Lewis Acid-Driven Meyer-Schuster-Type Rearrangement of Yne-Dienone

Article abstract of DOI:10.1021/acs.joc.1c00290

Developed herein is a Cu(II)-catalyzed Meyer-Schuster-type rearrangement of alkyne-tethered cyclohexadienone for the construction of m-enone-substituted phenols. The reaction involves an uncommon 5-exo-trig 1,6-enyne cyclization of alkyne-tethered-cyclohexadienone, aromatization-triggered C-O bond cleavage, and an electrocyclic 4π-ring-opening of oxetene intermediate. This atom-efficient transformation provides access to a wide range of synthetically important α-(m-substituted phenol)-α,β-unsaturated ketones, featuring a broad scope with labile functional group tolerance. The gram-scale demonstration makes this transformation synthetically viable. The synthetic application of α,β-unsaturated ketones is also showcased.

Full text of DOI:10.1021/acs.joc.1c00290

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Article
Lewis Acid-Driven Meyer−Schuster-Type Rearrangement of Yne-
Dienone
Rajendra K. Mallick, Srinivas Vangara, Nagarjuna Kommu, Tirumaleswararao Guntreddi,
and Akhila K. Sahoo*
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ABSTRACT: Developed herein is a Cu(II)-catalyzed Meyer−
Schuster-type rearrangement of alkyne-tethered cyclohexadienone
for the construction of m-enone-substituted phenols. The reaction
involves an uncommon 5-exo-trig 1,6-enyne cyclization of alkyne-
tethered-cyclohexadienone, aromatization-triggered C−O bond
cleavage, and an electrocyclic 4π-ring-opening of oxetene inter-
mediate. This atom-efficient transformation provides access to a
wide range of synthetically important α-(m-substituted phenol)-α,β-
unsaturated ketones, featuring a broad scope with labile functional group tolerance. The gram-scale demonstration makes this
transformation synthetically viable. The synthetic application of α,β-unsaturated ketones is also showcased.
Scheme 1. Previous Work and Current Hypothesis
INTRODUCTION
■
Propargyl alcohols have been largely used for the development
of novel synthetic transformations and the fabrication of
complex molecular scaffolds.1,2 In this regard, the atom-efficient
conversion of propargyl alcohol I to α,β-unsaturated carbonyl
compound II is a trustworthy testimony of the classical Meyer−
Schuster rearrangement (MSR; Scheme 1a).3 This trans-
formation primarily involves an acid-catalyzed 1,3-hydroxy
shift and tautomerization sequence of propargyl alcohol
(Scheme 1a). Over the years, new variants of electrophile-
intercepted MSRs have been developed, and their synthetic
potential has been significantly widened.4,5 Thus, transition-
metal (TM)/Lewis acid (LA)-catalyzed halo/aryl/CF3/NO2-
intercepted MSRs have led to diverse arrays of α-functionalized
enones (Scheme 1a).5 Among all, the aryl-electrophile (available
from the respective boronic acids, diazonium salts, hypervalent
iodine complexes, etc.)-intercepted MSRs of propargyl alcohols
are noteworthy, leading to highly functionalized α-arylated
enones (Scheme 1a).5d,e However, such transformations are
possible in the presence of external electrophiles, expensive
metal catalysts, and ligands.
Along this line, yne-dienones 1 are unequivocally important as
these moieties have been largely used for the development of
novel synthetic methods and the construction of unusual fused
heteroaryls.6 In this line, the transition-metal (TM)-catalyzed
arylative/borylative/silylative/reductive and acetate-triggered
cyclizations of yne-dienones are most significant (Scheme
1b).7,8 These reactions primarily happen via nucleophile/
radical-assisted 5-exo-trig/6-exo-trig cyclizations of yne-dien-
ones to make [5,6]/[6,6]-fused heterocycles IV/V, respectively
(Scheme 1b).
Received: February 5, 2021
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© XXXX American Chemical Society
A

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Further to the recent demonstration on the thioarylative
radical cyclization of yne-dienones,9 a Lewis acid-driven
cyclization−aromatization−rearrangement cascade of 1 is
envisaged (Scheme 1c). Inspired by the MSR of propargyl
alcohols,3a the O-bridged alkyne-tethered-cyclohexadienones 1
in the presence of Lewis acid could undergo an intramolecular 6-
exo-trig/5-exo-trig Michael attack by the tethered alkyne to
respectively generate alkyl enabled vinyl carbocation VI and aryl
stabilized vinyl carbocation VII (Scheme 1c). Next, aromatiza-
tion of the stable intermediate VII with the concomitant
cleavage of the C−O bond could form a strained oxetene species
(see Scheme 6). Finally, rearrangement of oxetene could provide
access to peripheral decorated m-enone-substituted phenols 2
[Baylis−Hillman−Basavaiah (BHB) type adduct],10 which are
otherwise difficult to prepare in a conventional synthetic method
(Scheme 1c). Despite the broad synthetic transformations
uncovered in MSRs, a detailed investigation on the current
findings α-arylative MSR is yet to be explored in detail. During
the preparation of this manuscript, a silver(I)-catalyzed and
TfOH-mediated cyclization-aromatization cascade of alkyne-
tethered-cyclohexadienone has recently been appeared.11
yields, respectively (entries 2, 3, and 4). To our delight, the
compound 2a was obtained in 75% yield when the reaction was
conducted in Cu(OTf)2 (10 mol %) at 85 °C for 12 h (entry 5).
In the absence of catalyst, 2a was not even formed (entry 6). The
product yield was not enhanced when the reaction was carried
out in ClCH2CH2Cl, 1,4-dioxane, toluene, and/or CHCl3
solvents (entries 7−10). However, the reaction under the
identical condition of entry 5 in 5 h affected product formation
affording 30% 2a (entry 11). The reaction at room temperature
did not proceed (entry 12), whereas, at 60 °C, a trace of 2a was
detected (entry 13). To our delight, the reaction was clean at 95
°C providing access to 2a in 98% yield (entry 14). Thus,
rearrangement of 1a was very smooth when conducted in the
presence of Cu(OTf)2 (10 mol %) in THF at 95 °C for 12 h
(entry 14). We next scrutinized various copper salts and
Brønsted acid catalysts. The reaction in the presence of 10 mol %
CuOTf−toluene delivered the desired product in 64% yield
(entry 15). Disappointingly, Cu(MeCN)4PF6 and CuCl
catalysts were not suitable (entries 16 and 17). However, the
reaction in the presence of Brønsted acids (TfOH and Tf2NH)
successfully delivered the product 2a in 72% and 74% yields,
respectively (entries 18 and 19).
The scope and limitation of the Cu(OTf)2-catalyzed
rearrangement of alkyne-tethered-cyclohexadienones 1 were
explored, and the results are shown in Schemes 2 and 3. The
rearrangement of 1a (0.3 mmol) was smooth to afford 95% of
2a. The electron-rich arenes (having substituents p-Me/p-
OMe/p-tBu) on alkyne terminus of yne-dienones 1b−d
RESULTS AND DISCUSSION
■
To make the envisioned plan workable, 4-methyl-4-((3-
phenylprop-2-yn-1-yl)oxy)cyclohexa-2,5-dienone (1a) was ex-
posed to various Lewis acids (Table 1). At first, subjecting 1a
with Sc(OTf)3 (10 mol %) in tetrahydrofuran (THF) at 85 °C
for 12 h led to α,β-unsaturated enone rearranged product 2a in
63% yield (entry 1). Screening other Lewis acids, Yb(OTf)3,
Fe(OTf)3, and In(OTf)3, provided 2a in 73%, 54%, and 66%
a
Scheme 2. Substrate Scope I
a b
,
Table 1. Optimization of Reaction Conditions
entry
catalyst
Sc(OTf)3
Yb(OTf)3
Fe(OTf)3
In(OTf)3
Cu(OTf)2
solvent
THF
THF
THF
THF
temp (°C)
yield
1
2
3
4
5
85
85
85
85
85
85
85
85
85
85
85
rt
60
95
95
95
95
95
95
63
73
54
66
75
THF
THF
c
6
c
no reaction
trace
42
no reaction
trace
30
no reaction
trace
98
7
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
CuOTf−toluene
Cu(MeCN)4PF6
CuCl
ClCH2CH2Cl
1,4-dioxane
toluene
CHCl3
THF
THF
THF
THF
THF
THF
THF
THF
THF
8
9
c
c
10
11
12
13
d
c
c
14
15
16
17
18
19
e
64
c
trace
trace
72
c
ef
,
TfOH
Tf2NH
ef
,
74
a
Reactions were carried out using 1a (0.06 mmol), Lewis acid (10
b
c
a
mol %), and solvent (0.1 M) for 12 h. Crude NMR yield. Observed
by TLC. Reaction stopped in 5 h. Reaction was carried out using 1a
(0.3 mmol) and isolated yield. Brønsted acid (20 mol %) was used.
