Gold-Catalyzed Ascorbic Acid-Induced Arylative Carbocyclization of Alkynes with Aryldiazonium Tetrafluoroborates

Article abstract of DOI:10.1021/acscatal.1c01826

We describe, herein, arylative carbocyclization of alkynes catalyzed by gold. In this process, Au(I) is oxidized to Au(III) with aryldiazonium tetrafluoroborates following a photosensitizer-free and irradiation-free protocol. Ascorbic acid acts as a radical initiator, generating aryl radicals. According to DFT calculations, these radicals are added to Au(I), leading to a Au(II) species that is further oxidized to Au(III) with the assistance of a tetrafluoroborate anion. The overall arylative carbocyclization process is very energetically favorable, transforming arylpropargyl ethers into valuable 3,4-diaryl-2H-chromenes in a completely regio- and stereoselective fashion. Furthermore, we show that one of the synthesized 3,4-diaryl-2H-chromenes exhibits polymorphism with marked differences in the color of its crystals, a property that could lead to the development of colored derivatives in the future.

Full text of DOI:10.1021/acscatal.1c01826

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Research Article
Gold-Catalyzed Ascorbic Acid-Induced Arylative Carbocyclization of
Alkynes with Aryldiazonium Tetrafluoroborates
Ignacio Medina-Mercado, Abraham Colin-Molina, José Enrique Barquera-Lozada,
Braulio Rodríguez-Molina, and Susana Porcel*
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ABSTRACT: We describe, herein, arylative carbocyclization of
alkynes catalyzed by gold. In this process, Au(I) is oxidized to
Au(III) with aryldiazonium tetrafluoroborates following a photo-
sensitizer-free and irradiation-free protocol. Ascorbic acid acts as a
radical initiator, generating aryl radicals. According to DFT
calculations, these radicals are added to Au(I), leading to a Au(II)
species that is further oxidized to Au(III) with the assistance of a
tetrafluoroborate anion. The overall arylative carbocyclization
process is very energetically favorable, transforming arylpropargyl ethers into valuable 3,4-diaryl-2H-chromenes in a completely
regio- and stereoselective fashion. Furthermore, we show that one of the synthesized 3,4-diaryl-2H-chromenes exhibits
polymorphism with marked differences in the color of its crystals, a property that could lead to the development of colored
derivatives in the future.
KEYWORDS: arylative carbocyclization, gold, ascorbic acid, aryldiazonium salts, polymorphism
processes where the diazonium salt is thermally or chemically
activated.11 Initial reports on catalytic redox processes of Au(I)
with aryldiazonium salts required the use of a cocatalyst and
light irradiation to promote the formation of Au(III) species,
but later studies manifested that, in some cases, just light, heat,
or certain ligands and bases are enough to promote this
process.12,13 Recently, we evidenced that ascorbic acid, a
natural reducing agent, is able to promote the oxidative
addition of Au(I) with aryldiazonium chlorides, and used this
protocol for the arylation of N-methyl indoles.11c In that
transformation, we needed to use a stoichiometric amount of
gold because of the competitive formation of N-methylindol-
diazo coupling derivatives. In this paper, we show that ascorbic
acid in combination with aryldiazonium tetrafluoroborates is
able to promote arylative carbocyclization of alkynes using a
catalytic amount of gold in the absence of a cocatalyst or an
external irradiating source. The products obtained are
tetrasubstituted alkenes with total control of regio- and
stereoselectivity.
I. INTRODUCTION
Tetrasubstituted olefins are important structural motifs present
in biologically active compounds,1 molecular switches,
molecular motors, organic light-emitting diodes, and bioimag-
ing.2 However, the synthesis of stereodefined tetrasubstitued
olefins is far from trivial.3 It is well known that traditional
methodologies such as elimination,4 Wittig reactions,5 the
McMurry coupling,6 and even olefin metathesis7 suffer from
poor values of regio- and/or stereoselectivity. On the other
hand, multicomponent reactions like Cattellani type reactions
have reached high levels of regio- and stereoselectivity in some
cases,8 although the most widely used method for the synthesis
of stereodefined tetraolefins is the carbometallation of alkynes.9
This approach involves the formation of a nucleophilic vinyl
metal species that is transformed stepwise or in situ into the
desired olefin. Complementary alkynes can be transformed
into tetrasubstitued olefins by a less explored metal-catalyzed
electrophilic carbofunctionalization (Figure 1).10 It was
initially described by Greany10a using a palladium catalyst
and aryliodonium salt as an electrophile and was later extended
by Gaunt, who used a copper source.10 Other metals like iron,
calcium, indium, or borderline bismuth have been shown to be
active in this transformation, and along with aryliodonium
salts, alcohols, acetals, and acrylates have been used as an
electrophilic source. In this context, we were intrigued by
exploring the synthesis of tetrasubstituted alkenes using a gold-
catalyzed electrophilic carbofunctionalization. Our group has
been focused on the development of gold redox processes with
aryldiazonium salts. In particular, we have been interested in
Received: April 21, 2021
Revised: June 24, 2021
Published: July 8, 2021
https://doi.org/10.1021/acscatal.1c01826
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Figure 1. State-of-the-art of electrophilic arylative carbocyclizations for the synthesis of tetrasubstituted alkenes in this work.
a
Table 1. Optimization of the Reaction Conditions
II. RESULTS AND DISCUSSION
To perform our study, we chose arylpropargyl ethers as alkyne
models because of the easy access to a variety of skeletal
scaffolds and the biological significance of chromene
derivatives.14 We first synthesized arylpropargyl ethers 1a
and 2a containing methyl and p-methoxyphenyl, respectively
(Table 1), with the aim of enriching the electron density onto
the alkyne. As an aryldiazonium model, we took p-nitro-
benzendiazonium tetrafluoroborate, as we have already
observed that the nitro group confers special reactivity toward
Au(I) because of its electron-withdrawing character. In our
precedent work related to the arylation of indoles, we noticed
that the nature of the counteranion of the diazonium salt has a
significant influence on the oxidative addition step.11c In that
case, we found that chloride was the best counteranion to
attain high arylation yields. Nonetheless, this time we replaced
chloride with tetrafluoroborate, with the purpose of creating a
coordination vacancy on the gold coordination sphere, which
facilitates the coordination of the alkyne. With this in mind, we
examined the reaction of 1a with p-nitrobenzendiazonium
tetrafluoroborate using Ph3PAuCl (10 mol %) as a gold source
in the presence of ascorbic acid (5 mol %). After stirring in
acetonitrile at rt for 16 h, the desired 2H-chromene 1c was
gratifyingly formed although in a modest yield (23%, Table 1,
entry 1). Decreasing the amount of ascorbic acid to 1 and to
0.5 mol % increased the yield up to 55% and 57%, respectively
(entries 2 and 5). The latter can be understood because a
decrease in the amount of ascorbic acid decreases the rate at
which radicals are being formed, avoiding competing
decomposition pathways. Soon after, we examined the effect
of replacing a Ph3P ligand with a more electron-donating
ligand like carbene IPr and by the electron-withdrawing
phosphite (2,4-tBu2PhO)3P (entries 3 and 4). In both cases,
the yield decreased below 5%. Using the more electron-rich
arylproprargyl ether 2a (entry 6) under the conditions
depicted in entry 5, 2H-chromene 2c was isolated in a similar
yield (55%). With this arylpropargyl ether, we tested the
b
substrate
[Au]
Ph3PAuCl
Ph3PAuCl
IPrAuCl
(ArO)3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
Ph3PAuCl
ascorbic acid
base
yield
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1a
1a
1a
1a
1a
2a
2a
2a
2a
2a
1a
2a
2a
2a
2a
2a
2a
2a
2a
2a
5
1
1
1
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
23%
55%
<5%
<5%
57%
55%
70%
65%
42%
80%
64%
nr
c
c
Li2CO3
Cs2CO3
DBU
DTBPy
DTBPy
BPy
BPy
nr
(pCF3C6H4)3PAuCl
JhonphosAuCl
Ph3PAuNTf2
Ph3PAuCl
0.5
0.5
0.5
DTBPy
DTBPy
DTBPy
DTBPy
DTBPy
DTBPy
29%
nr
d
nr
47%
nr
47%
32%
0.5
e
Ph3PAuCl
Ph3PAuCl
f
DTBPy
a
b
c
d
[1a or 2a] = 0.1 M. Isolated yield. Ar = 2,4-tBu2Ph. Reaction
carried out with chloride as a counteranion of the diazonium salt.
