Indium(III) bromide catalyzed rapid propargylation of heteroaromatic systems by α-aryl-substituted propargyl alcohols

Article abstract of DOI:10.1055/s-2007-990797

A variety of heteroaromatic compounds such as indole, carbazole, pyrrole, and furan underwent smooth coupling with propargylic alcohols in the presence of 10 mol% of indium(III) bromide under mild conditions to furnish exclusively propargylated heterocycl

Full text of DOI:10.1055/s-2007-990797

PAPER
A
Indium(III) Bromide Catalyzed Rapid Propargylation of Heteroaromatic
Systems by a-Aryl-Substituted Propargyl Alcohols
I
ndium(III
.
)
B
romide
C
S
atalyze
d
Propa
.
rgylationof
Y
H
eteroaromatic
S
a
ystems dav,* B. V. Subba Reddy, K. V. Raghavendra Rao, G. G. K. S. Narayana Kumar
Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad 500007, India
Fax +91(40)27160512; E-mail: yadavpub@iict.res.in
Received 6 July 2007; revised 25 July 2007
vated alcohols and allylation of doubly activated alco-
hols.8b,9 However, there have been no reports on the use of
indium(III) bromide as catalyst for the propargylation of
heteroaromatic systems by a-aryl-substituted propargyl
Abstract: A variety of heteroaromatic compounds such as indole,
carbazole, pyrrole, and furan underwent smooth coupling with pro-
pargylic alcohols in the presence of 10 mol% of indium(III) bro-
mide under mild conditions to furnish exclusively propargylated
heterocycles in excellent yields and high regioselectivity. The use alcohols.
of indium(III) bromide makes this procedure simple, convenient,
In continuation of our interest in the catalytic use of indi-
and practical. The hydroxy groups of the propargylic alcohols were
simply replaced by the nucleophiles in an SN2¢ manner.
um(III) bromide,10 the work we report herein is on a novel
and efficient propargylation of heteroaromatics by a-aryl-
substituted propargyl alcohols. In a preliminary study, in-
dole (1a) was treated with 1,3-diphenylprop-2-yn-1-ol
(2a) in the presence of 10 mol% of indium(III) bromide
(Scheme 1). The reaction went to completion at room
temperature within 15 minutes to give product 3a in 91%
yield (Scheme 1; Table 1, entry 1).
Key words: indium reagents, nucleophilic substitution, C-alkyla-
tion, propargylation
The indole nucleus is a prominent structural motif found
in numerous natural products and synthetic compounds
with important biological activities, and thus considerable
attention has been focused toward general, flexible, and
selective methods for the synthesis of highly functional-
ized indole derivatives.1 Currently, the implementation of
mild and selective procedures with ample functional
group tolerance for the preparation of indoles is of great
interest.2–5 Nucleophilic substitution of the hydroxy group
in alcohols with nucleophiles generally requires preacti-
vation of the alcohols because of the poor leaving ability
of the hydroxy group.6 Consequently, hydroxy groups are
generally transformed into the corresponding halides, car-
boxylates, carbonates, phosphonates, or related com-
pounds.7 However, such processes inevitably produce
stoichiometric amounts of salt waste and, also, substitu-
tion with halides requires a stoichiometric amount of base,
which limits their use in large-scale synthesis. In most
cases, either a high reaction temperature is required or a
promoter is added to enhance the leaving ability of the hy-
droxy group. Therefore, the direct catalytic substitution of
alcohols by indoles with the aid of an efficient, water-tol-
erant, and recyclable catalyst is highly desirable. Recent-
ly, indium(III) bromide has received increasing attention
as a water-tolerant green Lewis acid catalyst for organic
synthesis, and has demonstrated highly chemo-, regio-,
and stereoselective results.8 Compared to conventional
Lewis acids, it has the advantages of water stability, recy-
clability, operational simplicity, strong tolerance toward
oxygen and nitrogen-containing substrates and functional
groups, and that it can often be used in catalytic amounts.
It has recently been utilized for the deoxygenation of acti-
Ph
Ph
OH
10 mol% InBr3
+
DCE, r.t.
