4.1.3.6. N-(2-(4-Fluorophenyl)ethynyl)-2-ethynyl-N-tosylbenz-
enamine (2f). 1H NMR (CDCl3) d: 7.74 (d, J¼8.4 Hz, 2H,
ArH), 7.52 (dd, J¼7.0, 2.4 Hz, 1H, ArH), 7.40e7.29 (m,
7H, ArH), 6.99e6.95 (m, 2H, ArH), 3.04 (s, 1H, CCH),
2.46 (s, 3H, CH3); 13C NMR/DEPT (CDCl3) d: 162.3 (d,
JCeF¼249 Hz, C), 145.0 (C), 139.8 (C), 134.2 (CH), 133.6
(d, JCeF¼8 Hz, 2ꢁCH), 129.6 (CH), 129.6 (2ꢁCH), 129.1
(CH), 129.0 (CH), 128.5 (2ꢁCH), 122.1 (C), 118.8 (C),
118.8 (C), 115.4 (d, JCeF¼22 Hz, 2ꢁCH), 83.0 (CH), 82.1
(C), 18.8 (C), 69.2 (C), 21.7 (CH3); MS ESI-TOF m/z (%):
390 (Mþþ1, 12), 245 (100), 149 (84); HRMS:
(C27H36NO2SSi) calcd: 390.0959; found: 390.0970.
4.1.4. General procedure for intramolecular dehydro
DielseAlder reaction
A toluene solution of 1 or 2 (0.01 M) and 0.5 mL of Et3N
were placed in a sealed tube and heated overnight at 150 ꢀC
in a silicon oil bath. After evaporation of the solvent, the crude
material was purified by column chromatography on silica gel
using a mixture of hexanes/EtOAc as eluent.
1
4.1.4.1. 2-Methyl-9-tosyl-9H-carbazole (3a). H NMR (CDCl3)
d: 8.29 (d, J¼8.4 Hz, 1H, ArH), 8.14 (s, 1H, ArH), 7.48 (d,
J¼7.5 Hz, 1H, ArH), 7.77 (d, J¼7.8 Hz, 1H, ArH), 7.69 (d, J¼
8.2 Hz, 2H, ArH), 7.45 (t, J¼8.4 Hz, 1H, ArH), 7.33 (t, J¼
7.5 Hz, 1H, ArH), 7.18 (d, J¼7.8 Hz, 1H, ArH), 7.10 (d,
J¼8.2, 2H, ArH), 2.56 (s, 3H, CH3), 2.26 (s, 3H, CH3).
4.1.3.7. N-2-Ethynylphenyl-N-2-(pyridin-3-yl)ethynyl tosyl-
amide (2h). 1H NMR (CDCl3) d: 8.59 (s, 1H, ArH), 8.49 (d,
J¼4.8 Hz, 1H, ArH), 7.76 (d, J¼8.4 Hz, 2H, ArH), 7.66 (dt,
J¼7.9, 1.7 Hz, 1H, ArH), 7.55 (dd, J¼6.9, 2.3 Hz, 1H,
ArH), 7.44e7.32 (m, 5H, ArH), 7.22 (dd, J¼7.8, 4.8 Hz,
1H, ArH), 3.05 (s, 1H, C^CH), 2.48 (s, 3H, CH3).
4.1.4.2.
7,8,9,10-Tetrahydro-5-tosyl-5H-benzo[b]carbazole
(3b). 1H NMR (CDCl3) d: 8.27 (d, J¼8.3 Hz, 1H, ArH),
8.02 (s, 1H, ArH), 7.81 (d, J¼7.0 Hz, 1H, ArH), 7.69 (d,
J¼8.3 Hz, 2H, ArH), 7.56 (s, 1H, ArH), 7.43 (t, J¼8.3 Hz,
1H, ArH), 7.31 (t, J¼7.5 Hz, 1H, ArH), 7.09 (d, J¼8.1 Hz, 2H,
ArH), 2.99e2.90 (m, 4H, CH2), 2.25 (s, 3H, CH3), 1.87e1.84
(m, 4H, CH2).
4.1.3.8. 5-Chloro-2-ethynyl-N-(2-phenylethynyl)-N-tosylbenz-
enamine (2k). Clear oil. 1H NMR (CDCl3) d: 7.34 (d,
J¼8.3 Hz, 2H, ArH), 7.44 (d, J¼8.3 Hz, 1H, ArH), 7.34e
7.23 (m, 7H, ArH), 7.07 (d, J¼8.0 Hz, 2H, ArH), 3.07 (s,
1H, CCH), 2.46 (s, 3H, CH3), 2.32 (s, 3H, CH3).