Reaction carried out under irradiation with blue LEDs. Reaction
carried out with [Ru(bpy)3](PF6)2 (2.5 mol %) as a cocatalyst and
under irradiation with blue LEDs.
e
f
addition of inorganic bases like Cs2CO3 and Li2CO3, which
increased the yield up to 65% and 70%, respectively (entries 7
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and 8). Otherwise, the addition of an organic base like DBU
was detrimental, 2c being recovered in 40% (entry 9). On the
contrary, DTBPy had a marked positive effect, increasing the
yield to 80% (entry 10). Satisfyingly, we confirmed that this
base also increased the reaction yield of substrate 1a (64%,
entry 11). Next, we tested the effect of the chelating BPy
ligand, which has been successfully used in ligand-promoted
oxidative addition of Au(I) with aryldiazonium salts;12d
however, in our case, no reaction was observed (entries 12
and 13). Using DTBPy as a base, we also evaluated the
performance of (pCF3C6H4)3PAuCl and JhonphosAuCl
(entries 14 and 15). In the first case, the yield was 29%,
whereas, in the second, no reaction took place. Additionally,
we examined the reactivity of p-nitrobenzendiazonium chloride
and 2a in the presence of the cationic gold complex
Ph3PAuNTf2, but under these conditions, 2a was recovered
unchanged (entry 16). To summarize, the best results were
obtained using Ph3PAuCl(10 mol %) as a catalyst in the
presence of ascorbic acid (0.5 mol %) and DTBPy (1 equiv) as
a base. Phosphines bearing electron-withdrawing bulky groups
inhibited the reaction. We performed some control experi-
ments to verify the influence of the gold catalyst and ascorbic
acid. In the absence of the latter, the yield of the reaction of 2a
with p-nitrobenzendiazonium tetrafluoroborate dropped to
47% (entry 17), whereas, in the absence of Ph3PAuCl, no
reaction took place (entry 18). These results confirmed that
both ascorbic acid and Ph3PAuCl are essential for the reaction
to proceed in a good yield. Finally, to compare the efficiency of
the arylative cabocyclization of 2a under the optimized
conditions encountered by us (entry 10) versus previously
reported protocols, we studied the reactivity of 2a under
irradiation with blue LEDs and in the presence of [Ru(bpy)3]-
(PF6)2 (2.5 mol %) as a cocatalyst under irradiation with blue
LEDs. As shown in entries 19 and 20, the yield was lower in
both cases (47 and 32%, respectively), evidencing the major
performance of our optimized conditions.
Table 2. Influence of the Terminal Substituent on the
Alkynea
With the best reaction conditions encountered, we next
studied the effect of a terminal substituent onto an alkyne
(Table 2). Compound 3a bearing an n-butyl group gave 2H-
chromene 3c in a 58% yield. We were pleased by this result
since the arylative carbocyclization methods described so far
have not been applied to alkynes containing an alkyl group at
the terminal position.10 Compounds 4a and 5a with a phenyl
and a naphthyl group reacted with a 66% and 51% yield,
respectively. Compound 6a with a methyl group at the ortho
position reacted in a 59% yield, whereas compound 7a bearing
a p-methoxy group reacted in a 62% yield. The presence of a p-
nitro group at the aryl moiety completely inhibited the reaction
with 8c not being formed. This is probably due to the less
nucleophilic character of the alkyne. We inspected the effect of
electron-rich heteroarenes such as thiophene (9a) and
benzofurane (10a). In the first case, the yield was 64%,
whereas, in the second, the yield was 54%. Compound 11a
with a phenylsulfanyl group attached to the alkyne reacted in a
64% yield. It is important to note that the reaction was not
inhibited even in the presence of a pendant sulfur atom, which
may strongly coordinate gold. To end, we examined the
behavior of a terminal alkyne 12a (R = H). This compound
reacted to give the Sonogashira type coupling product 8a in a
42% yield; however, the product from arylative carbocycliza-
tion was not observed from arylative carbocyclization. The
results given in Table 2 show that the reaction is sensitive to
both electronic properties and steric hindrance of the group
attached at the terminal position of the alkyne. Thus, electron-
withdrawing groups can inhibit the reaction, and steric
hindrance decreases the yields.
Thereafter, we focused our attention on exploring the effect
of modifying the nucleophilic character of the phenol moiety
(Table 3). Electron-donating groups such as MeO-, t-Bu,
-OBn, and -Ph at the para position of a propargyl ether link
maintained yields in the range of 55−77%. As expected,
substrates containing electron-withdrawing groups reacted
more sluggishly and required an increase in the amount of
the diazonium salt to achieve better yields. Thus, substrates
containing halogens atoms such us p-Br (17a) and o-I (18a)
reacted in a 44 and 45% yield, respectively, using 2 equiv of 1b,
whereas the substrate containing p-CH3CO (19a) required 3.5
equiv of 1b to form 19c in a 34% yield. It is important to note
the good compatibility of this arylative carbocyclization
protocol with C-halogen bonds, enabling further functionaliza-
tion of halogenated 2H-chromenes. We also replaced the
oxygen link by an atom of sulfur (20a) and by a NTs (Ts
=Tosyl) group (21a). Arylative carbocyclization of substrate
20a took place in a 18% yield. We suspect that, in this case,
diazo coupling is a competing reaction because when substrate
20a was mixed with 1b, the solution turned its color, and a
second polar compound was observed by TLC at the end of
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a b
,
Table 3. Effect of the Nature of Substituents on the Phenol Moiety
a
b
c
d
e
[13a−21a] = 0.1 M, 1.5 equiv of 1b. Isolated yield. 2 equiv of 1b. 2.5 equiv of 1b. 3.5 equiv of 1b.
the reaction, which we were not able to characterize. Substrate
21a bearing a NT group reacted in a 35% yield, which shows
the lower nucleophilic character of the aryl ring by means of
the NTs (Ts =Tosyl) group.
groups, we examined the reactivity of benzendiazonium
tetrafluoroborate, p-methylbenzendiazonium tetrafluoroborate,
and p-methoxybenzendiazonium tetrafluoroborate toward 2a,
but in all cases, we recovered the arylpropargyl ether or it was
decomposed. So this arylative carbocyclization protocol is
limited to aryldiazonium salts bearing electron-withdrawing
groups.
