Employing Water as the Hydride Source in Synthesis: A Case Study of Diboron Mediated Alkyne Hydroarylation

Article abstract of DOI:10.1021/acs.joc.8b01965

We present an approach to utilize water as the hydride source via Pd(II)/Pd(0) catalysis. As a case study, we have achieved a diboron mediated Pd(II)-catalyzed hydroarylation of alkynes using arylboronic acids. This approach not only complements conventional reactivity of Pd via Pd(0)/Pd(II) cycle for the hydroarylation but also utilizes water as the hydride source. We believe this would particularly be beneficial in utilizing water as a reagent.

Full text of DOI:10.1021/acs.joc.8b01965

Subscriber access provided by REGIS UNIV
Article
Employing Water as the Hydride Source in Synthesis: A
Case Study of Diboron Mediated Alkyne Hydroarylation
Santhosh Rao, M. Nibin Joy, and Kandikere Ramaiah Prabhu
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.8b01965 • Publication Date (Web): 15 Oct 2018
Downloaded from http://pubs.acs.org on October 16, 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 30
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Employing Water as the Hydride Source in Synthesis: A Case Study
of Diboron Mediated Alkyne Hydroarylation
Santhosh Rao, M. Nibin Joy and Kandikere Ramaiah Prabhu*
Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, Karnataka, India.
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
ABSTRACT: We present an approach to utilize water as the hydride source via Pd(II)/Pd(0) catalysis.
As a case study, we have achieved a diboron mediated Pd(II)ꢀcatalyzed hydroarylation of alkynes using
arylboronic acids. This approach not only complements conventional reactivity of Pd via Pd(0)/Pd(II)
cycle for the hydroarylation, but also utilizes water as the hydride source. We believe, this would particꢀ
ularly be beneficial in utilizing water as a reagent.
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 2 of 30
INTROUDCTION
1
2
3
4
5
6
7
8
9
Diboron compounds have proved to be an efficient mediator of various transformations by undergoing
BꢀB bond cleavage.1,2 The characteristic high oxophilicity of the boron center can facilitate energetically
demanding transformations. With this understanding, we have successfully carried out a homogeneous
palladium catalyzed hydride transfer from water to reduce alkenes and alkynes.3,4 In this direction, we
identified HꢀPdꢀOAc as the crucial catalytic intermediate and was employed to construct CꢀH bonds
(hydrogenation) in a stereodivergent fashion.4 Recognizing the catalytic species’ importance in
generating hydrometallated species, we undertook an investigation to explore its application in the CꢀC
bond formation (Scheme 1).5,6
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. Utilizing Water as the Hydride Source
Oxidative addition to Pd(0) is one of the most studied modes of reactivity in the organopalladium
chemistry.7 Since the discovery of the SuzukiꢀMiyaura coupling, arylboron reagents have been extenꢀ
sively used for crossꢀcoupling reactions using Pd(0) catalysts.7ꢀ9 In this direction, alkyne hydroarylation
2
ACS Paragon Plus Environment

Page 3 of 30
The Journal of Organic Chemistry
was achieved independently by Hayashi and Shirakawa in 2001 using Rhꢀ and Niꢀcatalysts respectiveꢀ
ly.10,11 Oh reported the first example of Pd(0)ꢀcatalyzed alkyne hydroarylation using arylboronic acids12
in the presence of acetic acid. Subsequently, other variations of organoboronic acid addition reactions to
alkynes have also been explored.13ꢀ21 In all these cases, an occurrence of Pd(0)/Pd(II) catalysis was esꢀ
sential.
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
In continuation of our study of diboron reagents,22,23 we hypothesized an alkyne hydroarylation with
organoboronic acids. The mechanistic underpinning of the reactivity of the Pdꢀcatalyst in the B2pin2ꢀ
H2O system served as the basis for the development for the new reaction. Our approach consisted of
probing the reactivity of Pd species with organoboronic acids via Pd(II)/Pd(0) cycle. Herein, we present
a new means to generate reactive alkenylpalladium intermediates comprising hydrogen derived from
water via Pd(II)/Pd(0) catalysis.24,25 As a proof of the concept, we also attempted to explore the scope of
different substrates.
RESULTS AND DISCUSSION
We undertook the optimization studies with diphenylacetylene (1a) and 4ꢀacetylphenylboronic acid (2w)
as model substrates, Pd(OAc)2 as the catalyst, PCy3 as the ligand, B2pin2 as a sacrificial transfer hydroꢀ
genating reagent, and H2O as an hydride source. We were pleased to see the product formation in the
initial set of controls as the reaction in toluene furnished the desired product 3aw in 42% yield along
with the corresponding hydroborylated product 4a in 40% (entry 1). Additional solvent screening conꢀ
trols (entries 2ꢀ6, see SI, Table Sꢀ1 for additional details) indicated THF as the most suitable solvent to
obtain 3aw exclusively (87% yield) and only a trace amount of 4a was observed (entry 6).
3
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 4 of 30
Table 1. Reaction Optimizationa
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
entry
1
B2pin2/ H2O
1.1/5
2w (equiv)
1.1
solvent/t (°C)
toluene/100
3aw%b
(42)
4a%b
(40)
2
1.1/5
1.1
1.1
1.1
1.0
1.0
DME/80
51
22
3
1.1/5
DMEꢀH2O/80
DME/80
14
65
4
1.0/2.5
1.0/2.5
1.0/2
51
22
5
DME/80
70
trace
<1
6c
THF/80
>95(87)
Deviation from the above standard conditions (entry 6)
7
PCy3 omitted
PPh3
no reaction
no reaction
no reaction
no reaction
47
8
9
P(oꢀTol)3
P(tꢀBu)3
10
11
12
13
14
15
16
17
18
B2(OH)4 instead of B2pin2
ꢀ
D2O instead of H2O (77% of 1a recovered)
“Hg drop” (903 mg) (49% of 1a recovered)
B2pin2 omitted (19% of 1a recovered)
B2pin2 (0.1 equiv) (15% of 1a recovered)
B2pin2 (0.2 equiv) (44% of 1a recovered)
B2pin2 (0.5 equiv) (27% of 1a recovered)
B2pin2 (0.9 equiv) (>95% conversion)
12
<5
<5
ꢀ
(40)
(76)
(77)
2
(44)
3
(64)
4
(85)
14
4
ACS Paragon Plus Environment

Page 5 of 30
The Journal of Organic Chemistry
B2pin2 (2.1 equiv) (>95% conversion)
Pd(PPh3)4 instead of Pd(OAc)2/PCy3
19
20
(82)
<5
1
2
3
4
no reaction
5
6
7
8
a Reaction conditions: 1a (0.5 mmol), B2pin2 (0.5 mmol), 2w (0.5 mmol), Pd(OAc)2 (5 mol %), PCy3 (10 mol %), solvent (2
mL), 16 h. b Measured by 1H NMR with terephthalaldehyde as the internal standard, nr = no reaction, nd = not detected. The
numbers in parentheses are isolated yields. c Pd(OAc)2 (1 mol %), PCy3 (2 mol %), 4 h.
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
Further, excluding PCy3 did not result in a reaction (entry 7), suggesting that the ligand is an integral
part of the catalytic system. We also investigated different phosphine ligands viz. PPh3 (triꢀ
arylphosphine), P(oꢀTol)3 (relatively bulky triarylphosphine), and P(tꢀBut)3 (bulky trialkylphosphine)
under the standard conditions (entries 8ꢀ10). In all these cases, the reaction did not occur and the starting
material was intact. Using tetrahydroxydiboron instead of B2pin2 resulted in a low yield of the product
3aw (47%, entry 11).26 When H2O was replaced with D2O, the yield of the product 3aw reduced drastiꢀ
cally to 12% and unreacted 1a was recovered in 77% (entry 12). This observation indicated a possible
breakage of an OꢀD bond of D2O (OꢀH bond in H2O) during the rate determining step.
To verify the homogeneity of the catalytic system, we performed a “mercury drop” test to rule out the
possible heterogeneous Pd nanoparticles as the active catalytic system (entry 13).26,27 The result did not
show inhibition of the reaction. This and the ligand exclusion result (entry 7) together indicated that the
present catalytic system is indeed homogeneous.
Next, varying amounts of B2pin2 was employed to understand its role in the reaction (entries 14ꢀ19).
Interestingly, the control studies revealed the existence of an alternate Pd(0)/Pd(II) mechanism in the
absence of B2pin2.12 With no diboron included, the reaction yielded 76% of the product and 19% of 1a
was recovered (entry 14). Prior studies12,13 related to this have observed that the presence of acid
additive is crucial for the completion of the reaction, especially when additional substrates were
explored. As the loading of diboron reagent was increased gradually to 0.5 equiv, the yield of the
product decreased and the quantity of unreacted 1a increased. However, when the loading of diboron
5
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 6 of 30
reagent was further increased (entries 18, 6 and 19), the yield of 3aw also increased accordingly. An
exclusive formation of the product was observed when the diboron reagent was used in 1 or more equiv.
These observations suggest a probable shift in the product formation routes.
1
2
3
4
5
6
7
8
9
We also tested a Pd(0) catalyst i.e. Pd(PPh3)4 (Table 1, entry 20) instead of the standard catalytic sysꢀ
tem (entry 6) to check its catalytic activity.12 However, here 1a did not undergo any observable reaction
and was found to be intact.
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
We then turned our attention to identify possible intermediates in the reaction mixture. During the
optimization study, 4a was observed in varying amounts (Table 1). This suggested two possibilities:
either 4a is an intermediate leading to the desired product 3aw, or 4a is a side product formed during the
reaction.
To verify if 4a was indeed the intermediate, following two controls were performed (Scheme 2). First,
4a was obtained as a crude mixture under PdꢀPPh3 conditions (Scheme 2A). This crude mixture, after
filtration and concentration, was subjected to the standard hydroarylation conditions. Here, no trace of
the desired product was observed and only quantitative amount of 4a was remaining (77%). In the seꢀ
cond control, 4a was directly subjected to standard reaction conditions (Scheme 2B). Here also, a trace
amount of 3aw was observed. These controls clearly confirmed that 4a is not the intermediate leading to
3aw.
6
ACS Paragon Plus Environment

