Photoredox Generated Vinyl Radicals: Synthesis of Bisindoles and β-Carbolines

Article abstract of DOI:10.1021/acs.joc.8b02193

A photoredox catalyzed approach enabling use of alkynes as surrogate of 2-oxoaldehydes/1,2-diones is reported. The method overcomes the difficulty associated with application of unsubstituted aliphatic α-oxoaldehydes, which has hitherto limited their general use. Indoles, tryptamine, and tryptophan methyl ester participated in the reaction to give a variety of α-oxo based analogues. Quantum yield investigations support a radical chain mechanism.

Full text of DOI:10.1021/acs.joc.8b02193

Subscriber access provided by University of Sunderland
Article
Photoredox Generated Vinyl Radicals:
Synthesis of Bisindoles and #-Carbolines
neha chalotra, Ajaz Ahmed, MASOOD AHMAD RIZVI,
Zakir Hussain, Qazi Naveed Ahmed, and Bhahwal Ali Shah
J. Org. Chem., Just Accepted Manuscript • Publication Date (Web): 08 Nov 2018
Downloaded from http://pubs.acs.org on November 8, 2018
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 42
The Journal of Organic Chemistry
1
2
3
4
5
6
7
Photoredox Generated Vinyl Radicals: Synthesis of Bisindoles and β-Carbolines
8
9
Neha Chalotra,†,║ Ajaz Ahmed,†,║ Masood Ahmad Rizvi,‡ Zakir Hussain, ‡ Qazi Naveed Ahmed† and
Bhahwal Ali Shah†,*
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
†AcSIR and Natural Product Microbes, CSIR-Indian Institute of Integrative Medicine, Jammu-180001.
‡Department of Chemistry, University of Kashmir, Srinagar, 190006
║Both authors contributed equally
E-mail: bashah@iiim.ac.in
ABSTRACT: A photoredox catalyzed approach enabling use of alkynes as surrogate of 2-
oxoaldehydes/1,2-diones is reported. The method overcomes the difficulty associated with application
of unsubstituted aliphatic α-oxoaldehydes, which has hitherto limited their general use. Indoles, trypta-
mine and tryptophan methyl ester participated in the reaction to give a variety of α-oxo based analogues.
Quantum yield investigations support a radical chain mechanism.
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 2 of 42
INTRODUCTION
1
2
3
4
5
6
7
8
9
Arylglyoxals (AGs) like other α-oxo compounds represent valuable starting materials to access a diverse
array of skeletons.1 Of particular intrigue is the electron-withdrawing characteristic of carbonyl group,
which imparts divergent reactive behavior to both aldehyde and ketone functional groups. The reaction
around AGs either involve nucleophilic addition,2 condensation3 and cross coupling reactions4 on alde-
hydic group or both carbonyls encompassing transformations such as Biginelli and Petasis reactions
(Figure 1).5 However, a key inadequacy associated with all the synthetic routes towards AGs include the
failure to generate aliphatic products as (i) owing to its unsubstituted α-position it may act either as a
nucleophile or electrophile, thereby leading to formation of side products, (ii) the comparable reactivity
of two electrophilic centers viz., aldehyde and ketone can result in mixture of regioisomers and (iii)
most importantly the synthesis of aliphatic α-oxoaldehyde is very difficult to achieve which limits their
use as starting material. In this regard, thiol promoted photoredox reactions,6 and addition reactions
through thiyl radicals are well known on a wide range of unsaturated systems such as alkenes, isoni-
triles, thiocarbonyls and particularly to alkynes through vinyl radical (I) has generated highly regio- and
stereoselective products.7 Unlike alkenes, the vinyl radicals generated from alkynes have capability of
undergoing further reactions, however, their application as the surrogate of α-oxoaldehydes/1,2-
dicarbonyls has no precedence. As an overarching goal of this work we hoped to demonstrate that pho-
toredox generated vinyl radical (I) can provide a complementary approach to aliphatic glyoxals which
can give a new dimension to the area of 1,2-dicarbonyls.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 1. Alkynes as precursors of 2-oxoaldehydes and 1,2-diones.
2
ACS Paragon Plus Environment

Page 3 of 42
The Journal of Organic Chemistry
Thus, in continuation of our interests,8 we report a solution under which thiol mediated photoredox-
catalyzed reaction of alkynes led to synthesis of different valuable N-heterocyles. The paramount feature
of the present method is its selectivity/general applicability to both aromatic and aliphatic systems. De-
spite, reports in the bisindolylation reactions around simple arylglyoxals, acetophenones and styrenes
(Figure 1),9 there are no reports on the reaction of indoles that could be highly regioselective and appli-
cable to different 1,2-dicarbonyls. Furthermore, different β-carbolines and dihydro-β-carbolines could
be easily generated by Pictet-Spengler reaction of tryptophan methylester and tryptamine with different
alkynes.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
RESULTS AND DISCUSSION
Our efforts initiated with the reaction of octyne and indole as model substrates. The reaction was
irradiated under blue LEDs in presence of thiophenol (PhSH) and trifluoroacetic acid (TFA) with
Ru(bpy)3Cl2.6H2O as photocatalyst using CH3CN as solvent (Table 1, entry 1). To our delight the reaction
led to the formation of bisindole derivative (1) in 67% yields (entry 1). The change of solvents to
CH3OH and 1,4 dioxane caused a drop in reaction yields, whereas no product formation was observed in
+
-
DMSO (Table 1, entries 2-4). The use of mesitylacridinium tetrafluoroborate (Mes-Acr BF4 ), eosin-Y,
and Rose-Bengal as photocatalyst gave the corresponding product (1), in 37, 46 and 15% yields respec-
tively (Table 1, entries 5-7). The presence of thiophenol, TFA, photocatalyst and light was critical as
there was either no product formation or in traces in their absence (Table 1, entries 8-11). Notably, the
10
use of TFA in excess of 10 mol% resulted in indole dimer and trimer as side products.
3
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 4 of 42
Table 1. Optimization of Reaction Conditionsa
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
yield (%)
entry
conditions
photocatalyst
solvent
*
67
25
1
2
as shown
as shown
Ru(bpy)3Cl2
Ru(bpy)3Cl2
CH3CN
CH3OH
3
4
5
6
7
8
9
10
11
as shown
as shown
as shown
as shown
as shown
no thiophenol
no TFA
Ru(bpy)3Cl2
Ru(bpy)3Cl2
1,4-dioxane
DMSO
43
ND
37
46
15
ND
10
traces
traces
-
Mes-Acr+BF4
eosin-Y
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
Rose Bengal
Ru(bpy)3Cl2
Ru(bpy)3Cl2
no photocatlyst
no light
as shown
as shown
aPerformed with photocatalyst (2 mol%), thiophenol (0.1 mmol), trifluoroacetic acid (TFA, 0.1 mmol); temp: 25 °C; solvent
(2ml), under air, time: 18 h.; *Isolated yields.
We next investigated the scope of the reaction with different alkynes and indoles (Scheme 1). The reac-
tion of indole with heptyne, hexyne, pentyne and cyclopropyl acetylene proceeded smoothly to give cor-
responding derivatives (2-5) in 61-73% yields. The 5- F, Cl, Br, CN and NO2 indole were also found
amenable to present reaction protocol producing (6-10) in good yields. The reaction of 5-bromoindole
with pentyne gave (11) in 70% yields. We also studied the reaction viability with different phenylacety-
lenes and indoles. The reaction of phenylacetylene, 4-F, 4-OMe and 4-alkyl-substituted (tert-butyl, ethyl
and methyl) phenylacetylene proceeded in a facile manner to produce (12-17) in good yields. Also, var-
ious indoles such as 6-Cl and 5-F, Cl, Br, I, CN, NO2 indoles served as suitable substrates with phenyla-
cetylene to give the desired products (18-24). The reaction with 2-methylindole also produced (25) in
71% yield. We further examined the feasibility of present reaction with internal alkynes. Notably, a
4
ACS Paragon Plus Environment

Page 5 of 42
The Journal of Organic Chemistry
comparable reaction scenario with diketones would probably lead to the formation of regiosisomers
with challenge of handling unsusbstituted α- position in aliphatic chains. The diaryl and arylalkyl alky-
nes viz., diphenylacetylene and 1-phenyl-1-propyne gave corresponding products (26-27) in 73 and 69%
yields. Furthermore, different indoles viz., 6-F and 5-Cl, Br and 5-NO2 indoles produced (28-31) in 62-
75% yield.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Scheme 1. Substrate Scope with Different Alkynes and Indoles
5
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 6 of 42
The cross-coupling of two different indoles was also studied (Scheme 2). The reaction of phe-
nylacetylene with 2-methylindole and indole/5-flouro/5-bromo indole led to the formation of asymmet-
rical products (32-34) in 34-41% yields accompanying self coupled product (25) and monohydroxy in-
dole product (35) as side products. This implies that monohydroxy indole is a possible intermediate in
the reaction.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Scheme 2. Cross Coupling of Indoles.
A plausible reaction mechanism is proposed in figure 2. The reaction initiates upon reductive
quenching of photoexcited Ru(bpy)3+2 (36) by thiophenol which affords the thiyl radical cation (39) that
subsequently deprotonates to form thiyl radical (40).11 Ru(bpy)3+2 is regenerated by molecular oxygen.12
The reactive thiyl radical adds to alkyne generating vinyl radical (41),13 which undergo oxygen insertion
to give superoxide radical (42).14 The radical 42 can undergo intermolecular cycloaddition with concom-
itant release of thiyl radical to form intermediate (43).15 The nucleophilic addition of C-3 of indole gives
intermediate (44), which on subsequent dehydration in presence of TFA generates intermediate
(45).16,9b,c,e The conjugate addition of another molecule of indole followed by deprotonation gives the
final product. The incorporation of 18O2 in the corresponding product evidenced by LC-MS studies im-
plies that oxygen in the product is sourced from atmospheric oxygen. The Stern−Volmer analysis re-
vealed that the photoluminescence of Ru(bpy)3Cl2 was quenched by thiophenol in CH3CN at 25 °C.
Furthermore, reaction quantum yields of 23.9 shows that reaction propagates via radical chain mecha-
nism. Moreover, complete inhibition of the reaction in presence of radical-quencher TEMPO also indi-
cates its radical nature (see supporting information).
6
ACS Paragon Plus Environment