After a thorough examination of the reaction scope, we
turned our attention to the reaction mechanism.15 In our
previous study on the arylation of indoles with aryldiazonium
chlorides,11c we confirmed by EPR and electrochemical
experiments that ascorbic acid generates aryl radicals. In
addition, DFT calculations showed that these radicals are
added barrierless to Au(I), generating an arylAu(II) species
that is lastly oxidized by a reaction with a second equivalent of
aryldiazonium chloride. Surprisingly, this reaction is also
barrierless, and it is triggered by the high affinity of a Cl−
anion to the Au(II) center. In the present case, we wondered if
a fluoride atom from the BF4− anion would be able to display a
similar role to chloride, inducing Au(II)/Au(III) oxidation. We
were also interested in calculating the overall energetic profile
of the arylative carbocyclization reaction. Figure 2 shows the
Lastly, we explored the scope of the reaction over a variety
of aryldiazonium salts (Table 4). We began by examining the
effect of electron-withdrawing substituents at the para position.
Aryldiazonium salts containing halogen substituents (2b = p-
Cl, 3b = p-Br, and 4b = p-F) reacted in a 68−44% yield, the
lower yield being obtained with p-fluorobenzendiazonium
tetrafluoroborate. The introduction of an ester moiety in the
aryldiazonium ring led to the corresponding 2H-chromene
(25c) in a 49% yield. A bulky group, such as p-benzophenone
led to the desired 2H-chromene 26c in a 46% yield, whereas
nitrile increased the yield up to 74% (compound 27c). Next,
we examined the influence of placing certain groups at the
meta and the ortho positions of the aryldiazonium salt (8b =
m-NO2, 9b = m-CN and 10b = m-Cl, and 11b = o-NO2).
These types of couplings are challenging because of steric
reasons, and although the yields were comparatively lower, the
corresponding 3,4-diaryl 2H-chromenes were obtained in a
satisfactory 41−60% yield. Concerning electron-donating
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a b
,
much higher when the oxidizing anion was Cl− (−16.63 kcal/
mol in the gas phase). The larger energy value indicates that
the formation of a Cl−Au(III) bond is more favorable than the
F3B−F−Au(III) interaction.16
Table 4. Scope over Aryldiazonium Tetrafluoroborate
Once the arylAu(III) complex is generated, it coordinates to
the alkyne, leading to an arylAu(III)-alkyne adduct, in which
the carbon placed at the β position to the oxygen is more
strongly bonded to the metal (2.36 Å) than the carbon placed
at the γ position (2.51 Å). The latter carbon is also relatively
close to the ortho carbon of the aryl ring, which facilitates the
cyclization step. In fact, the LUMO of this intermediate is
located both on the metal center and on the alkyne carbon
placed at the γ position to the oxygen (Figure 3). This acid
carbon can then easily react with the π electrons of the aryl
group (HOMO). These MOs explain the low activation barrier
for the cyclization step, only 10.28 kcal/mol. The bicyclic
compound formed after cyclization is further stabilized by
rearomatization. The transition state (TS) of the rear-
omatization has very low energy, such that once the entropy
is added, the activation free energy (ΔG‡) became slightly
negative. The last step is also very favorable. The reductive
elimination proceeds through TS5 with relatively low energy
(7.54 kcal/mol), leading to the final 2H-chromene product and
the initial Au(I) complex. The low energy barrier of the
reductive elimination step is remarkable, considering that
protodeauration is frequently a strong competitive reaction in
vinyl-gold(III) complexes. In our precedent study, we found
that the formation of arylAu(II) and arylAu(III) species
proceeds without the energy barrier for both NO2 and OMe
groups at the aryl moiety,11c and now a similar trend is
expected. This time to better understand the lack of reactivity
of aryldiazonium salts containing electron-donating groups, we
studied if there is a significant difference in the energy barrier
of the carbocyclization step (TS4) depending on the nature of
the substituent at the aryl ring. However, the energy values for
TS4 when the aryl ring bears an OMe group or a NO2 group
are very similar (Figure 4). Considering these results, the lack
of reactivity of aryldiazonium salts containing electron-
donating groups must come from potential decomposition of
the aryl-generated radicals due to stability reasons. A similar
trend has been observed recently in gold-catalyzed aryl
couplings under light irradiations.12s Detailed mechanistic
studies evidenced that aryldiazonium salts with electron-
donating substituents are harder to react.12s
In summary, all of the TSs and the intermediaries depicted
in the reaction mechanism (Figure 2) are of relatively low
energy, which shows the plausibility of the proposed reaction
path. Importantly, the results derived from the DFT
calculations further support that under our conditions, Au(I)
oxidation with aryldiazonium salts can be accessed in the
absence of a cocatalyst or an external irradiating source, being
simply triggered by the affinity of the counteranion of the
diazonium salt to the Au(II) center. The counteranion thus
releases electron density onto Au(II), assisting the transfer of
one electron from Au(II) to the aryldiazonium cation. This
lastly leads to a Au(III) complex and an aryldiazonium radical,
which regenerates the initial aryl radical by losing nitrogen.
After the examination of the reaction scope and the
mechanism, we became interested in analyzing in detail the
highly noticeable chromism exhibited in the solid state of some
2H-chromenes derivatives, especially 2c. When this compound
was isolated after purification by column chromatography, the
evaporation of the fractions in hexane at room temperature
a
b
c
[2a] = 0.1 M. Isolated yield. reaction at 50 °C.
energy profile of a proposed reaction mechanism. The energy
of the proposed intermediates was calculated at the M06/
Def2TZVP level of theory. To simplify the system, we replaced
triphenylphosphine with trimethyl phosphine as a ligand. To
our delight, it was confirmed that Au(I)/Au(III) oxidation
with 4-NO2C6H4BF4 proceeds by a similar pathway as that
shown by 4-NO2C6H4Cl. First, Me3PAuCl is barrierlessly
oxidized to a 4-NO2C6H4Au(II) species by a 4-NO2C6H4·
radical. Next, gold is further oxidized to 4-NO2C6H4Au(III) by
a reaction with another equivalent of the aryldiazonium salt.