Reactions were carried out using 1 (0.3 mmol), Cu(OTf)2 (10 mol
d
e
b
%), in THF (0.1 M; 3 mL) at 95 °C for 12 h. Stirred for 36 h.
f
c
Unreacted starting precursor recovered.
B
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a
heteroaryl-enabled yne-dienone 1r, leading to 2-thienyl-bearing
enones 2r in a quantitative yield (Scheme 3). The alkyne-
cyclohexadienone with various alkyl substituents at the angular
position [for example, ethyl (1s), n-propyl (1t), and n-pentyl
(1u)] smoothly underwent cyclization−aromatization−rear-
rangement cascade to furnish the desired BHB-type adducts 2s−
u in good yields (Scheme 3). A tetrasubstituted phenol
derivative, 2v, with a m-enone motif was successfully made in
85% yield. Likewise, yne-dienone 1w with the bulky-phenyl
group on the angular position successfully participated in the
rearrangement to provide the desired product 2w in 66% yield.
To our disappointment, compound 1x (having a methoxy group
in the angular position of yne-dienone) decomposed during the
course of the reaction. Overall, the present demonstration is
comparatively productive and effective over the complementary
method.11 In addition, the electron-rich alkyne-containing yne-
dienone delivers the best result; this information supports the
involvement of a cationic intermediate in this transformation.
To further study the scope and limitations of α-aryl-α,β-
unsaturated ketones 2, the reaction was performed with yne-
dienone 1 having substituents at the α-position (Scheme 4). In
Scheme 3. Substrate Scope II
a b
,
Scheme 4. Substrate Scope III
a
Reactions were carried out using 1 (0.3 mmol), Cu(OTf)2 (10 mol
b
%), in THF (0.1 M; 3 mL) at 95 °C for 12 h. Unreacted starting
precursor recovered.
a
Reactions were carried out using 1aa−ac (0.3 mmol), Cu(OTf)2 (10
successfully underwent the cationic rearrangement to deliver the
respective products 2b−d in excellent yields (94−97%; Scheme
2). Although the reaction took a longer time, 36 h for
completion, the desired product 2e (62%) was isolated in a
moderate yield from the electron-deficient p-COMe arene-
enabled 1e. Presumably, the substituent −I effect affects the
stability of vinyl carbocation intermediates and the reaction
productivity. Likewise, Cu(OTf)2-catalyzed rearrangement of
yne-dienones 1f−i, having halo-substitution −F/Cl/Br/I on the
p-position of arenes in alkyne terminus, provided 2f−i in 58−
80% yields (Scheme 2); the labile halo groups survived under
the catalytic conditions, and hence, further functionalization of
these groups is possible. The yne-dienones 1j−m exhibiting m-
Me or the transformable halo (m-F/m-Cl/m-I) at the arene
moiety also reacted well to furnish the corresponding meta-
substituted phenols 2j−m in 54−78% yields (Scheme 2).
To further examine the effect of steric bulkiness in this
cyclization−aromatization−rearrangement cascade, the reac-
tion of alkyne-tethered-cyclohexadienones with ortho-substi-
tuted arene [o-Me (1n) and o-OMe (1o)] on the alkyne
terminus was carried out under the optimized conditions that
lead to 2n (75%) and 2o (99%), respectively (Scheme 3),
whereas the transformable o-Cl arene-substituted yne-dienone
1p delivered 2p, albeit in a moderate yield. An excellent product
yield of 2q was isolated from 1q (the m,p-dimethyl arene-
substituted yne-dienone). The reaction was compatible with the
b
mol %), in THF (0.1 M; 3 mL) at 95 °C for 12 h. The diasteriomeric
ratio was calculated by H NMR analysis.
1
this context, the reaction of a sterically encumbered ortho-Me-
substituted yne-dienone 1aa under the optimized conditions
delivered the desired product 2aa in 75% yield as a single E-
isomer (Scheme 4). Similarly, the yne-dienone 1ab having ortho-
OMe on the arene terminus provided 2ab in 73% yield as an
inseparable mixture of diastereomers (E/Z 76:24). The
respective major adduct 2ac (E-isomer) was obtained from
1ac (Scheme 4). The structure of 2ac was further confirmed by
single-crystal X-ray analysis (Scheme 4).
To expand the synthetic versatility of α-aryl-α,β-unsaturated
ketones, common organic transformations were performed on
2a/2c (Scheme 5a). For instance, the BrØnsted acid (TfOH)-
mediated intramolecular electrophilic cyclization of enone 2a
delivered 2-arylated-2,3-dihydro-indenone 3 in 63% yield
(Scheme 5a).12 Next, NaBH4-mediated reduction of olefin
moiety of 2c in MeOH led to aryl-alkyl ketone 4 in 68% yield
(Scheme 5a).13 Moreover, thioether 5 (91%) was constructed
from the Michael addition of p-tolylthiol to 2c (Scheme 5a).14
Finally, peroxide-mediated epoxidation of electron-deficient
olefin in 2c furnished the desired product 6 in 98% yield
(Scheme 5a).15 The catalytic system developed for the
rearrangement of 1 to 2 was robust; the gram-scale conversion
C
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Scheme 5. Applications and Reaction Scalability
of 1a (1.0 g) → 2a (0.9 g, 90%) and 1c (1.0 g) → 2c (0.93 g,
93%) under standard conditions justified the synthetic potential
of the current strategy (Scheme 5b).
To understand the major Van der Waals interactions of α-aryl-
α,β-unsaturated ketones, we have carried out Hirshfeld surface
analysis16 and 2D-fingerprint plots of compounds 2b and 2v, the
images (a, e) in Figure 1; the deep red circles indicate strong
intermolecular interactions (O···H/H···O), and other spots are
due to H···H and C···H/H···C interactions. The 2D-fingerprint
plots (b, f) in Figure 1 denote a pair of spikes at the bottom left,
which indicates strong O···H and H···O interactions. The H···H
and C···H/H···C interactions are scattered in the middle of the
2D-fingerprint plots. The 2D-fingerprint images (c, g) show H···
H (2b, 53.8%; 2v, 56.2%) contacts and contribute to the total
Hirshfeld surface. The presence of an additional methyl group in
compound 2v increases H···H interactions by 2.4% than
compound 2b. The individual atomic contact distributions of
2b and 2v are shown in images d and h in Figure 1. Hence, these
studies disclose the stabilization of crystal lattices 2b and 2v by
three main interactions: H···H, O···H/H···O, and C···H/H···C.
Based on the experimental facts and the literature reports, the
electronic factor controls the reaction dynamics. The plausible
mechanism is depicted in Scheme 6. The transformation begins
with the activation of enone by Cu(OTf)2 to form the activated
complex VIII.17 Next, intramolecular 5-exo-trig Michael attack
of alkyne to the activated-olefin of VIII gives aryl-stabilized
vinyl-carbocation intermediate IX. The aromatization triggered
C−O bond cleavage, and intramolecular charged recombination
generates an unstable oxa-cyclobutene intermediate X. Finally,
electrocyclic 4π-ring-opening of X produces the desired product
2 and regenerates the active catalyst for the next cycle.
Figure 1. Hirshfeld surface plots for compounds 2b and 2v in the crystal
structures. Images a and e are the Hirshfeld surface graphs with
proximity of close contacts around 2b and 2v molecules. Images b and f
are 2D-fingerprint plots in crystal packing found in 2b and 2v. Images c
and g are the H···H atomic contact percentage contribution to the
Hirshfeld surface for 2b and 2v molecules. Images d and h are the
percentage contributions of the individual atomic contacts to the
Hirshfeld surface for compounds 2b and 2v.
Scheme 6. Plausible Mechanism
CONCLUSION
■
In summary, a Cu-catalyzed α-arylative MSR of yne-dienones
for the synthesis of m-enone-substituted phenol derivatives has
been developed. The labile halo groups, heteroaryl systems, and
the aliphatic chains did not affect the reaction outcome and were
well tolerated. The overall process is atom-efficient, providing
D
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added aryliodide (1.2 mmol) under a nitrogen atmosphere. Finally,
triethylamine (3.0 mmol, 0.42 mL) was added to the above mixture, and
the resulting mixture was stirred at room temperature overnight. After
completion, the reaction mixture was filtered, concentrated in vacuo,
and purified by silica gel (100−200 mesh) column chromatography to
give the desired alkynyl cyclohexadienones 1a−ac. The analytical and
spectral data for compounds 1a−c, 1e−h, 1j−k, 1m, 1n, 1p, 1r−t, 1v,
and 1w exactly match the reported values.