Page 7 of 42
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Figure 2. Plausible mechanism
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
We were further intrigued to explore if this reaction can be expanded to other nucleophiles. In
this regard, we chose a related indole substrate, tryptophan methyl ester, which is expected to give β-
carbolines showcasing C-N bond formation instead of C-C bond. Notably, the synthesis of β-carbolines
(pyrido[3,4-b]indoles) is one of the most addressed problems in the synthetic organic chemistry, owing
to their presence in a large number of natural products and medicinally important molecules.17 Over the
years many approaches have been developed for their synthesis, including reactions such as Bischler-
Napieralski,18 Graebe-Ullmann19 and Pictet-Spengler reaction.20 Particularly, Pictet-Spengler reaction of
tryptamines has been used to access cores of almost all the monoterpene indole alkaloids.21 Conspicu-
ously, synthesis of β-carbolines with oxo-substitution at C-1, with aliphatic side chain remains hitherto
unaddressed. The reaction of tryptophan methyl ester with octyne as expected produced indolocarbazole
(47) in 72% yields (Scheme 3). Moreover, the reaction with heptyne, hexyne, pentyne as well as cyclo-
propyl acetylene produced (48-51) in 66-71% yields. The reaction was also found agreeable to 4-F, -
OMe, 4-alkyl (tert-butyl, propyl, ethyl and methyl), and 2-CF3 as substituent to give (53-59) in 65-80%
yields. Also, 6-methoxynaphthyl acetylene afforded (60) in 78% yields. Remarkably, the reaction of
tryptamine with cyclopropyl acetylene instead led to the formation of dihydro-β-carboline (61) as exclu-
sive product in 65% yield. This observation was significant as previous reports show them as either an
7
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 8 of 42
intermediate in low yields or it forms in situ which immediately aromatizes.22 Also, the reaction with 4-
F, OMe, pentyl, tert-butyl, propyl, ethyl and methyl phenylacetylene proceeded smoothly to generate
dihydro-β-carbolines (63-69) in 69-75% yields. Completely aromatized products with tryptamine (70-
75) could be easily obtained by increasing the reaction temperature to 40 °C.
1
2
3
4
5
6
7
8
9
Scheme 3. Substrate Scope of Alkynes with Tryptophan methylester and Tryptamine.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
CONCLUSION
In conclusion, we have developed a visible light mediated aerobic oxidative conversion of acety-
lenes to access a wide variety of aliphatic α-oxo analogues from indoles, tryptamine and tryptophan me-
thyl ester. The method opens a new window for studying the unexplored reactivity of aliphatic α-oxo
compounds owing to the reactive nature of α-carbon. It would be pertinent to mention that having α-
CH2 to carbonyl makes it available for an extensive array of reactions. Furthermore, the reaction is regi-
oselective, easy to set up with broad substrate scope and excellent functional group tolerance. We antic-
ipate that the synthetic utility it offers in terms of overcoming the limitations of AGs will lead to com-
8
ACS Paragon Plus Environment

Page 9 of 42
The Journal of Organic Chemistry
plex heterocycles synthesis and late stage modifications/functionalizations. The further reactivity and
applicability of this reaction system is currently under investigation in our laboratory.
1
2
3
4
5
6
EXPERIMENTAL SECTION
7
8
9
General Information. All reactions were conducted in oven-dried glasswares. All reactions were irra-
diated using blue light-emitting diode (LED) array. 1H and 13C NMR spectra were recorded on FT-NMR
500 and 400 MHz instruments. Chemical data for protons are reported in parts per million (ppm) down-
field from tetramethylsilane and are referenced to the residual proton in the NMR solvent (CDCl3, 7.26
ppm). Carbon nuclear magnetic resonance spectra (13C NMR) were recorded at 125 MHz or 100 MHz:
chemical data for carbons are reported in parts per million (ppm, δ scale) downfield from tetrame-
thylsilane and are referenced to the carbon resonance of the solvent. Mass spectra were obtained by us-
ing Q-TOF-LC/MS spectrometer using electron spray ionization.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
General experimental procedure:To an oven dried 30 ml glass vial, containing starting compounds
indole (2 equiv) /tryptophan methyl ester/ tryptamine (1 equiv) in CH3CN, was added alkyne (1 equiv),
thiophenol (0.1 equiv), trifluoroacetic acid (0.1 equiv for indoles/ 1 equiv for β-carbolines synthesis)
and Ru(bpy)3Cl2 (2 mol%) with continuous stirring under air. The reaction mixture was then irradiated
under blue light sourced from blue LED strips (40 mW/cm2 at 460 nm). After the completion of reac-
tion, as monitored by TLC, the reaction mixture was extracted with ethyl acetate and water. The aque-
ous layers were then washed with sodium bicarbonate (NaHCO3) and again extracted with ethyl acetate.
The combined organic layers were dried over Na2SO4 and concentrated under vacuum. The crude mix-
ture was purified by silica gel column chromatography using hexane/ethyl acetate as solvent system.
1,1-Di(1H-indol-3-yl)octan-2-one (1): The title compound was prepared according to the general pro-
cedure by taking indole (100 mg, 0.85 mmol), 1-octyne (66.7 µl, 0.4 mmol), thiophenol (9.3 µl, 0.085
mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%) and purified by column chromatog-
raphy (hexane:EA :: 77:23) as solid (205 mg, 67%), mp (159-161 °C). 1H NMR (400 MHz, CDCl3) δ =
8.06 (brs, 2H), 7.55 (d, J = 7.9 Hz, 2H), 7.36 (d, J = 8.1 Hz, 2H), 7.19 (t, J = 6.4 Hz, 2H), 7.12 – 7.07
9
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 10 of 42
(m, 4H), 5.58 (s, 1H), 2.67 (t, J = 7.4 Hz, 2H), 1.62–1.53 (m, 4H), 1.24–1.15 (m, 4H), 0.82 (t, J = 6.9
Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 209.3, 136.4, 126.9, 123.4, 122.2, 119.7, 119.1, 113.8,
111.3, 47.1, 41.7, 31.6, 28.8, 24.2, 22.5, 14.0. IR(CHCl3 cm-1) v; 3389, 3057, 2917, 2850, 1700, 1456,
1415, 1336; HRMS (ESI) (m/z): [M+H]+ calculated for C24H27N2O 359.2118; found: 359.2115.
1,1-Di(1H-indol-3-yl)heptan-2-one (2): The title compound was prepared according to the general pro-
cedure by taking indole (100 mg, 0.85 mmol), 1-heptyne (0.4 mmol), thiophenol (9.3 µl, 0.085 mmol),
TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%) and purified by column chromatography
(hexane:EA :: 75:25) as solid (179 mg, 61%), mp (152-154 °C). 1H NMR (400 MHz, CDCl3) δ = 8.05
(brs, 2H), 7.55 (d, J = 7.9 Hz, 2H), 7.34 (d, J = 8.1 Hz, 2H), 7.21–7.17 (m, 2H), 7.12–7.07 (m, 2H), 7.01
(d, J = 2.2 Hz, 2H), 5.58 (s, 1H), 2.67 (t, J = 7.4 Hz, 2H), 1.66-1.59 (m, 2H), 1.28–1.18 (m, 4H), 0.83 (t,
J = 6.9 Hz, 3H); 13C{1H} NMR (100 MHz, CDCl3) δ = 209.1, 136.4, 126.9, 123.5, 122.2, 119.7, 119.1,
113.7, 111.3, 47.1, 41.6, 31.3, 23.6, 22.4, 13.9. IR(CHCl3 cm-1) v; 3392, 2916, 1703, 1455, 1236;
HRMS (ESI) (m/z): [M+H]+ calculated for C23H25N2O 345.1961; found: 345.1958.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1,1-Di(1H-indol-3-yl)hexan-2-one (3): The title compound was prepared according to the general pro-
cedure by taking indole (100 mg, 0.85 mmol), 1-hexyne (49.8 µl, 0.4 mmol), thiophenol (9.3 µl, 0.085
mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%) and purified by column chromatog-
raphy (hexane:EA :: 75:25) as solid (206 mg, 73%), mp (145-147 °C). 1H NMR (400 MHz, CDCl3) δ =
8.07 (brs, 2H), 7.57 (d, J = 7.9 Hz, 2H), 7.36 (d, J = 8.1 Hz, 2H), 7.20 (t, J = 7.2 Hz, 2H), 7.11 (t, J =
7.5 Hz, 2H), 7.07 (d, J = 2.3 Hz, 2H), 5.59 (s, 1H), 2.67 (t, J = 7.3 Hz, 2H), 1.65 (dd, J = 14.7, 7.4 Hz,
13
2H), 1.39–1.09 (m, 2H), 0.87 (t, J = 7.4 Hz, 3H); C{1H} NMR (100 MHz, CDCl3) δ = 209.2, 136.4,
126.9, 123.4, 122.2, 119.7, 119.1, 113.8, 111.3, 47.1, 41.4, 26.4, 22.3, 13.8. IR(CHCl3 cm-1) v; 3406,
2929, 1705, 1457, 1215; HRMS (ESI) (m/z): [M+Na]+ calculated for C22H22N2NaO 353.1624; found:
353.1623 .
1,1-Di(1H-indol-3-yl)pentan-2-one (4): The title compound was prepared according to the general pro-
cedure by taking indole (100 mg, 0.85 mmol), 1-pentyne (48.2 µl, 0.4 mmol), thiophenol (9.3 µl, 0.085
mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%) and purified by column chromatog-
10
ACS Paragon Plus Environment