−
This step is assisted by a BF4 anion of the diazonium salt,
which accesses the coordination sphere of the metal. The
metal−BF4 interaction is strong enough to significantly
−
elongate the B−F bond that is in the coordination sphere
(1.55 Å). However, this F−BF3 bond is still energetically
enough to pyrimidalize the BF3 moiety. Notably, the oxidation
of Au(II) by a penetrating anion was observed in our
precedent study with Cl−, and as previously noticed, this
step is barrierless. The energy difference between the
arylAu(II) and the arylAu(III) species (EAu(III) − EAu(II)) was
−7.19 kcal/mol. Comparatively, this energy difference was
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Figure 2. Relative energy of the intermediaries and transition states of the reaction mechanism of catalytic arylative carbocyclization of alkynes. The
L and R groups used for the DFT calculations were P(CH3)3 and CH3, respectively, Ar4-NO2C6H4. Energies are given in kcal/mol.
Considering the abovementioned, we grew and diffracted
suitable crystalline specimens of both solids at the mentioned
temperatures. Their diffraction patterns were indexed and
̅
refined in triclinic P1 or monoclinic P21 spatial groups,
respectively. Careful examination of their crystalline molecular
structures showed that there are significant differences (ca. 5
and 10°) for the dihedral angles φ1 and φ2 formed between
aromatic substituents and the 2H-chromene framework, as
shown in Figure 5a,b. Furthermore, it was possible to recognize
the formation of π-stacking interactions between adjacent
nitroaromatic rings with a centroid−centroid distance of 4.046
Å (Figure 5c). Otherwise, the crystal arrangement of 2c(II) is
governed by an O···π(N)NO2 interaction, with a distance of
2.944 Å (Figure 5d), which is within the range reported for this
contact in organic crystals (2.939−3.006 Å).28
Figure 3. HOMO and LUMO of the Au(III)-alkyne adduct.
Large batches of both solids were prepared for further
analysis, and the resulting phase purity was confirmed by
PXRD analyses (Figures S1 and S2). To complement the
structural diffraction results, we carried out 13C CPMAS NMR
experiments at 298 K (Figures S3 and S4). Particularly, in the
case of the spectrum from 2c(II), the data confirmed the
presence of two molecules with different crystallographic
environments (Z′ = 2), as obtained by single-crystal X-ray
diffraction. To determine the thermal stability of these
crystalline solids, we carried out differential scanning
calorimetry (DSC) and thermogravimetric analyses (TGA).
It was confirmed that their crystalline structure is unaffected by
heating and that both compounds melt without interconver-
sion of their forms, with distinctive melting points of 157 °C
for 2c(I) and 153 °C for 2c(II) (Figures S5 and S6).
These results demonstrated that the orange and yellow
solids obtained for 2c represent a case of conformational
dimorphism.19 After studying the X-ray structure of each form,
we can conclude that the color change is due to the different
molecular conformations, which modify the π-extension of the
chromophore and therefore, the energetic gap between basal
and excited states. We consider that the torsion of the angle φ2
Figure 4. Relative energy to Int3 of the carbocyclization step with a
electron-withdrawing group (NO2, blue) and with an electron-
donating group (OMe, red). Energies are given in kcal/mol.
yielded a mixture of dark orange and yellow solids. Later, it was
found that when the solution was evaporated at 60 °C, the
dark orange solid 2c(I) was exclusively obtained, while if the
evaporation was carried out near 10 °C, the obtained solid
acquired a yellow color 2c(II). This behavior strongly
suggested crystal polymorphism17,18 because the eluates were
pure, as indicated by 1H NMR in solution. Thus, we employed
several solid-state techniques to gain further insights into this
phenomenon.
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Figure 5. (a and b) ORTEP diagrams of solid forms 2c(I) and 2c(II) highlighting dihedral angles φ1 and φ2. (c and d) Intermolecular interactions
in crystalline packing of polymorphic solids (hydrogens are omitted for clarity).
is decisive in the resulting color. Additionally, the lower
(PDF)
melting point, the high value of molecules in the asymmetric
(ZIP)
unit (Z′ = 2), and the unusual O···π(N) interactions allowed
us to infer that the yellow solid 2c(II) corresponds to the
Accession Codes
kinetic state. The solid-state behavior of these chromenes is
very interesting and it could be explored in other derivatives in
the future.
CCDC 2046490 and CCDC 2046491 contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/dat_request/
cis, or by emailing data_request@ccdc.cam.ac.uk, or by
contacting The Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, U.K.; fax: +44 1223
336033.
III. CONCLUSIONS
■
In conclusion, we have shown that Au(I) is able to catalyze
arylative carbocyclization of alkynes with aryldiazonium
tetrafluoroborates.20 The role of ascorbic acid is to generate
aryl radicals that are added to Au(I), forming an electrophilic
arylAu(II) species, which is further oxidized to Au(III) with
AUTHOR INFORMATION
■
−
the assistance of a BF4 anion. Notably, in this work, it is
Corresponding Author
further evidenced that the counteranion of the aryldiazonium
salt has a key role in the reaction, assisting the oxidation of the
ArAu(II) species into ArAu(III). This breakthrough sheds light
on the mechanism underlying the oxidative addition of Au(I)
with aryldiazonium salts. The results encountered will help in
the development of new catalytic processes involving the redox
pair Au(I)/Au(III), which will not require the use of a
cocatalyst or an irradiating source to achieve the desired
oxidation of Au(I), thus making these type of transformations
broadly accessible. Moreover, the protocol described allows the
regio- and stereoselective synthesis of 3,4-diaryl-2H-chro-
menes, which can exhibit drastic changes in the appearance
of the solids, a property that could be explored in future
studies.
Susana Porcel − Instituto de Química, Universidad Nacional
Autónoma de México, Ciudad de México 04510, México;
orcid.org/0000-0001-7954-7479; Email: sporcel@
unam.mx
Authors
Ignacio Medina-Mercado − Instituto de Química,
Universidad Nacional Autónoma de México, Ciudad de
México 04510, México
Abraham Colin-Molina − Instituto de Química, Universidad
Nacional Autónoma de México, Ciudad de México 04510,
México; orcid.org/0000-0002-2425-4254
José Enrique Barquera-Lozada − Instituto de Química,
Universidad Nacional Autónoma de México, Ciudad de
México 04510, México; orcid.org/0000-0002-9668-
5328
Braulio Rodríguez-Molina − Instituto de Química,
Universidad Nacional Autónoma de México, Ciudad de
México 04510, México; orcid.org/0000-0002-1851-
9957
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acscatal.1c01826.
■
sı
Experimental procedures, characterization of new
compounds, NMR spectra, X-ray data, and the crystal
structure of 2c(I) and 2c(II) (PDF)
Complete contact information is available at:
https://pubs.acs.org/10.1021/acscatal.1c01826
(CIF)
(CIF)
(PDF)
Notes
The authors declare no competing financial interest.
8974
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ACS Catal. 2021, 11, 8968−8977

ACS Catalysis
pubs.acs.org/acscatalysis
Research Article
(4) Selected examples: (a) Johnson, E. P.; Vollhardt, K. P. C.
Stereoselective, One-Pot Assembly of the Strained Protoilludane
Framework by Cobalt-Mediated Cyclization of an Acyclic Enediyne
Precursor. A total synthesis of illudol. J. Am. Chem. Soc. 1991, 113,
381−382. (b) Németh, G.; Kapiller-Dezofi, R.; Lax, G.; Simig, G.