4-((3-(4-(tert-Butyl)phenyl)prop-2-yn-1-yl)oxy)-4-methylcyclo-
hexa-2,5-dienone (1d). Compound 1d (153 mg) was obtained in 52%
yield: brown solid; mp = 93−95 °C; Rf = 0.40 (9:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.36−7.30 (m, 4H),
6.89 (dt, J = 10, 3.0 Hz, 2H), 6.32 (dt, J = 10, 3.5 Hz, 2H), 4.22 (s, 2H),
1.49 (s, 3H), 1.29 (s, 9H); 13C{1H} NMR (126 MHz, CDCl3) δ 185.0,
151.8, 151.0, 131.4, 130.3, 125.2, 119.3, 87.0, 85.1, 73.2, 54.6, 34.7,
31.1, 26.4; IR (neat) νmax 2964, 1661, 1604, 1512, 1452, 1369, 1274,
1194 cm−1; HRMS (ESI) m/z [M + H]+ calcd for C20H23O2+ 295.1693,
found 295.1703.
4-((3-(4-Iodophenyl)prop-2-yn-1-yl)oxy)-4-methylcyclohexa-2,5-
dienone (1i). Compound 1i (149 mg) was obtained in 41% yield:
colorless solid; mp = 117−119 °C; Rf = 0.31 (9:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.63 (dt, J = 8.5, 2.0
Hz, 2H), 7.12 (dt, J = 8.5, 2.0 Hz, 2H), 6.86 (dt, J = 10.5, 3.0 Hz, 2H),
6.32 (dt, J = 10, 3.5 Hz, 2H), 4.19 (s, 2H), 1.49 (s, 3H); 13C{1H} NMR
(126 MHz, CDCl3) δ 184.9, 150.7, 137.5, 133.1, 130.4, 121.8, 94.6,
87.1, 85.8, 73.2, 54.4, 26.3; IR (neat) νmax 2986, 2230, 1657, 1627, 1477,
1452, 1452, 1385, 1299, 1264, 1188 cm−1; HRMS (ESI) m/z [M + H]+
calcd for C16H14IO2+ 365.0033, found 365.0038.
4-((3-(3-Chlorophenyl)prop-2-yn-1-yl)oxy)-4-methylcyclohexa-
2,5-dienone (1l). Compound 1l (196 mg) was obtained in 72% yield:
brown solid; mp = 76−78 °C; Rf = 0.35 (9:1 hexane/EtOAc) [silica,
UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.38 (s, 1H), 7.30−7.27
(m, 2H), 7.23 (d, J = 8.0 Hz, 1H), 6.86 (dt, J = 10.5, 3.0 Hz, 2H), 6.32
(dt, J = 10, 3.5 Hz, 2H), 4.20 (s, 2H), 1.49 (s, 3H); 13C{1H} NMR (126
MHz, CDCl3) δ 184.9, 150.7, 134.1, 131.5, 130.4, 129.8, 129.5, 128.9,
124.0, 87.0, 85.3, 73.2, 54.3, 26.3; IR (neat) νmax 2983, 1661, 1621,
1595, 1484, 1398, 1372, 1299, 1198 cm−1; HRMS (ESI) m/z [M + H]+
calcd for C16H14ClO2+ 273.0677, found 273.0683.
access to a wide range of novel peripheral decorated m-phenol
derivatives in excellent yields. The transformation is also
scalable. Common synthetic transformations of enones make
this strategy synthetically useful.
EXPERIMENTAL SECTION
■
General Information. All reactions were performed in oven-dried
reaction vials under a nitrogen atmosphere. Commercial grade solvents
were distilled prior to use. Column chromatography was performed
using silica gel (100−200 Mesh) with a hexane and ethyl acetate
mixture. Thin-layer chromatography (TLC) was performed on silica gel
GF 254 plates. Visualization of spots on the TLC plate was
accomplished with UV light (254 nm) and staining over an I2 chamber.
Proton and carbon nuclear magnetic resonance spectra (1H NMR,
13C NMR, and 19F NMR) were recorded on a 400 MHz (1H NMR, 400
MHz; 13C NMR, 101 MHz; 19F NMR, 376 MHz) spectrometer, 500
MHz (1H NMR, 500 MHz; 13C NMR, 126 MHz; 19F NMR, 471 MHz)
spectrometer, and a 600 MHz (1H NMR, 600 MHz; 13C NMR, 151
MHz) spectrometer, having solvent resonance as an internal standard
(1H NMR, CHCl3 at 7.26 ppm; 13C NMR, CDCl3 at 77.0 ppm). In a
few cases, tetramethylsilane (TMS) at 0.00 ppm was used as an
reference standard. Data for 1H NMR are reported as follows: chemical
shift (ppm), multiplicity (s = singlet; br s = broad singlet; d = doublet;
bd = broad doublet, dd= doublet of doublet, dt = doublet of triplet, tt =
triplet of triplet, t = triplet; bt = broad triplet; q = quartet; pent = pentet,
m = multiplet), coupling constants J, in (Hz), and integration.
13C NMR and 19F NMR were reported in terms of chemical shift
(ppm). IR spectra were recorded on an FT/IR spectrometer and are
reported in cm−1. High-resolution mass spectra (HRMS) were
obtained in ESI mode by using a TOF analyzer. Melting points were
determined by electrothermal heating and are uncorrected. X-ray data
was collected at 298 and 296 K on a Bruker D8 Quest CCD and Bruker
D8 VENTURE Photon III detector diffractometer using Mo Kα
radiation (0.71073 Å).
Materials. Unless otherwise noted, all reagents and intermediates
were obtained commercially and used without purification. Toluene,
1,2-dichloroethane, 1,4-dioxane, chloroform, ethyl acetate, and hexane
were distilled over CaH2. THF was freshly distilled over sodium/
benzophenone ketyl under dry nitrogen. Cu(OTf)2, Sc(OTf)3,
Fe(OTf)3, In(OTf)3, Yb(OTf)3, triflic acid (TfOH), sodium
borohydride (NaBH4), p-thiocresol, triethylamine (Et3N), 30% aq
H2O2, sodium hydroxide (NaOH) pellets, methanol (CH3OH), p-
cresol, propargyl alcohol, iodosobenzene diacetate, CuI, and
PdCl2(PPh3)2 were commercially available and used as received. Aryl
iodides were purchased and used as such. Following the known
procedure,8c,9,18,19 compounds 1a−ac were synthesized. Analytical and
spectral data of all those known compounds exactly match the reported
values.
4-((3-(2-Methoxyphenyl)prop-2-yn-1-yl)oxy)-4-methylcyclohexa-
2,5-dienone (1o). Compound 1o (169 mg) was obtained in 63% yield:
colorless solid; mp = 124−126 °C; Rf = 0.20 (9:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.37 (dd, J = 7.5, 2.0
Hz, 1H), 7.31−7.27 (m, 1H), 6.94−6.88 (m, 3H), 6.86 (d, J = 8.5 Hz,
1H), 6.32 (dt, J = 10, 3.0 Hz, 2H), 4.28 (s, 2H), 3.86 (s, 3H), 1.50 (s,
3H); 13C{1H} NMR (126 MHz, CDCl3) δ 185.1, 160.2, 151.2, 133.7,
130.3, 130.0, 120.4, 111.6, 110.6, 90.0, 83.3, 73.3, 55.7, 54.8, 26.4; IR
(neat) νmax 2919, 2227, 1668, 1624, 1595, 1499, 1452, 1267, 1245, 1185
+
cm−1; HRMS (ESI) m/z [M + H]+ calcd for C17H17O3 269.1172,
found 269.1179.
General Method for the Preparation of Starting Materials.
4-((3-(3,4-Dimethylphenyl)prop-2-yn-1-yl)oxy)-4-methylcyclo-
hexa-2,5-dienone (1q). Compound 1q (120 mg) was obtained in 45%
yield: gray solid; mp = 142−144 °C; Rf = 0.38 (9:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.19 (s, 1H), 7.15
(d, J = 8.0 Hz, 1H), 7.05 (d, J = 8.0 Hz, 1H), 6.89 (dt, J = 10, 3.5 Hz,
2H), 6.32 (dt, J = 10, 3.0 Hz, 2H), 4.21 (s, 2H), 2.24 (s, 3H), 2.21 (s,
3H), 1.49 (s, 3H); 13C{1H} NMR (126 MHz, CDCl3) δ 185.1, 151.1,
137.5, 136.6, 132.7, 130.3, 129.5, 129.1, 119.6, 87.1, 84.8, 73.1, 54.6,
26.4, 19.7, 19.5; IR (neat) νmax 2932, 2224, 1662, 1627, 1493, 1449,
1372, 1309, 1245, 1182 cm−1; HRMS (ESI) m/z [M + H]+ calcd for
C18H19O2+ 267.1380, found 267.1389.