4.1.4.3. 7,8,9,10-Tetrahydro-6-(trimethylsilyl)-5-tosyl-5H-ben-
zo[b]carbazole (3b0). 1H NMR (CDCl3) d: 8.04 (d,
J¼8.0 Hz, 1H, ArH), 7.46 (d, J¼8.0 Hz, 1H, ArH), 7.34e
7.29 (m, 2H, ArH), 7.22e7.15 (m, 2H, ArH), 6.75e6.67 (m,
3H, ArH), 3.18e2.79 (m, 4H, CH2), 1.94e1.77 (m, 4H, CH2),
2.14 (s, 3H, (CH3)), 0.55 (s, 3H, Si(CH3)3).
4.1.3.9. N-(2-(4-Methylphenyl)ethynyl)-2-ethynyl-N-mesylbenz-
enamine (2l). Clear oil. 1H NMR (CDCl3) d: 7.61 (dd,
J¼7.4, 1.8 Hz, 1H, ArH), 7.55 (dd, J¼7.6, 1.5 Hz, 1H, ArH),
7.49e7.38 (m, 2H, ArH), 7.34 (d, J¼8.1 Hz, 2H, ArH), 7.10
(d, J¼8.0 Hz, 2H, ArH), 3.47 (s, 1H, CCH), 3.33 (s, 3H,
CH3), 2.34 (s, 3H, CH3); 13C NMR/DEPT (CDCl3) d: 139.4
(C), 138.3 (C), 134.4 (CH), 131.7 (2ꢁCH), 130.1 (CH), 129.9
(CH), 129.2 (CH), 129.0 (2ꢁCH), 121.3 (C), 119.3 (C), 84.0
(CH), 80.8 (C), 79.7 (C), 65.6 (C), 39.5 (CH3), 21.4 (CH3).
4.1.4.4. 5-Tosyl-5H-benzo[b]carbazole (3c). 1H NMR
(CDCl3) d: 8.69 (d, J¼8.6 Hz, 1H, ArH), 8.58 (d, J¼9.1,
1H, ArH), 8.51e8.43 (m, 2H, ArH), 7.99 (d, J¼8.4 Hz, 1H,
ArH), 7.93 (d, J¼9.1 Hz, 1H, ArH), 7.70e7.65 (m, 3H, ArH),
7.55e7.45 (m, 3H, ArH), 7.04 (d, J¼8.2 Hz, 2H, ArH), 2.22
(s, 3H, CH3).
4.1.3.10. N-(2-(4-Methoxyphenyl)ethynyl)-2-ethynyl-N-mesyl-
benzenamine (2m). Excess of KOH was added to a solution

3684
M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
1
4.1.4.5. 12-Tosyl-12H-naphtho[1,2-b]carbazole (3d). H NMR
(CDCl3) d: 9.66 (s, 1H, ArH), 8.93 (d, J¼8.3 Hz, 1H, ArH),
8.39 (d, J¼8.4 Hz, 1H, ArH), 8.34 (s, 1H, ArH), 8.03 (d,
J¼7.1 Hz, 1H, ArH), 7.93 (d, J¼7.8 Hz, 1H, ArH), 7.8 (d, J¼
8.8 Hz, 1H, ArH), 7.78e7.72 (m, 4H, ArH), 7.68 (t, J¼8.0 Hz,
1H, ArH), 7.55 (t, J¼7.3 Hz, 1H, ArH), 7.43 (t, J¼7.6 Hz, 1H,
ArH), 7.03 (d, J¼8.0 Hz, 2H, ArH), 2.20 (s, 3H, CH3).