New Practical Synthesis of Panomifene. The Effect of 2-Trifluor-
omethyl Substituent on the Stereoselectivity of Dehydration of 1,1,2-
Triarylethanols. Tetrahedron 1996, 52, 12821−12830. (c) Robertson,
D. W.; Katzenellenbogen, J. A. Synthesis of the (E) and (Z) Isomers
of the Antiestrogen and its Metabolite, Hydroxytamoxifen, in Tritium-
labeled form. J. Org. Chem. 1982, 47, 2387−2393. (d) Lim, N.-K.;
Weiss, P.; Li, B. X.; McCulley, C. H.; Hare, S. R.; Bensema, B. L.;
Palazzo, T. A.; Tantillo, D. J.; Zhang, H.; Gosselin, F. Aryne Relay
Chemistry en Route to Aminoarenes: Synthesis of 3-Aminoaryne
Precursors via Regioselective Silylamination of 3-(Triflyoxy)arynes.
Org. Lett. 2017, 19, 6212−6215.
ACKNOWLEDGMENTS
■
This work was supported by CONACyT (A1-S-7805) and
DGAPA (IN202017). I.M-M. and A.C.-M. thank CONACyT
for scholarships 701363 and 576483. J.E.B.-L. thanks DGTIC-
UNAM for the computer time (project: LANCAD-UNAM-
DGTIC-304) and CONACYT (project: CB 284373). The
authors would like to thank M. A. Pen
Salazar, B. Quiroz-García, C. Bustos-Brito, I. Chávez-Uribe, H.
Ríos-Olivares, R. A. Toscano, M. R. Patino-Maya, F. Javier
Pérez-Flores, M. C. García-González, and A. Nun
̃
a-González, E. Huerta-
̃
́
̃
ez-Pineda.
The authors also thank UNAM for support related to UNAM’s
BGSI node for solid-state NMR experiments.
REFERENCES
■
(5) Reviews: (a) Maryanoff, B. E.; Reitz, A. B. The Wittig
Olefination Reaction and Modifications Involving Phosphoryl-
Stabilized Carbanions. Stereochemistry, Mechanism, and Selected
(1) Selected examples: (a) Takahashi, A.; Kirio, Y.; Sodeoka, M.;
Sasai, H.; Shibasaki, M. Hightly stereoselective synthesis of exocyclic
tetrasubstituted enol ethers and olefins. A Synthesis of Nileprost. J.
Am. Chem. Soc. 1989, 111, 643−647. (b) Jordan, V. C. Tamoxifen: a
Most Unlikely Pioneering Medicine. Nat. Drug Rev. 2003, 2, 205−
213. (c) Organ, M. G.; Cooper, J. T.; Rogers, L. R.; Soleymanzadeh,
F.; Paul, T. Synthesis of Stereodefined Polysubstituted Olefins. 1.
Sequential Intermolecular Reactions Involving Selective, Stepwise
Insertion of Pd(0) into Allylic and Vinylic Halide Bonds. The
stereoselective Synthesis of Disubstituted Olefins. J. Org. Chem. 2000,
65, 7959−7970. (d) Bresalier, R. S.; Sandler, R. S.; Quan, H.;
Bolognese, J. A.; Oxenius, B.; Horgan, K.; Lines, C.; Riddell, R.;
Morton, D.; Lanas, A.; Konstam, M. A.; Baron, J. A. Cardiovascular
Events Associated with Rofecoxib in a Colorectal Adenoma
Chemoprevention Trial. N. Engl. J. Med. 2005, 352, 1092−1102.
(e) Beer, M. L.; Lemon, J.; Valliant, J. F. Preparation and Evaluation
of Carborane Analogues of Tamoxifen. J. Med. Chem. 2010, 53,
8012−8020. (f) Aziz, J.; Brachet, E.; Hamze, A.; Peyrat, J.-F.;
Bernadat, G.; Morvan, E.; Bignon, J.; Wdzieczak-Bakala, J.;
Desravines, D.; Dubois, J.; Tueni, M.; Yassine, A.; Brion, J.-D.;
Alami, M. Synthesis, Biological Evaluation, and Structure-Activity
Relationships of Tri- and Tetrasubstituted Olefins Related to
Isocombretastatin A-4 as New Tubulin Inhibitors. Org. Biomol.
Chem. 2013, 11, 430−442.
Synthetic Aspects. Chem. Rev. 1989, 89, 863−927. (b) Furstner, A.;
̈
Bogdanovic, B. New Developments in the Chemistry of Low-Valent
Titanium. Angew. Chem. Int. Ed. 1996, 35, 2442−2469.
(6) Takeda, T. Modern Carbonyl Olefination; Wiley-VCH:
Weinheim, 2004.
(7) Mukherjee, N.; Planer, S.; Grela, K. Formation of Tetrasub-
stituted C-C Double Bonds via Olefin Metathesis: Challenges,
Catalysts, and Applications in Natural Product Synthesis. Org.
Chem. Front. 2018, 5, 494−516.
(8) Cattelani: Selected examples: (a) Gericke, K. M.; Chai, D. I.;
Bieler, N.; Lautens, M. The Norbornene Shuttle: Multicomponent
Domino Synthesis of Tetrasubstituted Helical Alkenes Through
Multiple C-H Functionalization. Angew. Chem., Int. Ed. 2009, 48,
1447−1451. (b) Ye, J.; Lautens, M. Palladium-Catalysed Norbornene-
Mediated C-H Functionalization of Arenes. Nat. Chem. 2015, 7, 863−
870. (c) Naveen, K.; Nikson, S. A.; Perumal, P. T. Palladium-
Catalyzed Synthesis of Tetrasubstitutd Olefins by Triple Domino
Process. Adv. Synth. Catal. 2017, 359, 2407−2413. (d) Hao, T.-T.;
Liang, H.-R.; Ou-Hang, Y.-H.; Yin, C.-Z.; Zheng, X.-L.; Yuan, M.-L.;
Li, R.-X.; Fu, H.-Y.; Chen, H. Palladium-Catalyzed Domino Reaction
for Stereoselective Synthesis of Multisubstituted Olefins: Construc-
tion of Blue Luminogens. J. Org. Chem. 2018, 83, 4441−4454.
(e) Wang, J.; Dong, G. Palladium/Norbornene Cooperative Catalysis.
Chem. Rev. 2019, 119, 7478−7528. (f) Wang, J.; Dong, Z.; Yang, C.;
Dong, G. Modular and Regioselective Synthesis of All-Carbon
Tetrasubstituted Olefins Enabled by an Alkenyl Catellani Reaction.
Nat. Chem. 2019, 11, 1106−1112.
(9) Carbometalation: Selected examples: (a) Itami, K.; Kamei, T.;
Yoshida, J.-I. Diversity-Oriented Synthesis of Tamoxifen-type
Tetrasubstituted Olefins. J. Am. Chem. Soc. 2003, 125, 14670−
14671. (b) Patel, S. J.; Jamison, T. F. Catalytic Three-Component
Coupling of Alkynes, Imines, and Organoboron Reagents. Angew.