4-Pentyl-4-((3-phenylprop-2-yn-1-yl)oxy)cyclohexa-2,5-dienone
(1u). Compound 1u (218 mg) was obtained in 74% yield: colorless
solid; mp = 64−66 °C; Rf = 0.53 (9:1 hexane/EtOAc) [silica, UV, and
I2]; 1H NMR (500 MHz, CDCl3) δ 7.42−7.39 (m, 2H), 7.32−7.28 (m,
3H), 6.85 (dt, J = 10, 3.0 Hz, 2H), 6.37 (dt, J = 10.5, 3.0 Hz, 2H), 4.23
(s, 2H), 1.82−1.77 (m, 2H), 1.29−1.22 (m, 6H), 0.85 (t, J = 6.5 Hz,
3H); 13C{1H} NMR (126 MHz, CDCl3) δ 185.4, 150.4, 131.6, 131.3,
128.5, 128.2, 122.4, 86.7, 85.9, 76.4, 54.3, 39.3, 31.8, 23.1, 22.3, 13.9; IR
(neat) νmax 2964, 2932, 1662, 1621, 1496, 1449, 1374, 1334, 1264, 1182
General Procedure for the Synthesis of 1″ (GP-1). To a stirred
solution of 4-substituted phenol 1′ (10 mmol) in 10 mL of propargyl
alcohol was added phenyliodo(III)diacetate (15 mmol) in several
portions at 0 °C. The resulting reaction mixture was warmed to room
temperature and stirred overnight. Then the reaction was quenched
with saturated aqueous sodium bicarbonate (30 mL) and extracted with
ethyl acetate (3 × 20 mL). The combined organic layer was washed
with brine (20 mL), dried over Na2SO4, filtered, and concentrated in
vacuo. The crude reaction mixture was purified by silica gel (100−200
mesh) column chromatography (EtOAc/hexane) to give the respective
terminal cyclohexadienones 1″.
General Procedure for the Synthesis of Alkynyl Cyclohexadienone
1a−ac (GP-2):.8c,9,18,19 To a solution of 1″ (1.0 mmol), Pd(PPh3)2Cl2
(2.0 mol %, 14 mg), and CuI (4.0 mol %, 7.6 mg) in THF (2.0 mL) was
E
https://doi.org/10.1021/acs.joc.1c00290
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The Journal of Organic Chemistry
pubs.acs.org/joc
Article
+
cm−1; HRMS (ESI) m/z [M + H]+ calcd for C20H23O2 295.1693,
found 295.1704.
1-(4-Fluorophenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-en-1-
one (2f). Following the general procedure, compound 2f (62 mg) was
obtained in 80% yield: colorless liquid; Rf = 0.64 (4:1 hexane/EtOAc)
[silica, UV, and I2]; H NMR (500 MHz, CDCl3): δ 7.95−7.89 (m,
General Procedure for the Synthesis of α-Aryl-α,β-unsaturated
Ketones 2. A mixture of alkynyl-cyclohexadienone 1 (0.3 mmol) and
Cu(OTf)2 (11 mg, 0.03 mmol) in THF (3.0 mL) was taken in a screw-
cap sealed tube. The reaction mixture was heated to 95 °C and stirred
overnight. The reaction progress was monitored by thin-layer
chromatography (TLC) analysis. Upon completion, the reaction
mixture was cooled to room temperature and diluted with dichloro-
methane (3.0 mL). The crude residue was purified using column
chromatography on silica gel (100−200 mesh) to provide desired α-
aryl-α,β-unsaturated ketones 2.
1
2H), 7.13−7.07 (m, 2H), 6.96 (d, J = 8.0 Hz, 1H), 6.73 (d, J = 2.5 Hz,
1H), 6.69 (dd, J = 8.0, 2.5 Hz, 1H), 6.33 (s, 1H), 5.96 (d, J = 0.5 Hz,
1H), 5.93 (d, J = 0.5 Hz, 1H), 2.07 (s, 3H); 13C{1H} NMR (126 MHz,
CDCl3) δ 195.7, 165.6 (d, J = 256 Hz, 1C), 154.1, 148.7, 138.7, 133.1
(d, J = 2.5 Hz, 1C), 132.5 (d, J = 10 Hz, 1C), 131.3, 128.0, 127.1, 116.8,
115.6, 115.4, 19.4; 19F NMR (471 MHz, CDCl3) δ − 104.9; IR (neat)
νmax 3368, 2923, 1643, 1596, 1502, 1282, 1228, 1154 cm−1; HRMS
(ESI) m/z [M + H]+ calcd for C16H14FO2+ 257.0972, found 257.0977.
1-(4-Chlorophenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-en-1-
one (2g). Following the general procedure, compound 2g (61 mg) was
obtained in 75% yield: pale yellow solid; mp = 131−134 °C; Rf = 0.50
(4:1 hexane/EtOAc) [silica, UV, and I2]; 1H NMR (400 MHz, CDCl3)
δ 7.81 (dd, J = 8.4, 1.6 Hz, 2H), 7.39 (dd, J = 8.4, 1.6 Hz, 2H), 6.96 (d, J
= 8.0 Hz, 1H), 6.73 (d, J = 2.8 Hz, 1H), 6.68 (dd, J = 8.4, 2.4 Hz, 1H),
6.33 (bs, 1H), 5.97 (s, 1H), 5.94 (s, 1H), 2.07 (s, 3H); 13C{1H} NMR
(101 MHz, CDCl3) δ 195.9, 154.0, 148.6, 139.3, 138.6, 135.1, 131.3,
131.2, 128.7, 128.4, 127.1, 116.7, 115.6, 19.4; IR (neat) νmax 3361,
2922, 1630, 1602, 1583, 1562, 1498, 1432, 1400, 1346, 1284, 1207
cm−1; HRMS (ESI) m/z [M + H]+ calcd for C16H14ClO2+ 273.0677,
found 273.0683.
2-(5-Hydroxy-2-methylphenyl)-1-phenylprop-2-en-1-one (2a).
Following the general procedure, compound 2a (68 mg) was obtained
in 95% yield: yellow gummy liquid; Rf = 0.54 (4:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (600 MHz, CDCl3) δ 7.88 (d, J = 7.8 Hz,
2H), 7.56 (t, J = 7.2 Hz, 1H), 7.45 (t, J = 7.2 Hz, 2H), 7.00 (d, J = 7.2
Hz, 1H), 6.76 (d, J = 2.4 Hz, 1H), 6.72 (dd, J = 7.8, 3.0 Hz, 1H), 6.00 (s,
1H), 5.97 (s, 1H), 5.09 (s, 1H), 2.12 (s, 3H); 13C{1H} NMR (126
MHz, CDCl3) δ 197.3, 154.1, 148.8, 138.8, 136.9, 132.8, 131.2, 129.8,
128.4, 128.3, 127.0, 116.8, 115.5, 19.4; IR (neat) νmax 3368, 3058, 2922,
1649, 1596, 1576, 1495, 1446, 1281, 1253, 1228 cm−1; HRMS (ESI)
m/z [M + H]+ calcd for C16H15O2+ 239.1067, found 239.1073.
2-(5-Hydroxy-2-methylphenyl)-1-(p-tolyl)prop-2-en-1-one (2b).
Following the general procedure, compound 2b (73 mg) was obtained
in 96% yield: colorless solid; mp = 148−151 °C; Rf = 0.46 (4:1 hexane/
EtOAc) [silica, UV, and I2]; 1H NMR (400 MHz, CDCl3) δ 7.81 (dd, J
= 8.4, 1.6 Hz, 2H), 7.23 (d, J = 8.0 Hz, 2H), 6.95 (d, J = 8.0 Hz, 1H),
6.74 (bd, J = 2.4 Hz, 1H), 6.68 (dd, J = 8.4, 2.8 Hz, 1H), 6.40 (bs, 1H),
5.94 (s, 1H), 5.92 (s, 1H), 2.41 (s, 3H), 2.09 (s, 3H); 13C{1H} NMR
(101 MHz, CDCl3) δ 197.1, 154.1, 148.9, 143.8, 139.0, 134.2, 131.2,
130.1, 129.0, 127.7, 127.0, 116.9, 115.5, 21.6, 19.5; IR (neat) νmax 3331,
3031, 2920, 1631, 1597, 1563, 1498, 1437, 1408, 1286, 1218 cm−1;
1-(4-Bromophenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-en-1-
one (2h). Following the general procedure, compound 2h (55 mg) was
obtained in 58% yield: yellow solid; mp = 157−160 °C; Rf = 0.50 (4:1
1
hexane/EtOAc) [silica, UV, and I2]; H NMR (400 MHz, CDCl3) δ
7.73 (d, J = 8.8 Hz, 2H), 7.57 (d, J = 8.8 Hz, 2H), 6.97 (d, J = 8.0 Hz,
1H), 6.73 (bd, J = 2.8 Hz, 1H), 6.69 (dd, J = 8.0, 2.8 Hz, 1H), 5.98 (d, J
= 0.8 Hz, 1H), 5.95 (d, J = 0.8 Hz, 1H), 2.07 (s, 3H); 13C{1H} NMR
(101 MHz, CDCl3) δ 195.9, 154.0, 148.6, 138.7, 135.6, 131.7, 131.4,
131.3, 128.4, 128.0, 127.2, 116.7, 115.6, 19.4; IR (neat) νmax 3359,
2922, 1628, 1603, 1580, 1497, 1451, 1398, 1283, 1254 cm−1; HRMS
+
HRMS (ESI) m/z [M + H]+ calcd for C17H17O2 253.1223, found
+
(ESI) m/z [M + Na]+ calcd for C16H13BrNaO2 338.9991, found
253.1228.