Page 7 of 30
The Journal of Organic Chemistry
Scheme 2. Determining the Intermediate
1
2
3
A) Two-step Process
4
5
6
7
8
9
Ph
Pd(OAc)2 (5 mol %)
PPh3 (10 mol %)
Pd(OAc)2 (1 mol %)
PCy3 (2 mol %)
H
3aw
nd
Bpin
Ph
B2pin2 (0.6 mmol)
H2O (2.5 mmol)
toluene, rt, 14h
>95% conversion
2w (0.5 mmol)
H2O (1 mmol)
THF, 80 oC, 4h
Ph
Ph
1a
0.5 mmol
4a
crude mixture
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
4a: 71% remaining
B) Probing the Possible Hydroborylated Intermediate
Ac
Ac
Pd(OAc)2 (1 mol %)
H
H
PCy3 (2 mol %)
Bpin
+
Ph
Ph
H2O (1 mmol)
THF, 80 oC, 4h
30% conversion
Ph
Ph
3aw
B(OH)2
2w
0.5 mmol
4a
0.5 mmol
<5%
With the optimized conditions established and a preliminary understanding of the reaction route, we
examined the scope of the hydroarylation reaction (Scheme 3) employing a variety of arylboronic acids
(2aꢀ2z) and phenylacetylene 1a. Phenylboronic acid (2a) provided an excellent yield of the desired
product 3aa (90%). The reaction of aryl boronic acids bearing alkyl substitution on both orthoꢀ and pa-
raꢀpositions of the aryl moiety resulted in the formation of desired products in excellent yields (3abꢀ
3ad, yields 81ꢀ93%). A bulky 1ꢀnaphthylboronic acid also reacted well to give 3ae in 80% yield. To test
the effect of electron donating groups on the reaction, substrates containing –OEt and –OMe groups,
both on orthoꢀ and paraꢀpositions, were tested (2fꢀ2i). Pleasingly, these substrates resulted in the facile
formation of the desired products in good to excellent yields (3afꢀ3ai, 70ꢀ84% yields). Nitrile functionꢀ
ality on the aromatic system was well tolerated and furnished the products 3aj and 3ak in 87 and 65%
yields, respectively. Halogenꢀcontaining phenylboronic acids (2lꢀ2t) underwent a facile hydroarylation
(81ꢀ97% yields) showing that this method is highly chemoselective that can lead to functionalization of
olefins with the potential of lateꢀstage functionalization. The electronꢀwithdrawing ꢀCF3 group did not
affect the reaction yields of the desired products 3ar, 3as, and 3at which were obtained in 92, 95 and
7
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 8 of 30
97% yields, respectively. We also tested the substrate containing a free –OH group (2u) and were
pleased to see the product in good yield (3au, 70%). Carbonyl groups such as aldehyde, ketone, and esꢀ
ter on the substrates also furnished the products 3av, 3aw, and 3ax in 76, 87, and 60% yields, respecꢀ
tively (4a was detected in <10% which was lost during the column purification). Here, these groups
were stable under the given conditions and did not lead to any side products, making the reaction
chemoselective as well as a practical method.
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
8
ACS Paragon Plus Environment

Page 9 of 30
1
The Journal of Organic Chemistry
Scheme 3. Substrate Scope of the Arylboronic Acidsa
2
3
4
5
6
7
8
Pd(OAc)2 (1 mol %)
PCy3 (2 mol%)
H
Ph
R2
+
R2B(OH)2
Ph
B2pin2 (0.5 mmol)
H2O (1 mmol)
THF, 80 oC
Ph
Ph
3
1a
0.5 mmol
2
NMR yieldb (isolated yield)
0.5 mmol
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
Me
iPr
H
H
H
H
H
Ph
Ph
Ph
Ph
Ph
Ph
Ph Me
3acc
Ph
3abc
Ph
Ph
3aec
3aac
3add
>95% (90%)
>95% (93%)
90% (85%)
90% (81%)
(80%)
OEt
OMe
OMe
CN
H
H
H
H
H
Ph
Ph
Ph
Ph
Ph
Ph OEt
Ph OMe
Ph
3af
85% (77%)
Ph
3ag
Ph
3ahc
3aic
3ajc
75% (70%)
85% (75%)
90% (84%)
>95% (87%)
H
OCF3
F
H
H
H
H
Ph
Ph
Ph
F
Ph
Ph
Ph CN
3ake
Ph
F
Ph
Ph
Ph
3al
3am
3anc
3aoc
>95% (88%)
95% (89%)
68% (65%)
90% (81%)
>95% (93%)
F
Cl
CF3
F
H
H
H
H
H
Ph
CF3
Ph
Ph
Ph
CF3
Ph
F
Ph
3asf
>95% (97%)
Ph
Ph
3arf
Ph
3at
Ph
3apc
3aq
90% (80%)
>95% (92%)
>95% (92%)
92% (87%)
HO
CHO
COMe
CO2Me
H
H
H
H
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
3au
3av
87% (76%)
3aw
3ax
70% (60%)
74% (70%)
>95% (87%)
Reaction conditions: 1a (0.5 mmol), 2 (0.5 mmol), THF (2 mL), 4h. b 1H NMR yield is measured using terephthalaldehyde as
the internal standard. Numbers in parentheses are isolated yields. c 1h. d 2h. e 12 h. f 30 min.
9
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 10 of 30
Additionally, the scope of the alkynes was also studied (1b-1f) (Scheme 4). To begin with, a heterocyꢀ
clic system (1b) was tried and we were pleased to see an excellent yield of the product (3ba, 85%). On
the other hand, a terminal alkyne such as phenylacetylene (1c) provided the desired product as one regiꢀ
oisomer (3ca, 65%). This indicated a preferential addition of phenylboronic acid derived phenyl group
on to the activated alphaꢀcarbon. When other unsymmetrical internal alkynes (1dꢀ1f) were used, the reꢀ
gioselectivity was poor due to insufficient electronic control by the alkyne substrate necessary for the
regioselectivity. However, the results did show a promise that the method can be stabilized to obtain one
unconventional regioisomer (such as 3ea and 3fa, wherein conventional methods lead to alphaꢀ
functionalized products).6,13 We are at present pursuing the possibility of obtaining exclusive formation
of the unconventional regioisomer in the unsymmetrical alkynes. Further, when sterically differentiated
alkyne viz. trimethyl(phenylethynyl)silane was tested, it underwent a facile hydroarylation to provide
predominantly single regioisomer (3ga, 77%, regiomeric ratio α:β=97:3) with trace (<5%) amount of
unreacted starting alkyne. Hence, both steric and electronic factors decided the regioselectivity in the
present reaction. We also explored different unsymmetrical alkynes comprising a heterocyclic system
(1h), nitrile functionality (1i), electron donating –OMe group (1j) and electron withdrawing –NO2 group
(1k). 1h and 1j reacted well to give the corresponding products 3ha and 3ja in excellent yields of 80
and 85% yields, respectively. However, 1k resulted in poor yield of the product 3ka (26%). Surprisingꢀ
ly, presence of nitrile functionality (1i) did not result in any product formation (3ia) and quantitative
amount of starting material was recovered along with diboron impurities. Nonetheless, regioselectivity
observed here was also found to be poor. In all the cases, the corresponding transꢀaddition products were
found to be less than 3%.
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
Overall, the hydroarylation process not only shows tolerance towards a wide variety of groups to
achieve an extensive substrate scope but also proves that the catalytic system envisaged from our end
can be suitably used to develop many new reactions.
10
ACS Paragon Plus Environment