Chem., Int. Ed. 2003, 42, 1364−1367. (c) Zhou, C.; Emrich, D. E.;
Larock, R. C. An Efficient, Regio- and Stereoselective Palladium-
Catalyzed Route to Tetrasubstituted Olefins. Org. Lett. 2003, 5,
1579−1582. (d) Zhou, C.; Larock, R. C. Regio- and Stereoselective
Route to Tetrasubstituted Olefins by the Palladium-Catalyzed Three-
Component Coupling of Aryl Iodides, Internal Alkynes, and
Arylboronic Acids. J. Org. Chem. 2005, 70, 3765−3777. (e) Zhang,
D.; Ready, J. M. Iron-Catalyzed Carbometalation of Propargylic and
Homopropargylic Alcohols. J. Am. Chem. Soc. 2006, 128, 15050−
15051. (f) Yu, H.; Richey, R. N.; Carson, M. W.; Coghlan, M. J.
Cyclocarbopalladation of Alkynes: A Stereoselective Method for
Preparing Dibenzoxapine Containing Tetrasubstituted Exocyclic
Alkenes. Org. Lett. 2006, 8, 1685−1688. (g) Nishihara, Y.; Okada,
Y.; Jiao, J.; Suetsugu, M.; Lan, M.-T.; Kinoshita, M.; Iwasaki, M.;
Takagi, K. Highly Regio- and Stereoselective Synthesis of Multi-
alkylated Olefins through Carbozirconation of Alkynylboronates and
Sequential Negishi and Suzuki-Miyaura Coupling Reactions. Angew.
Chem., Int. Ed. 2011, 50, 8660−8664. (h) Zhou, Y.; You, W.; Smith,
(2) Selected examples: (a) D’Souza, D. M.; Muschelknautz, C.;
̈
Rominger, F.; Muller, T. J. J. Highly Satisfactory Procedures for the
Pd-Catalyzed Cross Coupling of Aryl Electrophiles with in Situ
Generated Alkynylzinc Derivatives. Org. Lett. 2010, 12, 3364−3367.
(b) Nandakumar, A.; Perumal, P. T. Tetrasubstituted Olefinic
Xanthene Dyes: Synthesis via Pd-Catalyzed 6-exo-dig Cyclization/C-
H Activation of 2-Bromobenzyl-N-propargylamines and Solid State
Fluorescence Properties. Org. Lett. 2013, 15, 382−385. (c) Liu, Y.; Lv,
Y.; Xi, H.; Zhang, X.; Chen, S.; Lam, J. W. Y.; Kwok, R. T. K.;
Mahtab, F.; Kwok, H. S.; Tao, X.; Tang, B. Z. Enlarged
Tetrasubstituted Alkenes with Enhanced Thermal and Optoelectronic
Properties. Chem. Commun. 2013, 49, 7216−7218. (d) Ding, D.; Li,
K.; Liu, F.; Tang, B. Z. Bioprobes Based on AIE Fluorogens. Acc.
Chem. Res. 2013, 46, 2441−2453. (e) Mei, J.; Leung, N. L. C.; Kwok,
R. T. K.; Lam, J. W. Y.; Tang, B. Z. Aggregation-Induced Emission:
Toguether We Shine, United We Soar! Chem. Rev. 2015, 115, 11718−
11940. (f) Watson, M. A.; Cockroft, S. L. Man-Made Molecular
Machines: Membrane Bound. Chem. Soc. Rev. 2016, 45, 6118−6129.
(g) García-López, V.; Chen, F.; Nilewski, L. G.; Duret, G.; Aliyan, A.;
Kolomeisky, A. B.; Robinson, J. T.; Wang, G.; Pal, R.; Tour, J. M.
Molecular Machines Open Cell Membranes. Nature 2017, 548, 567−
572. (h) Kassem, S.; Leeuwen, T. V.; Lubbe, A. S.; Wilson, M. R.;
Feringa, B. L.; Leigh, D. A. Artificial Molecular Motors. Chem. Soc.
Rev. 2017, 46, 2592−2621. (i) Kuwahara, S.; Suzuki, Y.; Sugita, N.;
Ikeda, M.; Nagatsugi, F.; Harada, N.; Habata, Y. Thermal E/Z
Isomerization in First Generation Molecular Motors. J. Org. Chem.
2018, 83, 4800−4804.
(3) Flynn, A. B.; Ogilvie, W. W. Stereocontrolled Synthesis of
Tetrasubstituted Olefins. Chem. Rev. 2007, 107, 4698−4745.
8975
https://doi.org/10.1021/acscatal.1c01826
ACS Catal. 2021, 11, 8968−8977

ACS Catalysis
pubs.acs.org/acscatalysis
Research Article
K. B.; Brown, M. K. Copper-Catalyzed Cross-Coupling of Boronic
Esters with Aryl Iodides and Application to the Carboboration of
Alkynes and Allenes. Angew. Chem., Int. Ed. 2014, 53, 3475−3479.
(i) Xue, F.; Zhao, J.; Hor, T. S. A.; Hayashi, T. Nickel-Catalyzed
Three-Component Domino Reactions of Aryl Grignard Reagents,
Alkynes, and Aryl Halides Producing Tetrasubstiuted Alkenes. J. Am.
Chem. Soc. 2015, 137, 3189−3192. (j) Domanski, S.; Chaladaj, W. A
Broadly Applicable Method for Pd-Catalyzed Carboperfluoro-
alkylation of Terminal and Internal Alkynes: A convenient Route to
Tri- and Tetrasubstitued Olefins. ACS Catal 2016, 6, 3452−3456.
(10) Selected examples of carboarylation: (a) López, L.; Greany, M.
F. Tandem Indole C-H Alkenylation/Arylation for Tetra-Substitued
Alkene Synthesis. Chem. Commun. 2011, 47, 7992−7994. (b) Ko-
meyama, K.; Yamada, T.; Igawa, R.; Takaki, K. Borderline Metal-
Catalyzed Carboarylation of Alkynylarenes Using N,O-acetals. Chem.
Commun. 2012, 48, 6372−6374. (c) Walkinshaw, A. J.; Xu, W.; Suero,
M. G.; Gaunt, M. J. Copper-Catalyzed Carboarylation of Alkynes via
Vinyl Cations. J. Am. Chem. Soc. 2013, 135, 12532−12535. (d) Suero,
M. G.; Bayle, E. D.; Collins, B. S. L.; Gaunt, M. J. Copper-Catalyzed
Electrophilic Carbofunctionalization of Alkynes to Highly Function-
alized Tetrasubstituted Alkenes. J. Am. Chem. Soc. 2013, 135, 5332−
5335. (e) Yang, Q.; Xu, T.; Yu, Z. Iron-Mediated Carboarylation/
Cyclization of Propargylanilines with Acetals: A concise Route to
Indeno[2,1-c]quinolines. Org. Lett. 2014, 16, 6310−6313. (f) Fu, L.;
Niggemann, M. Calcium-Catalyzed Carboarylation of Alkynes.