Page 11 of 42
The Journal of Organic Chemistry
raphy (hexane:EA :: 75:25) as solid (189 mg, 70%), mp (138-141 °C). 1H NMR (400 MHz, CDCl3) δ =
8.07 (brs, 2H), 7.56 (d, J = 7.9 Hz, 2H), 7.36 (d, J = 8.1 Hz, 2H), 7.20 (t, J = 7.6 Hz, 2H), 7.11 (t, J =
7.5 Hz, 2H), 7.07 (d, J = 2.3 Hz, 2H), 5.60 (s,1H), 2.69 (t, J = 7.4 Hz, 2H), 1.65–1.51 (m, 1H), 1.29-
1.23 (m, 1H), 0.84 (t, J = 7.3 Hz, 3H); 13C{1H} NMR (100 MHz, CDCl3) δ = 209.0, 136.4, 126.9,
123.4, 122.2, 119.7, 119.1, 113.8, 111.3, 47.1, 43.6, 17.7, 13.7. IR(CHCl3 cm-1) v; 3412, 2849, 2917,
1700, 1643, 1457, 1306, 743; HRMS (ESI) (m/z): [M+H]+ calculated for C21H21N2O 317.1648; found:
317.1642 .
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1-Cyclopropyl-2,2-di(1H-indol-3-yl) ethanone (5): The title compound was prepared according to the
general procedure by taking indole (100 mg, 0.85 mmol), cyclopropylacetylene (40.1 µl, 0.4 mmol),
thiophenol (9.3 µl, 0.085 mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%) and puri-
fied by column chromatography (hexane:EA :: 78:22) as solid (158 mg, 59%), mp (158-161 °C).1H
NMR (400 MHz, CDCl3) δ = 8.06 (brs, 1H), 8.03 (brs, 1H), 7.56 (d, J = 7.9 Hz, 2H), 7.35 (d, J = 8.1
Hz, 2H), 7.23-7.16 (m, 2H), 7.12-7.03 (m, 2H), 6.99 (d, J = 2.1 Hz, 2H), 5.69 (s, 1H), 2.34–2.09 (m,
1H), 1.23–1.03 (m, 2H), 0.90–0.78 (m, 2H); 13C{1H} NMR (125 MHz, CDCl3) δ = 209.3, 136.4, 127.0,
123.5, 122.2, 119.6, 119.2, 113.7, 111.3, 48.2, 20.1, 11.8. IR(CHCl3 cm-1) v; 3414, 2924, 2275, 1682,
1455, 1218; HRMS (ESI) (m/z): [M+H]+ calculated for C21H19N2O 315.1492; found: 315.1484.
1,1-Bis(5-fluoro-1H-indol-3-yl)octan-2-one (6): The title compound was prepared according to the
general procedure by taking 5-fluoroindole (100 mg, 0.73 mmol), 1-octyne (57.3 µl, 0.36 mmol), thio-
phenol (8.0 µl, 0.073 mmol), TFA (5.6 µl, 0.073 mmol), Ru(bpy)3Cl2 (10.9 mg, 2 mol%) and purified
by column chromatography (hexane:EA :: 76:24) as solid (195 mg, 67%), mp (134-137 °C). 1H NMR
(400 MHz, CDCl3) δ = 8.18 (brs, 2H), 7.21 (dd, J = 8.8, 4.3 Hz, 2H), 7.15 (d, J = 2.5Hz, 1H), 7.12(d, J
= 2.5Hz, 1H), 7.03 (d, J = 2.5 Hz, 2H), 6.97-6.85 (m, 2H), 5.41 (s, 1H), 2.65 (t, J = 7.4 Hz, 2H), 1.65–
1.51 (m, 2H), 1.24–1.14 (m, 6H), 0.82 (t, J = 6.9 Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 209.2,
157.8 (d, J = 233.8 Hz), 132.9, δ = 127.0 (d, J = 10 Hz), 125.2, 113.3 (d, J = 5 Hz), 112.1 (d, J = 10
Hz), 110.7 (d, J = 26.2 Hz), 104.1 (d, J = 23.8 Hz), 47.2, 41.7, 31.5, 28.8, 24.2, 22.5, 14.0. IR(CHCl3
11
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 12 of 42
cm-1) v; 3417, 2927, 2955, 1707, 1348, 1169; HRMS (ESI) (m/z): [M+H]+ calculated for C24H25F2N2O
395.1929; found: 395.1927.
1
2
3
4
5
6
7
8
9
1,1-Bis(5-chloro-1H-indol-3-yl)octan-2-one (7): The title compound was prepared according to the
general procedure by taking 5-chloroindole (100 mg, 0.65 mmol ), 1-octyne (51.1 µl, 0.32 mmol), thio-
phenol (7.1 µl, 0.065 mmol), TFA (5 µl, 0.065 mmol), Ru(bpy)3Cl2 (9.7 mg, 2 mol%) and purified by
column chromatography (hexane:EA :: 76:24) as solid (177 mg, 63%), mp (140-142 °C). 1H NMR (400
MHz, CDCl3) δ = 8.16 (brs, 2H), 7.47 (d, J = 1.9 Hz, 2H), 7.27 (s, 1H), 7.25 (s, 1H), 7.15 (d, J = 2.0 Hz,
1H), 7.12 (d, J = 2.0 Hz, 1H), 7.08 (d, J = 2.4 Hz, 2H), 5.44 (s, 1H), 2.65 (t, J = 7.4 Hz, 2H), 1.72–1.38
(m, 2H), 1.29–1.15 (m, 6H), 0.83 (t, J = 6.8 Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 208.8,
134.7, 127.7, 125.5, 124.8, 122.7, 118.6, 113.1, 112.4, 46.9, 41.8, 31.6, 28.8, 24.2, 22.5, 14.0. IR(CHCl3
cm-1) v; 3351, 2928, 1705, 1463, 798; HRMS (ESI) (m/z): [M+NH4]+ calculated for C24H28Cl2N3O
444.1604; found: 444.1605.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1,1-Bis(5-bromo-1H-indol-3-yl)octan-2-one (8): The title compound was prepared according to the
general procedure by taking 5- bromoindole (100 mg, 0.51 mmol), 1-octyne (40 µl, 0.25 mmol), thio-
phenol (5.6 µl, 0.051 mmol), TFA (3.9 µl, 0.051 mmol), Ru(bpy)3Cl2 (7.6 mg, 2 mol%) and purified by
column chromatography (hexane:EA :: 75:25) as solid (188 mg, 72%), mp (148-150 °C). 1H NMR (400
MHz, CDCl3) δ = 8.21 (brs, 2H), 7.61 (s, 2H), 7.24 (d, J = 9.8 Hz, 2H), 7.17 (d, J = 8.6 Hz, 2H), 6.95 (s,
2H), 5.42 (s, 1H), 2.64 (t, J = 7.4 Hz, 2H), 1.79-1.44 (m, 2H), 1.28–1.16 (m, 6H), 0.83 (t, J = 6.8 Hz,
13
3H) ; C{1H} NMR (125 MHz, CDCl3) δ = 209.1, 135.0, 128.4, 125.2, 124.7, 121.6, 113.1, 112.9,
112.8, 46.9, 41.8, 31.6, 28.8, 24.2, 22.5, 14.1. IR(CHCl3 cm-1) v; 3362, 2922, 1704, 1461, 1218, 582;
HRMS (ESI) (m/z): [M+NH4]+ calculated for C24H2881Br 79Br N3O 534.0573; found: 534.0573.
3,3'-(2-Oxooctane-1,1-diyl)bis(1H-indole-5-carbonitrile) (9): The title compound was prepared ac-
cording to the general procedure by taking indole-5-carbonitrile (100 mg, 0.70 mmol), 1-octyne (55 µl,
0.35 mmol), thiophenol (7.7 µl, 0.070 mmol), TFA (5.39 µl, 0.070 mmol), Ru(bpy)3Cl2 (10.4 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 72:28) as solid (186 mg, 65%), mp (150-
152 °C). 1H NMR (400 MHz, CDCl3) δ = 8.77 (brs, 2H), 7.82 (s, 2H), 7.43–7.37 (m, 4H), 7.28 (d, J =
12
ACS Paragon Plus Environment

Page 13 of 42
The Journal of Organic Chemistry
2.2 Hz, 2H), 5.54 (s, 1H), 2.68 (t, J = 7.4 Hz, 2H), 1.62-1.53 (m, 2H), 1.25–1.14 (m, 6H), 0.81 (t, J = 6.8
Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 208.4, 138.2, 126.4, 125.6, 125.3, 125.0, 120.7, 113.7,
112.5, 102.8, 46.9, 42.0, 31.5, 28.7, 24.0, 22.5, 14.0. IR(CHCl3 cm-1) v; 3330, 2918, 2850, 2222, 1708,
1653, 1248; HRMS (ESI) (m/z): [M+H]+ calculated for C26H25N4O 409.2023; found: 409.2018.
1,1-Bis(5-nitro-1H-indol-3-yl)octan-2-one (10): The title compound was prepared according to the
general procedure by taking 5-nitroindole (100 mg, 0.6 mmol), 1-octyne (47.9 µl, 0.3 mmol), thiophenol
(6.7 µl, 0.06 mmol), TFA (4.69 µl, 0.06 mmol), Ru(bpy)3Cl2 (9.1 mg, 2 mol%) and purified by column
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
chromatography (hexane:EA :: 72:28) as solid (160 mg, 58%), mp (200-202 °C). H NMR (400 MHz,
CD3OD) δ = 8.37 (d, J = 2.1 Hz, 2H), 8.02–7.82 (m, 3H), 7.40–7.36 (m, 2H), 7.30 (s, 1H), 5.74 (s, 1H),
2.64 (t, J = 7.1 Hz, 2H), 1.50 – 1.45 (m, 2H), 1.09–0.96 (m, 6H), 0.68 (t, J = 6.9 Hz, 3H); 13C{1H}
NMR (125 MHz, CD3OD) δ = 209.4, 141.1, 140.0, 127.2, 125.9, 117.4, 116.3, 114.6, 111.7, 46.9, 41.7,
31.4, 28.6, 24.0, 22.3, 13.7. IR(CHCl3 cm-1) v; 3347, 2918, 1701, 1623, 1518, 1331; HRMS (ESI) (m/z):
[M+NH4]+ calculated for C24H28N5O5 466.2085; found:466.2073.
1,1-Bis(5-bromo-1H-indol-3-yl)pentan-2-one (11): The title compound was prepared according to the
general procedure by taking 5-bromoindole (100 mg, 0.5 mmol), 1-pentyne (28.9 µl, 0.25 mmol), thio-
phenol (5.6 µl, 0.05 mmol), TFA (3.9 µl, 0.05 mmol), Ru(bpy)3Cl2 (7.6 mg, 2 mol%) and purified by
column chromatography (hexane:EA :: 78:22) as solid (168 mg, 70%), mp (174-176 °C). 1H NMR (400
MHz, CDCl3) δ = 8.19 (brs, 2H), 7.63 (d, J = 1.6 Hz, 2H), 7.28–7.24 (m, 2H), 7.20 (d, J = 8.6 Hz, 2H),
7.01 (d, J = 2.1 Hz, 2H), 5.43 (s, 1H), 2.64 (t, J = 7.3 Hz, 2H), 1.69–1.59 (m, 2H), 0.87 (t, J = 7.4 Hz,
13
3H); C{1H} NMR (125 MHz, CDCl3) δ = 208.7, 135.0, 128.4, 125.2, 124.6, 121.6, 113.1, 112.9,
112.9, 46.8, 43.7, 17.6, 13.7. IR(CHCl3 cm-1) v; 3347, 2926, 1706, 1461, 583; HRMS (ESI) (m/z):
[M+NH4]+ calculated for C21H2281Br 79BrN3O 492.0104; found: 492.0094.
2,2-Di(1H-indol-3-yl)-1-phenylethan-1-one (12): The title compound was prepared according to the
general procedure by taking indole (100 mg, 0.85 mmol), phenylacetylene (48.2 µl, 0.4 mmol), thiophe-
nol (9.3 µl, 0.08 mmol), TFA (6.5 µl, 0.08 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%) and purified by col-
umn chromatography (hexane:EA :: 72:28) as solid (215 mg, 72%). 1H NMR (400 MHz, CDCl3) δ =
13
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 14 of 42
8.12 (d, J = 7.2 Hz, 2H), 8.06 (brs, 2H), 7.58 (d, J = 7.9 Hz, 2H), 7.52 (d, J = 7.4 Hz, 1H), 7.42 (t, J =
7.7 Hz, 2H), 7.36 (d, J = 8.1 Hz, 2H), 7.20 (t, J = 7.6 Hz, 2H), 7.10 (t, J = 6.6 Hz, 2H), 6.99 (d, J = 2.3
Hz, 2H), 6.53 (s, 1H); 13C{1H} NMR (125 MHz, CDCl3) δ = 198.6, 136.9, 136.5, 132.9, 128.8, 128.6,
126.6, 124.0, 122.2, 119.7, 119.0, 114.3, 111.3, 42.1. HRMS (ESI) (m/z): [M+Na]+ calculated for
C24H18N2NaO 373.1311; found: 373.1300. The observed characterization data (1H & 13C) was con-
sistent with that previously reported in the literature.9a
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1-(4-Fluorophenyl)-2,2-di(1H-indol-3-yl)ethan-1-one (13): The title compound was prepared accord-
ing to the general procedure by taking indole (100 mg, 0.85 mmol), 4-fluorophenylacetylene (51 µl, 0.4
mmol), thiophenol (9.3 µl, 0.085 mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%)
and purified by column chromatography (hexane:EA :: 76:24) as solid (245 mg, 78%), mp (204-207
°C). 1H NMR (400 MHz, CDCl3 and CD3OD) δ = 8.16–8.07 (m, 2H), 7.53 (d, J = 7.8 Hz, 2H), 7.37 (d, J
= 8.1 Hz, 2H), 7.18–7.09 (m, 2H), 7.08–6.99 (m, 4H), 6.94 (s, 2H), 6.48 (s, 1H); 13C{1H} NMR (100
MHz, CD3OD and CDCl3) δ = 202.0, 169.2 (d, J = 296 Hz), 140.7 (d, J = 15 Hz), 137.2, 135.3 (d, J = 9
Hz), 130.4, 128.2 (d, J = 16 Hz), 125.7, 123.1, 122.5, 119.5 (d, J = 22 Hz), 117.2, 115.4 (d, J = 6 Hz),
46.3. IR(CHCl3 cm-1) v; 3400, 3058, 2917, 1679, 1457, 1338, 1216; HRMS (ESI) (m/z): [M+H]+ calcu-
lated for C24H18FN2O 369.1398; found: 369.1398 .
2,2-Di(1H-indol-3-yl)-1-(4-methoxyphenyl)ethan-1-one (14): The title compound was prepared ac-
cording to the general procedure by taking indole (100 mg, 0.85 mmol), 4-methoxyphenylacetylene
(56.16 µl, 0.4 mmol), thiophenol (9.3 µl, 0.085 mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7
mg, 2 mol%) and purified by column chromatography (hexane:EA :: 72:28) as solid (224 mg, 69%). 1H
NMR (400 MHz, CDCl3) δ = 8.15–8.10 (m, 2H), 8.04 (brs, 2H), 7.58 (d, J = 7.9 Hz, 2H), 7.35 (d, J =
8.1 Hz, 2H), 7.19 (t, J = 7.2 Hz, 2H), 7.09 (t, J = 5.8 Hz, 2H), 6.97 (d, J = 2.3 Hz, 2H), 6.92–6.86 (m,
2H), 6.49 (s, 1H), 3.85 (s, 3H); 13C{1H} NMR (100MHz, CDCl3) δ = 197.1, 163.4, 136.6, 131.1, 129.9,
126.8, 123.9, 122.2, 119.7, 119.0, 114.7, 113.8, 111.3, 55.4, 41.7. HRMS (ESI) (m/z): [M+Na]+ calcu-
lated for C25H20N2NaO2 403.1417; found: 403.1415. The observed characterization data (1H & 13C) was
consistent with that previously reported in the literature.9a
14
ACS Paragon Plus Environment