Page 11 of 30
The Journal of Organic Chemistry
Scheme 4. Substrate Scope of the Akynesa
1
2
3
4
5
6
7
Pd(OAc)2 (1 mol %)
PCy3 (2 mol%)
H
R1
Ph
+
Ph-B(OH)2
R1
R2
B2pin2 (0.5 mmol)
H2O (1 mmol)
THF, 80 oC
R2
3
1
2a
0.5 mmol
NMR yieldb (isolated yield)
0.5 mmol
8
9
H
Ph
H
Ph
S
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
Ph
H
Ph
H
Ph
Ph
S
Ph
3ba
3ca
75% (65%)
3da
(84%)
48:52
95% (85%)
Ph
H
Ph
H
H
Ph
H
Ph
OH
Ph
CO2Et
H
Ph
Ph
Ph
Ph
Ph
CO2Et
SiMe3
OH
3ea
(94%)
71:29
3fa
(43%)
69:31
3gac
(77%)
H
Ph
H
Ph
Ph
H
Ph
H
Ph
Ph
S
Ph
S
Ph
NC
NC
3ha
3ia
nd
(80%)
71:29
H
Ph
H
Ph
Ph
H
Ph
H
Ph
Ph
Ph
Ph
MeO
MeO
O2N
O2N
3kad
3ja
(85%)
50:50
(26%)
76:24
Reaction conditions: 1 (0.5 mmol), 2a (0.5 mmol), THF (2 mL), 4h. b 1H NMR yield is measured using terephthalaldehyde as
c
d
the internal standard. Numbers in parentheses are isolated yields. Pd(OAc)2 (2 mol %), PCy3 (4 mol %), 12 h. 0.15 mmol
scale, 2 mol % Pd (OAc)2, 4 mol % PCy3, THF (0.5 mL).
Proceeding further, we decided to probe the catalytic system (Scheme 5). Our hypothesis presented the
formation of a catalytic Pd(0)L2 species at the end of the catalytic cycle. Hence, commercially procured
11
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 12 of 30
Pd(0)(PCy3)2 was tested to determine if it was indeed the active catalytic system for the present transꢀ
formation (Scheme 3). Here, we were not able to reproduce the standard reaction outcome and the startꢀ
ing alkyne 1a underwent incomplete conversion. Next, an additional amount of catalytic AcOH was inꢀ
cluded along with Pd(0)(PCy3)2. Here, complete conversion of 1a was observed and the result was in
agreement with the standard reaction outcome. This observation suggested the formation of Hꢀ
[Pd(II)(PCy3)2]ꢀOAc as being the crucial catalytic intermediate.28,29
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
12
ACS Paragon Plus Environment

Page 13 of 30
The Journal of Organic Chemistry
Scheme 5. Understanding the Mechanism
1
2
3
A) Determining the Active Catalyst
4
5
6
7
8
9
Ac
Ph
Ac
H
H
Pd(PCy3)2 (1 mol %)
Bpin
+
Ph
B2pin2 (0.5 mmol)
H2O (1 mmol)
THF, 80 oC, 4h
Ph
Ph
Ph
Ph
3aw
B(OH)2
2w
0.5 mmol 0.5 mmol
1a
4a
trace
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
46% conversion
(42%)
Ac
Ac
Pd(PCy3)2 (1 mol %)
AcOH (20 mol %)
H
Ph
H
Bpin
+
Ph
Ph
B2pin2 (0.5 mmol)
H2O (1 mmol)
THF, 80 oC, 4h
Ph
Ph
Ph
B(OH)2
3aw
1a
2w
4a
26%
NMR yield = 69%
Isolated yield = (62%)
>95% conversion
0.5 mmol 0.5 mmol
Ac
Ac
Pd(PCy3)2 (1 mol %)
AcOH (2 mol %)
H
Ph
H
Bpin
+
Ph
Ph
B2pin2 (0.5 mmol)
H2O (1 mmol)
THF, 80 oC, 4h
Ph
4a
Ph
Ph
B(OH)2
1a
2w
3aw
83%
90% conversion
0.5 mmol 0.5 mmol
trace
Ac
Ac
Pd(PCy3)2 (1 mol %)
AcOH (2 mol %)
H
Ph
H
Bpin
+
Ph
Ph
H2O (1 mmol)
THF, 80 oC, 4h
70% conversion
Ph
Ph
Ph
B(OH)2
1a
2w
3aw
66%
4a
0.5 mmol 0.5 mmol
trace
B) Probing Palladium's C-B Oxidative Addition Capability
Ac
Ac
Ac
Pd(OAc)2 (1 mol %)
PCy3 (2 mol %)
B2pin2 (0.5 mmol)
H2O (1 mmol)
O
B
O
B
Ac
THF, 80 oC, 4h
HO
OH
2w
0.5 mmol
2ww
nd
2w'
76%
>95% conversion
13
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 14 of 30
Pd(0)ꢀcatalysts are known to oxidatively insert between CꢀB bond.7 Hence, in order to uncover the
reactivity of Pd in our system, we performed a control experiment under standard conditions but with 1a
omitted. Here, the formation of homocoupled biaryl product (2ww) from 2w would suggest the
oxidative addition of CꢀB bond to Pd(0) is possible in the present system.7b However, we did not
observe 2ww in the reaction mixture, instead only the corresponding transesterified boronate ester (2w’)
was observed in 76% yield. This control ruled out the possibility of oxidative addition in the reaction.
This also suggested that the arylboronic acid may be converted to corresponding arylbornate ester
before undergoing the transmetallation with Pd(II).
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
Hence, considering our experimental observations and the literature precedence,6,7,28 we propose a
plausible mechanism (Scheme 6). The first step is the coordination of the ligands to the Pd(OAc)2 center
to obtain Pd(II)(PCy3)2(OAc)2. Pd(PCy3)2 is here afterwards represented as [Pd] for simplicity.
[Pd](OAc)2 species can now undergo transmetallation with B2pin2 to generate pinBꢀ[Pd]ꢀOAc species
with the elimination of AcOꢀBpin. In the presence of water, pinBꢀ[Pd]ꢀOAc can undergo σꢀbond
metathesis to furnish Hꢀ[Pd]ꢀOAc catalytic species. Above mentioned steps constitute an efficient
transfer of a hydride from water to the metalꢀcenter. Now Hꢀ[Pd]ꢀOAc can undergo hydropalladation
with an alkyne (1) followed by transmetallation with organoboronic acids (2, R1B(OR2)2). A reductive
elimination of this hydropalladated intermediate can now lead to the hydroarylated product (3).
Oxidative addition of AcOH generated during the reaction can now undergo oxidative addition to
[Pd](0) species,[12,28] which leads to the active Pd(II) species for the continuation of the catalytic cycle.
14
ACS Paragon Plus Environment

Page 15 of 30
The Journal of Organic Chemistry
Scheme 6. Plausible Mechanism
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
CONCLUSION
In summary, we have utilized water as a hydride source via Pd(II)/Pd(0) catalysis. As a proof of concept,
we have developed a simple yet effective hydroarylation method to obtain functionalized olefins. The
method, accomplished under externally added acidꢀfree conditions, would particularly be useful in the
late stage functionalization of natural products/biomolecules. To conclude, we believe our approach of
utilizing water for molecular construction holds promise from a mechanistic standpoint.
EXPERIMENTAL SECTION
General Information: All chemicals were purchased from commercial suppliers and used as delivꢀ
ered. Pd(OAc)2 (product number: 10516) has been obtained from Alfa Aesar. Tricyclohexylphosphine
(product number: 261971) was procured from Sigma Aldrich. THF (Finar AR dry grade) was used diꢀ
1
13
rectly for all the procedures. H NMR and C NMR spectra were recorded at 400 MHz and 100 MHz,
15
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 16 of 30
respectively. Chemical shifts are reported in parts per million (ppm) and coupling constants in Hertz
(Hz). Tetramethylsilane (TMS) (δ = 0.00 ppm) or residual CHCl3 in CDCl3 (δ = 7.26 ppm) served as inꢀ
1
2
3
4
5
1
ternal standard for recording. H NMR and the residual nonꢀdeuterated solvent signal of CDCl3 (δ =
6
7
8
13
77.16 ppm) was used as internal standard for C NMR (proton decoupled).1,2 IR spectra were recorded
9
using Perkin Elmer FTꢀIR instrument; Mass spectra (EI) were recorded using Shimadzu; and Highꢀ
resolution mass spectra (HRMS) were recorded on QꢀTOF (Micromass) spectrometer. Melting points of
the product were determined on Buchi melting point apparatus. Flash column chromatography was carꢀ
ried out using commercially obtained silica gel and thinꢀlayer chromatography (TLC) was performed
using Merck silica gel 60 F254 TLC plates.
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 for the Hydroarylation of Alkynes Using Arylboronic Acids:
To a preꢀdried 10 mL screw cap equipped reaction vial, water (1 mmol, 18 mg), alkyne (1, 0.5 mmol),
B2Pin2 (0.5 mmol, 127 mg), arylboronic acid (2, 0.5 mmol), PCy3 (2 mol %, 2.8 mg) and Pd(OAc)2 (1
mol %, 1.1 mg) were added, dissolved in dry THF (2 mL) and the reaction mixture was heated at 80 °C
in a preꢀheated metal block for 30 min to 12h with continuous stirring. After the completion of the reacꢀ
tion, the reaction mixture was filtered using a short column using diethyl ether. The filtrate was distilled
under reduced pressure and the crude mixture was dissolved in sufficient amount of CDCl3. To this,
0.125 mmol terephthalaldehyde as the internal standard was added, dissolved and submitted for NMR
analysis. The crude mixture was then purified by column chromatography to afford the hydroarylated
yield.
Characterization Data for Products.
3aa: Ethene-1,1,2-triyltribenzene.15 General procedure was followed for 1h; yellow oily liquid; yield
90% (115 mg); Rf (petroleum ether) 0.9; IR (neat, cmꢀ1) νmax 3023, 1492; 1H NMR (CDCl3, 400 MHz) δ
7.33 – 7.25 (m, 8H), 7.21 – 7.18 (m, 2H), 7.13 – 7.06 (m, 3H), 7.05 – 7.01 (m, 2H), 6.96 (s, 1H);
16
ACS Paragon Plus Environment