(s, 1H, ArH), 8.53 (s, 1H, ArH), 8.35 (d, J¼8.4 Hz, 1H, ArH),
8.29 (d, J¼9.1, 1H, ArH), 8.15 (d, J¼9.1 Hz, 1H, ArH), 8.07
(d, J¼7.7 Hz, 1H, ArH), 7.74 (d, J¼8.4 Hz, 2H, ArH), 7.61 (t,
J¼7.3 Hz, 1H, ArH), 7.45 (t, J¼7.4 Hz, 1H, ArH), 7.11 (d,
J¼8.5 Hz, 2H, ArH), 2.26 (s, 3H, CH3); 13C NMR/DEPT
(CDCl3) d: 145.4 (C), 140.2 (C), 139.8 (C), 135.1 (C), 134.6
(C), 129.9 (CH), 129.8 (2ꢁCH), 129.6 (C), 129.4 (CH), 128.7
(C), 128.6 (C), 126.6 (2ꢁCH), 125.1 (C), 125.0 (CH), 124.5
(CH), 121.0 (CH), 120.7 (CH), 119.1 (CH), 115.3 (CH), 112.1
(CH), 21.5 (CH3); MS (70 eV) m/z (%): 416 (Mþ, 5), 261
(57), 214 (72), 91 (100); HRMS: (C23H16N2O4S): calcd:
416.0830; found: 416.0831.
4.1.4.6. 8-Tosyl-8H-naphtho[2,1-b]carbazole (3e). 1H NMR
(CDCl3) d: 9.18 (s, 1H, ArH), 8.80e8.78 (m, 2H, ArH),
7.80e7.41 (m, 10H, ArH), 7.13 (d, J¼7.6 Hz, 1H, ArH),
7.06 (d, J¼8.3 Hz, 2H, ArH), 2.22 (s, 3H, CH3).
4.1.4.7. 10-Tosyl-10H-phenanthro[9,10-b]carbazole (3f). 1H
NMR (CDCl3) d: 9.56 (s, 1H, ArH), 9.06 (s, 1H, ArH), 8.85
(dd, J¼8.1, 1.3 Hz, 1H, ArH), 8.71e8.68 (m, 1H, ArH),
8.38 (d, J¼8.3 Hz, 1H, ArH), 8.08 (d, J¼7.7 Hz, 1H, ArH),
7.77e7.63 (m, 7H, ArH), 7.57e7.53 (m, 2H, ArH), 7.44 (dt,
J¼7.6, 0.9 Hz, 1H, ArH), 7.04 (d, J¼8.1 Hz, 2H, ArH), 2.19
(s, 3H, (CH3)).
4.1.4.13.
5-[(4-Methylphenyl)sulfonyl]-9-methoxy-5H-ben-
zo[b]carbazole (3l). 1H NMR (CDCl3) d: 8.65 (s, 1H, ArH),
8.32 (d, J¼8.4 Hz, 1H, ArH), 8.19 (s, 1H, ArH), 7.96e7.92
(m, 2H, ArH), 7.67 (d, J¼8.4 Hz, 2H, ArH), 7.50 (t,
J¼8.5 Hz, 1H, ArH), 7.36 (t, J¼8.4 Hz, 1H, ArH), 7.25e
7.20 (m, 2H, ArH), 7.02 (d, J¼8.1 Hz, 2H, ArH), 3.93 (s,
3H, OCH3), 2.20 (s, 3H, CH3); 13C NMR/DEPT (CDCl3) d:
157.1 (C), 144.7 (C), 140.0 (C), 135.9 (C), 134.7 (C), 131.7
(C), 129.8 (CH), 129.5 (2ꢁCH), 128.6 (C), 128.2 (CH),
127.3 (C), 126.5 (2ꢁCH), 126.4 (C), 124.1 (CH), 120.5
(CH), 119.3 (CH), 116.9 (CH), 115.4 (CH), 112.4 (CH),
105.4 (CH), 55.3 (OCH3), 21.4 (CH3); MS (70 eV) m/z (%):
401 (Mþ, 10), 246 (100), 203 (72); HRMS (C24H19NO3S):
calcd: 401.1085; found: 401.1082.
4.1.4.8.
9-Nitro-11-phenyl-5-tosyl-5H-benzo[b]carbazole
(3g). 1H NMR (CDCl3) d: 8.92 (s, 1H, ArH), 8.58 (d, J¼
2.3 Hz, 1H, ArH), 8.35 (d, J¼8.4 Hz, 1H, ArH), 8.29 (dd,
J¼9.1, 2.3 Hz, 1H, ArH), 8.20 (d, J¼9.1 Hz, 1H, ArH), 7.80
(d, J¼8.4 Hz, 2H, ArH), 7.66e7.63 (m, 3H, ArH), 7.48 (t, J¼
8.4 Hz, 1H, ArH), 7.40e7.37 (m, 2H, ArH), 7.16 (d,
J¼8.1 Hz, 2H, ArH), 7.07 (t, J¼8.1 Hz, 1H, ArH), 6.65
(d, J¼8.4 Hz, 1H, ArH), 2.29 (s, 3H, (CH3)).