Page 15 of 42
The Journal of Organic Chemistry
1-(4-(Tert-butyl)phenyl)-2,2-di(1H-indol-3-yl)ethan-1-one (15): The title compound was prepared ac-
cording to the general procedure by taking indole (100 mg, 0.85 mmol), 4-tert-butylphenylacetylene (84
µl, 0.4 mmol), thiophenol (9.3 µl, 0.085 mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 71:29) as solid (260 mg, 75%), mp (153-
155 °C). 1H NMR (400 MHz, CDCl3 and CD3OD) δ = 8.06 (d, J = 8.5 Hz, 2H), 7.54 (d, J = 7.9 Hz, 2H),
7.48–7.30 (m, 4H), 7.15 (t, J = 7.6 Hz, 2H), 7.04 (t, J = 7.5 Hz, 2H), 6.97 (s, 2H), 6.54 (s, 1H), 1.31 (s,
9H); 13C{1H} NMR (125 MHz, CDCl3 and CD3OD) δ = 199.3, 156.7, 136.6, 134.1, 128.7, 126.6, 125.5,
124.2, 121.7, 119.1, 118.7, 113.6, 111.3, 42.0, 35.0, 30.9. IR(CHCl3 cm-1) v; 3330, 2921, 2957, 2851,
1695, 1642, 1336; HRMS (ESI) (m/z): [M+Na]+ calculated for C28H26N2NaO 429.1937; found:
429.1934 .
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1-(4-Ethylphenyl)-2,2-di(1H-indol-3-yl)ethan-1-one (16): The title compound was prepared according
to the general procedure by taking indole (100 mg, 0.85 mmol), 4-ethylphenylacetylene (61.5µl, 0.4
mmol), thiophenol (9.3 µl, 0.085 mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%)
and purified by column chromatography (hexane:EA :: 76:24) as solid (223 mg, 69%), mp (142-149
°C). 1H NMR (400 MHz, CDCl3) δ = 8.04 (d, J = 8.3 Hz, 4H), 7.56 (d, J = 7.9 Hz, 2H), 7.32 (d, J = 8.1
Hz, 2H), 7.22 (d, J = 8.3 Hz, 2H), 7.19–7.14 (m, 2H), 7.09–7.04 (m, 2H), 6.94 (d, J = 2.1 Hz, 2H), 6.50
(s, 1H), 2.68 (q, J =7.4 Hz, 2H), 1.22 (t, J = 7.6 Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 198.2,
149.8, 136.5, 134.6, 129.0, 128.1, 126.7, 124.0, 122.2, 119.6, 119.0, 114.5, 111.3, 41.9, 28.9, 15.1.
IR(CHCl3 cm-1) v; 3403, 2956, 1667, 1457; HRMS (ESI) (m/z): [M+Na]+ calculated for C26H22N2NaO
401.1624; found: 401.1612.
2,2-Di(1H-indol-3-yl)-1-(p-tolyl)ethan-1-one (17): The title compound was prepared according to the
general procedure by taking indole (100 mg, 0.85 mmol), p-tolylacetylene (54.8 µl, 0.4 mmol), thiophe-
nol (9.3 µl, 0.085 mmol), TFA (6.5 µl, 0.085 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%) and purified by
column chromatography (hexane:EA :: 76:24) as solid (220 mg, 71%). 1H NMR (400 MHz, CDCl3) δ =
8.04 (brs, 2H), 8.01 (d, J = 8.3 Hz, 2H), 7.55 (d, J = 8.0 Hz, 2H), 7.33 (d, J = 8.1 Hz, 2H), 7.23 – 7.13
(m, 4H), 7.06 (t, J = 7.1 Hz, 2H), 6.96 (d, J = 2.1 Hz, 2H), 6.49 (s, 1H), 2.36 (s, 3H); 13C{1H} NMR
15
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 16 of 42
(125 MHz, DMSO-d6) δ = 198.0, 143.7, 136.8, 134.5, 129.7, 129.1, 126.9, 124.8, 121.5, 119.4, 118.9,
113.5, 112.0, 41.8, 21.5. HRMS (ESI) (m/z): [M+Na]+ calculated for C25H20N2NaO 387.1468; found:
387.1461. The observed characterization data (1H & 13C) was consistent with that previously reported in
the literature.9a
1
2
3
4
5
6
7
8
9
2,2-Bis(6-chloro-1H-indol-3-yl)-1-phenylethanone (18): The title compound was prepared according
to the general procedure by taking 6-chloroindole (100 mg, 0.65 mmol), phenylacetylene (36.9 µl, 0.3
mmol), thiophenol (7.1 µl, 0.065 mmol), TFA (5 µl, 0.065 mmol), Ru(bpy)3Cl2 (9.7 mg, 2 mol%) and
purified by column chromatography (hexane:EA :: 77:23) as solid (201 mg, 73%), mp (138-140 °C). 1H
NMR (400 MHz, CDCl3) δ = 8.12 (brs, 2H), 8.09-8.05 (m, 2H), 7.54 (t, J = 7.4 Hz, 1H), 7.45-7.39 (m,
4H), 7.30 (s, 2H), 7.03 (dd, J = 8.5, 1.6 Hz, 2H), 6.89 (s, 2H), 6.41 (s, 1H); 13C{1H} NMR (125 MHz,
CDCl3) δ = 198.3, 136.8, 136.6, 133.2, 128.8, 128.8, 128.3, 125.1, 124.6, 120.6, 119.8, 114.1, 111.4,
42.0. IR(CHCl3 cm-1) v; 3424, 2922, 1674, 1460, 1226, 770; HRMS (ESI) (m/z): [M+H]+ calculated
for C24H17Cl2N2O 419.0712; found: 419.0707.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
2,2-Bis(5-fluoro-1H-indol-3-yl)-1-phenylethan-1-one (19): The title compound was prepared accord-
ing to the general procedure by taking 5-fluoroindole (100 mg, 0.73 mmol), phenylacetylene (41.4 µl,
0.36 mmol), thiophenol (8.0 µl, 0.073 mmol), TFA (5.6 µl, 0.073 mmol), Ru(bpy)3Cl2 (10.9 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 75:25) as solid (217 mg, 76%), mp (144-
148 °C). 1H NMR (400 MHz, CDCl3) δ = 8.16–8.06 (m, 4H), 7.55 (t, J = 7.4 Hz, 1H), 7.44 (t, J = 7.7
Hz, 2H), 7.27–7.22 (m, 2H), 7.18 (dd, J = 9.6, 2.3 Hz, 2H), 7.03 (d, J = 2.2 Hz, 2H), 6.96-6.91 (m, 2H),
6.37 (s, 1H); 13C{1H} NMR (125 MHz, CDCl3) δ = 198.2, 157.9 (d, J = 233.8 Hz), 136.5, 133.5, 133.1
(d, J = 26.2 Hz), 128.8 (d, J = 7.5 Hz), 126.9 (d, J = 10 Hz), 125.6, 125.4, 114.1 (d, J = 4.6 Hz), 112.0
(d, J = 10 Hz), 110.8 (d, J = 26.2 Hz), 104.0, (d, J = 23.7 Hz),42.1. IR(CHCl3 cm-1) v; 3354, 2923, 2852,
1677, 1485, 1216, 1181; HRMS (ESI) (m/z): [M+Na]+ calculated for C24H16F2N2NaO 409.1123; found:
409.1121.
2,2-Bis(5-chloro-1H-indol-3-yl)-1-phenylethan-1-one (20): The title compound was prepared accord-
ing to the general procedure by taking 5-chloroindole (100 mg, 0.65 mmol), phenylacetylene (36.9 µl,
16
ACS Paragon Plus Environment