Page 17 of 30
The Journal of Organic Chemistry
13C{1H} NMR (CDCl3, 100 MHz) δ 143.5, 142.7, 140.5, 137.5, 130.5, 129.7, 128.8, 128.3, 128.3,
128.1, 127.7, 127.6, 127.5, 126.9.
1
2
3
4
5
6
3ab: (E)-(1-(p-Tolyl)ethene-1,2-diyl)dibenzene.15 General procedure was followed for 1h; white solid;
7
8
9
1
yield 93% (126 mg); Rf (petroleum ether) 0.8; mp 76 – 78 °C; IR (neat, cmꢀ1) νmax 1509; H NMR
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
(CDCl3, 400 MHz) δ 7.32 – 7.29 (m, 3H), 7.22 – 7.18 (m, 4H), 7.13 – 7.07 (m, 5H), 7.02 – 7.00 (m,
13
2H), 6.93 (s, 1H), 2.34 (s, 3H); C{1H} NMR (CDCl3, 100 MHz) δ 142.6, 140.7, 140.6, 137.6, 137.5,
130.5, 129.6, 129.1, 128.7, 128.1, 127.6, 127.5, 126.7, 21.1.
3ac: (E)-(1-(o-Tolyl)ethene-1,2-diyl)dibenzene.15 General procedure was followed for 1h; yellow liquid;
1
yield 85% (115 mg); Rf (petroleum ether) 0.8; IR (neat, cmꢀ1) νmax 2362, 1446; H NMR (CDCl3, 400
MHz) δ 7.29 – 7.27 (m, 1H), 7.22 – 7.19 (m, 5H), 7.17 – 7.12 (m, 8H), 6.61 (s, 1H), 2.11 (s, 3H);
13C{1H} NMR (CDCl3, 100 MHz) δ 144.1, 143.1, 140.4, 137.5, 136.4, 130.6, 130.3, 130.2, 130.0,
129.6, 128.3, 128.1, 127.6, 127.2, 126.9, 125.8, 20.7.
3ad: (E)-(1-(4-Isopropylphenyl)ethene-1,2-diyl)dibenzene.15 General procedure was followed for 2h;
colorless liquid; yield 81% (121 mg); Rf (petroleum ether) 0.8; IR (neat, cmꢀ1) νmax 3022, 2960, 1505;
1H NMR (CDCl3, 400 MHz) δ 7.33 – 7.29 (m, 3H), 7.25 (d, J = 8 Hz, 2H), 7.21 – 7.19 (m, 2H), 7.16 (d,
J = 8 Hz, 2H), 7.12 – 7.06 (m, 3H), 7.00 (d, J = 6.8 Hz, 2H), 6.95 (s, 1H), 2.89 (m, J = 6.8 Hz, 1H), 1.25
(d, J = 7.2 Hz, 6H); 13C{1H} NMR (CDCl3, 100 MHz) δ 148.5, 142.6, 141.0, 140.6, 137.6, 130.5, 129.6,
128.7, 128.1, 127.61, 127.56, 127.45, 126.7, 126.4, 33.9, 24.1. HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd
for C23H22Na 321.1619; Found 321.1617.
3ae: (E)-1-(1,2-Diphenylvinyl)naphthalene.14 General procedure was followed for 1h; orange liquid;
1
yield 80% (123 mg); Rf (petroleum ether) 0.7; IR (neat, cmꢀ1) νmax 3053, 1494; H NMR (CDCl3, 400
MHz) δ 8.10 (d, J = 8.4 Hz, 1H), 7.83 – 7.78 (m, 2H), 7.45 – 7.18 (m, 15H), 6.79 (s, 1H); 13C{1H}
17
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 18 of 30
NMR (CDCl3, 100 MHz) δ 142.3, 141.5, 141.1, 137.5, 134.1, 132.0, 131.7, 129.9, 129.6, 128.5, 128.4,
128.2, 128.0, 127.5, 127.4, 127.1, 126.3, 126.1, 125.8, 125.4.
1
2
3
4
5
6
3af: (E)-(1-(4-Ethoxyphenyl)ethene-1,2-diyl)dibenzene. General procedure was followed; yellow solid;
7
8
9
yield 77% (116 mg); Rf (10% EtOAc – petroleum ether) 0.9; mp 93 – 95 °C; IR (neat, cmꢀ1) νmax 3446,
1
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
2979, 1508; H NMR (CDCl3, 400 MHz) δ 7.32 – 7.27 (m, 3H), 7.23 – 7.17 (m, 4H), 7.09 – 7.03 (m,
3H), 6.98 (d, J = 7.2 Hz, 2H), 6.87 (s, 1H), 6.81 – 6.79 (m, 2H), 3.97 (q, J = 7.2 Hz, 2H), 1.37 (t, J = 6.8
Hz, 3H); 13C{1H} NMR (CDCl3, 100 MHz) δ 158.7, 142.2, 140.7 137.7, 135.9, 131.7, 130.5, 129.5,
128.8, 128.7, 128.0, 127.4, 126.5, 114.2, 63.5, 14.9; HRMS (ESIꢀTOF) m/z: [M + H]+ Calcd for
C22H20OH 301.1592; Found 301.1591.
3ag: (E)-(1-(3,4-Dimethoxyphenyl)ethene-1,2-diyl)dibenzene. General procedure was followed; white
solid; yield 70% (111 mg); Rf (10% EtOAc – petroleum ether) 0.5; mp 120 – 122 °C; IR (neat, cmꢀ1)
1
ν
max 3434, 2362, 1512; H NMR (CDCl3, 400 MHz) δ 7.34 – 7.31 (m, 3H), 7.22 – 7.20 (m, 2H), 7.13 –
7.06 (m, 3H), 7.01 (d, J = 6.8 Hz, 2H), 6.90 (s, 2H), 6.84 – 6.78 (m, 2H), 3.88 (s, 3H), 3.82 (s, 3H);
13C{1H} NMR (CDCl3, 100 MHz) δ 148.9, 148.8, 142.5, 140.5, 137.6, 136.6, 130.6, 129.6, 128.7,
128.1, 127.5, 126.9, 126.7, 120.7, 110.9, 56.1, 56.0; HRMS (ESIꢀTOF) m/z: [M + H]+ Calcd for
C22H21O2H 317.1542; Found 317.1538.
3ah: (E)-(1-(2-Ethoxyphenyl)ethene-1,2-diyl)dibenzene. General procedure was followed for 1h; yellow
liquid; yield 75% (113 mg); Rf (10% EtOAc – petroleum ether) 0.8; IR (neat, cmꢀ1) νmax 3398, 1445; 1H
NMR (CDCl3, 400 MHz) δ 7.33 (dd , J = 7.2 Hz, J = 1.6 Hz, 1H), 7.26 – 7.21 (m, 1H), 7.19 – 7.16 (m,
5H), 7.14 – 7.06 (m, 5H), 6.96 – 6.91 (m, 1H), 6.80 (d, J = 8 Hz, 1H), 6.77 (s, 1H), 3.74 (q, J = 7.2 Hz,
13
2H), 0.95 (t, J = 7.2 Hz, 3H); C{1H} NMR (CDCl3, 100 MHz) δ 156.8, 141.3, 141.3, 137.7, 133.8,
131.2, 129.9, 129.7, 129.7, 129.0, 127.96, 127.94, 126.8, 126.7, 120.6, 112.7, 64.0, 14.5. HRMS (ESIꢀ
TOF) m/z: [M + H]+ Calcd for C22H20OH 301.1592; Found 301.1591.
18
ACS Paragon Plus Environment