4.1.4.14. 9-Chloro-5-[(4-methylphenyl)sulfonyl]-5H-benzo[b]-
carbazole (3m). 1H NMR (CDCl3) d: 8.70 (s, 1H, ArH),
8.33 (d, J¼8.4 Hz, 1H, ArH), 8.19 (s, 1H, ArH), 7.98e7.95
(m, 2H, ArH), 7.90 (d, J¼1.7 Hz, 1H, ArH), 7.70 (d,
J¼8.4 Hz, 2H, ArH), 7.54 (td, J¼8.5, 1.3 Hz, 1H, ArH),
7.46 (dd, J¼8.8, 2.1 Hz, 1H, ArH), 7.38 (t, J¼7.6 Hz, 1H,
ArH), 7.05 (d, J¼8.2 Hz, 2H, ArH), 2.22 (s, 3H, CH3); 13C
NMR/DEPT (CDCl3) d: 145.0 (C), 140.1 (C), 137.4 (C),
134.6 (C), 131.0 (C), 131.0 (C), 130.8 (C), 129.9 (CH),
129.6 (2ꢁCH), 128.7 (CH), 127.7 (C), 126.8 (CH), 126.5
(2ꢁCH), 126.4 (CH), 125.8 (C), 124.2 (CH), 120.7 (CH),
117.4 (CH), 115.3 (CH), 112.2 (CH), 21.4 (CH3); MS
(70 eV) m/z (%): 407 (MþCl 37, 6), 405 (MþCl 35, 15),
252 (34), 250 (100), 58 (66); HRMS (C23H16NO2SCl): calcd
405.0590; found 405.0592.
4.1.4.9.
6-(Pyrimidin-2-yl)-5-tosyl-5H-benzo[b]carbazole
(3h). 1H NMR (CDCl3) d: 8.90 (d, J¼4.8 Hz, 2H, ArH),
8.57 (d, J¼8.3 Hz, 1H, ArH), 8.47 (s, 1H, ArH), 8.34e8.27
(m, 3H, ArH), 8.11 (d, J¼7.9 Hz, 1H, ArH), 7.11 (t,
J¼7.1 Hz, 1H, ArH), 7.60 (t, J¼7.3 Hz, 1H, ArH), 7.48e7.41
(m, 3H, ArH), 7.32 (t, J¼4.8 Hz, 1H, ArH), 7.00 (d, J¼8.2 Hz,
2H, ArH), 6.74 (d, J¼8.1 Hz, 2H, ArH), 2.09 (s, 3H, CH3).
4.1.4.10.
11-Cyclohexenyl-5-tosyl-5H-benzo[b]carbazole
(3i). 1H NMR (CDCl3) d: 8.69 (s, 1H, ArH), 8.36 (d, J¼
8.4 Hz, 1H, ArH), 8.15 (d, J¼7.8 Hz, 1H, ArH), 8.08 (d,
J¼8.4 Hz, 1H, ArH), 8.04 (d, J¼8.1 Hz, 1H, ArH), 7.73 (d, J¼
8.0 Hz, 2H, ArH), 7.56e7.47 (m, 3H, ArH), 7.34 (t, J¼7.4 Hz,
1H, ArH), 7.07 (d, J¼8.0 Hz, 2H, ArH), 5.84 (br s, 1H, C]CH),
2.38e2.33 (m, 4H, CH2), 2.24 (s, 3H, CH3), 1.98e1.93 (m, 4H,
CH2).