Page 17 of 42
The Journal of Organic Chemistry
0.3 mmol), thiophenol (7.1 µl, 0.065 mmol), TFA (5 µl, 0.065 mmol), Ru(bpy)3Cl2 (9.7 mg, 2 mol%)
and purified by column chromatography (hexane:EA :: 75:25) as solid (196 mg, 71%), mp (132-134
°C). 1H NMR (400 MHz, CDCl3) δ = 8.21 (brs, 2H), 8.08 (d, J = 1.2 Hz, 2H), 7.56 (t, J = 7.4 Hz, 1H),
7.50 (d, J = 1.7 Hz, 2H), 7.45 (t, J = 7.7 Hz, 2H), 7.19 (d, J = 8.6 Hz, 2H), 7.11 (dd, J = 8.6, 1.9 Hz,
2H), 6.84 (d, J = 2.4 Hz, 2H), 6.38 (s, 1H); 13C{1H} NMR (125 MHz, CDCl3) δ = 198.5, 136.4, 134.9,
133.4, 128.9, 128.8, 127.5, 125.5, 125.4, 122.7, 118.3, 113.4, 112.5, 42.1. IR(CHCl3 cm-1) v; 3429,
1677, 1462, 1216, 762; HRMS (ESI) (m/z): [M+Na]+ calculated for C24H16Cl2N2NaO 441.0532; found:
441.0518.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
2,2-Bis(5-bromo-1H-indol-3-yl)-1-phenylethan-1-one (21): The title compound was prepared accord-
ing to the general procedure by taking 5-bromoindole (100 mg, 0.51 mmol), phenylacetylene (28.9 µl,
0.25 mmol), thiophenol (5.6 µl, 0.051 mmol), TFA (3.9 µl, 0.051 mmol), Ru(bpy)3Cl2 (7.6mg, 2 mol%)
and purified by column chromatography (hexane:EA :: 76:24) as solid (178 mg, 69%). 1H NMR (400
MHz, CDCl3) δ = 8.18 (brs, 2H), 8.13-8.05 (m, 2H), 7.67 (s, 2H), 7.56 (t, J = 7.4 Hz, 1H), 7.45 (t, J =
13
7.7 Hz, 2H), 7.28-7.23 (m, 2H), 7.22-7.17 (m, 2H), 6.94 (s, 2H), 6.38 (s, 1H); C{1H} NMR (125
MHz, CDCl3) δ = 197.9, 136.4, 135.2, 133.2, 128.8, 128.8, 128.2, 125.3, 125.1, 121.5, 113.6, 113.2,
112.9, 42.0. HRMS (ESI) (m/z): [M-H]-calculated for C24H15Br79Br81N2O 506.9531; found: 506.9528.
The observed characterization data (1H & 13C) was consistent with that previously reported in the litera-
ture.9d
2,2-Bis(5-iodo-1H-indol-3-yl)-1-phenylethan-1-one (22): The title compound was prepared according
to the general procedure by taking 5-iodoindole (100 mg, 0.41 mmol), phenylacetylene (23.3 µl, 0.2
mmol) , thiophenol (4.5 µl, 0.04 mmol), TFA (3.2 µl, 0.04 mmol), Ru(bpy)3Cl2 (6.1 mg, 2 mol%) and
purified by column chromatography (hexane:EA :: 74:26) as solid (173 mg, 70%), mp (156-158 °C). 1H
NMR (400 MHz, CDCl3) δ = 8.18 (brs, 2H), 8.07 (d, J = 8.2 Hz, 2H), 7.83 (s, 2H), 7.55 (t, J = 7.4 Hz,
1H), 7.46–7.36 (m, 4H), 7.13–6.92 (m, 2H), 6.71 (s, 2H), 6.33 (s, 1H); 13C {1H} NMR (125
MHz,CDCl3 and CD3OD) δ = 199.1, 136.3, 135.8, 133.2, 130.1, 129.0, 128.8, 128.7, 127.3, 125.1,
17
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 18 of 42
113.6, 112.4, 82.6, 42.1. IR(CHCl3 cm-1) v; 3418, 2924, 1674, 1454, 1215; HRMS (ESI) (m/z): [M+H]+
calculated for C24H17I2N2O 602.9425; found: 602.9422.
1
2
3
4
5
6
7
8
9
3,3'-(2-Oxo-2-phenylethane-1,1-diyl)bis(1H-indole-5-carbonitrile) (23): The title compound was pre-
pared according to the general procedure by taking indole-5-carbonitrile (100 mg, 0.70 mmol), phenyla-
cetylene (39.7 µl, 0.35 mmol), thiophenol (7.7 µl, 0.07 mmol), TFA (5.4 µl, 0.07 mmol), Ru(bpy)3Cl2
(10.4 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 72:28) as solid (188 mg,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
67%), mp (192-194 °C). H NMR (400 MHz, CDCl3) δ = 8.66 (brs, 2H), 8.12–8.07 (m, 2H), 7.88 (s,
2H), 7.60 (t, J = 7.4 Hz, 1H), 7.49 (t, J = 7.7 Hz, 2H), 7.41 (d, J = 0.9 Hz, 4H), 7.18 (d, J = 2.4 Hz, 2H),
6.49 (s, 1H); 13C{1H} NMR (125 MHz, CDCl3) δ = 197.6, 138.3, 136.0, 133.7, 129.0, 128.8, 126.3,
125.9, 125.4, 125.0, 120.6, 114.4, 112.5, 103.0, 41.9. IR(CHCl3 cm-1) v; 3331, 2923, 2223, 1669, 1446,
1217; HRMS (ESI) (m/z): [M+NH4]+ calculated for C26H20N5O 418.1662; found: 418.1666.
2,2-Bis(5-nitro-1H-indol-3-yl)-1-phenylethan-1-one (24): The title compound was prepared according
to the general procedure described as above by taking 5-nitroindole (100 mg, 0.6 mmol), phenylacety-
lene (34.6 µl, 0.3 mmol), thiophenol (6.7 µl, 0.06 mmol), TFA (4.7 µl, 0.06 mmol), Ru(bpy)3Cl2 (9.1
mg, 2 mol%) and purified by column chromatography (hexane:EA :: 70:30) as solid (171 mg, 63%), mp
(252-254 °C). 1H NMR (400 MHz, CDCl3 and CD3OD) δ = 8.42 (s, 2H), 8.10–7.86 (m, 4H), 7.54–7.45
(m, 1H), 7.43–7.31 (m, 4H), 7.29–7.26 (m, 1H), 7.17 (s, 1H), 6.51 (s, 1H); 13C{1H} NMR (125 MHz,
Acetone-d6) δ = 197.3, 141.4, 140.0, 136.6, 133.2, 128.9, 128.7, 128.1, 126.2, 116.9, 116.5, 116.1,
111.9, 41.6. IR(CHCl3 cm-1) v; 3432, 2923, 1653, 1520, 1468, 1336; HRMS (ESI) (m/z): [M+H]+ calcu-
lated for C24H17N4O5 441.1193; found: 441.1192 .
2,2-Bis(2-methyl-1H-indol-3-yl)-1-phenylethan-1-one (25): The title compound was prepared accord-
ing to the general procedure by taking 2-methylindole (100 mg, 0.76 mmol), phenylacetylene (43.1 µl,
0.38 mmol), thiophenol (8.3 µl, 0.076 mmol), TFA (5.6 µl, 0.076 mmol), Ru(bpy)3Cl2 (11.4 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 78:22) as solid (204 mg, 71%). 1H NMR
(400 MHz, CDCl3) δ = 8.10–8.05 (m, 2H), 7.82 (brs, 2H), 7.49 (t, J = 7.4 Hz, 1H), 7.42–7.32 (m, 4H),
7.25 (d, J = 8.1 Hz, 2H), 7.08 (t, J = 7.5 Hz, 2H), 6.98 (t, J = 6.8 Hz, 2H), 6.43 (s, 1H), 2.17 (s, 6H);
18
ACS Paragon Plus Environment

Page 19 of 42
The Journal of Organic Chemistry
13C{1H} NMR (125 MHz, CDCl3) δ = 198.8, 137.2, 135.0, 132.8, 132.4, 128.7, 128.6, 128.5, 121.0,
119.5, 118.5, 110.2, 108.8, 42.8, 12.6. HRMS (ESI) (m/z): [M+Na]+ calculated for C26H22N2NaO
401.1624; found: 401.1623. The observed characterization data (1H & 13C) was consistent with that pre-
viously reported in the literature.9a
1
2
3
4
5
6
7
8
9
2,2-Di(1H-indol-3-yl)-1,2-diphenylethan-1-one (26): The title compound was prepared according to
the general procedure by taking indole (100 mg, 0.85 mmol), diphenylacetylene (75.7 mg, 0.4 mmol),
thiophenol (9.3 µl, 0.08 mmol), TFA (6.5 µl, 0.08 mmol), Ru(bpy)3Cl2 (12.7 mg, 2 mol%) and purified
by column chromatography (hexane:EA :: 80:20) as solid (265 mg, 73%), mp (192-194 °C). 1H NMR
(400 MHz, CDCl3) δ = 8.02 (brs, 2H), 7.89–7.82 (m, 2H), 7.36 (dd, J = 7.7, 1.9 Hz, 2H), 7.27–7.22 (m,
4H), 7.22–7.15 (m, 2H), 7.12–7.04 (m, 4H), 7.03 (d, J = 7.3 Hz, 2H), 6.88 (d, J = 2.5 Hz, 2H), 6.81 (t, J
= 7.2 Hz, 2H); 13C{1H} NMR (100 MHz, CDCl3) δ = 199.1, 142.6, 138.3, 136.5, 131.7, 130.7, 130.1,
127.6, 127.5, 127.4, 126.5, 124.5, 121.9, 121.9, 119.5, 119.0, 111.0, 61.1. IR(CHCl3 cm-1) v; 3408,
2917, 2849, 1755, 1746, 1453, 1359, 1208; HRMS (ESI) (m/z): [M+Na]+ calculated for C30H22N2NaO
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
13
449.1624; found: 449.1620 . The observed characterization data (1H & C) was consistent with that
previously reported in the literature.23
2,2-Di(1H-indol-3-yl)-1-phenylpropan-1-one (27): The title compound was prepared according to the
general procedure described as above by taking indole (100 mg, 0.85 mmol), 1-phenyl-1-propyne (54.8
µl, 0.4 mmol), thiophenol (9.3 µl, 0.08 mmol), TFA (6.5 µl, 0.08 mmol), Ru(bpy)3Cl2 (12.7 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 79:21) as solid (214 mg, 69%), mp (132-
134 °C). 1H NMR (400 MHz, CDCl3) δ = 8.06 (brs, 2H), 7.75–7.71 (m, 2H), 7.57 (d, J = 8.1 Hz, 2H),
7.38 (d, J = 8.1 Hz, 2H), 7.29 (d, J = 7.4 Hz, 1H), 7.20–7.14 (m, 4H), 7.07–7.02 (m, 2H), 6.94 (d, J =
2.5 Hz, 2H), 2.20 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3) δ = 202.6, 138.4, 136.9, 131.2, 129.4,
127.6, 126.2, 123.2, 122.0, 121.6, 119.8, 119.5, 111.3, 51.8, 26.6. IR(CHCl3 cm-1) v; 3405, 2919, 2850,
1688, 1619, 1240; HRMS (ESI) (m/z): [M+Na]+ calculated for C25H20N2NaO 387.1468; found:
387.1464.
19
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 20 of 42
2,2-Bis(5-fluoro-1H-indol-3-yl)-1,2-diphenylethanone (28): The title compound was prepared accord-
ing to the general procedure by taking 6-fluoroindole (100 mg, 0.73 mmol), diphenylacetylene (65 mg,
0.36 mmol), thiophenol (8.0 µl, 0.073 mmol), TFA (5.6 µl, 0.073 mmol), Ru(bpy)3Cl2 (10.9 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 76:24) as solid (243 mg, 71%), mp (133-
135 °C). 1H NMR (400 MHz, CDCl3) δ = 8.08 (brs, 2H), 7.87–7.81 (m, 2H), 7.39–7.34 (m, 2H), 7.31 (d,
J = 7.4 Hz, 1H), 7.27–7.23 (m, 3H), 7.15 (t, J = 7.8 Hz, 2H), 6.96 – 6.91 (m, 4H), 6.84 (s, 2H), 6.61–
6.54 (m, 2H); 13C{1H} NMR (125 MHz, CDCl3) δ = 199.0, 159.6 (d, J = 236.2 Hz),142.1, 137.8, 136.3
(d, J = 12.4 Hz), 132.1, 130.7, 129.8, 127.8 (d, J = 36.2 Hz) , 126.9, 124.6, 124.6, 123.9, 122.4 (d, J =
10 Hz), 119.1, 108.4 (d, J = 23.8 Hz), 97.2 (d, J = 26.2 Hz), 60.9. IR(CHCl3 cm-1) v; 3370, 2926, 1627,
1446, 1217; HRMS (ESI) (m/z): [M-H]- calculated for C30H19F2N2O 461.1471; found: 461.1499.
2,2-Bis(5-chloro-1H-indol-3-yl)-1,2-diphenylethanone (29): The title compound was prepared accord-
ing to the general procedure by taking 5-chloroindole (100 mg, 0.65 mmol), diphenylacetylene (57.9
mg, 0.32 mmol), thiophenol (7.1 µl, 0.065 mmol), TFA (5 µl, 0.065 mmol), Ru(bpy)3Cl2 (9.7 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 75:25) as solid (238 mg, 73%), mp (152-
154 °C). 1H NMR (400 MHz, CDCl3) δ = 8.15 (brs, 2H), 7.82–7.79 (m, 2H), 7.37–7.32 (m, 3H), 7.27–
7.24 (m, 3H), 7.18–7.13 (m, 4H), 6.98 (d, J = 2.0 Hz, 1H), 6.95 (s, 3H), 6.83 (d, J = 2.6 Hz, 2H);
13C{1H} NMR (125MHz, CDCl3) δ = 198.5, 141.4, 137.5, 134.9, 132.1, 130.8, 129.6, 128.3, 128.2,
127.8, 127.1, 125.7, 125.1, 122.5, 120.9, 118.5, 112.2, 60.9. IR(CHCl3 cm-1) v; 3421, 3421, 2928, 1603,
1217, 749; HRMS (ESI) (m/z): [M+Na]+ calculated for C30H20Cl2N2NaO 517.0839; found: 517.0815.
2,2-Bis(5-bromo-1H-indol-3-yl)-1,2-diphenylethanone (30): The title compound was prepared accord-
ing to the general procedure by taking 5-bromoindole (100 mg, 0.51 mmol), diphenylacetylene (45 mg,
0.25 mmol), thiophenol (5.6 µl, 0.051 mmol), TFA (3.92 µl, 10 mol%), Ru(bpy)3Cl2 (7.6 mg, 2 mol%)
and purified by column chromatography (hexane:EA :: 75:25) as solid (222 mg, 75%), mp (168-171
°C). 1H NMR (400 MHz, CDCl3) δ = 8.19 (brs, 2H), 7.81–7.77 (m, 2H), 7.36–7.30 (m, 3H), 7.28–7.23
(m, 4H), 7.15 (t, J = 7.8 Hz, 2H), 7.10 (s, 2H), 7.08 (s, 3H), 6.78 (d, J = 2.6 Hz, 2H); 13C{1H} NMR
(125 MHz, CDCl3) δ = 198.6, 141.4, 137.5, 135.2, 132.2, 130.8, 129.6, 128.9, 128.2, 127.8, 127.1,
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
20
ACS Paragon Plus Environment