Page 19 of 30
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
3ai: (E)-(1-(2-Methoxyphenyl)ethene-1,2-diyl)dibenzene. General procedure was followed for 1h; light
yellow solid; yield: 84% (120 mg); Rf (10% EtOAc – petroleum ether) 0.7; mp 79 – 81 °C; IR (neat, cmꢀ
1) νmax 3022, 1250; 1H NMR (CDCl3, 400 MHz) δ 7.29 – 7.24 (m, 2H), 7.21 – 7.17 (m, 5H), 7.13 – 7.05
(m, 5H), 6.96 – 6.92 (m, 1H), 6.86 (d, J = 8.4 Hz, 1H), 6.79 (s, 1H), 3.58 (s, 3H); 13C{1H} NMR
(CDCl3, 100 MHz) δ 157.4, 141.2, 140.5, 137.6, 133.8, 131.2, 130.3, 129.7, 129.6, 128.9, 128.1, 128.0,
126.9, 126.7, 120.7, 111.9, 55.8; HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd for C21H18ONa 309.1255;
Found 309.1252.
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
3aj: (E)-4-(1,2-Diphenylvinyl)benzonitrile. General procedure was followed for 1h; white solid; yield
87% (122 mg); Rf (10% EtOAc – petroleum ether) 0.6; mp 117 – 119 °C; IR (neat, cmꢀ1) νmax 2924,
1
2361, 1598; H NMR (CDCl3, 400 MHz) δ 7.58 (d, J = 8.4 Hz, 2H), 7.40 (d, J = 8.4 Hz, 2H), 7.36 –
7.35 (m, 3H), 7.18 – 7.13 (m, 5H), 7.05 – 7.02 (m, 3H); 13C{1H} NMR (CDCl3, 100 MHz) δ 147.9,
141.0, 139.3, 136.6, 132.1, 131.0, 130.3, 129.8, 129.1, 128.2, 128.1, 128.1, 127.7, 119.1, 110.8; HRMS
(ESIꢀTOF) m/z: [M + Na]+ Calcd for C21H15NNa 304.1102; Found 304.1103.
3ak: (E)-2-(1,2-Diphenylvinyl)benzonitrile. General procedure was followed for 12h; white solid; yield
65% (74 mg); Rf (10% EtOAc – petroleum ether) 0.5; mp 76 – 78 °C; IR (neat, cmꢀ1) νmax 3057, 2362;
1H NMR (CDCl3, 400 MHz) δ 7.69 (dd, J = 7.6 Hz, J = 0.8 Hz, 1H), 7.38 – 7.33 (m, 1H), 7.30 – 7.28
13
(m, 4H), 7.20 – 7.11 (m, 7H), 6.92 (s, 1H); C{1H} NMR (CDCl3, 100 MHz) δ 147.9, 139.3, 139.3,
136.4, 133.8, 133.3, 132.4, 130.5, 130.4, 129.8, 128.7, 128.2, 128.0, 127.7, 127.7, 118.5, 111.8; HRMS
(ESIꢀTOF) m/z: [M + Na]+ Calcd for C21H15NNa 304.1102; Found 304.1100.
3al: (E)-(1-(4-(Trifluoromethoxy)phenyl)ethene-1,2-diyl)dibenzene.15 General procedure was followed;
yellow liquid; Isolated yield 88% (150 mg); Rf (5% EtOAc – petroleum ether) 0.8; IR νmax (neat, cmꢀ1)
3056, 2362, 1260; 1H NMR (CDCl3, 400 MHz) δ 7.34 – 7.32 (m, 5H), 7.21 – 7.17 (m, 2H), 7.15 – 7.10
19
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 20 of 30
(m, 5H), 7.03 – 7.01 (m, 2H), 6.94 (s, 1H); C{1H} NMR (CDCl3, 100 MHz) δ 148.7 (d, J = 1.8 Hz),
142.3, 141.4, 140.1, 137.2, 132.1, 130.5, 129.7, 129.0, 128.9, 128.2, 127.8, 127.2, 120.8, 120.7 (q, J =
255.5 Hz).
13
1
2
3
4
5
6
7
8
9
3am: (E)-(1-(4-Fluorophenyl)ethene-1,2-diyl)dibenzene.15 General procedure was followed; white solꢀ
id; yield 89% (122 mg); mp 67 – 69 °C; Rf (5% EtOAc – petroleum ether) 0.9; IR (neat, cmꢀ1) νmax
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
3054, 1504; H NMR (CDCl3, 400 MHz) δ 7.33 – 7.26 (m, 5H), 7.19 – 7.17 (m, 2H), 7.15 – 7.09 (m,
3H), 7.02 – 6.97 (m, 4H), 6.89 (s, 1H); C{1H} NMR (CDCl3, 100 MHz) δ 162.5 (d, J = 245.6 Hz),
13
141.7, 140.3, 139.7 (d, J = 3.2 Hz), 137.4, 130.5, 129.7, 129.3 (d, J = 8 Hz), 128.8, 128.1, 127.7, 126.9,
115.2 (d, J = 21.3 Hz).
3an: (E)-(1-(2-Fluorophenyl)ethene-1,2-diyl)dibenzene.32a General procedure was followed for 1h; yelꢀ
low liquid; yield 81% (111 mg); Rf (5% EtOAc – petroleum ether) 0.9; IR (neat, cmꢀ1) νmax 3024, 1488;
1H NMR (CDCl3, 400 MHz) δ 7.26 – 7.18 (m, 7H), 7.13 – 7.00 (m, 7H), 6.88 (s, 1H); C{1H} NMR
13
(CDCl3, 100 MHz) δ 160.5 (d, J = 247.4, Hz), 140.3, 137.2 (d, J = 17.1 Hz), 131.8 (d, J = 3.8 Hz), 131.4
(d, J = 3.2 Hz), 129.9, 129.7, 129.1 (d, J = 8.3 Hz), 128.6, 128.1, 127.5, 127.1, 124.0 (d, J = 3.6 Hz),
116.1 (d, J = 22.5 Hz).
3ao: (E)-(1-(3-Fluorophenyl)ethene-1,2-diyl)dibenzene.32b General procedure was followed for 1h;
white solid; yield 93% (127 mg); mp 76 – 78 °C; Rf (5% EtOAc – petroleum ether) 0.9; IR (neat, cmꢀ1)
1
νmax 3024, 1579; H NMR (CDCl3, 400 MHz) δ 7.34 – 7.30 (m, 3H), 7.25 – 7.21 (m, 1H), 7.20 – 7.17
(m, 2H), 7.14 – 7.09 (m, 4H), 7.02 – 6.99 (m, 3H), 6.97 – 6.93 (m, 2H); 13C{1H} NMR (CDCl3, 100
MHz) δ 163.0 (d, J = 243.7 Hz), 145.9 (d, J = 7.3 Hz), 141.6 (d, J = 2.1 Hz), 140.0, 137.1, 130.4, 129.8,
129.7 (d, J = 8.3 Hz), 129.2, 128.9, 128.1, 127.8, 127.2, 123.3 (d, J = 2.5 Hz), 114.5 (d, J = 22.0 Hz),
114.4 (d, J = 21.2 Hz).
20
ACS Paragon Plus Environment