4.1.4.15. 9-Fluoro-5-[(4-methylphenyl)sulfonyl]-5H-benzo[b]-
carbazole (3n). 1H NMR (CDCl3) d: 8.73 (s, 1H, ArH), 8.33
(d, J¼8.4 Hz, 1H, ArH), 8.24 (s, 1H, ArH), 8.03 (dd, J¼9.0,
5.6 Hz, 1H, ArH), 7.99 (d, J¼7.2 Hz, 1H, ArH), 7.70 (d,
J¼8.4 Hz, 2H, ArH), 7.57e7.52 (m, 2H, ArH), 7.39 (t,
J¼7.5 Hz, 1H, ArH), 7.33 (td, J¼8.7, 2.5 Hz, 1H, ArH), 7.06
(d, J¼8.4 Hz, 2H, ArH), 2.22 (s, 3H, ArH); 13C NMR/DEPT
(CDCl3) d: 160.1 (d, JCeF¼245 Hz, C), 144.9 (C), 140.1 (C),
134.6 (C), 131.1 (C), 131.1 (C), 130.7 (d, JCeF¼9 Hz, CH),
129.9 (C), 129.6 (2ꢁCH), 128.7 (CH), 127.8 (C), 126.5
4.1.4.11. 7,8,9,10-Tetrahydro-6-phenyl-5-tosyl-5H-benzo[b]-
carbazole (3j). 1H NMR (CDCl3) d: 8.09 (d, J¼7.6 Hz, 2H,
ArH), 7.67 (d, J¼8.1 Hz, 1H, ArH), 7.51 (s, 1H, ArH),
7.42e7.29 (m, 6H, ArH), 7.05 (d, J¼8.2 Hz, 2H, ArH), 6.89
(d, J¼8.2 Hz, 2H, ArH), 2.98e2.95 (m, 2H, CH2), 2.62e
2.59 (m, 2H, CH2), 2.24 (s, 3H, (CH3)), 1.85e1.79 (m, 2H,
CH2), 1.74e1.69 (m, 2H, CH2).
(2ꢁCH), 125.9 (C), 124.2 (CH), 120.7 (CH), 117.5 (d, JCeF
¼
4.1.4.12. 5-[(4-Methylphenyl)sulfonyl]-9-nitro-5H-benzo[b]-
carbazole (3k). 1H NMR (CDCl3) d: 8.95 (s, 1H, ArH), 8.83
6 Hz, CH), 116.6 (d, JCeF¼26 Hz, CH), 115.4 (CH), 112.4
(CH), 110.6 (d, JCeF¼21 Hz, CH), 21.4 (CH3); ESI-TOF m/z

M.F. Mart´ınez-Espero´n et al. / Tetrahedron 64 (2008) 3674e3686
3685
(%): 390 (Mþþ1, 6), 245 (100), 149 (76); HRMS
4.1.4.20. 9-Methoxy-5-(methylsulfonyl)-5H-benzo[b]carbazole
(3t). 1H NMR (CDCl3) d: 8.48 (s, 1H, ArH), 8.33 (s, 1H,
ArH), 8.17 (d, J¼8.0 Hz, 1H, ArH), 8.09 (d, J¼7.7 Hz, 1H,
ArH), 7.89 (d, J¼9.0 Hz, 1H, ArH), 7.54 (td, J¼8.1, 1.4 Hz,
1H, ArH), 7.44 (td, J¼7.5, 1.1 Hz, 1H, ArH), 7.29 (d,
J¼2.4 Hz, 1H, ArH), 7.23 (dd, J¼9.0, 2.5 Hz, 1H, ArH),
3.97 (s, 3H, CH3), 2.96 (s, 3H, CH3); 13C NMR/DEPT
(CDCl3) d: 157.3 (C), 140.0 (C), 135.8 (C), 131.8 (C), 129.8
(CH), 128.6 (C), 128.5 (CH), 127.1 (C), 126.3 (C), 124.3
(CH), 120.7 (CH), 119.5 (CH), 117.2 (CH), 115.0 (CH),
111.9 (CH), 105.5 (CH), 55.3 (CH3), 37.7 (CH3). MS
(70 eV) m/z (%): 325 (Mþ, 19), 246 (100), 203 (50); HRMS
(C18H15NO3S): calcd: 325.0773; found: 325.0769.
(C23H17FNO2S): calcd: 390.0959; found: 390.0970.
4.1.4.16. 10-[(4-Methylphenyl)sulfonyl]-10H-pyrido[3,4-b]-
carbazole (3p). 1H NMR (CDCl3) d: 9.48 (s, 1H, ArH),
8.87 (s, 1H, ArH), 8.53 (d, J¼5.8 Hz, 1H, ArH), 8.37 (d,
J¼8.4 Hz, 1H, ArH), 8.33 (s, 1H, ArH), 8.07 (d, J¼8.4 Hz,
1H, ArH), 7.77 (d, J¼5.8 Hz, 1H, ArH), 7.73 (d, J¼8.4 Hz,
2H, ArH), 7.61 (t, J¼8.4 Hz, 1H, ArH), 7.44 (t, J¼7.9 Hz, 1H,
ArH), 7.10 (d, J¼8.4 Hz, 2H, ArH), 2.25 (s, 3H, CH3); 13C
NMR/DEPT (CDCl3) d: 145.0 (C), 140.7 (C), 134.4 (C),
132.6 (C), 130.9 (CH), 129.9 (CH), 129.8 (2ꢁCH), 129.7 (C),
128.8 (CH), 126.6 (2ꢁCH), 126.5 (C), 125.1 (C), 124.5 (CH),
121.4 (CH), 117.0 (CH), 115.4 (CH), 112.4 (CH), 29.7 (CH3);
MS (70 eV) m/z (%): 372 (Mþ, 21), 217 (100), 190 (12);
HRMS: (C22H16N2O2S): calcd: 372.0932; found: 372.0925.