339.0008.
2-(5-Hydroxy-2-methylphenyl)-1-(4-methoxyphenyl)prop-2-en-
1-one (2c). Following the general procedure, compound 2c (76 mg)
was obtained in 94% yield: colorless solid; mp = 178−180 °C; Rf = 0.35
(4:1 hexane/EtOAc) [silica, UV, and I2]; 1H NMR (500 MHz, DMSO-
d6) δ 9.29 (s, 1H), 7.84 (d, J = 8.5 Hz, 2H), 7.04 (d, J = 9.0 Hz, 2H),
6.95 (d, J = 8.0 Hz, 1H), 6.69−6.64 (m, 2H), 5.91 (s, 1H), 5.79 (s, 1H),
3.83 (s, 3H), 1.99 (s, 3H); 13C{1H} NMR (126 MHz, DMSO-d6) δ
194.9, 163.5, 155.8, 149.1, 139.6, 132.2, 131.5, 129.6, 126.2, 125.4,
116.7, 115.5, 114.3, 56.0, 19.5; IR (neat) νmax 3282, 3022, 2918, 1624,
1591, 1563, 1313, 1291, 1255, 1217 cm−1; HRMS (ESI) m/z [M +
Na]+ calcd for C17H16NaO3+ 291.0992, found 291.0998.
1-(4-(tert-Butyl)phenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-
en-1-one (2d). Following the general procedure, compound 2d (86
mg) was obtained in 97% yield: pale yellow solid; mp = 127−130 °C; Rf
= 0.64 (4:1 hexane/EtOAc) [silica, UV, and I2]; 1H NMR (400 MHz,
CDCl3) δ 7.86 (dt, J = 8.4, 2.0 Hz, 2H), 7.46 (dt, J = 8.8, 2.0 Hz, 2H),
6.98 (d, J = 8.4 Hz, 1H), 6.75 (d, J = 2.8 Hz, 1H), 6.70 (dd, J = 8.0, 2.8
Hz, 1H), 5.95 (dd, J = 14, 1.2 Hz, 2H), 5.85 (bs, 1H), 2.11 (s, 3H), 1.34
(s, 9H); 13C{1H} NMR (101 MHz, CDCl3) δ 196.7, 156.6, 154.0,
149.0, 139.2, 134.3, 131.2, 129.9, 127.5, 127.3, 125.3, 116.9, 115.4, 35.1,
31.1, 19.5; IR (neat) νmax 3382, 3055, 1602, 1497, 1461, 1375, 1264
cm−1; HRMS (ESI) m/z [M + Na]+ calcd for C20H22NaO2+ 317.1512,
found 317.1517.
2-(5-Hydroxy-2-methylphenyl)-1-(4-iodophenyl)prop-2-en-1-one
(2i). Following the general procedure, compound 2i (67 mg) was
obtained in 61% yield: colorless solid; mp = 158−160 °C; Rf = 0.58 (4:1
hexane/EtOAc) [silica, UV, and I2]; 1H NMR (400 MHz, DMSO-d6) δ
9.33 (s, 1H), 7.91 (d, J = 8.4 Hz, 2H), 7.58 (d, J = 8.4 Hz, 2H), 6.96 (d, J
= 8.0 Hz, 1H), 6.68 (bd, J = 2.4 Hz, 1H), 6.65 (s, 1H), 6.03 (s, 1H), 5.88
(s, 1H), 1.97 (s, 3H); 13C{1H} NMR (101 MHz, DMSO-d6) δ 195.9,
155.9, 148.5, 139.2, 138.1, 136.6, 131.6, 131.5, 128.7, 125.5, 116.9,
115.7, 102.0, 19.6; IR (neat) νmax 3357, 1627, 1575, 1496, 1432, 1390,
+
1344, 1283 cm−1; HRMS (ESI) m/z [M + H]+ calcd for C16H14IO2
365.0033, found 365.0042.
2-(5-Hydroxy-2-methylphenyl)-1-(m-tolyl)prop-2-en-1-one (2j).
Following the general procedure, compound 2j (59 mg) was obtained
in 78% yield: pale yellow solid; mp = 152−154 °C; Rf = 0.57 (4:1
1
hexane/EtOAc) [silica, UV, and I2]; H NMR (400 MHz, CDCl3) δ
7.72 (s, 1H), 7.67 (d, J = 7.6 Hz, 1H), 7.37 (d, J = 7.6 Hz, 1H), 7.32 (t, J
= 7.6 Hz, 1H), 6.96 (d, J = 8.4 Hz, 1H), 6.74 (d, J = 2.8 Hz, 1H), 6.69
(dd, J = 8.4, 2.8 Hz, 1H), 6.61 (bs, 1H), 5.98 (bd, J = 1.2 Hz, 1H), 5.93
(bd, J = 1.2 Hz, 1H), 2.39 (s, 3H), 2.10 (s, 3H); 13C{1H} NMR (101
MHz, CDCl3) δ 197.5, 154.1, 148.9, 138.8, 138.2, 137.0, 133.6, 131.1,
130.2, 128.3, 128.1, 127.2, 127.0, 116.9, 115.5, 21.3, 19.4; IR (neat) νmax
3383, 1654, 1602, 1581, 1496, 1358, 1264 cm−1; HRMS (ESI) m/z [M
+ H]+ calcd for C17H17O2+ 253.1223, found 253.1232.
1-(3-Fluorophenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-en-1-
one (2k). Following the general procedure, compound 2k (42 mg) was
obtained in 54% yield: pale yellow solid; mp = 120−122 °C; Rf = 0.53
(4:1 hexane/EtOAc) [silica, UV, and I2]; 1H NMR (500 MHz, CDCl3)
δ 7.65 (d, J = 8.0 Hz, 1H), 7.59−7.54 (m. 1H), 7.44−7.39 (m, 1H),
7.28−7.23 (m, 1H), 6.99 (d, J = 8.0 Hz, 1H), 6.74−6.69 (m, 2H), 6.02
(s, 1H), 5.98 (s, 1H), 5.74 (bs, 1H), 2.09 (s, 3H); 13C{1H} NMR (126
MHz, CDCl3) δ 195.3, 162.5 (d, J = 250 Hz, 1C), 153.9, 148.5, 139.1
(d, J = 6.3 Hz, 1C), 138.7, 131.4, 130.0 (d, J = 7.6 Hz, 1C), 128.6, 127.3,
125.5 (d, J = 2.5 Hz, 1C), 119.8 (d, J = 21 Hz, 1C), 116.7, 116.5 (d, J =
22 Hz, 1C), 115.6, 19.4; 19F NMR (376 MHz, CDCl3) δ − 111.7; IR
1-(4-Acetylphenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-en-1-
one (2e). Following the general procedure, compound 2e (52 mg) was
obtained in 62% yield: yellow solid; mp = 193−196 °C; Rf = 0.21 (4:1
hexane/EtOAc) [silica, UV, and I2]; 1H NMR (400 MHz, DMSO−D6)
δ 9.05 (s, 1H), 8.00 (s, 1H), 7.99 (d, J = 3.6 Hz, 1H), 7.87 (d, J = 8.4 Hz,
2H), 6.91 (d, J = 8.8 Hz, 1H), 6.70−6.63 (m, 2H), 6.01 (s, 1H), 5.91 (s,
1H), 2.60 (s, 3H), 2.01 (s, 3H); 13C{1H} NMR (101 MHz, CDCl3 +
DMSO-d6) δ 195.4, 193.7, 153.9, 147.0, 138.9, 137.9, 136.8, 129.3,
127.9, 126.9, 126.5, 123.6, 114.9, 113.8, 25.3, 17.6; IR (neat) νmax 3310,
2919, 1683, 1637, 1604, 1560, 1494, 1451, 1354, 1286, 1253 cm−1;
+
HRMS (ESI) m/z [M + H]+ calcd for C18H17O3 281.1172, found
281.1179.
F
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Article
(neat) νmax 3371, 3056, 1656, 1585, 1497, 1440, 1264 cm−1; HRMS
(ESI) m/z [M + H]+ calcd for C16H14FO2+ 257.0972, found 257.0977.
1-(3-Chlorophenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-en-1-
one (2l). Following the general procedure, compound 2l (53 mg) was
obtained in 65% yield: colorless solid; mp = 134−136 °C; Rf = 0.48 (4:1
(101 MHz, CDCl3) δ 197.3, 154.1, 149.0, 142.6, 139.0, 136.8, 134.6,
131.2, 131.0, 129.5, 127.9, 127.6, 127.0, 116.9, 115.5, 20.0, 19.7, 19.5;
IR (neat) νmax 3337, 2921, 2854, 1626, 1600, 1563, 1498, 1437, 1356,
+
1291, 1224 cm−1; HRMS (ESI) m/z [M + H]+ calcd for C18H19O2
267.1380, found 267.1385.