Page 21 of 30
The Journal of Organic Chemistry
3ap: (E)-(1-(3,5-Difluorophenyl)ethene-1,2-diyl)dibenzene.15 General procedure was followed for 1h;
1
2
3
light yellow solid; yield 92% (135 mg); mp 69 – 71 °C; Rf (5% EtOAc – petroleum ether) 0.9; IR (neat,
4
5
1
cmꢀ1) νmax 3400, 2361, 1618; H NMR (CDCl3, 400 MHz) δ 7.34 – 7.33 (m, 3H), 7.18 – 7.11 (m, 5H),
6
7
8
13
7.02 – 6.99 (m, 2H), 6.98 (s, 1H), 6.84 – 6.82 (m, 2H), 6.73 – 6.67 (m, 1H); C{1H} NMR (CDCl3, 100
9
MHz) δ 163.0 (dd, J = 246.1, 13.1 Hz), 146.9 (t, J = 9 Hz), 140.6 (t, J = 2.3 Hz), 139.3, 136.7, 130.4,
130.0, 129.9, 129.1, 128.2, 128.0, 127.5, 110.4 (dd¸ J = 18.6, 6.8 Hz), 102.8 (t, J = 25.5 Hz).
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
3aq: (E)-(1-(4-Chlorophenyl)ethene-1,2-diyl)dibenzene.15 General procedure was followed; yellow liqꢀ
1
uid; yield 80% (116 mg); Rf (petroleum ether) 0.8; IR (neat, cmꢀ1) νmax 3445, 1644; H NMR (CDCl3,
400 MHz) δ 7.32 – 7.30 (m, 3H), 7.24 – 7.21 (m, 4H), 7.20 – 7.13 (m, 2H), 7.12 – 7.09 (m, 3H), 7.02 –
7.00 (m, 2H), 6.92 (s, 1H); 13C{1H} NMR (CDCl3, 100 MHz) δ 142.02, 141.52, 140.01, 137.17, 133.45,
130.43, 129.67, 128.98, 128.88, 128.61, 128.47, 128.13, 127.75, 127.08.
3ar: (E)-(1-(4-(Trifluoromethyl)phenyl)ethene-1,2-diyl)dibenzene.15 General procedure was followed
for 30 min; yellow liquid; yield 87% (141 mg); Rf (petroleum ether) 0.8; IR (neat, cmꢀ1) νmax 3057,
1324; 1H NMR (CDCl3, 400 MHz) δ 7.54 (d, J = 8 Hz, 2H), 7.41 (d, J = 8 Hz, 2H), 7.34 – 7.31 (m, 3H),
7.21 – 7.12 (m, 5H), 7.05 – 7.02 (m, 2H), 7.01 (s, 1H); 13C{1H} NMR (CDCl3, 100 MHz) δ 147.1,
141.5, 139.8, 136.9, 131.1, 130.4, 130.2, 129.8, 129.0, 128.2, 128.2 (q, J = 22.0 Hz), 127.9, 127.4, 125.3
(q, J = 3.6 Hz), 124.4 (q, J = 270.1 Hz).
3as: (E)-(1-(3-(Trifluoromethyl)phenyl)ethene-1,2-diyl)dibenzene.32c General procedure was followed
for 30 min; white solid; yield 97% (157 mg); mp 72 – 74 °C; Rf (petroleum ether) 0.9; IR (neat, cmꢀ1)
1
νmax 3060, 1329; H NMR (CDCl3, 400 MHz) δ 7.62 (s, 1H), 7.52 (d, J = 7.2 Hz, 1H), 7.45 – 7.37 (m,
2H), 7.34 – 7.32 (m, 3H), 7.21 – 7.17 (m, 2H), 7.13 – 7.12 (m, 3H), 7.05 – 7.03 (m, 2H), 6.98 (s, 1H);
13C{1H} NMR (CDCl3, 100 MHz) δ 144.4, 141.5, 139.7, 137.0, 131.1, 130.5, 130.9 (q, J = 31.9 Hz),
21
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 22 of 30
129.81, 129.78, 129.0, 128.8, 128.2, 128.0, 127.4, 124.4 (q, J = 270.7 Hz), 124.3 (m, J = 3.9 Hz), 124.0
1
2
3
(q, J = 4.0 Hz) .
4
5
6
3at: (E)-(1-(4-Fluoro-3-(trifluoromethyl)phenyl)ethene-1,2-diyl)dibenzene.15 General procedure was
7
8
9
followed; yellow liquid; yield 92% (157 mg); Rf (5% EtOAc – petroleum ether) 0.8; IR (neat, cmꢀ1) νmax
1
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
1502, 1136; H NMR (CDCl3, 400 MHz) δ 7.59 (d, J = 6.8 Hz, 1H), 7.43 – 7.41 (m, 1H), 7.35 – 7.33
13
(m, 3H), 7.18 – 7.09 (m, 6H), 7.04 – 7.02 (m, 2H), 6.92 (s, 1H); C{1H} NMR (CDCl3, 100 MHz) δ
159.2 (dq, J = 255.0, 2.0 Hz), 140.5, 140.1 (d, J = 3.9 Hz), 139.5, 136.9, 133.0 (d, J = 8.2 Hz), 130.4,
129.7, 129.6, 129.1, 128.2, 128.1, 127.4, 126.1 (q, J = 4.5 Hz), 122.3 (q, J = 270.6 Hz), 116.8 (d, J =
20.6 Hz).
3au: (E)-(3-(1,2-Diphenylvinyl)phenyl)methanol. General procedure was followed; yellow oily liquid;
yield 70% (100 mg); Rf (10% EtOAc – petroleum ether) 0.1; IR (neat, cmꢀ1) νmax 3332, 3021, 1026; H
1
NMR (CDCl3, 400 MHz) δ 7.32 – 7.28 (m, 4H), 7.27 – 7.25 (m, 2H), 7.23 – 7.21 (m, 1H), 7.19 – 7.17
(m, 2H), 7.13 – 7.08 (m, 3H), 7.02 – 6.99 (m, 2H), 6.96 (s, 1H), 4.61 (s, 2H), 1.95 (s, 1H); 13C{1H}
NMR (CDCl3, 100 MHz) δ 143.9, 142.5, 140.9, 140.3, 137.4, 130.4, 129.7, 128.8, 128.6, 128.1, 127.6,
127.1, 126.9, 126.3, 126.2, 65.3; HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd for C21H18ONa 309.1255;
Found 309.1252.
3av: (E)-4-(1,2-Diphenylvinyl)benzaldehyde. General procedure was followed; white solid; yield 76%
(108 mg); mp 75 – 77 °C; Rf (10% EtOAc – petroleum ether) 0.6; IR (neat, cmꢀ1) νmax 2362, 1696; H
1
NMR (CDCl3, 400 MHz) δ 9.97 (s, 1H), 7.80 (d, J = 8 Hz, 2H), 7.46 (d, J = 8.4 Hz, 2H), 7.35 – 7.33
(m, 3H), 7.19 – 7.17 (m, 2H), 7.14 – 7.12 (m, 3H), 7.08 (s, 1H), 7.04 – 7.02 (m, 2H); C{1H} NMR
13
(CDCl3, 100 MHz) δ 191.8, 149.5, 141.5, 139.6, 136.7, 135.3, 130.8, 130.3, 129.8, 129.8, 129.0, 128.2,
128.1, 127.9, 127.5; HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd for C21H16ONa 307.1099; Found
307.1089.
22
ACS Paragon Plus Environment

Page 23 of 30
The Journal of Organic Chemistry
3aw: (E)-1-(4-(1,2-Diphenylvinyl)phenyl)ethan-1-one. General procedure was followed; liquid; yield
87% (130 mg); Rf (5% EtOAc – petroleum ether) 0.3; IR (neat, cmꢀ1) νmax 3023, 1681; 1H NMR (CDCl3,
400 MHz) δ 7.89 (d, J = 8.4 Hz, 2H), 7.40 (d, J = 8.4 Hz, 2H), 7.36 – 7.33 (m, 3H), 7.19 – 7.17 (m, 2H),
7.14 – 7.12 (m, 3H), 7.06 – 7.02 (m, 3H), 2.58 (s, 3H); 13C{1H} NMR (CDCl3, 100 MHz) δ 197.8,
148.1, 141.6, 139.8, 136.9, 136.0, 130.4, 130.2, 129.8, 129.0, 128.5, 128.2, 127.9, 127.7, 127.4, 26.7;
HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd for C22H18ONa 321.1255; Found 321.1259.
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
3ax: Methyl (E)-4-(1,2-diphenylvinyl)benzoate. General procedure was followed; white solid; yield 60%
1
(94 mg); mp 124 – 126 °C; Rf (10% EtOAc – petroleum ether) 0.7; IR (neat, cmꢀ1) νmax 1721, 1280; H
NMR (CDCl3, 400 MHz) δ 7.97 (d, J = 8.4 Hz, 2H), 7.38 (d, J = 8.4 Hz, 2H), 7.35 – 7.33 (m, 3H), 7.19
– 7.14 (m, 2H), 7.13 – 7.11 (m, 3H), 7.05 – 7.02 (m, 3H), 3.91 (s, 3H); 13C{1H} NMR (CDCl3, 100
MHz) δ 167.1, 148.0, 141.7, 139.8, 137.0, 130.4, 130.1, 129.8, 129.6, 129.0, 128.9, 128.2, 127.8, 127.6,
127.3, 52.2; HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd for C22H18O2Na 337.1204; Found 337.1206.
3ba: (Z)-2,2'-(1-Phenylethene-1,2-diyl)dithiophene.32d General procedure was followed; brown solid;
1
yield 85% (114 mg); mp 78 – 80 °C; Rf (petroleum ether) 0.6; IR (neat, cmꢀ1) νmax 3070, 2362, 849; H
NMR (CDCl3, 400 MHz) δ 7.50 (dd , J = 5.2 Hz, J = 1.2 Hz, 1H), 7.41 – 7.37 (m, 3H), 7.32 – 7.23 (m,
13
3H), 7.17 – 7.15 (m, 1H), 7.11 (d, J = 5.2 Hz, 1H), 7.05 – 7.02 (m, 2H), 6.91 – 6.89 (m, 1H); C{1H}
NMR (CDCl3, 100 MHz) δ 141.7, 140.9, 139.7, 131.9, 129.9, 129.0, 128.4, 127.8, 127.7, 127.7, 127.3,
126.6, 126.3, 124.3.
3ca: Ethene-1,1-diyldibenzene.31 General procedure was followed; liquid; yield 65% (59 mg); Rf (petroꢀ
1
leum ether) 0.8; H NMR (CDCl3, 400 MHz) δ 7.34 – 7.33 (m, 10H), 5.47 (s, 2H); 13C{1H} NMR
(CDCl3, 100 MHz) δ 150.2, 141.6, 128.4, 128.3, 127.8, 114.5.
3da: Prop-1-ene-1,1-diyldibenzene and (E)-prop-1-ene-1,2-diyldibenzene.31 General procedure was folꢀ
1
lowed; white solid; yield 84% (81 mg); Rf (petroleum ether) 0.5; IR (neat, cmꢀ1) νmax 1443; H NMR
23
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 24 of 30
(CDCl3, 400 MHz) Aromatic protons were not assigned to the individual diastereomers due to the comꢀ
plexity of the spectrum: α isomer δ 7.51 – 7.49 (m, 1H), 7.35 – 7.32 (m, 4H), 7.28 – 7.16 (m, 5H), 6.15
(q, 1H), 1.74 (d, 3H), β isomer δ 7.51 – 7.49 (m, 1H), 7.35 – 7.32 (m, 4H), 7.28 – 7.16 (m, 5H), 6.83 (s,
1
2
3
4
5
6
7
8
13
1H), 2.26 (s, 3H); C{1H} NMR (CDCl3, 100 MHz) δ 144.1, 143.1, 142.6, 140.1, 138.5, 137.5, 130.2,
9
129.3, 128.4, 128.3, 128.3, 128.2, 127.8, 127.3, 127.0, 126.8, 126.6, 126.1, 124.2, 17.6, 15.8.
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
3ea: Ethyl 3,3-diphenylacrylate and ethyl (Z)-2,3-diphenylacrylate. General procedure was followed;
colorless liquid; yield 94% (109 mg); Rf (10% EtOAc – petroleum ether) 0.4; IR (neat, cmꢀ1) νmax 2982,
1
1720, 1162; H NMR (CDCl3, 400 MHz): Aromatic protons were not assigned to the individual diaꢀ
stereomers due to the complexity of the spectrum. minor isomer δ 7.47 (d, J = 7.6 Hz, 2H), 7.36 – 7.29
(m, 7H), 7.24 – 7.20 (m, 1H), 7.03 (s, 1H), 4.26 (q, 2H), 1.18 (t, 3H); major isomer δ 7.36 – 7.29 (m,
13
8H), 7.24 – 7.20 (m, 2H), 6.36 (s, 1H), 4.04 (q, 2H), 1.10 (t, 3H); C{1H} NMR δ (CDCl3, 100 MHz):
169.7, 166.2, 156.5, 140.9, 139.1, 137.0, 135.4, 131.3, 129.4, 129.2, 128.8, 128.5, 128.4, 128.4, 128.3,
128.2, 127.9, 126.5, 117.6, 61.4, 60.1, 14.1, 13.9; HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd for
C17H16O2Na 275.1048; Found 275.1047.
3fa: 3,3-Diphenylprop-2-en-1-ol. General procedure was followed; brown solid; yield 43% (45 mg); mp
1
62 – 64 °C; Rf (20% EtOAc – petroleum ether) 0.3; IR (neat, cmꢀ1) νmax 3336, 1016; H NMR (CDCl3,
400 MHz) δ 7.36 – 7.30 (m, 3H), 7.22 – 7.29 (m, 5H), 7.14 (d, J =6 Hz, 2H), 6.22 (t, 1H), 4.19 (d, J =
6.8 Hz, 2H), 1.88(bs, 1H); 13C{1H} NMR (CDCl3, 100 MHz) δ 144.2, 141.9, 139.1, 129.8, 128.29,
128.27, 127.70, 127.67, 127.6, 60.7; HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd for C15H14ONa 233.0942;
Found 233.0944.
3ga: (2,2-Diphenylvinyl)trimethylsilane.30 General procedure was followed; liquid); yield 77% (97 mg);
Rf (petroleum ether) 0.8; 1H NMR (CDCl3, 400 MHz) δ 7.41 – 7.28 (m, 10H), 6.39 (s, 1H), 0.02 (s, 9H);
24
ACS Paragon Plus Environment