4.1.4.21. 5-[(4-Methylphenyl)sulfonyl]-11-(trimethylsilyl)-5H-
benzo[b]carbazole (3u). 1H NMR (CDCl3) d: 8.74 (s, 1H,
ArH), 8.35e8.33 (m, 2H, ArH), 8.06 (d, J¼8.1 Hz, 1H, ArH),
8.01 (d, J¼7.7 Hz, 1H, ArH), 7.97 (d, J¼8.1 Hz, 1H, ArH),
7.71 (d, J¼8.4 Hz, 2H, ArH), 7.57e7.48 (m, 2H, ArH), 7.39
(t, J¼7.7 Hz, 1H, ArH), 7.05 (d, J¼8.4 Hz, 2H, ArH), 2.22 (s,
3H, CH3); 0.07 (s, 9H, Si(CH3)3); 13C NMR/DEPT (CDCl3) d:
144.9 (C), 140.1 (C), 138.8 (C), 137.3 (C), 134.7 (C), 133.0 (C),
130.6 (C), 129.6 (2ꢁCH), 128.5 (CH), 128.4 (CH), 128.0 (CH),
126.9 (C), 126.5 (2ꢁCH), 126.3 (C), 125.9 (CH), 125.1
(CH), 124.1 (CH), 120.6 (CH), 118.3 (CH), 115.4 (CH), 112.2
(CH), 21.5 (CH3), 1.9 (Si(CH3)3); MS FAB m/z (%): 444
(Mþþ1.4), 371 (50), 216 (100); HRMS: (C26H25NO2SSiNa)
calcd: 466.1273; found: 466.1267.
4.1.4.17. 9-[(4-Methylphenyl)sulfonyl]-9H-thieno[2,3-b]carb-
azole (3q). 1H NMR (CDCl3) d: 8.84 (s, 1H, ArH), 8.33 (d,
J¼8.3 Hz, 1H, ArH), 8.28 (s, 1H, ArH), 7.94 (d, J¼7.6 Hz,
1H, ArH), 7.69 (d, J¼8.4 Hz, 2H, ArH), 7.51 (d, J¼7.3 Hz,
1H, ArH), 7.48 (d, J¼5.9 Hz, 1H, ArH), 7.41e7.34 (m, 2H,
ArH), 7.07 (d, J¼8.5 Hz, 2H, ArH), 2.23 (s, 3H, CH3); 13C
NMR/DEPT (CDCl3) d: 144.9 (C), 139.7 (C), 139.2 (C),
136.6 (C), 136.4 (2ꢁC), 134.7 (C), 129.6 (2ꢁCH), 127.5
(CH), 126.5 (2ꢁCH), 125.2 (C), 124.0 (CH), 123.4 (CH),
119.9 (CH), 115.4 (2ꢁCH), 114.0 (CH), 108.5 (CH), 21.5
(CH3); MS (70 eV) m/z (%): 377 (Mþ, 11), 222 (100), 196 (7);
HRMS: (C21H15NO2S): calcd: 377.0544; found: 377.0549.