Ph
N
N
H
H
Ph
1a
2a
3a
Scheme 1
Encouraged by this result, we turned our attention to var-
ious other indoles (Table 1). Interestingly, 5-bromo-, 5-
nitro-, and 2-phenyl-substituted indoles (1b–d) reacted
smoothly with 1,3-diphenylprop-2-yn-1-ol (2a) to furnish
the corresponding 3-propargylated indoles 3b–d in excel-
lent yields (Table 1, entries 2–4). Other propargylic alco-
hols such as 1-(p-tolyl)hept-2-yn-1-ol (2b) and 1-
phenylhept-2-yn-1-ol (2c) reacted efficiently with indole
(1a), 5-cyanoindole (1e), and 5-nitroindole (1c) at room
temperature under identical conditions (Table 1, entries
5–9). In addition, the reaction with (E)-1,5-diphenylpent-
1-en-4-yn-3-ol (2d) also proceeded well (Scheme 2;
Table 1, entries 10 and 11). Similarly, (E)-1-phenylnon-1-
en-4-yn-3-ol (2e) reacted smoothly with 5-bromoindole
(1b) and 7-ethylindole (1f) (Table 1, entries 12 and 13).
Pyrrole (1g) and furan (1h) gave the respective 2-propar-
gylated pyrrole and furan derivatives 3o and 3p (Table 1,
entries 15 and 16). Like with indole (1a), the propargyla-
tion of carbazole (1i) occurred at the C-3 position
(Table 1, entry 17).
SYNTHESIS 2007, No. x, pp 000A–000F
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Advanced online publication: xx.xx.2007
DOI: 10.1055/s-2007-990797; Art ID: Z16307SS
© Georg Thieme Verlag Stuttgart · New York

B
J. S. Yadav et al.
PAPER
Table 1 Indium(III) Bromide Catalyzed Alkylation of Heteroaromatic Systems by a-Aryl-Substituted Propargylic Alcohols
Entry Hetarene
1
Propargylic alcohol
2
Producta
3
Time Yieldb
(min) (%)
Ph
Ph
OH
1
1a
2a
3a
15
25
40
35
91
93
85
88
Ph
N
H
Ph
N
H
Ph
Ph
OH
Br
Br
2
1b
1c
1d
2a
2a
2a
3b
3c
3d
Ph
N
H
Ph
N
H
Ph
Ph
OH
O2N
3
O2N
Ph
N
H
Ph
N
H
Ph
Ph
OH
4
5
Ph
Ph
N
H
Ph
Ph
N
H
Me
OH
1a
2b
3e
20
90
N
H
Me
N
H
Me
OH
NC
6
1e
1a
1c
1c
2b
2c
2b
2c
3f
35
20
30
35
87
92
86
87
N
NC
H
Me
N
H
Ph
OH
Ph
7
3g
3h
3i
N
H
N
H
Me
OH
O2N
8
N
O2N
H
Me
N
H
Ph
O2N
OH
Ph
O2N
9
N
H
N
H
Synthesis 2007, No. x, A–F © Thieme Stuttgart · New York

PAPER
Indium(III) Bromide Catalyzed Propargylation of Heteroaromatic Systems
C
Table 1 Indium(III) Bromide Catalyzed Alkylation of Heteroaromatic Systems by a-Aryl-Substituted Propargylic Alcohols (continued)
Entry Hetarene
1
Propargylic alcohol
2
Producta
3
Time Yieldb
(min) (%)
Ph
Ph
OH
10
1a
2d
3j
30
35
30
86c
84c
91c
Ph
N
H
Ph
N
H
Ph
Ph
OH
OH
NC
11
1e
2d
2e
3k
3l
NC
Ph
Ph
N
H
Ph
Ph
N
H
Ph
Br
12
1b
Br
N
H
N
H
Ph
OH
13
1f
2e
2f
3m
25
35
88c
N
H
Ph
Ph
Et
N
H
Et
F
OH
Ph
14
1a
3n
92
N
H
Ph
F
N
H
OH
OH
15
16
1g
1h
2c
2a
3o
3p
40
35
84
86
Ph
Ph
N
H
N
H
Ph
Ph
Ph
O
O
Ph
Ph
OH
Ph
17
1i
2a
3q
35
88
Ph
N
Ph
H
N
H
a All products were characterized by 1H and 13C NMR, IR, and mass spectroscopy.
b Isolated and non-optimized yield.
c E/Z ratio 9:1.