Page 21 of 42
The Journal of Organic Chemistry
125.6, 125.0, 123.9, 118.3, 112.8, 112.7,60.9. IR(CHCl3 cm-1) v; 3416, 2926, 1668, 1446, 1216, 582;
HRMS (ESI) (m/z): [M+H]+ calculated for C30H21Br2N2O 583.0015; found: 583.0019.
1
2
3
4
5
6
7
8
9
2,2-Bis(5-nitro-1H-indol-3-yl)-1,2-diphenylethanone (31): The title compound was prepared according
to the general procedure by taking 5-nitroindole (100 mg, 0.6 mmol), diphenylacetylne (54.3 mg, 0.3
mmol) , thiophenol (6.7 µl, 0.06 mmol), TFA (4.7 µl, 0.06 mmol), Ru(bpy)3Cl2 (9.1 mg, 2 mol%) and
purified by column chromatography (hexane:EA :: 66:34) as solid (197 mg, 62%), mp (197-200 °C). 1H
NMR (400 MHz, CD3OD) δ = 8.43 (d, J = 2.3 Hz, 1H), 8.37 (dd, J = 9.3, 2.3 Hz, 1H), 8.34 (d, J = 2.4
Hz, 1H), 8.26 (d, J = 2.1 Hz, 1H), 8.20 (d, J = 2.1 Hz, 2H), 7.98–7.87 (m, 4H), 7.49–7.26 (m, 6H),
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
13
7.08–6.94 (m, 2H); C{1H} NMR (125 MHz, CD3OD) δ = 199.1, 162.8, 141.2, 140.6, 139.2, 132.9,
127.0, 126.7, 126.0, 124.6, 122.2, 120.1, 116.2, 115.3, 111.7, 111.3, 111.2, 68.8. IR(CHCl3 cm-1) v;
3422, 3023, 1647, 1335, 1216; HRMS (ESI) (m/z): [M+H]+ calculated for C30H21N4O5 517.1506;
found: 517.1522.
2-(1H-Indol-3-yl)-2-(2-methyl-1H-indol-3-yl)-1-phenylethan-1-one (32): The title compound was pre-
pared according to the general procedure by taking 2-methylindole (100 mg, 0.76 mmol), indole (88.92
mg, 0.76 mmol), phenylacetylene (86.24 µl, 0.38 mmol) , thiophenol (8.3 µl, 0.076 mmol), TFA (5.8 µl,
0.076 mmol), Ru(bpy)3Cl2 (11.4 mg, 2 mol%) and purified by column chromatography (hexane:EA ::
1
76:24) as solid (94 mg, 34%), mp (160-162 °C). H NMR (400 MHz, CDCl3) δ = 8.08 (d, J = 7.4 Hz,
2H), 7.99 (s, 1H), 7.86 (s, 1H), 7.65 (d, J = 7.7 Hz, 1H), 7.48 (t, J = 7.4 Hz, 1H), 7.43–7.33 (m, 3H),
7.31 (d, J = 8.2 Hz, 1H), 7.24 (d, J = 7.9 Hz, 1H), 7.19–7.09 (m, 2H), 7.09–7.02 (m, 2H), 6.84 (d, J =
13
1.6 Hz, 1H), 6.40 (s, 1H), 2.34 (s, 3H); C{1H} NMR (100 MHz, CDCl3) δ = 198.2, 137.2, 136.5,
135.2, 132.7,132.7, 128.6, 128.5, 128.1, 127.0, 124.1, 122.1, 121.2, 119.7, 119.6, 119.0, 118.9, 114.4,
111.3, 110.3, 108.2, 42.2, 12.4. IR(CHCl3 cm-1) v; 3396, 2849, 2917, 1680, 1459, 1306; HRMS (ESI)
(m/z): [M+Na]+ calculated for C25H20N2NaO 387.1473; found: 387.1467. The observed characteriza-
tion data (1H & 13C) was consistent with that previously reported in the literature.9c
2-(5-Fluoro-1H-indol-3-yl)-2-(2-methyl-1H-indol-3-yl)-1-phenylethan-1-one (33): The title com-
pound was prepared according to the general procedure by taking 2-methylindole (100 mg, 0.76 mmol),
21
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 22 of 42
5-fluoroindole (102.7 mg , 0.76 mmol), phenylacetylene (86.2 µl, 0.38 mmol) , thiophenol (8.3 µl,
0.076 mmol), TFA (5.8 µl, 0.076 mmol), Ru(bpy)3Cl2 (11.4 mg, 2 mol%) and purified by column
1
2
3
4
5
6
1
chromatography (hexane:EA :: 75:25) as solid (110 mg, 38%), mp (168-169 °C). H NMR (400 MHz,
7
8
9
CDCl3) δ = 8.06 (d, J = 1.3 Hz, 2H), 8.02 (s, 1H), 7.90 (s, 1H), 7.61 (d, J = 7.8 Hz, 1H), 7.49 (t, J = 7.4
Hz, 1H), 7.38 (t, J = 7.7 Hz, 2H), 7.21 (dd, J = 15.5, 7.3 Hz, 1H), 7.13–7.00 (m, 4H), 6.87 (t, J = 9.1 Hz,
1H), 6.79 (s, 1H), 6.30 (s, 1H), 2.32 (s, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 198.0, 157.7 (d, J =
233.8 Hz), 136.9, 135.2, 133.0, 132.9, 132.7, 128.6, 127.9, 127.1 (d, J = 10 Hz), 126.0, 121.3, 119.7,
118.8, 114.4 (d, J = 3.8 Hz), 112.0 (d, J = 10 Hz), 110.4, 110.4, 110.2, 107.9, 103.9 (d, J = 23.7 Hz),
42.3, 12.3. IR(CHCl3 cm-1) v; 3393, 2919, 1679, 1454, 1316, 1184; HRMS (ESI) (m/z): [M+H]+ calcu-
lated for C25H20FN2O 383.1554; found: 383.1561.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
2-(5-Bromo-1H-indol-3-yl)-2-(2-methyl-1H-indol-3-yl)-1-phenylethan-1-one (34): The title compound
was prepared according to the general procedure by taking 2-methylindole (100 mg, 0.76 mmol), 5-
bromoindole (148.9 mg, 0.76 mmol), phenylacetylene (86.2 µl, 0.38 mmol) , thiophenol (8.3 µl, 0.076
mmol), TFA (5.8 µl, 0.076 mmol), Ru(bpy)3Cl2 (11.4 mg, 2 mol%) and purified by column chromatog-
raphy (hexane:EA :: 75:25) as solid (138 mg, 41%), mp (170-172 °C). 1H NMR (400 MHz, CDCl3) δ =
8.05 (d, J = 7.3 Hz, 3H), 7.89 (s, 1H), 7.60 (d, J = 7.7 Hz, 1H), 7.53–7.45 (m, 2H), 7.38 (t, J = 7.6 Hz,
13
2H), 7.23 (d, J = 10.7 Hz, 2H), 7.19–6.97 (m, 3H), 6.81 (s, 1H), 6.30 (s, 1H), 2.36 (s, 3H); C{1H}
NMR (125 MHz, CDCl3) δ = 197.8, 136.8, 135.2, 135.2, 132.9, 132.5, 128.6, 128.6, 127.9, 125.5,
124.9, 121.5, 121.3, 119.8, 118.8, 114.1, 112.8, 112.8, 110.4, 108.0, 42.2, 12.4. IR(CHCl3 cm-1) v;
3400.0, 2923.3, 1677.2, 1459.5, 1216.3, 584.2; HRMS (ESI) (m/z): [M+H]+ calculated for
C25H20BrN2O 443.0754; found: 443.0736. The observed characterization data (1H & 13C) was consistent
with that previously reported in the literature.9c
Methyl 1-heptanoyl-9H-pyrido[3,4-b]indole-3-carboxylate (47): The title compound was prepared ac-
cording to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), 1-octyne (70.8
µl, 0.45 mmol), thiophenol (4.9 µl, 0.045 mmol), TFA (34.6 µl, 0.45 mmol), Ru(bpy)3Cl2 (6.8 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 97:3) as solid (111 mg, 72%), mp (162-
22
ACS Paragon Plus Environment