Page 25 of 30
The Journal of Organic Chemistry
13C{1H} NMR (CDCl3, 100 MHz) δ 157.2, 143.4, 142.8, 129.8, 128.4, 128.3, 128.2, 128.0, 127.7,
127.5, 127.3, 0.1.
1
2
3
4
5
6
7
8
9
3ha: 2-(2,2-Diphenylvinyl)thiophene and (Z)-2-(1,2-Diphenylvinyl)thiophene. General procedure was
followed; colorless liquid; yield 80% (105 mg); Rf (5% EtOAc – petroleum ether) 0.7; IR (neat, cmꢀ1)
νmax 3057, 1492; 1H NMR (CDCl3, 400 MHz) Aromatic protons were not assigned to the individual diaꢀ
stereomers due to the complexity of the spectrum. minor isomer: δ 7.46 – 7.39 (m, 3H), 7.38 – 7.27 (m,
5H), 7.25 – 7.22 (m, 2H), 7.00 – 6.95 (m, 3H), 6.85 (s, 1H); major isomer: δ 7.46 – 7.39 (m, 3H), 7.38 –
7.27 (m, 5H), 7.25 – 7.22 (m, 3H), 7.18 – 7.14 (m, 1H), 6.90 – 6.88 (m, 1H), 6.83 (s, 1H); 13C{1H}
NMR (CDCl3, 100 MHz) δ 143.3, 141.8, 141.7, 141.4, 139.9, 139.6, 137.3, 135.3, 130.6, 130.5, 129.6,
129.4, 129.1, 128.6, 128.4, 128.3, 128.21, 128.17, 128.0, 127.7, 127.5, 127.3, 127.2, 126.9, 126.5,
126.4, 126.3, 121.0; HRMS (ESIꢀTOF) m/z: [M + H]+ Calcd for C18H14SH 263.0894; Found 263.0890.
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
3ja:
(2-(4-Methoxyphenyl)ethene-1,1-diyl)dibenzene
and
(Z)-(1-(4-Methoxyphenyl)ethene-1,2-
diyl)dibenzene. General procedure was followed; Colorless liquid; yield 85% (121 mg); Rf (5% EtOAc
1
– petroleum ether) 0.6; IR (neat, cmꢀ1) νmax 3024, 1249; H NMR (CDCl3, 400 MHz) minor isomer: δ
7.33 – 7.21 (m, 8H), 7.19 – 7.04 (m, 4H), 6.95 – 6.82 (m, 3H), 6.64 (d, J =8.8 Hz, 1H), 3.77 (s, 3H);
major isomer: δ 7.33 – 7.21 (m, 8H), 7.19 – 7.04 (m, 4H), 6.95 – 6.82 (m, 3H), 6.64 (d, J =8.8 Hz, 1H),
3.68 (s, 3H); 13C{1H} NMR (CDCl3, 100 MHz) δ 159.1, 158.5, 143.9, 143.7, 142.4, 140.8, 140.7,
137.8, 132.6, 131.7, 130.9, 130.5, 130.2, 129.6, 128.8, 128.4, 128.3, 128.1, 127.9, 127.8, 127.8, 127.6,
127.5, 127.4, 127.3, 126.7, 114.1, 113.5, 55.2, 55.2; HRMS (ESIꢀTOF) m/z: [M + H]+ Calcd for
C21H18OH 287.1436; Found 287.1431.
3ka: (2-(4-Nitrophenyl)ethene-1,1-diyl)dibenzene General procedure was followed; Yellow solid; yield
20% (40 mg); Rf (5% EtOAc – petroleum ether) 0.5; IR (neat, cmꢀ1) νmax 3436, 1341; 1H NMR (CDCl3,
13
400 MHz) δ 7.97 (d, J =9.2 Hz, 2H), 7.37 – 7.34 (m, 8H), 7.18 – 7.12 (m, 4H), 6.99 (s, 1H); C{1H}
NMR (CDCl3, 100 MHz) δ 147.2, 146.1, 144.4, 142.5, 139.4, 130.3, 130.1, 129.1, 128.6, 128.5, 128.4,
25
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 26 of 30
128.0, 125.9, 123.5; HRMS (ESIꢀTOF) m/z: [M + H]+ Calcd for C20H15NO2H 302.1181; Found
302.1180.
1
2
3
4
5
6
7
8
ASSOCIATED CONTENT
Supporting Information
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
The Supporting Information is available free of charge on the ACS Publications website at DOI:
Preliminary mechanistic controls, 1H NMR and 13C spectra for all compounds (PDF).
AUTHOR INFORMATION
Corresponding Author
* Eꢀmail: prabhu@iisc.ac.in.
Notes
The authors declare no competing financial interests.
ACKNOWLEDGMENTS
This work was supported by SERB (EMR/2016/006358), NewꢀDelhi, CSIR (No. 02(0226)15/EMRꢀ
II), NewꢀDelhi, Indian Institute of Science, and R. L. Fine Chem. We thank Dr. A. R. Ramesha (R. L.
Fine Chem) for useful discussion. SR thanks UGC for a fellowship.
REFERENCES
(1) Neeve, E. C.; Geier, S. J.; Mkhalid, I. A. I.; Westcott, S. A.; Marder, T. B. Diboron(4) Compounds:
From Structural Curiosity to Synthetic Workhorse. Chem. Rev. 2016, 116, 9091–9161.
(2) Wei, C. S.; Davies, G. H. M.; Soltani, O.; Albrecht, J.; Gao, Q.; Pathirana, C.; Hsiao, Y.; Tummala,
S.; Eastgate, M. D. The Impact of Palladium(II) Reduction Pathways on the Structure and Activity of
Palladium(0) Catalysts. Angew. Chem. Int. Ed. 2013, 52, 5822–5826.
26
ACS Paragon Plus Environment