Interestingly, electron-deficient indoles such as 5-nitro- in high selectivity and were completed within 15–40 min-
(1c) and 5-cyanoindole (1e) also underwent smooth alky- utes. In the absence of indium(III) bromide, no reaction
lation with propargylic alcohols under similar reaction was observed. No addition or rearranged products were
conditions to give the corresponding 3-substituted indoles observed when secondary alcohols activated by both al-
(Table 1). In all cases, the reactions proceeded efficiently lylic and propargylic functionalities were used (Table 1,
Synthesis 2007, No. x, A–F © Thieme Stuttgart · New York

D
J. S. Yadav et al.
PAPER
Ph
Ph
OH
10 mol% InBr3
DCE, r.t.
+
Ph
N
H
Ph
N
H
3j
2d
1a
Scheme 2
1H NMR (200 MHz, CDCl3): d = 5.33 (s, 1 H), 6.99 (d, J = 1.7 Hz,
1 H), 7.11 (d, J = 8.4 Hz, 1 H), 7.18–7.33 (m, 6 H), 7.39–7.47 (m, 6
H), 7.69 (d, J = 1.7 Hz, 1 H), 7.89 (br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 35.4, 83.2, 90.5, 111.1, 116.7,
119.5, 122.1, 122.5, 123.6, 126.0, 126.7, 127.7, 127.8, 128.1, 128.4,
131.6, 136.6, 141.2.
entries 10–13). The hydroxy group was simply replaced
by the indole in an SN2¢ manner. This method is compati-
ble with alkenyl-, alkynyl-, halo-, nitro-, cyano-, and free
amino groups. Acid-sensitive substrates such as pyrrole
and furan were also well tolerated under these conditions.
Primary benzylic alcohols failed to react with indoles un-
der these conditions. As solvent, 1,2-dichloroethane ap-
peared to give the best results. All the products were
characterized by 1H- and 13C NMR-, IR-, and mass spec-
troscopy. To examine the efficacy of indium(III) bromide,
this reaction was carried out with various other indi-
um(III) salts such as indium(III) fluoride, -chloride, -per-
chlorate, and -triflate. Of these, indium(III) bromide was
found to give the best results in terms of conversion. Al-
ternatively, 10 mol% of bismuth(III) triflate was also
equally effective for this conversion. The results present-
ed in Table 1 illustrate the scope and generality of this
process with regard to various heteroaromatic systems
and secondary propargylic alcohols.
MS (EI, 70 eV): m/z (%) = 308 (100) [M + H+].
HRMS: m/z calcd for C23H18N: 308.1439; found: 308.1446.
5-Bromo-3-(1,3-diphenylprop-2-ynyl)-1H-indole (3b)
Brown liquid.
IR (KBr): 3425, 2924, 2855, 1453, 756, 695 cm–1.
1H NMR (200 MHz, CDCl3): d = 5.35 (s, 1 H), 7.05 (d, J = 1.4 Hz,
1 H), 7.14–7.36 (m, 9 H), 7.39–7.51 (m, 3 H), 7.70 (d, J = 1.4 Hz, 1
H), 7.97 (br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 31.6, 82.1, 87.5, 111.1, 112.1,
117.5, 121.0, 121.6, 122.7, 123.5, 126.2, 128.4, 128.8, 129.1, 129.9,
130.4, 133.3, 134.4, 140.8.
MS (EI, 70 eV): m/z (%) = 409 (40) [M+ + Na].
HRMS: m/z calcd for C23H16BrNNa: 408.0363; found: 408.0369.
In summary, indium(III) bromide has proved to be an ef-
fective catalyst for the propargylation of heteroaromatic
systems by propargylic alcohols in high yields and short
reaction times with high selectivity, making it a useful and
attractive process for the alkylation of heteroaromatics.
The use of indium(III) bromide makes this procedure sim-
ple, convenient, and practical.
3-(1,3-Diphenylprop-2-ynyl)-5-nitro-1H-indole (3c)
Yellow solid; mp 110–113 °C.
IR (KBr): 3410, 2923, 2853, 1622, 1517, 1466, 1331, 1098, 755,
695 cm–1.
1H NMR (200 MHz, CDCl3): d = 5.44 (s, 1 H), 7.19–7.37 (m, 8 H),
7.44–7.51 (m, 4 H), 8.10 (dd, J = 2.4, 9.4 Hz, 1 H), 8.31 (br s, 1 H),
8.63 (d, J = 1.7 Hz, 1 H).