1
hexane/EtOAc) [silica, UV, and I2]; H NMR (500 MHz, CDCl3) δ
2-(5-Hydroxy-2-methylphenyl)-1-(thiophen-2-yl)prop-2-en-1-
one (2r). Following the general procedure, compound 2r (72 mg) was
obtained in 98% yield: yellow liquid; Rf = 0.55 (4:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.63 (dd, J = 5.0, 1.0
Hz, 1H), 7.53 (dd, J = 4.0, 1.0 Hz, 1H), 7.05−7.02 (m, 1H), 6.96 (d, J =
8.0 Hz, 1H), 6.79 (d, J = 3.0 Hz, 1H), 6.74 (dd, J = 8.5, 2.5 Hz, 1H), 6.13
(bd, J = 1.0 Hz, 1H), 5.81 (bd, J = 1.0 Hz, 1H), 2.07 (s, 3H); 13C{1H}
NMR (126 MHz, CDCl3) δ 188.2, 154.2, 148.7, 143.1, 138.7, 134.8,
134.6, 131.3, 128.1, 127.4, 126.5, 116.9, 115.8, 19.4; IR (neat) νmax
3365, 2920, 1605, 1577, 1495, 1407, 1353, 1233, 1052 cm−1; HRMS
(ESI) m/z [M + H]+ calcd for C14H13O2S+ calcd 245.0631, found
245.0637. The −OH proton is not detected by 1H NMR.
7.86 (bt, J = 1.5 Hz, 1H), 7.73 (d, J = 7.5 Hz, 1H), 7.54−7.50 (m, 1H),
7.37 (t, J = 8.0 Hz, 1H), 6.97 (d, J = 8.5 Hz, 1H), 6.72 (d, J = 3.0 Hz,
1H), 6.69 (dd, J = 8.0, 2.5 Hz, 1H), 6.40 (bs, 1H), 6.02 (s, 1H), 5.96 (s,
1H), 2.08 (s, 3H); 13C{1H} NMR (126 MHz, CDCl3) δ 195.6, 154.0,
148.5, 138.6, 138.4, 134.6, 132.7, 131.3, 129.64, 129.59, 128.9, 127.9,
127.1, 116.8, 115.7, 19.4; IR (neat) νmax 3383, 3064, 1661, 1569, 1497,
+
1419, 1235 cm−1; HRMS (ESI) m/z [M + H]+ calcd for C16H14ClO2
273.0677, found 273.0682.
2-(5-Hydroxy-2-methylphenyl)-1-(3-iodophenyl)prop-2-en-1-one
(2m). Following the general procedure, compound 2m (68 mg) was
obtained in 62% yield: colorless semisolid; mp = 125−127 °C; Rf = 0.49
(4:1 hexane/EtOAc) [silica, UV, and I2]; 1H NMR (400 MHz, CDCl3)
δ 8.01−7.97 (m, 1H), 7.68 (dd, J = 8.0, 0.8 Hz, 1H), 7.60 (dd, J = 8.0,
1.2 Hz, 1H), 7.00 (t, J = 7.6 Hz, 1H), 6.81−6.75 (m, 1H), 6.60−6.54
(m, 2H), 5.82 (s, 1H), 5.76 (s, 1H), 1.88 (s, 3H); 13C{1H} NMR (101
MHz, CDCl3 + DMSO-d6) δ 194.3, 154.9, 148.2, 140.8, 138.6, 138.0,
137.7, 130.7, 129.6, 128.4, 127.9, 125.4, 116.2, 115.2, 93.6, 19.0; IR
(neat) νmax 3360, 1656, 1579, 1495, 1457, 1410, 1229 cm−1; HRMS
(ESI) m/z [M + H]+ calcd for C16H14IO2+ 365.0033, found 365.0040.
The −OH proton is not detected by 1H NMR.
2-(2-Ethyl-5-hydroxyphenyl)-1-phenylprop-2-en-1-one (2s). Fol-
lowing the general procedure, compound 2s (58 mg) was obtained in
76% yield: yellow liquid; Rf = 0.64 (4:1 hexane/EtOAc) [silica, UV, and
1
I2]; H NMR (500 MHz, CDCl3) δ 7.89 (dd, J = 8.0, 1.0 Hz, 2H),
7.59−7.54 (m, 1H), 7.45 (t, J = 8.0 Hz, 2H), 7.02 (d, J = 8.0 Hz, 1H),
6.74 (dd, J = 8.5, 3.0 Hz, 1H), 6.72 (d, J = 2.5 Hz, 1H), 6.31 (bs, 1H),
6.00 (bd, J = 0.5 Hz, 1H), 5.95 (bd, J = 1.0 Hz, 1H), 2.43 (q, J = 7.5 Hz,
2H), 1.09 (t, J = 7.5 Hz, 3H); 13C{1H} NMR (126 MHz, CDCl3) δ
197.3, 153.9, 148.7, 138.4, 137.0, 133.3, 132.8, 129.8, 129.4, 128.8,
128.3, 117.1, 115.8, 25.8, 15.3; IR (neat) νmax 3367, 2964, 2871, 1648,
1597, 1576, 1495, 1446, 1260, 1226 cm−1; HRMS (ESI) m/z [M + H]+
calcd for C17H17O2+ 253.1223, found 253.1233.
2-(5-Hydroxy-2-methylphenyl)-1-(o-tolyl)prop-2-en-1-one (2n).
Following the general procedure, compound 2n (57 mg) was obtained
in 75% yield: pale yellow solid; mp = 156−158 °C; Rf = 0.60 (4:1
1
hexane/EtOAc) [silica, UV, and I2]; H NMR (400 MHz, CDCl3) δ
2-(5-Hydroxy-2-propylphenyl)-1-phenylprop-2-en-1-one (2t).
Following general the procedure, compound 2t (64 mg) was obtained
in 80% yield: pale yellow solid; mp = 116−118 °C; Rf = 0.56 (4:1
7.45 (dd, J = 7.6, 1.2 Hz, 1H), 7.39−7.34 (m, 1H), 7.29−7.20 (m, 2H),
7.05 (d, J = 8.4 Hz, 1H), 6.72 (dd, J = 8.4, 2.8 Hz, 1H), 6.68 (d, J = 2.4
Hz, 1H), 6.09 (bd, J = 0.8 Hz, 1H), 5.97 (bd, J = 1.2 Hz, 1H), 5.28 (bs,
1H), 2.43 (s, 3H), 2.17 (s, 3H); 13C{1H} NMR (101 MHz, CDCl3) δ
198.6, 153.6, 150.1, 138.3, 138.1, 137.2, 131.9, 131.2, 131.1, 130.4,
128.6, 127.9, 125.0, 116.8, 115.2, 20.0, 19.3; IR (neat) νmax 3385, 3055,
1659, 1497, 1320, 1264 cm−1; HRMS (ESI) m/z [M + H]+ calcd for
C17H17O2+ 253.1223, found 253.1229.
1
hexane/EtOAc) [silica, UV, and I2]; H NMR (400 MHz, CDCl3) δ
7.90 (dd, J = 7.6, 0.4 Hz, 2H), 7.60−7.55 (m, 1H), 7.45 (t, J = 8.0 Hz,
2H), 7.02−6.97 (m, 1H), 6.75−6.70 (m, 2H), 6.48 (bs, 1H), 5.99 (bd, J
= 1.2 Hz, 1H), 5.94 (bd, J = 0.8 Hz, 1H), 2.36 (t, J = 7.6 Hz, 2H), 1.55−
1.45 (m, 2H), 0.83 (t, J = 7.2 Hz, 3H); 13C{1H} NMR (101 MHz,
CDCl3) δ 197.4, 153.9, 148.8, 138.6, 136.9, 132.8, 131.8, 130.2, 129.8,
128.8, 128.3, 117.3, 115.6, 35.1, 24.4, 13.9; IR (neat) νmax 3367, 2956,
2867, 1629, 1595, 1493, 1441, 1345, 1318, 1253 cm−1; HRMS (ESI)
m/z [M + H]+ calcd for C18H19O2+ 267.1380, found 267.1386.
2-(5-Hydroxy-2-pentylphenyl)-1-phenylprop-2-en-1-one (2u).