Page 23 of 42
The Journal of Organic Chemistry
166 °C). 1H NMR (400 MHz, CDCl3) δ = 10.51 (brs, 1H), 9.00 (s, 1H), 8.19 (d, J = 7.9 Hz, 1H), 7.66–
7.52 (m, 2H), 7.37 (t, J = 7.2 Hz, 1H), 4.06 (s, 3H), 3.46 (t, J = 7.4 Hz, 2H), 1.87–1.75 (m, 2H), 1.49–
1
2
3
4
5
6
13
1.23 (m, 6H), 0.89 (t, J = 6.6 Hz, 3H); C{1H} NMR (125 MHz, CDCl3) δ = 205.5, 166.2, 141.4,
7
8
9
136.8, 136.5, 135.1, 131.9, 129.7, 122.1, 121.6,121.0, 121.2, 112.3, 52.8, 37.5, 31.8, 29.1, 24.1, 22.6,
14.1. IR(CHCl3 cm-1) v; 3364, 2928, 1720, 1360, 1260; HRMS (ESI) (m/z): [M+H]+ calculated for
C20H23N2O3 339.1703; found: 339.1699.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Methyl 1-hexanoyl-9H-pyrido[3,4-b]indole-3-carboxylate (48): The title compound was prepared ac-
cording to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), 1-heptyne
(61.7 µl, 0.45 mmol), thiophenol (4.9 µl, 0.045 mmol), TFA (34 µl, 0.45 mmol), Ru(bpy)3Cl2 (6.8 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 97:3) as solid (102 mg, 69%), mp (156-
158 °C). 1H NMR (400 MHz, CDCl3) δ = 10.50 (brs, 1H), 9.00 (s, 1H), 8.19 (d, J = 7.9 Hz, 1H), 7.66–
7.56 (m, 2H), 7.48-7.27(m, 1H), 4.06 (s, 3H), 3.46 (t, J = 7.4 Hz, 2H), 1.82 (dd, J = 14.7, 7.4 Hz, 2H),
1.46–1.38 (m, 4H), 0.92 (t, J = 5.6 Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 205.5, 166.2, 141.4,
136.7, 136.5, 135.1, 131.9, 129.7,121.0, 122.1, 121.6, 121.2, 112.3, 52.8, 37.5, 31.6, 23.8, 22.6, 14.0.
IR(CHCl3 cm-1) v; 3417, 2954, 2926, 1713, 1626, 1511, 1261, 1121; HRMS (ESI) (m/z): [M+H]+ calcu-
lated for C19H21N2O3 325.1547; found: 325.1549.
Methyl 1-pentanoyl-9H-pyrido[3,4-b]indole-3-carboxylate (49): The title compound was prepared ac-
cording to the general procedure described as above by taking tryptophan methyl ester (100 mg, 0.45
mmol), 1-hexyne (52.8 µl, 0.45 mmol), thiophenol (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45 mmol) ,
Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 98:2) as solid
1
(100 mg, 71%), mp (145-148 °C). H NMR (400 MHz, CDCl3) δ = 10.54 (brs, 1H), 9.02 (s, 1H), 8.21
(d, J = 7.8 Hz, 1H), 7.68–7.60 (m, 2H), 7.54–7.30 (m, 1H), 4.09 (s, 3H), 3.50 (t, J = 7.4 Hz, 2H), 1.89–
1.77 (m, 2H), 1.56–1.42 (m, 2H), 1.02 (t, J = 7.3 Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 205.5,
166.2, 141.4, 136.7, 136.5, 135.1, 131.9, 129.7, 122.0, 121.6, 121.2,120.8, 112.3, 52.8, 37.2, 26.2, 22.5,
14.0. IR(CHCl3 cm-1) v; 3363, 2923, 1715, 1495, 1337, 1261; HRMS (ESI) (m/z): [M+H]+ calculated
for C18H19N2O3 311.1390; found: 311.1396.
23
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 24 of 42
Methyl 1-butyryl-9H-pyrido[3,4-b]indole-3-carboxylate (50):The title compound was prepared accord-
ing to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), 1-pentyne (51.1
µl, 0.45 mmol) , thiophenol (4.9 µl, 0.045 mmol), TFA (34 µl, 0.45 mmol) , Ru(bpy)3Cl2 (6.8 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 97:3) as solid (92 mg, 68%), mp (194-
196 °C). 1H NMR (400 MHz, CDCl3) δ = 10.53 (brs, 1H), 9.01 (s, 1H), 8.20 (d, J = 7.9 Hz, 1H), 7.66–
7.57 (m, 2H), 7.41–7.35 (m, 1H), 4.08 (s, 3H), 3.47 (t, J = 7.3 Hz, 2H), 1.93–1.83 (m, 2H), 1.08 (t, J =
7.4 Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 205.2, 166.2, 141.4, 136.7, 136.5, 135.2, 131.8,
129.7, 122.0, 121.6, 121.1, 112.3, 53.5, 52.8, 39.4, 17.5, 13.9. IR(CHCl3 cm-1) v; 3400, 2932, 2874,
1704, 1664, 1436, 1332, 1266; HRMS (ESI) (m/z): [M+H]+ calculated for C17H17N2O3 297.1234; found:
297.1239.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Methyl 1-(cyclopropanecarbonyl)-9H-pyrido[3,4-b]indole-3-carboxylate (51): The title compound was
prepared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol),
cyclopropylacetylene (42.5 µl, 0.45 mmol), thiophenol (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45 mmol),
Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 98:2) as solid
(89 mg, 66%), mp (245-247 °C). 1H NMR (400 MHz, CDCl3) δ = 10.57 (brs, 1H), 9.06 (s, 1H), 8.22 (d,
J = 7.9 Hz, 1H), 7.65–7.59 (m, 2H), 7.40 (t, J = 6.8 Hz, 1H), 4.10 (s, 3H), 3.94–3.88 (m, 1H), 1.41–1.36
13
(m, 2H), 1.30–1.18 (m, 2H); C{1H} NMR (125 MHz, CDCl3) δ = 203.9, 166.2, 141.4, 136.8, 136.4,
135.4, 131.9, 129.7, 122.1, 121.6, 121.1, 120.9, 112.3, 52.9, 16.0, 13.6. IR(CHCl3 cm-1) v; 3363, 2920,
2850, 1700, 1495, 1327, 1266; HRMS (ESI) (m/z): [M+H]+ calculated for C17H15N2O3 295.1077;
found: 295.1057.
Methyl 1- benzoyl-9-H-pyrido(3,4-b)indole-3 carboxylate (52): The title compound was prepared ac-
cording to general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), phenylacetylene
(51.9 µl, 0.45 mmol), thiophenol (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45 mmol) , Ru(bpy)3Cl2 (6.8 mg,
2 mol%) and purified by column chromatography (hexane:EA :: 95:5) as solid (113 mg, 75%).1H NMR
(400 MHz, CDCl3) δ = 10.70 (brs, 1H), 9.06 (s, 1H), 8.63 (d, J = 7.4 Hz, 2H), 8.25 (d, J = 7.8 Hz, 1H),
7.71–7.62 (m, 3H), 7.57 (t, J = 7.5 Hz, 2H), 7.45–7.39 (m, 1H), 4.07 (s, 3H); 13C{1H} NMR (125 MHz,
24
ACS Paragon Plus Environment

Page 25 of 42
The Journal of Organic Chemistry
CDCl3) δ = 193.8, 166.2, 141.3, 138.3, 136.8, 136.4, 135.6, 133.0, 132.1, 132.0, 129.8, 128.2, 122.1,
121.7, 121.2, 120.7, 112.4, 52.9. HRMS (ESI) (m/z): [M+H]+ calculated for C20H15N2O3 331.1077;
found: 331.1043. The observed characterization data (1H & 13C) was consistent with that previously re-
ported in the literature.20d
1
2
3
4
5
6
7
8
9
Methyl 1-(4-fluorobenzoyl)-9H-pyrido[3,4-b]indole-3-carboxylate (53): The title compound was pre-
pared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), 4-
fluoro phenylacetylene (54 µl, 0.45 mmol), thiophenol, (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45 mmol),
Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 96:4) as solid
(114 mg, 72%). 1H NMR (400 MHz, CDCl3) δ = 10.73 (brs, 1H), 9.11 (s, 1H), 8.90 – 8.70 (m, 2H), 8.29
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
13
(d, J = 7.8 Hz, 1H), 7.71 (s, 2H), 7.48 (d, J = 6.3 Hz, 1H), 7.32 – 7.27 (m, 2H), 4.13 (s, 3H); C{1H}
NMR (125 MHz, CDCl3) δ = 191.9, 166.1, 165.9 (d, J = 253.8 Hz), 141.3, 138.3, 136.3, 135.4, 134.7
(d, J = 8.7 Hz), 133.1, 133.0, 132.2, 129.9, 121.9 (d, J = 41.2 Hz), 121.2, 120.7, 115.3 (d, J = 21.2
Hz),112.4, 52.9. HRMS (ESI) (m/z): [M+H]+ calculated for C20H14FN2O3 349.0983; found: 349.0946.
The observed characterization data (1H & 13C) was consistent with that previously reported in the litera-
ture.20h
Methyl 1-(4-methoxybenzoyl)-9H-pyrido[3,4-b]indole-3-carboxylate (54): The title compound was
prepared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), 4-
methoxy phenylacetylene (59.4 µl, 0.45 mmol), thiophenol (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45
mmol), Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 94:6) as
solid (115 mg, 70%).1H NMR (400 MHz, CDCl3) δ = 10.71 (brs, 1H), 9.05 (s, 1H), 8.76 (d, J = 9.0 Hz,
2H), 8.25 (d, J = 7.9 Hz, 1H), 7.75–7.58 (m, 2H), (7.46–7.38 (m, 1H), 7.07 (d, J = 9.0 Hz, 2H), 4.09 (s,
13
3H), 3.94 (s, 3H); C{1H} NMR (125 MHz, CDCl3) δ = 191.7, 166.3, 163.7, 141.2, 141.2, 138.3,
136.2, 136.2, 134.5, 131.9, 129.7, 122.0, 121.6, 121.2, 120.4, 113.6, 112.4, 55.5, 52.8. HRMS (ESI)
(m/z): [M+H]+ calculated for C21H17N2O4 361.1183; found: 361.1190. The observed characterization
data (1H & 13C) was consistent with that previously reported in the literature.20d
25
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 26 of 42
Methyl 1-(4-(tert-butyl)benzoyl)-9H-pyrido[3,4-b]indole-3-carboxylate (55): The title compound was
prepared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), 4-
tert- butylphenylacetylene (89 µl, 0.45 mmol), thiophenol (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45
mmol), Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 95:5) as
solid (131 mg, 74%). 1H NMR (400 MHz, CDCl3) δ = 10.75 (brs, 1H), 9.06 (s, 1H), 8.65–8.60 (m, 2H),
8.25 (d, J = 7.8 Hz, 1H), 7.70 – 7.63 (m, 2H), 7.62 – 7.59 (m, 2H), 7.47 – 7.37 (m, 1H), 4.10 (s, 3H),
1.41 (s, 9H); 13C{1H} NMR (125 MHz, CDCl3) δ = 193.3, 166.3, 156.8, 141.3, 138.3, 136.3, 135.8,
134.1, 132.0, 131.9, 129.8, 125.3, 122.1, 121.6, 121.1, 120.6, 112.4, 52.9,35.2, 31.1. HRMS (ESI)
(m/z): [M+H]+ calculated for C24H23N2O3 387.1703; found: 387.1706. The observed characterization
data (1H & 13C) was consistent with that previously reported in the literature.20d
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Methyl 1-(4-propylbenzoyl)-9H-pyrido[3,4-b]indole-3-carboxylate (56): The title compound was pre-
pared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), 4n-
Propyl phenylacetylene (72.1 µl, 0.45 mmol) , thiophenol (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45
mmol), Ru(bpy)3Cl2 (6.8 mg, 2 mol% ) and purified by column chromatography(hexane:EA :: 96:4) as
solid (136 mg, 80%), mp (157-159 °C). 1H NMR (400 MHz, CDCl3) δ = 10.73 (brs, 1H), 9.06 (s, 1H),
8.60 (d, J = 8.3 Hz, 2H), 8.25 (d, J = 7.9 Hz, 1H), 7.69–7.64 (m, 2H), 7.44–7.39 (m, 2H), 7.38 (s, 1H),
4.08 (s, 3H), 2.72 (t, J = 7.2 Hz, 2H), 1.79–1.69 (m, 2H), 1.01 (t, J = 7.3 Hz, 3H); 13C{1H} NMR (125
MHz, CDCl3) δ = 193.2, 166.3, 148.6, 141.3, 138.3, 136.3, 135.9, 134.4, 132.1, 132.0, 129.7, 128.4,
122.0, 121.6, 121.2, 120.5, 112.4, 52.8, 38.2, 24.3, 13.9. IR(CHCl3 cm-1) v; 3389, 2924, 1716, 1603,
1455, 1293, 1260; HRMS (ESI) (m/z): [M+H]+ calculated for C23H21N2O3 373.1547; found: 373.1543.
Methyl 1-(4-ethylbenzoyl)-9H-pyrido[3,4-b]indole-3-carboxylate (57): The title compound was pre-
pared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), 4-
ethyl phenylacetylene (65 µl, 0.45 mmol) , thiophenol (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45 mmol) ,
Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 96:4) as solid
(126 mg, 77%), mp (194-196 °C). 1H NMR (400 MHz, CDCl3) δ = 10.69 (brs, 1H), 9.04 (s, 1H), 8.57
(d, J = 8.3 Hz, 2H), 8.23 (d, J = 7.9 Hz, 1H), 7.71–7.56 (m, 2H), 7.45–7.31 (m, 3H), 4.06 (s, 3H), 2.75
26
ACS Paragon Plus Environment