Melting points were recorded on a Buchi R-535 apparatus and are
uncorrected. IR spectra were recorded on a Perkin-Elmer FT-IR
240-c spectrophotometer using KBr optics. 1H and 13C NMR spec-
tra were recorded on Gemini-200 and Varian Bruker-300 spectrom-
eters; samples were dissolved in CDCl3 and TMS was used as
internal standard. Mass spectra were recorded on a Finnigan MAT
1020 mass spectrometer operating at 70 eV. HRMS were conducted
under ESI mode.
13C NMR (50 MHz, CDCl3): d = 31.8, 81.2, 87.2, 111.0, 111.6,
115.0, 122.7, 123.6, 125.4, 126.9, 128.3, 128.4, 128.5, 128.7, 129.0,
134.3, 140.4, 142.8.
MS (EI, 70 eV): m/z (%) = 375 (100) [M+ + Na].
HRMS: m/z calcd for C23H16N2O2Na: 375.1109; found: 375.1116.
3-(1,3-Diphenylprop-2-ynyl)-2-phenyl-1H-indole (3d)
Liquid.
Propargylation of Hetarenes 1a–h by Propargyl Alcohols 2a–f;
General Procedure
IR (KBr): 3412, 2924, 2854, 1744, 1599, 1489, 1452, 756, 695
cm–1.
1H NMR (200 MHz, CDCl3): d = 5.60 (s, 1 H), 7.08–7.58 (m, 19 H),
7.99 (br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 30.4, 81.4, 87.8, 112.1, 112.8,
119.8, 121.4, 122.6, 123.0, 123.8, 125.9, 127.4, 127.8, 128.0, 128.5,
128.9, 129.2, 130.2, 131.1, 132.4, 134.2, 137.7, 142.8.
A mixture of hetarene 1 (1.0 mmol), propargylic alcohol 2 (1.0
mmol), and InBr3 (10 mol%) in DCE (5 mL) was stirred at r.t. for
the appropriate time (Table 1). After completion of the reaction as
indicated by TLC, the reaction mixture was diluted with H2O and
extracted with CH2Cl2 (2 × 15 mL). The combined organic layers
were dried (Na2SO4), concentrated in vacuo, and purified by col-
umn chromatography (silica gel, Merck, 100–200 mesh, EtOAc–
hexane, 1:9); this afforded pure product 3.
MS (EI, 70 eV): m/z (%) = 406 (70) [M+ + Na].
HRMS: m/z calcd for C29H21NNa: 406.1571; found: 406.1588.
3-(1,3-Diphenylprop-2-ynyl)-1H-indole (3a)
Dark brown liquid.
3-[1-(4-Tolyl)hept-2-ynyl]-1H-indole (3e)
Liquid.
IR (KBr): 3418, 3061, 2923, 2853, 2360, 2196, 1696, 1595, 1451,
1285, 1214, 882, 795, 755, 697 cm–1.
IR (KBr): 3417, 3051, 2956, 2927, 2863, 1613, 1510, 1456, 1421,
1344, 1093, 772, 742 cm–1.
Synthesis 2007, No. x, A–F © Thieme Stuttgart · New York

PAPER
Indium(III) Bromide Catalyzed Propargylation of Heteroaromatic Systems
E
1H NMR (300 MHz, CDCl3): d = 0.91 (t, J = 6.7 Hz, 3 H), 1.36–1.57
(m, 4 H), 2.24 (dt, J = 2.2, 6.7 Hz, 2 H), 2.30 (s, 3 H), 5.09 (s, 1 H),
6.93–7.10 (m, 6 H), 7.18–7.28 (m, 2 H), 7.44 (d, J = 8.3 Hz, 1 H),
7.81 (br s, 1 H).
13C NMR (50 MHz, CDCl3): d = 13.4, 19.6, 22.3, 32.2, 33.2, 75.4,
79.7, 111.2, 113.1, 118.9, 120.6, 122.4, 123.5, 126.4, 128.9, 129.0,
129.8, 137.2, 141.2.
13C NMR (CDCl3, 300 MHz): d = 13.5, 18.5, 22.0, 30.9, 34.7, 79.7,
84.3, 111.0, 117.1, 117.8, 120.6, 125.2, 125.5, 126.9, 127.6, 128.5,
139.6, 141.0, 141.6.
MS (EI, 70 eV): m/z (%) = 333 (100) [M + H+].