Following the general procedure, compound 2u (45 mg) was obtained
in 51% yield: colorless gummy liquid; Rf = 0.70 (4:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.90 (dd, J = 8.0, 1.0
Hz, 2H), 7.59−7.55 (m, 1H), 7.45 (t, J = 8.0 Hz, 2H), 7.00 (dd, J = 7.0,
1.5 Hz, 1H), 6.75−6.71 (m, 2H), 6.12 (bs, 1H), 5.99 (bd, J = 1.5 Hz,
1H), 5.95 (bd, J = 1.5 Hz, 1H), 2.37 (t, J = 8.0 Hz, 2H), 1.50−1.43 (m,
2H), 1.27−1.15 (m, 4H), 0.82 (t, J = 7.0 Hz, 3H); 13C{1H} NMR (101
MHz, CDCl3) δ 197.2, 153.8, 148.8, 138.6, 137.0, 132.8, 132.2, 130.2,
129.9, 128.7, 128.3, 117.2, 115.6, 33.0, 31.6, 30.9, 22.4, 14.0; IR (neat)
νmax 3381, 2954, 2926, 2857, 1648, 1597, 1576, 1494, 1445, 1260, 1228
2-(5-Hydroxy-2-methylphenyl)-1-(2-methoxyphenyl)prop-2-en-
1-one (2o). Following the general procedure, compound 2o (80 mg)
was obtained in 99% yield: yellow liquid; Rf = 0.36 (4:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.44−7.39 (m, 2H),
7.00 (d, J = 7.5 Hz, 2H), 6.92 (d, J = 8.5 Hz, 1H), 6.68 (dd, J = 8.0, 3.0
Hz, 1H), 6.66 (d, J = 3.0 Hz, 1H), 5.98 (d, J = 1.0 Hz, 1H), 5.96 (d, J =
1.0 Hz, 1H), 5.83 (bs, 1H), 3.78 (s, 3H), 2.16 (s, 3H); 13C{1H} NMR
(126 MHz, CDCl3) δ 197.2, 157.3, 153.6, 150.1, 138.2, 132.0, 130.9,
130.4, 129.7, 128.7, 127.8, 120.3, 116.9, 115.1, 111.4, 55.4, 19.2; IR
(neat) νmax 3379, 2924, 1651, 1597, 1487, 1460, 1285, 1248 cm−1;
+
HRMS (ESI) m/z [M + H]+ calcd for C17H17O3 269.1172, found
269.1179.
1-(2-Chlorophenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-en-1-
one (2p). Following the general procedure, compound 2p (36 mg) was
obtained in 44% yield: yellow semisolid; Rf = 0.50 (4:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.45−7.42 (m, 1H),
7.41−7.38 (m, 2H), 7.35−7.31 (m, 1H), 7.06 (d, J = 8.5 Hz, 1H), 6.72
(dd, J = 8.0, 2.5 Hz, 1H), 6.67 (d, J = 2.5 Hz, 1H), 6.16 (d, J = 0.5 Hz,
1H), 6.02 (d, J = 0.5 Hz, 1H), 5.50 (bs, 1H), 2.20 (s, 3H); 13C{1H}
NMR (126 MHz, CDCl3) δ 195.5, 153.5, 149.0, 138.4, 137.3, 133.7,
131.2, 131.1, 131.0, 130.1, 129.0, 128.1, 126.5, 116.8, 115.4, 19.2; IR
(neat) νmax 3349, 3056, 2922, 1641, 1604, 1587, 1496, 1346, 1286, 1205
cm−1; HRMS (ESI) m/z [M + H]+ calcd for C16H14ClO2+ 273.0677,
found 273.0686.
1-(3,4-Dimethylphenyl)-2-(5-hydroxy-2-methylphenyl)prop-2-
en-1-one (2q). Following the general procedure, compound 2q (73
mg) was obtained in 91% yield: pale yellow solid; mp = 150−152 °C; Rf
= 0.44 (4:1 hexane/EtOAc) [silica, UV, and I2]; 1H NMR (400 MHz,
CDCl3) δ 7.71 (s, 1H), 7.64 (dd, J = 7.6, 1.6 Hz, 1H), 7.19 (d, J = 8.0
Hz, 1H), 6.95 (d, J = 8.0 Hz, 1H), 6.72 (d, J = 2.4 Hz, 1H), 6.67 (dd, J =
8.4, 2.8 Hz, 1H), 6.33 (bs, 1H), 5.95 (bd, J = 1.2 Hz, 1H), 5.90 (bd, J =
1.2 Hz, 1H), 2.32 (s, 3H), 2.30 (s, 3H), 2.09 (s, 3H); 13C{1H} NMR
+
cm−1; HRMS (ESI) m/z [M + H]+ calcd for C20H23O2 295.1693,
found 295.1695.
2-(5-Hydroxy-2,4-dimethylphenyl)-1-phenylprop-2-en-1-one
(2v). Following the general procedure, compound 2v (64 mg) was
obtained in 85% yield: pale yellow solid; mp = 102−105 °C; Rf = 0.60
(4:1 hexane/EtOAc) [silica, UV, and I2]; 1H NMR (600 MHz, CDCl3)
δ 7.89 (dd, J = 8.4, 1.2 Hz, 2H), 7.57−7.53 (m, 1H), 7.44 (t, J = 7.8 Hz,
2H), 6.89 (s, 1H), 6.66 (s, 1H), 5.96 (bd, J = 1.2 Hz, 1H), 5.91 (bd, J =
1.2 Hz, 1H), 5.58 (bs, 1H), 2.18 (s, 3H), 2.09 (s, 3H); 13C{1H} NMR
(151 MHz, CDCl3) δ 197.2, 152.1, 148.8, 137.1, 136.3, 132.8, 132.7,
129.9, 128.3, 127.8, 127.1, 124.3, 116.4, 19.4, 15.5; IR (neat) νmax 3372,
1630, 1592, 1507, 1445, 1412, 1348, 1324, 1270 cm−1; HRMS (ESI)
m/z [M + H]+ calcd for C17H17O2+ 253.1223, found 253.1240.
2-(4-Hydroxy-[1,1′-biphenyl]-2-yl)-1-phenylprop-2-en-1-one
(2w). Following the general procedure, compound 2w (60 mg) was
obtained in 66% yield: colorless solid; mp = 205−207 °C; Rf = 0.41 (4:1
1
hexane/EtOAc) [silica, UV, and I2]; H NMR (600 MHz, CDCl3) δ
7.46−7.40 (m, 3H), 7.28−7.23 (m, 2H), 7.19 (t, J = 7.2 Hz, 2H), 7.16−
G
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7.09 (m, 4H), 6.92 (d, J = 3.0 Hz, 1H), 6.84 (dd, J = 9.0, 3.0 Hz, 1H),
6.25 (bs, 1H), 6.08 (s, 1H), 5.91 (s, 1H); 13C{1H} NMR (151 MHz,
CDCl3) δ 196.6, 155.4, 149.1, 140.7, 138.5, 136.7, 133.6, 132.3, 131.2,
129.9, 129.6, 128.8, 128.0, 127.7, 126.7, 117.5, 115.8; IR (neat) νmax
3324, 1978, 1640, 1597, 1447, 1271, 1200, 980 cm−1; HRMS (ESI) m/z
[M + H]+ calcd for C21H17O2+ 301.1223, found 301.1230.
tube. To the above mixture was added methanol (2.5 mL) at 0 °C, and
the mixture was stirred for 20 h at the same temperature. Upon
completion, the reaction was quenched with water (20 mL) and
extracted in ethyl acetate (15 mL × 3). The combined organic layers
were dried with anhydrous Na2SO4, filtered, and concentrated in
reduced pressure. The crude residue was purified by silica gel column
chromatography (100−200 mesh) to provide 4 in 68% yield (37 mg) as
a colorless solid: mp = 163−165 °C; Rf = 0.50 (4:1 hexane/EtOAc)
[silica, UV, and I2]; 1H NMR (500 MHz, CDCl3) δ 7.76 (d, J = 8.0 Hz,
2H), 7.08 (d, J = 8.5 Hz, 1H), 6.79 (d, J = 8.0 Hz, 2H), 6.66 (dd, J = 8.0,
2.0 Hz, 1H), 6.63 (s, 1H), 6.59 (d, J = 2.5 Hz, 1H), 4.67 (q, J = 6.5 Hz,
1H), 3.79 (s, 3H), 2.43 (s, 3H), 1.40 (d, J = 7.0 Hz, 3H); 13C{1H} NMR
(126 MHz, CDCl3) δ 200.5, 163.3, 154.9, 141.5, 132.0, 130.9, 129.2,
125.7, 114.0, 113.7, 113.6, 55.4, 44.2, 18.6, 18.0; IR (neat) νmax 3317,
1653, 1591, 1511, 1449, 1340, 1303, 1271 cm−1; HRMS (ESI) m/z [M
+ H]+ calcd for C17H19O3+ 271.1329, found 271.1342.