Page 27 of 42
The Journal of Organic Chemistry
(q, J = 7.6 Hz, 2H), 1.29 (t, J = 7.4 Hz, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 193.3, 166.3, 150.1,
141.3, 138.3, 136.3, 135.9, 134.4, 132.2, 132.0, 129.8, 127.8, 122.1, 121.6, 121.2, 120.6, 112.4, 52.8,
29.1, 15.3. IR(CHCl3 cm-1) v; 3363, 2958, 2851, 1714, 1495, 1359, 1260; HRMS (ESI) (m/z): [M+H]+
calculated for C22H19N2O3 359.1390; found: 359.1355.
1
2
3
4
5
6
7
8
9
Methyl 1-(4-methylbenzoyl)-9H-pyrido[3,4-b]indole-3-carboxylate (58): The title compound was pre-
pared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45 mmol), p-
tolyl acetylene(58 µl, 0.45 mmol), thiophenol (4.95 µl, 0.045 mmol), TFA (34 µl, 0.45 mmol),
Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 97:3) as solid
(107 mg, 68%). 1H NMR (400 MHz, CDCl3) δ = 10.68 (brs, 1H), 9.03 (s, 1H), 8.54 (d, J = 8.2 Hz, 2H),
8.22 (d, J = 7.9 Hz, 1H), 7.72–7.60 (m, 2H), 7.44–7.30 (m, 3H), 4.05 (s, 3H), 2.45 (s, 3H); 13C{1H}
NMR (125 MHz, CDCl3) δ = 193.3, 166.3, 143.9, 141.3, 138.3, 136.3, 135.9, 134.2, 132.1, 132.0,
129.8, 129.0, 122.0, 121.6, 121.2, 120.5, 112.4, 52.8, 21.8. HRMS (ESI) (m/z): [M+H]+ calculated for
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
13
C21H17N2O3 345.1234; found: 345.1206. The observed characterization data (1H & C) was consistent
with that previously reported in the literature.20d
Methyl 1-(2-(trifluoromethyl)benzoyl)-9H-pyrido[3,4-b]indole-3-carboxylate (59): The title compound
was prepared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45
mmol), 2- (trifluoromethyl)phenylacetylene (62.7 µl, 0.45 mmol), thiophenol (4.95 µl, 0.045 mmol),
TFA (34 µl, 0.45 mmol), Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hex-
ane:EA :: 94:6) as solid (118 mg , 65%). 1H NMR (400 MHz, CDCl3) δ = 10.69 (brs, 1H), 9.09 (s, 1H),
8.30 (d, J = 7.9 Hz, 1H), 7.88 (d, J = 7.2 Hz, 2H), 7.79–7.69 (m, 4H), 7.54–7.45 (m, 1H), 4.00 (s, 3H);
13C{1H} NMR (125 MHz, CDCl3) δ = 197.4, 165.9, 141.5, 137.8, 137.1, 136.6, 134.6 (q, J = 8.8 Hz),
132.2, 130.9, 130.5,130.4, 130.0, 129.2, 128.9, 128.2, 126.8 (q, J = 17.5 Hz), 121.9, 121.6(q, J = 216.2
Hz), 119.8, 112.5, 52.7; 19F NMR (376 MHz, CDCl3) δ = -57.6; HRMS (ESI) (m/z): [M+H]+ calculated
for C21H14F3N2O3 399.0951; found: 399.0948. The observed characterization data (1H & 13C) was con-
sistent with that previously reported in the literature.20d
27
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 28 of 42
Methyl 1-(6-methoxy-2-naphthoyl)-9H-pyrido[3,4-b]indole-3-carboxylate (60): The title compound
was prepared according to the general procedure by taking tryptophan methyl ester (100 mg, 0.45
mmol), 2-Ethynyl- 6-methoxynaphthalene (81.9 µl, 0.45 mmol), thiophenol (4.95 µl, 0.045 mmol), TFA
(34 µl, 0.45 mmol), Ru(bpy)3Cl2 (6.8 mg, 2 mol%) and purified by column chromatography (hex-
ane:EA :: 93:7) as solid (146 mg, 78%), mp (239-241 °C). 1H NMR (400 MHz, CDCl3) δ = 10.77 (brs,
1H), 9.60 (s, 1H), 9.08 (s, 1H), 8.52 (dd, J = 8.7, 1.7 Hz, 1H), 8.26 (d, J = 7.9 Hz, 1H), 7.97 (d, J = 8.9
Hz, 1H), 7.87 (d, J = 8.7 Hz, 1H), 7.72 – 7.64 (m, 2H), 7.50 – 7.40 (m, 1H), 7.27 – 7.17 (m, 2H), 4.12
(s, 3H), 4.00 (s, 3H); 13C{1H} NMR (125 MHz, CDCl3) δ = 192.5, 166.3, 160.0, 141.3, 138.3, 137.3,
136.2, 136.1, 135.3, 132.1,132.0, 131.9, 129.8, 128.0, 127.4, 126.6, 122.1, 121.6, 121.2, 120.5, 119.4,
112.4, 105.6, 55.5, 52.9. IR(CHCl3 cm-1) v; 3416, 2921, 2850, 1711, 1436, 1304, 1261; HRMS (ESI)
(m/z): [M+H]+ calculated for C25H19N2O4 411.1339; found: 411.1373.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Cyclopropyl(4,9-dihydro-3H-pyrido[3,4-b]indol-1-yl)methanone (61): The title compound was pre-
pared according to the general procedure by taking tryptamine (100 mg, 0.62 mmol), cyclopropylacety-
lene (58.5 µl, 0.62 mmol), thiophenol (6.8 µl, 0.062 mmol), TFA (47.7 µl, 0.62 mmol), Ru(bpy)3Cl2
(9.3 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 97:3) as semi solid (96 mg,
65%). 1H NMR (400 MHz, CDCl3) δ = 9.62 (brs, 1H), 7.59 (d, J = 7.9 Hz, 1H), 7.39 (d, J = 8.3 Hz, 1H),
7.30 (d, J = 8.0 Hz, 1H), 7.14 (t, J = 7.5 Hz, 1H), 4.20–4.14 (m, 2H), 3.32–3.22 (m, 1H), 3.01–2.95 (m,
2H), 1.28–1.17 (m, 1H), 1.15–1.10 (m, 2H); 13C{1H} NMR (100 MHz, CDCl3) δ = 202.6, 155.4, 137.0,
126.3, 125.0, 120.7, 120.2, 119.9, 117.8, 112.2, 49.4, 19.0, 15.2, 13.1. IR( CHCl3 cm-1) v; 3239, 2923,
2350, 1659, 1214; HRMS (ESI) (m/z): [M+H]+ calculated for C15H15N2O 239.1179; found: 239.1202.
(4,9-Dihydro-3H-pyrido[3,4-b]indol-1-yl)(phenyl)methanone (62): The title compound was prepared
according to the general procedure by taking tryptamine (100 mg, 0.62 mmol), phenylacetylene (70.3
µl, 0.62 mmol), thiophenol (6.82 µl, 0.062 mmol), TFA (47.7 µl, 0.62 mmol), Ru(bpy)3Cl2 (9.3 mg, 2
mol%) and purified by column chromatography (hexane:EA :: 96:4) as semi solid (121 mg, 71%). 1H
NMR (400 MHz, CDCl3) δ = 9.43 (brs, 1H), 8.20 – 8.15 (m, 2H), 7.62 (t, J = 6.7 Hz, 2H), 7.50 (t, J =
7.7 Hz, 2H), 7.44 (d, J = 8.3 Hz, 1H), 7.32 (t, J = 7.1 Hz, 1H), 7.17 (t, J = 7.1 Hz, 1H), 4.18 (dd, J = 9.5,
28
ACS Paragon Plus Environment

Page 29 of 42
The Journal of Organic Chemistry
8.1 Hz, 2H), 3.04 (dd, J = 9.5, 8.1 Hz, 2H); 13C{1H} NMR (125 MHz, CDCl3) δ = 193.4, 155.9, 137.0,
135.3, 133.6, 131.1, 128.3, 126.7, 125.2, 124.8, 120.4, 120.0, 118.1, 112.3, 49.3, 19.1. HRMS (ESI)
(m/z): [M+H]+ calculated for C18H15N2O 275.1179; found: 275.1175. The observed characterization
data (1H & 13C) was consistent with that previously reported in the literature.22c
1
2
3
4
5
6
7
8
9
(4,9-Dihydro-3H-pyrido[3,4-b]indol-1-yl)(4-fluorophenyl)methanone (63): The title compound was
prepared according to the general procedure by taking tryptamine (100 mg, 0.62 mmol), 4-
fluorophenylacetylene (74.4 µl, 0.62 mmol), thiophenol (6.82 µl, 0.062 mmol), TFA (47.7 µl, 0.62
mmol), Ru(bpy)3Cl2 (9.3 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 95:5) as
solid (136 mg, 75%), mp (122-124 °C). 1H NMR (400 MHz, CDCl3) δ = 9.42 (brs, 1H), 8.30 – 8.25 (m,
2H), 7.63 (d, J = 8.0 Hz, 1H), 7.43 (d, J = 8.3 Hz, 1H), 7.35 – 7.29 (m, 1H), 7.19 (d, J = 1.8 Hz, 1H),
7.16 (d, J = 8.7 Hz, 2H), 4.18 (dd, J = 9.5, 8.1 Hz, 2H), 3.03 (dd, J = 9.4, 8.1 Hz, 2H); 13C{1H} NMR
(100 MHz, CDCl3) δ = 191.6, 166.2 (d, J = 254 Hz), 155.9, 137.0, 134.0 (d, J = 10 Hz), 131.6, 131.64,
126.6, 125.3, 124.8, 120.22 (d, J = 40 Hz), 118.2, 115.48 (d, J = 21.8 Hz), 112.3, 49.3, 19.1. IR(CHCl3
cm-1) v; 3436, 2924, 2852, 1665, 1428, 1230, 1155; HRMS (ESI) (m/z): [M+H]+ calculated for
C18H14FN2O 293.1085; found: 293.1090.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(4,9-Dihydro-3H-pyrido[3,4-b]indol-1-yl)(4-methoxyphenyl)methanone (64): The title compound was
prepared according to the general procedure by taking tryptamine (100 mg, 0.62 mmol), 4-methoxy
phenylacetylene (81.9 µl, 0.62 mmol), thiophenol (6.82 µl, 0.062 mmol), TFA (47.7 µl, 0.62 mmol),
Ru(bpy)3Cl2 (9.3 mg, 2 mol%) and purified by column chromatography (hexane:EA :: 93:7) as semi
solid (138 mg, 73%). 1H NMR (400 MHz, CDCl3) δ = 9.40 (brs, 1H), 8.28–8.24 (m, 2H), 7.63 (d, J =
8.0 Hz, 1H), 7.43 (d, J = 8.3 Hz, 1H), 7.34–7.29 (m, 1H), 7.17 (t, J = 6.9 Hz, 1H), 6.98 (d, J = 2.0 Hz,
2H) ,4.18 (dd, J = 9.4, 8.1 Hz, 2H), 3.91 (s, 3H), 3.04 (dd, J = 9.4, 8.1 Hz, 2H); 13C{1H} NMR (100
MHz, CDCl3)δ = 191.5, 164.2, 156.2, 136.9, 133.6, 128.1, 127.0 125.1, 124.9, 120.3, 119.9, 117.9,
113.7, 112.3, 55.6, 49.2, 19.1. IR(CHCl3 cm-1) v; 3210, 2926, 1623, 1217, 1169; HRMS (ESI) (m/z):
[M+H]+ calculated for C19H17N2O2 305.1285; found: 305.1290.
29
ACS Paragon Plus Environment