HRMS: m/z calcd for C21H21N2O2: 333.1603; found: 333.1609.
3-[(E)-3-Phenyl-1-(2-phenylethynyl)allyl]-1H-indole (3j)
Brown liquid.
MS (EI, 70 eV): m/z (%) = 324 (90) [M+ + Na].
HRMS: m/z calcd for C22H23NNa: 324.1728; found: 324.1736.
IR (KBr): 3421, 2923, 2853, 1596, 1489, 1455, 1416, 1337, 1218,
1095, 958, 747, 695 cm–1.
3-[1-(4-Tolyl)hept-2-ynyl]-1H-indole-5-carbonitrile (3f)
Dark brown liquid.
1H NMR (200 MHz, CDCl3): d = 4.96 (d, J = 7.2 Hz, 1 H), 5.58 (dd,
J = 1.4, 16.0 Hz, 1 H), 6.62 (dd, J = 7.2, 16.0 Hz, 1 H), 6.75 (d,
J = 2.1 Hz, 1 H), 6.87–7.37 (m, 14 H), 7.81 (br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 34.6, 83.9, 90.6, 111.1, 112.2,
118.9, 120.1, 121.0, 122.1, 122.7, 123.6, 126.3, 127.6, 128.4, 128.9,
129.5, 130.0, 131.1, 133.2, 136.6, 141.1.
IR (KBr): 3330, 2957, 2929, 2865, 2221, 1617, 1510, 1467, 1430,
1355, 1093, 805, 769 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.92 (t, J = 7.5 Hz, 3 H), 1.36–1.57
(m, 4 H), 2.25 (dt, J = 2.2, 7.5 Hz, 2 H), 2.32 (s, 3 H), 5.08 (s, 1 H),
7.02–7.16 (m, 3 H), 7.23–7.29 (m, 2 H), 7.31–7.40 (m, 2 H), 7.87
(s, 1 H), 8.50 (br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 13.7, 19.5, 22.0, 25.1, 30.9, 33.9,
78.7, 83.8, 102.2, 111.0, 113.8, 116.2, 123.9, 124.6, 126.6, 128.7,
129.2, 129.9, 136.6, 140.1, 142.2.
MS (EI, 70 eV): m/z (%) = 334 (80) [M + H+].
HRMS: m/z calcd for C25H20N: 334.1595; found: 334.1601.
3-[(E)-3-Phenyl-1-(2-phenylethynyl)allyl]-1H-indole-5-carbo-
nitrile (3k)
Yellow liquid.
MS (EI, 70 eV): m/z (%) = 349 (100) [M+ + Na].
HRMS: m/z calcd for C23H22N2Na: 349.1680; found: 349.1688.
IR (KBr): 3416, 2922, 2853, 2220, 1618, 1436, 1356, 8.5, 756, 694
cm–1.
3-(1-Phenylhept-2-ynyl)-1H-indole (3g)
Yellow liquid.
IR (KBr): 3416, 2925, 2856, 1454, 1339, 1091, 742, 700 cm–1.
1H NMR (200 MHz, CDCl3): d = 4.97 (d, J = 6.7 Hz, 1 H), 5.65 (dd,
J = 1.5, 15.8 Hz, 1 H), 6.37 (dd, J = 6.7, 15.8 Hz, 1 H), 7.02 (d,
J = 1.5 Hz, 1 H), 7.16–7.49 (m, 12 H), 8.13 (s, 1 H), 8.33 (m, 1 H).
1H NMR (200 MHz, CDCl3): d = 0.88 (t, J = 6.7 Hz, 3 H), 1.18–1.58
(m, 4 H), 2.24 (dt, J = 1.5, 6.7 Hz, 2 H), 5.28 (s, 1 H), 6.94–7.49 (m,
10 H), 7.87 (br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 34.6, 83.9, 90.6, 102.2, 111.1,
112.2, 116.0, 122.1, 122.7, 123.0, 124.1, 126.1, 126.9, 127.8, 128.4,
128.9, 129.4, 129.7, 131.1, 133.3, 136.6, 142.2.
13C NMR (75 MHz, CDCl3): d = 13.5, 18.5, 22.0, 30.9, 34.7, 79.7,
84.3, 111.0, 117.1, 117.8, 120.6, 125.2, 125.5, 126.9, 127.6, 128.5,
139.6, 141.0, 141.6.