Chem.−Eur. J. 2015, 21, 6367−6370. (g) Pérez-Saavedra, B.;
K. A General Access to Organogold(III) Complexes by Oxidative
Addition of Diazonium Salts. Chem. Commun 2016, 52, 6435−6438.
(j) Witzel, S.; Xie, J.; Rudolph, M.; Hashmi, A. S. K. Photosensitizer-
Free, Gold-Catalyzed C-C Cross-Coupling of Boronic Acids and
Diazonium Salts Enabled by Visible Light. Adv. Synth. Catal. 2017,
359, 1522−1528. (k) Deng, J.-R.; Chang, W.-C.; Lai, N. C.-H.; Yang,
B.; Tsang, C.-S.; Ko, B. C.-B.; Chan, S. L.-F.; Wong, M.-K.
Photosensitizer-Free Visible Light-Mediated Gold-Catalysed Cis-
Difunctionalization of Silyl-Substituted Alkynes. Chem. Sci. 2017, 8,
7537−7544. (l) Wang, Z.-S.; Tan, T.-D.; Wang, C.-M.; Yuan, D.-Q.;
Zhang, T.; Zhu, P.; Zhu, C.; Zhou, J.-M.; Ye, L.-W. Dual Gold/
Photoredox-Catalyzed Bis-Arylative Cyclization of Chiral Homopro-
pargyl Sulfonamides with Diazonium Salts: Rapid Access to
Enantioenriched 2,3-Dihydropyrroles. Chem. Commun. 2017, 53,
6848−6851. (m) Alcaide, B.; Almendros, P.; Busto, E.; Herrera, F.;
Lázaro-Milla, C.; Luna, A. Photopromoted Entry to Benzothiophenes,
Benzoselenophenes, 3H-Indoles, Isocumarins, Benzosultams, and
(Thio)flavones by Gold-Catalyzed Arylative Heterocyclization of
Alkynes. Adv. Synth. Catal. 2017, 359, 2640−2652. (n) Akram, M. O.;
Shinde, P. S.; Chintawar, C. C.; Patil, N. T. Gold(I)-Catalyzed Cross-
Coupling Reactions of Aryldiazonium Salts with Organostannanes.
Org. Biomol, Chem. 2018, 16, 2865−2869. (o) Barbero, M.; Dughera,
S. Gold-Catalyzed Heck-Coupling of Arenediazonium o-benzenedi-
sulfonimides. Org. Biomol. Chem. 2018, 16, 295−301. (p) Tashinski,
S.; Döpp, R.; Ackermann, M.; Rominger, F.; de Vries, F.; Menger, M.
F. S. J.; Rudolph, M.; Hashmi, A. S. K.; Klein, J. E. M. N. Light-
Induced Mechanistic Divergence in Gold(I) Catalysis: Revisiting the
Reactivity of Diazonium Salts. Angew. Chem., Int. Ed. 2019, 58,
16988−16993. (q) Jimoh, A. A.; Hosseyni, S.; Ye, X.; Wojtas, L.; Hu,
Y.; Shi, X. Gold Redox Catalysis for Cyclization/Arylation of Allylic
Oximes: Synthesis of Isoxazoline Derivatives. Chem. Commun. 2019,
55, 8150−8153. (r) Tabey, A.; Berlande, M.; Hermange, P.; Fouquet,
E. Mechanistic and Asymmetric Investigations of the Au-Catalysed
Cross-Coupling between Aryldiazonium Salts and Arylboronic Acids
Using (P,N) Gold Complexes. Chem. Commun. 2018, 54, 12867−
12870. (s) Sherborne, G. J.; Gevondian, A. G.; Funes-Ardoiz, I.; A.
Dahiya, A.; Fricke, C.; Schoenebeck, F. Modular and Selective
Arylation of Aryl Germanes (C-GeEt3) over C-Bpin, C-SiR3 and
Halogens Enabled by Light-Activated Gold Catalysis. Angew. Chem.
Int. Ed. 2020, 59, 15543−15548. (t) Mayans, J. G.; Suppo, J-S.;
Echavarren, A. M. Photoredox-assisted Gold-Catalyzed Arylative
Alkoxycyclization of 1,6-Enynes. Org. Lett. 2020, 22, 3045−3049.
(13) Recent reviews: (a) Hopkinson, M. N.; Sahoo, B.; Li, J.-L.;
Glorius, F. Dual Catalysis Sees the Light: Combining Photoredox with
Organo-, Acid, and Transition-Metal Catalysis. Chem.−Eur. J. 2014,
20, 3874−3886. (b) Zhang, M.; Zhu, C.; Ye, L.-W. Recent Advances
in Dual Visible Light Photoredox and Gold-Catalyzed Reactions.
Synthesis 2017, 49, 1150−1157. (c) Xie, J.; Jin, H.; Hashmi, A. S. K.
The Recent Achievements of Redox-Neutral Radical C-C Cross-
Coupling Enabled by Visible-Light. Chem. Soc. Rev. 2017, 46, 5193−
5203. (d) Akram, M. O.; Banerjee, S.; Saswade, S. S.; Bedi, V.; Patil,
N. T. Oxidant-Free Oxidative Gold Catalysis: The New Paradigm in
Cross-Coupling Reactions. Chem. Commun. 2018, 54, 11069−11083.
(e) Zidan, M.; Rohe, S.; McCallum, T.; Barriault, L. Recent Advances
in Mono and Binuclear Gold Photoredox Catalysis. Catal. Sci. Technol.
2018, 8, 6019−6028. (f) Nijamudheen, A.; Datta, A. Gold-Catalyzed
Cross-Coupling Reactions: An Overview of Design Strategies,
Mechanistic Studies, and Applications. Chem.−Eur. J. 2020, 26,
1442−1487. (g) Medina-Mercado, I.; Porcel, S. Insights into The
Mechanism of Gold(I) Oxidation with Aryldiazonium Salts. Chem.-
Eur. J. 2020, 26, 16206−16221. (h) Rocchigiani, L.; Bochmann, M.
Recent Advances in Gold(III) Chemistry: Structure, Bonding,
Reactivity, and Role in Homogeneous Catalysis. Chem. Rev. 2021,
Doi: DOI: 10.1021/acs.chemrev.0c00552. (i) Witzel, S.; Hashmi, S.
K.; Xie, J. Light in Gold Catalysis Chem. Rev. 2021, DOI: 10.1021/
acs.chemrev.0c00841. (j) Font, P.; Ribas, X. Fundamental Basis for
Implementign Oxidan-Free Au(I)/Au(III) Catalysis Eur. J. Inog.
Chem. 2021, DOI: 10.1002/ejic.202100301.
Vázquez-Galinanes, N.; Saá, C.; Fananás-Mastral, M. Copper(I)-
̃ ̃
Catalyzed Tandem Carboarylation/Cyclization of Alkynyl Phospho-
nates with Diaryliodonium Salts. ACS Catal 2017, 7, 6104−6109.
(h) Zhang, Q.-C.; Zhang, W.-W.; Shen, L.; Shen, Z.-L.; Loh, T.-P.