Page 27 of 30
The Journal of Organic Chemistry
(3) Ojha, D. P.; Gadde, K.; Prabhu, K. R. Generation of Hydrogen from Water: A PdꢀCatalyzed Reꢀ
1
2
3
4
5
6
7
8
duction of Water Using Diboron Reagent at Ambient Conditions. Org. Lett. 2016, 18, 5062–5065.
(4) Rao, S.; Prabhu, K. R. Stereodivergent Alkyne Reduction by using Water as the Hydrogen Source.
Chem. –Eur. J. 2018, 24, 13954–13962
9
(5) Chinchilla, R.; Nájera, C. Chemicals from Alkynes with Palladium Catalysts. Chem. Rev. 2013,
114, 1783–1826.
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
(6) Catalytic Hydroarylation of Carbon‐Carbon Multiple Bonds; Ackermann, L.; Gunnoe, T. B.;
Habgood, L. G., Eds.; WileyꢀVCH Verlag GmbH & Co. KGaA: Weinheim, 2018.
(7) (a) Miyaura, N.; Suzuki, A. PalladiumꢀCatalyzed CrossꢀCoupling Reactions of Organoboron
Compounds. Chem. Rev. 1995, 95, 2457–2483. (b) Miyaura, N.; Suzuki, A. Palladiumꢀcatalyzed dimeriꢀ
zation of 1ꢀalkenylboronates. A simple synthesis of symmetrical 1,3ꢀalkadienes from alkynes via hyꢀ
droboration. Main Group Met. Chem. 1987, 10, 295–300. (c) Cho, C. S.; Uemura, S. Palladiumꢀ
catalyzed crossꢀcoupling of aryl and alkenyl boronic acids with alkenes via oxidative addition of a carꢀ
bon–boron bond to palladium(0). J. Organomet. Chem. 1994, 465, 85–92.
(8) Miyaura, N.; Yamada, K.; Suzuki, A. A new stereospecific crossꢀcoupling by the palladiumꢀ
catalyzed reaction of 1ꢀalkenylboranes with 1ꢀalkenyl or 1ꢀalkynyl halides. Tetrahedron Lett. 1979, 20,
3437–3440.
(9) Miyaura, N.; Suzuki, A. Stereoselective synthesis of arylated (E)ꢀalkenes by the reaction of alkꢀ1ꢀ
enylboranes with aryl halides in the presence of palladium catalyst. J. Chem. Soc. Chem. Commun.
1979, 0, 866–867.
(10) Hayashi, T.; Inoue, K.; Taniguchi, N.; Ogasawara, M. RhodiumꢀCatalyzed Hydroarylation of Alꢀ
kynes with Arylboronic Acids:ꢁ 1,4ꢀShift of Rhodium from 2ꢀArylꢀ1ꢀalkenylrhodium to 2ꢀ
Alkenylarylrhodium Intermediate. J. Am. Chem. Soc. 2001, 123, 9918–9919.
27
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 28 of 30
(11) Shirakawa, E.; Takahashi, G.; Tsuchimoto, T.; Kawakami, Y. Nickelꢀcatalysed hydroarylation of
alkynes using arylboron compounds: selective synthesis of multisubstituted arylalkenes and aryldienes.
Chem. Commun. 2001, 0, 2688–2689.
1
2
3
4
5
6
7
8
9
(12) Oh, C. H.; Jung, H. H.; Kim, K. S.; Kim, N. The palladiumꢀcatalyzed addition of organoboronic
acids to alkynes. Angew. Chem. Int. Ed. 2003, 42, 805–808.
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) (a) Gupta, A. K.; Kim, K. S.; Oh, C. H. PdꢀCatalyzed Addition of Organoboronic Acids to Alꢀ
kynes at Room Temperature. Synlett 2005, 3, 457ꢀ460. (b) Oh, C. H.; Ryu, J. H. PalladiumꢀCatalyzed
Addition of Organoboronic Acids to Conjugated Alkynecarboxylates. Bull. Korean Chem. Soc. 2003,
24, 1563–1564. (c) Yamamoto, Y.; Kirai, N.; Harada, Y. Cuꢀcatalyzed stereoselective conjugate addition
of arylboronic acids to alkynoates. Chem. Commun. 2008, 0, 2010–2012.
(14) Xu, X.; Chen, J.; Gao, W.; Wu, H.; Ding, J.; Su, W. Palladiumꢀcatalyzed hydroarylation of alꢀ
kynes with arylboronic acids. Tetrahedron 2010, 66, 2433–2438.
(15) Liu, S.; Bai, Y.; Cao, X.; Xiao, F.; Deng, G.ꢀJ. Palladiumꢀcatalyzed desulfitative hydroarylation of
alkynes with sodium sulfinates. Chem. Commun. 2013, 49, 7501–7503.
(16) Liu, Z.; Derosa, J.; Engle, K. M. Palladium(II)ꢀCatalyzed Regioselective synꢀHydroarylation of
Disubstituted Alkynes Using a Removable Directing Group. J. Am. Chem. Soc. 2016, 138, 13076–
13081.
(17) Kim, N.; Kim, K. S.; Gupta, A. K.; Oh, C. H. On the regioselectivity of Pdꢀcatalyzed additions of
organoboronic acids to unsymmetrical alkynes. Chem. Commun. 2004, 0, 618–619.
(18) Arcadi, A.; Aschi, M.; Chiarini, M.; Ferrara, G.; Marinelli, F. Rhodium‐ and Palladium‐Catalyzed
Hydroarylation of Propargylic Amines with Arylboronic Acids. Adv. Synth. & Catal. 2010, 352, 493–
498.
(19) Rodriguez, A.; Moran, W. J. The Nitrile Functionality as a Directing Group in the Palladiumꢀ
Catalysed Addition of Aryl Boronic Acids to Alkynes. Lett. Org. Chem. 2010, 7, 7–10.
28
ACS Paragon Plus Environment

Page 29 of 30
The Journal of Organic Chemistry
(20) Yang, Y.; Wang, L.; Zhang, J.; Jin, Y.; Zhu, G. An unprecedented Pdꢀcatalyzed transꢀaddition of
1
2
3
boronic acids to ynamides. Chem. Commun. 2014, 50, 2347–2349.
4
5
6
7
8
9
(21) Bai, Y.; Yin, J.; Kong, W.; Mao, M.; Zhu, G. Pdꢀcatalyzed addition of boronic acids to ynol
ethers: a highly regioꢀ and stereoselective synthesis of trisubstituted vinyl ethers. Chem. Commun. 2013,
49, 7650–7652.
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
(22) Ojha, D. P.; Prabhu, K. R. PdꢀCatalyzed Hydroborylation of Alkynes: A Ligand Controlled Regiꢀ
oselectivity Switch for the Synthesis of αꢀ or βꢀVinylboronates. Org. Lett. 2016, 18, 432–435.
(23) Ojha, D. P.; Gadde, K.; Prabhu, K. R. PdꢀBoronꢀCatalyzed One Carbon Isomerization of Olefins:
Water Assisted Process at Room Temperature. J. Org. Chem. 2017, 82, 4859–4865.
(24) Moritani, I.; Fujiwara, Y. Aromatic substitution of styreneꢀpalladium chloride complex. Tetrahe-
dron Lett. 1967, 8, 1119–1122.
(25) Fujiwara, Y.; Moritani, I.; Danno, S.; Asano, R.; Teranishi, S. Aromatic substitution of olefins. VI.
Arylation of olefins with palladium(II) acetate. J. Am. Chem. Soc. 1969, 91, 7166–7169.
(26) Cummings, S. P.; Le, T.ꢀN.; Fernandez, G. E.; Quiambao, L. G.; Stokes, B. J. Tetrahydroxydiboꢀ
ronꢀMediated PalladiumꢀCatalyzed Transfer Hydrogenation and Deuteriation of Alkenes and Alkynes
Using Water as the Stoichiometric H or D Atom Donor. J. Am. Chem. Soc. 2016, 138, 6107–6110.
(27) Crabtree, R. H. Resolving Heterogeneity Problems and Impurity Artifacts in Operationally
Homogeneous Transition Metal Catalysts. Chem. Rev. 2012, 112, 1536–1554.
(28) Trost, B. M.; Romero, D. L.; Rise, F. PdꢀCatalyzed Cycloisomerization to 1,2ꢀ
Dialkylidenecycloalkanes. 2. Alternative Catalyst System. J. Am. Chem. Soc. 1994, 116, 4268–4278.
(29) Kadota, I.; Shibuya, A.; Gyoung, Y. S.; Yamamoto, Y. Palladium/Acetic Acid Catalyzed Allylaꢀ
tion of Some Pronucleophiles with Simple Alkynes. J. Am. Chem. Soc. 1998, 120, 10262–10263.
29
ACS Paragon Plus Environment