MS (EI, 70 eV): m/z (%) = 359 (100) [M + H+].
HRMS: m/z calcd for C26H19N2: 359.1548; found: 359.1555.
MS (EI, 70 eV): m/z (%) = 310 (100) [M+ + Na].
5-Bromo-3-{1-[(E)-2-phenylvinyl]hept-2-ynyl}-1H-indole (3l)
Liquid.
HRMS: m/z calcd for C21H21NNa: 310.1571; found: 310.1577.
IR (KBr): 3425, 2923, 2853, 1457, 1215, 1097, 958, 794 cm–1.
5-Nitro-3-[1-(4-tolyl)hept-2-ynyl]-1H-indole (3h)
Yellow solid; mp 175–177 °C.
1H NMR (200 MHz, CDCl3): d = 0.91 (t, J = 7.5 Hz, 3 H), 1.34–1.51
(m, 4 H), 2.21–2.30 (m, 2 H), 4.88 (d, J = 6.8 Hz, 1 H), 5.38 (dd,
J = 1.5, 15.8 Hz, 1 H), 6.43 (dd, J = 7.5, 15.8 Hz, 1 H), 7.09–7.37
(m, 9 H), 7.94 (br s, 1 H).
IR (neat): 3325, 2928, 2860, 1508, 1454, 1319, 1229, 1089, 740,
677 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.91 (t, J = 7.5 Hz, 3 H), 1.39–1.60
(m, 4 H), 2.26 (dt, J = 2.2, 7.5 Hz, 2 H), 2.33 (s, 3 H), 5.13 (s, 1 H),
7.07–7.12 (m, 2 H), 7.24–7.34 (m, 4 H), 8.06 (dd, J = 2.2, 9.0 Hz, 1
H), 8.25 (br s, 1 H), 8.54 (d, J = 2.2 Hz, 1 H).
13C NMR (75 MHz, CDCl3): d = 13.5, 18.6, 21.0, 22.0, 30.9, 34.4,
80.6, 84.1, 111.1, 117.2, 117.8, 120.7, 125.5, 127.5, 129.3, 136.6,
138.1, 139.7, 141.6.
13C NMR (75 MHz, CDCl3): d = 13.5, 18.5, 22.0, 30.9, 34.7, 79.7,
84.3, 111.0, 114.1, 118.6, 121.2, 121.9, 122.6, 123.5, 126.4, 128.2,
129.0, 130.8, 131.6, 136.6, 137.9.
MS (EI, 70 eV): m/z (%) = 314 (50) [M + H+].
HRMS: m/z calcd for C23H24N: 314.1908; found: 314.1912.
7-Ethyl-3-{1-[(E)-2-phenylvinyl]hept-2-ynyl}-1H-indole (3m)
Liquid.
MS (EI, 70 eV): m/z (%) = 369 (100) [M+ + Na].
HRMS: m/z calcd for C22H22N2O2Na: 369.1578; found: 369.1589.
IR (KBr): 3419, 2958, 2924, 2854, 2211, 1625, 1452, 1262, 751,
698 cm–1.
5-Nitro-3-(1-phenylhept-2-ynyl)-1H-indole (3i)
Yellow solid; mp 169–171 °C.
1H NMR (200 MHz, CDCl3): d = 0.83–0.98 (m, 5 H), 1.36 (dt,
J = 1.5, 7.5 Hz, 3 H), 1.49 (m, 2 H), 2.27 (m, 2 H), 2.80 (m, 2 H),
4.70 (d, J = 6.0 Hz, 1 H), 6.33 (dd, J = 6.0, 15.6 Hz, 1 H), 6.72 (d,
J = 15.6 Hz, 1 H), 6.97 (m, 2 H), 7.10–7.39 (m, 6 H), 7.50 (d, J = 7.5
Hz, 1 H), 7.86 (br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 13.5, 14.2, 18.8, 22.0, 28.1, 31.2,
34.7, 79.7, 84.3, 111.0, 117.1, 117.8, 122.2, 123.0, 123.8, 125.5,
126.4, 127.3, 128.0, 129.9, 131.6, 136.8, 140.1.