In(III)-TMSBr-Catalyzed Cascade Reaction of Diarylalkynes with
Acrylates for the Synthesis of Aryldihydronapthalene Derivatives.
Molecules 2018, 23, 979−990.
(11) (a) Asomoza-Solís, E. O.; Rojas-Ocampo, J.; Toscano, R. A.;
Porcel, S. Arenediazonium salts as electrophiles for the oxidative
addition of gold(I). Chem. Commun. 2016, 52, 7295−7298.
(b) Carrillo-Arcos, U. A.; Porcel, S. Gold promoted arylative
cyclization of alkynoic acids with arenediazonium salts. Org. Biomol.
Chem. 2018, 16, 1837−1842. (c) Medina-Mercado, I.; Asomoza-Solís,
E. O.; Martínez-González, E.; Ugalde-Saldívar, V. M.; Ledesma-
Olvera, L. G.; Barquera-Lozada, J. E.; Gómez-Vidales, V.; Barroso-
Flores, J.; Frontana-Uribe, B. A.; Porcel, S. Ascorbic Acid as an Aryl
Radical Inducer in the Gold Mediated Arylation of Indoles with
Aryldiazonium Chlorides. Chem.-Eur. J. 2020, 26, 634−642.
(12) Selected examples: (a) Sahoo, B.; Hopkinson, M. N.; Glorius,
F. Combining Gold an Photoredox Catalysis: Visible Light-Mediated
Oxy- and Aminoarylation of Alkenes. J. Am. Chem. Soc. 2013, 135,
5505−5508. (b) Shu, X.-Z.; Zhang, M.; He, Y.; Frei, H.; Toste, F. D.
Dual Visible Light Photoredox and Gold-Catalyzed Arylative Ring
Expansion. J. Am. Chem. Soc. 2014, 136, 5844−5847. (c) Patil, D. V.;
Yun, H.; Shin, S. Catalytic Cross-Coupling of Vinyl Golds with
Diazonium Salts under Photoredox and Thermal Conditions. Adv.
Synth. Catal. 2015, 357, 2622−2628. (d) Cai, R.; Lu, M.; Aguilera, E.
Y.; Xi, Y.; Akhmedov, N. G.; Peterson, J. L.; Chen, H.; Shi, X. Ligand-
Assited Gold-Catalyzed Cross-Coupling with Aryldiazonium Salts:
Redox Gold Catalysis without an External Oxidant. Angew. Chem., Int.
Ed. 2015, 54, 8772−8776. (e) Tlauext-Aca, A.; Hopkinson, M. N.;
Garza-Sánchez, R. A.; Glorius, F. Alkyne Difunctionalization by Dual
Gold/Photoredox Catalysis. Chem.−Eur. J. 2016, 22, 5909−5913.
(f) Alcaide, B.; Almendros, P.; Busto, E.; Luna, A. Domino Meyer-
Schuster/arylation Reaction of Alkynols or Alkynil Hydroperoxides
with Diazonium Salts Promoted by Visible Light under Dual Gold
and Ruthenium Catalysis. Adv. Synth. Catal. 2016, 358, 1526−1533.
(g) Kim, S.; Rojas-Martin, J.; Toste, F. D. Visible Light-Mediated
Gold-Catalysed Carbon(sp2)-Carbon(sp) Cross-Coupling. Chem. Sci.
2016, 7, 85−88. (h) Huang, L.; Rudolph, M.; Rominger, F.; Hashmi,
A. S. K. Photosensitizer-Free Visible-Light-Mediated Gold-Catalyzed
1,2-Difunctionalization of Alkynes. Angew. Chem., Int. Ed. 2016, 55,
4808−4813. (i) Huang, L.; Rominger, F.; Rudolph, M.; Hashmi, A. S.
8976
https://doi.org/10.1021/acscatal.1c01826
ACS Catal. 2021, 11, 8968−8977

ACS Catalysis
pubs.acs.org/acscatalysis
Research Article
(14) Recent reviews: (a) Pratap, R.; Ram, V. J. Natural and Synthetic
Chromenes, Fused Chromenes, and Versatility of Dihydrobenzo[h]-
Chromenes in Organic Synthesis. Chem. Rev. 2014, 114, 10476−
10526. (b) Majumdar, N.; Paul, N. D.; Mandal, S.; de Bruin, B.;
Wulff, W. D. Catalytic Synthesis of 2H-Chromenes. ACS Catal 2015,
5, 2329−2366. (c) Fazeli, A.; Pflästerer, D.; Rudolph, M.; Hashmi, A.
S. K. An Easy Access to Chromanes via the Gold-Catalyzed
Hydroarylation of Allenes. J. Organomet. Chem. 2015, 795, 68−70.
(d) Costa, M.; Dias, T. A.; Brito, A.; Proenca̧ , F. Biological
Importance of Structurally Diversified Chromenes. Eur. J. Med.
Chem. 2016, 123, 487−507. (e) Yang, Q.; Guo, R.; Wang, J. Catalytic
Asymmetric Syntheses of 2-Aryl Chromenes. Asian J. Org. Chem.
2019, 8, 1742−1765.
(15) (a) Hashmi, A. S. K. Homogeneous Gold Catalysis Beyond
Assumptions and Proposals-Characterized Intermediates. Angew.
Chem., Int. Ed. 2010, 49, 5232−5241. (b) Lauterbach, T.; Asiri, A.
M.; Hashmi, A. S. K. Organometallic Intermediates of Gold Catalysis.
In Advances in Organometallic Chemistry; 2014; Vol. 62, pp 261−297.
(16) To see anion effects on reaction of aryldiazonium salts with
gold see: Peng, H.; Cai, R.; Xu, C.; Chen, H.; Shi, X. Nucleophile
Promoted Gold Redox Catalysis with Diazonium Salts: C-Br, C-S and
C-P Bond Formation Through Catalytic Sandmeyer Coupling. Chem.
Sci. 2016, 7, 6190−6196.
(17) Nogueira, B. A.; Castiglioni, C.; Fausto, R. Color Poly-
morphism in Organic Crystals. Commun. Chem. 2020, 3, No. 34.
(18) Daszkiewicz, M. Importance of O···N Interaction Between
Nitro Groups in Crystals. CrystEngComm 2013, 15, No. 10427.
(19) Cruz-Cabeza, A. J.; Bernstein, J. Conformational Poly-
morphism. Chem. Rev. 2014, 114, 2170−2191.
(20) Recently have been described related 1,2-diarylation of alkenes:
(a) Chintawar, C. C.; Yadav, A. K.; Patil, N. T. Gold-Catalyzed 1,2-
Diarylation of Alkenes. Angew. Chem., Int. Ed. 2020, 59, 11808−
11813. (b) Rigoulet, M.; Thillaye du Boullay, O.; Amgoune, A.;
Bourissou, D. Gold(I)/Gold(III) Catalysis that Merges Oxidative
Addition and π-Alkene Activation. Angew. Chem., Int. Ed. 2020, 59,
16625−16630.
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ACS Catal. 2021, 11, 8968−8977