4.1.4.22. 6-Tosyl-6H-pyrido[4,3-b]carbazole (3v). 1H NMR
(CDCl3) d: 9.39 (s, 1H, ArH), 8.71 (s, 1H, ArH), 8.55 (d,
J¼5.9 Hz, 1H, ArH), 8.50 (s, 1H, ArH), 8.36 (d, J¼8.4 Hz, 1H,
ArH), 8.07 (d, J¼7.2 Hz, 1H, ArH), 7.86 (d, J¼5.9 Hz, 1H,
ArH), 7.74 (d, J¼8.4 Hz, 2H, ArH), 7.59 (t, J¼7.2 Hz,
1H, ArH), 7.44 (t, J¼7.2 Hz, 1H, ArH), 7.11 (d, J¼8.4 Hz,
2H, ArH), 2.26 (s, 3H, CH3); 13C NMR/DEPT (CDCl3) d:
152.7 (CH), 145.3 (C), 142.3 (CH), 140.1 (C), 140.0 (C),
135.1 (C), 134.6 (C), 131.1 (C), 129.8 (2ꢁCH), 129.1 (CH),
128.0 (C), 126.5 (2ꢁCH), 125.5 (C), 124.4 (CH), 120.8 (CH),
118.6 (CH), 115.2 (CH), 110.4 (CH), 21.5 (CH3); MS (70 eV)
m/z (%): 372 (Mþ, 13), 217 (100), 190 (12); HRMS:
(C22H16N2O2S): calcd: 372.0932; found: 372.0937.
4.1.4.18. 3-Chloro-9-methyl-5-[(4-methylphenyl)sulfonyl]-5H-
benzo[b]carbazole (3r). 1H NMR (CDCl3) d: 8.64 (s, 1H,
ArH), 8.35 (d, J¼1.8 Hz, 1H, ArH), 8.16 (s, 1H, ArH), 7.94
(d, J¼8.5 Hz, 1H, ArH), 7.87 (d, J¼8.3 Hz, 1H, ArH), 7.72e
7.70 (m, 3H, ArH), 7.39 (dd, J¼8.5, 1.6 Hz, 1H, ArH), 7.34
(d, J¼8.0, 1.7 Hz, 1H, ArH), 7.08 (d, J¼8.3 Hz, 2H, ArH),
2.55 (s, 3H, CH3), 2.24 (s, 3H, CH3); 13C NMR/DEPT
(CDCl3) d: 145.1 (C), 140.6 (C), 136.8 (C), 135.0 (C), 134.5
(C), 133.9 (C), 131.3 (C), 130.9 (C), 129.7 (2ꢁCH), 128.6
(CH), 128.2 (CH), 126.7 (CH), 126.6 (2ꢁCH), 125.9 (C),
125.0 (C), 124.5 (CH), 121.2 (CH), 117.7 (CH), 115.6 (CH),
112.1 (CH), 21.7 (CH3), 21.5 (CH3); ESI-TOF m/z (%): 420
(Mþþ1, 9), 356 (100), 282 (66); HRMS (C24H19NO2SCl):
calcd: 420.0820; found: 420.0836.
Acknowledgements
4.1.4.19. 9-Methyl-5-(methylsulfonyl)-5H-benzo[b]carbazole
(3s). H NMR (CDCl3) d: 8.51 (s, 1H, ArH), 8.33 (s, 1H,
´
We thank the Ministerio de Educacion y Ciencia (Spain),
1
the European Regional Development Fund and the Xunta
de Galicia (XUGA) for financial support under projects
CTQ2005-08613 and PGIDIT06PXIC209041PN. M.F.M-.E.
and D.R. also thank XUGA and the Universidad de Santiago
de Compostela for predoctoral and postdoctoral grants,
respectively.
ArH), 8.17 (d, J¼8.2 Hz, 1H, ArH), 8.10 (d, J¼8.2 Hz, 1H,
ArH), 7.91 (d, J¼8.4 Hz, 1H, ArH), 7.77 (s, 1H, ArH), 7.53 (td,
J¼7.6, 1.4 Hz, 1H, ArH), 7.45 (td, J¼7.5, 1.0 Hz, 1H, ArH),
7.39 (dd, J¼8.4, 1.5 Hz, 1H, ArH), 2.96 (s, 3H, CH3), 2.57 (s,
3H, CH3); 13C NMR/DEPT (CDCl3) d: 140.0 (C), 136.7 (C),
134.9 (C), 131.3 (C), 130.9 (C), 128.6 (CH), 128.4 (CH), 128.1
(CH), 126.8 (CH), 126.8 (CH), 126.7 (C), 126.4 (C), 124.3
(CH), 120.7 (CH), 117.9 (CH), 111.5 (CH), 37.7 (CH3), 21.7
(CH3); ESI-TOF m/z (%): 310 (Mþþ1, 6), 245 (100), 149 (86);
HRMS (C18H16NO2S): calcd: 310.0896; found: 310.0902.
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aniline and the mesyl-protected analogue of 1i either with TIPS (for 2l)
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on the reacting and non-reacting aryl ring (e.g., 2e, 2f and 2k) underwent
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