IR (KBr): 3439, 3309, 2957, 2925, 2854, 2362, 1625, 1515, 1456,
1324, 1209, 1083, 730, 697 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.91 (t, J = 7.3 Hz, 3 H), 1.34–1.62
(m, 4 H), 2.26 (dt, J = 2.2, 6.6 Hz, 2 H), 5.20 (s, 1 H), 7.16–7.33 (m,
4 H), 7.38–7.48 (m, 3 H), 7.95 (dd, J = 2.2, 8.8 Hz, 1 H), 8.46 (d,
J = 2.2 Hz, 1 H), 11.2 (br s, 1 H).
MS (EI, 70 eV): m/z (%) = 342 (100) [M + H+].
Synthesis 2007, No. x, A–F © Thieme Stuttgart · New York

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J. S. Yadav et al.
PAPER
HRMS: m/z calcd for C25H28N: 342.2221; found: 342.2230.
References
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1996, 7. (b) Faulkner, D. J. Nat. Prod., Rep. 2001, 18, 1.
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Chemistry II, Vol. 2; Katritzky, A. R.; Rees, C. W.; Scriven,
E. F. V.; Bird, C. W., Eds.; Pergamon: Oxford, 1996, 207.
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Koskinen, A. Tetrahedron 2003, 59, 5395.
3-[1-(4-Fluorophenyl)-3-phenylprop-2-ynyl]-1H-indole (3n)
Brown liquid.
IR (KBr): 3416, 3056, 2923, 2853, 1601, 1503, 1453, 1222, 1156,
1093, 846, 746, 692 cm–1.
1H NMR (200 MHz, CDCl3): d = 5.38 (s, 1 H), 6.93–7.03 (m, 3 H),
7.08–7.16 (m, 2 H), 7.21–7.35 (m, 4 H), 7.38–7.50 (m, 5 H), 7.91
(br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 13.4, 19.6, 22.5, 32.2, 34.6, 79.4,
84.2, 111.0, 112.1, 115.4, 119.6, 121.1, 123.3, 124.1, 128.8, 131.5,
138.9, 141.6, 163.3.
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(b) Bandini, M.; Melloni, A.; Tommasi, S.; Umani-Ronchi,
A. Synlett 2005, 1199. (c) Humphrey, G. R.; Kuethe, J. T.
Chem. Rev. 2006, 106, 2875.
MS (EI, 70 eV): m/z (%) = 348 (60) [M+ + Na].
HRMS: m/z calcd for C23H16FNNa: 348.1164; found: 348.1173.
(4) (a) Bandini, M.; Melloni, A.; Umani-Ronchi, A. Angew.
Chem. Int. Ed. 2004, 43, 550. (b) Austin, J. F.; MacMillan,
D. W. C. J. Am. Chem. Soc. 2002, 124, 1172. (c) Jensen, K.
B.; Thorhange, J.; Hazel, R. G.; Jorgensen, K. A. Angew.
Chem. Int. Ed. 2001, 40, 160.
(5) (a) Srivastava, N.; Banik, B. K. J. Org. Chem. 2003, 68,
2109. (b) Bartoli, G.; Bartolacci, M.; Bosco, M.; Foglia, G.;
Giuliani, A.; Marcantoni, E.; Sambri, L.; Torregiani, E. J.
Org. Chem. 2003, 68, 4594.
(6) (a) Trost, B. M.; Crawley, M. L. Chem. Rev. 2003, 2921.
(b) Ma, S.; Yu, S.; Peng, Z.; Guo, H. J. Org. Chem. 2006, 71,
9865. (c) Yadav, J. S.; Reddy, B. V. S.; Basak, A. K.;
Narsaiah, A. V.; Prabhakar, A.; Jagadeesh, B. Tetrahedron
Lett. 2005, 46, 639.
2-(1-Phenylhept-2-ynyl)-1H-pyrrole (3o)
Dark brown liquid.
IR (KBr): 3429, 2957, 2926, 2855, 1490, 1455, 1026, 717 cm–1.
1H NMR (300 MHz, CDCl3): d = 0.93 (t, J = 7.1 Hz, 3 H), 1.38–1.60
(m, 4 H), 2.27 (dt, J = 2.4, 6.9 Hz, 2 H), 4.97 (m, 1 H), 5.87 (m, 1
H), 6.04 (dd, J = 2.8, 3.2 Hz, 1 H), 6.60 (m, 1 H), 7.16–7.34 (m, 5
H), 8.00 (br s, 1 H).
13C NMR (75 MHz, CDCl3): d = 13.2, 18.2, 21.7, 30.6, 36.3, 78.6,
84.1, 105.6, 108.2, 116.5, 126.6, 127.2, 128.2, 131.0, 140.5.
MS (EI, 70 eV): m/z (%) = 238 (100) [M + H+].
HRMS: m/z calcd for C17H20N: 238.1595; found: 238.1604.
(7) (a) Westermaier, M.; Mayr, H. Org. Lett. 2006, 8, 4791.
(b) Bandini, M.; Melloni, A.; Umani-Ronchi, A. Org. Lett.
2004, 6, 3199. (c) De la Herrán, G.; Segura, A.; Csáky, A.
G. Org. Lett. 2007, 9, 961. (d) Liu, Z.; Liu, L.; Shafiq, Z.;
Wu, Y. C.; Wang, D.; Chen, Y. J. Tetrahedron Lett. 2007,
48, 3963.
(8) (a) Zhang, Z.-H. Synlett 2005, 711. (b) Sakai, N.; Hirasawa,
M.; Konakahara, T. Tetrahedron Lett. 2005, 46, 6407.
(c) Agnusdei, M.; Bandini, M.; Melloni, A.; Umani-Ronchi,
A. J. Org. Chem. 2003, 68, 7126. (d) Huang, J.-M.; Wong,
C.-M.; Xu, F.-X.; Loh, T.-P. Tetrahedron Lett. 2007, 48,
3375. (e) Harada, S.; Takita, R.; Ohshima, T.; Matsunaga,
S.; Shibasaki, M. Chem. Commun. 2007, 948.
2-(1,3-Diphenylprop-2-ynyl)furan (3p)
Pale brown liquid.
IR (KBr): 2923, 2853, 2361, 1596, 1492, 1177, 1071, 1009, 753,
725, 692 cm–1.
1H NMR (200 MHz, CDCl3): d = 5.20 (s, 1 H), 6.23 (m, 2 H), 7.20–
7.35 (m, 7 H), 7.40–7.47 (m, 4 H).
13C NMR (75 MHz, CDCl3): d = 35.5, 85.6, 93.3, 107.5, 110.6,
123.3, 126.5, 127.4, 128.0, 128.8, 129.5, 133.5, 143.9, 146.8, 154.1.
MS (EI, 70 eV): m/z (%) = 281 (100) [M+ + Na].
HRMS: m/z calcd for C19H14ONa: 281.0942; found: 281.0951.
(9) Sang, H. K.; Shin, C.; Ae, N. P.; Hun, Y. K.; Moon, H. C.;
Bong, Y. C.; Yong, S. C. Synthesis 2004, 1581.
3-(1,3-Diphenylprop-2-ynyl)-9H-carbazole (3q)
Dark brown liquid.
(10) (a) Yadav, J. S.; Reddy, B. V. S.; Rao, K. V.; Raj, K. S.;
Prasad, A. R.; Kumar, S. K.; Kunwar, A. C.; Jayaprakash, P.
J.; Jagannath, B. Angew. Chem. Int. Ed. 2003, 42, 5198.
(b) Yadav, J. S.; Reddy, B. V. S.; Kumar, G. M. Synlett 2001,
1781. (c) Yadav, J. S.; Reddy, B. V. S.; Baishya, G. Synlett
2003, 396. (d) Yadav, J. S.; Reddy, B. V. S.; Krishna, A. D.;
Swamy, T. Tetrahedron Lett. 2003, 44, 6055. (e) Yadav, J.
S.; Reddy, B. V. S.; Swamy, T. Synthesis 2004, 106.
(f) Yadav, J. S.; Reddy, B. V. S.; Gakul, B. Green Chem.
2003, 5, 264. (g) Yadav, J. S.; Reddy, B. V. S.; Reddy, M.
S.; Parimala, G. Synthesis 2003, 2390.
IR (KBr): 3420, 2947, 2926, 2855, 1480, 1455, 1026, 720 cm–1.
1H NMR (300 MHz, CDCl3): d = 5.35 (s, 1 H), 7.11–7.38 (m, 12 H),
7.40–7.53 (m, 3 H), 7.89–8.11 (m, 3 H).
MS (EI, 70 eV): m/z (%) = 380 (100) [M+ + Na].
HRMS: m/z calcd for C27H19NNa: 380.1415; found: 380.1422.
Synthesis 2007, No. x, A–F © Thieme Stuttgart · New York