Synthesis of 2-(5-Hydroxy-2-methylphenyl)-1-(4-methoxyphen-
yl)-3-(p-tolylthio)propan-1-one (5). To a solution of 2c (0.2 mmol, 54
mg) in CHCl3 (2.5 mL) were added 4-methylbenzenethiol (0.4 mmol,
50 mg) and trimethylamine (0.6 mmol, 83 μL) subsequently. The
resulting mixture was stirred at room temperature for 48 h. Upon
completion, the crude reaction mixture was purified using column
chromatography (hexane/ethyl acetate) on silica gel (100−200 mesh)
to afford 5 in 91% yield (72 mg) as a colorless solid: mp = 129−131 °C;
Rf = 0.42 (4:1 hexane/EtOAc) [silica, UV, and I2]; 1H NMR (500 MHz,
CDCl3) δ 8.42 (s, 1H), 7.42 (d, J = 8.5 Hz, 2H), 6.92 (d, J = 8.0 Hz,
2H), 6.77 (d, J = 7.5 Hz, 2H), 6.62 (d, J = 9.0 Hz, 1H), 6.51 (d, J = 9.0
Hz, 2H), 6.26−6.15 (m, 2H), 4.44 (dd, J = 9.5, 4.0 Hz, 1H), 3.46 (s,
3H), 3.28 (dd, J = 13.5, 10 Hz, 1H), 2.66 (dd, J = 13.5, 4.0 Hz, 1H), 1.99
(s, 3H), 1.81 (s, 3H); 13C{1H} NMR (126 MHz, CDCl3) δ 196.1,
162.5, 155.0, 136.8, 135.9, 131.4, 131.1, 130.5, 129.7, 128.9, 128.8,
124.3, 113.9, 113.0, 112.9, 54.6, 48.3, 37.0, 20.2, 17.6; IR (neat) νmax
3369, 1670, 1597, 1506, 1459, 1412, 1261, 1235 cm−1; HRMS (ESI)
m/z [M + H]+ calcd for C24H25O3S+ 393.1519, found 393.1530.
Synthesis of (2-(5-Hydroxy-2-methylphenyl)oxiran-2-yl)(4-
methoxyphenyl)methanone (6). A mixture of compound 2c (0.2
mmol, 54 mg) and NaOH (0.6 mmol, 24 mg) in MeOH (2.5 mL) was
taken in a Schlenk tube. To the above solution was added 30% aqueous
hydrogen peroxide (150 μL) at 0 °C, and the mixture was stirred for 20
h at same temperature. Upon completion, the reaction was quenched
with aqueous Na2S3O2 solution and then extracted with ethyl acetate (3
× 15 mL). The combined organic layer was dried over anhydrous
Na2SO4, filtered, and evaporated under reduced pressure. The residue
was purified by silica gel (100−200 mesh) column chromatography
(hexane/ethyl acetate) to afford product 6 in 98% yield (56 mg) as a
colorless gummy liquid: Rf = 0.29 (4:1 hexane/EtOAc) [silica, UV, and
I2]; 1H NMR (400 MHz, CDCl3) δ 8.03 (d, J = 8.8 Hz, 2H), 7.10 (d, J =
2.8 Hz, 1H), 6.95 (d, J = 8.4 Hz, 1H), 6.82 (d, J = 9.2 Hz, 2H), 6.72 (dd,
J = 8.0, 2.8 Hz, 1H), 6.26 (bs, 1H), 3.79 (s, 3H), 3.40 (d, J = 6.0 Hz,
1H), 3.12 (d, J = 5.6 Hz, 1H), 2.24 (s, 3H); 13C{1H} NMR (101 MHz,
CDCl3) δ 194.2, 163.7, 154.0, 135.9, 132.0, 131.8, 129.2, 127.6, 115.7,
114.4, 113.7, 63.7, 55.4, 53.0, 18.8; IR (neat) νmax 3385, 1668, 1598,
1507, 1459, 1307, 1263, 1170 cm−1; HRMS (ESI) m/z [M + Na]+ calcd
for C17H16NaO4+ 307.0941, found 307.0959.
2-(5-Hydroxy-2-methylphenyl)-1-(o-tolyl)but-2-en-1-one (2aa).
Following the general procedure, compound 2aa (60 mg) was obtained
in 75% yield: pale yellow liquid; Rf = 0.39 (4:1 hexane/EtOAc) [silica,
UV, and I2]; 1H NMR (600 MHz, CDCl3) δ 7.36−7.28 (m, 2H), 7.25−
7.19 (m, 2H), 7.12 (d, J = 7.8 Hz, 1H), 6.72 (dd, J = 7.8, 2.4 Hz, 1H),
6.65 (q, J = 6.6 Hz, 1H), 6.55 (d, J = = 2.4 Hz, 1H), 5.04 (bs, 1H), 2.36
(s, 3H), 2.12 (s, 3H), 1.68 (d, J = 7.2 Hz, 3H); 13C{1H} NMR (151
MHz, CDCl3) δ 199.0, 153.5, 146.7, 144.5, 139.6, 135.8, 135.7, 131.1,
130.7, 129.5, 128.4, 127.5, 125.1, 116.6, 115.0, 19.63, 18.74, 16.02; IR
(neat) νmax 3317, 2943, 2831, 1449, 1416, 1264, 1021 cm−1; HRMS
(ESI) m/z [M + H]+ calcd for C18H19O2+ 267.1380, found 267.1394.
2-(5-Hydroxy-2-methylphenyl)-1-(o-tolyl)but-2-en-1-one (2ab).
Following the general procedure, compound 2ab (62 mg) was obtained
in 73% overall yield (inseparable mixture of diasteriomers): colorless
solid; mp = 158−160 °C; Rf = 0.33 (4:1 hexane/EtOAc) [silica, UV,
1
and I2]; H NMR (600 MHz, CDCl3) δ 7.99 (dd, J = 7.2, 1.8 Hz,
0.77H), 7.80 (dd, J = 6.6, 1.8 Hz, 2H), 7.09−7.03 (m, 1.37H), 6.98−
6.88 (m, 3H), 6.71 (dd, J = 8.4, 3.0 Hz, 1H), 6.67−6.59 (m, 3H), 3.88
(s, 0.67H), 3.86 (s, 3H), 2.19 (s, 0.94H), 2.10 (s, 3H), 1.83 (d, J = 7.2
Hz, 0.94H), 1.75 (d, J = 7.2 Hz, 3H); 13C{1H} NMR (151 MHz,
CDCl3) δ 196.5, 195.6, 163.6, 162.8, 153.9, 153.6, 142.4, 140.6, 136.8,
134.8, 132.0, 131.3, 131.1, 130.9, 130.8, 130.7, 129.8, 128.9, 128.5,
128.2, 117.2, 117.0, 114.9, 114.0, 113.9, 113.83, 113.78, 113.4, 55.5,
55.4, 43.1, 18.9, 18.85, 15.6; IR (neat) νmax 3282, 3011, 2921, 1727,
1651, 1617, 1592, 1502, 1418, 1280 cm−1; HRMS (ESI) m/z [M + H]+
+
calcd for C18H19O3 283.1329, found 283.1338. The −OH proton is
not detected by 1H NMR.
2-(5-Hydroxy-2-methylphenyl)-1-(4-methoxyphenyl)but-2-en-1-
one (2ac). Following the general procedure, compound 2ac (73 mg)
was obtained in 86% overall yield (inseparable mixture of
diasteriomers): colorless solid; mp = 164−166 °C; Rf = 0.34 (4:1
1
hexane/EtOAc) [silica, UV, and I2]; H NMR (600 MHz, CDCl3) δ
8.03 (d, J = 8.4 Hz, 0.11H), 7.99 (d, J = 9.6 Hz, 0.81H), 7.80 (d, J = 9.6
Hz, 2H), 7.05 (t, J = 8.4 Hz, 1.18H), 6.98−6.88 (m, 3.20H), 6.70 (dd, J
= 7.8, 2.4 Hz, 1H), 6.66−6.58 (m, 2.28H), 5.24 (bs, 1H), 5.11 (bs,
0.12H), 4.18 (s, 0.32H), 3.87 (s, 3H), 2.18 (s, 0.28H), 2.10 (s, 3H),
1.75 (d, J = 6.6 Hz, 3H), 1.31 (d, J = 6.6 Hz, 0.20H); 13C{1H} NMR
(151 MHz, CDCl3) δ 196.4, 195.5, 163.6, 162.8, 153.8, 153.5, 142.4,
140.6, 131.9, 131.1, 130.7, 128.3, 117.1, 117.0, 114.8, 114.0, 113.9,
113.8, 113.4, 55.5, 55.4, 43.1, 18.91, 18.86, 15.6; IR (neat) νmax 2985,
2907, 2257, 1737, 1447, 1373, 1235, 1098, 1044 cm−1; HRMS (ESI)
m/z [M + H]+ calcd for C18H19O3+ 283.1329, found 283.1339.
Synthesis of 2-(5-Hydroxy-2-methylphenyl)-2,3-dihydro-1H-
inden-1-one (3). A mixture of 2a (0.3 mmol, 72 mg) in triflic acid
(30 mmol, 2.3 mL) was taken in a screw-cap sealed tube. The reaction
mixture was stirred at room temperature for 72 h. Upon completion, the
whole mixture was poured into ice−water (30 mL) and extracted with
CH2Cl2 (15 mL × 3). The combined organic layers were washed with
brine (30 mL), dried over Na2SO4, filtered, and evaporated to give a
residue, which was purified by silica gel (100−200 mesh) column
chromatography (hexane/ethyl acetate) to give the desired product 3 in
63% yield (45 mg) as a colorless solid: mp = 166−168 °C; Rf = 0.40 (4:1
Gram-Scale Synthesis of α-Aryl-α,β-unsaturated Ketones 2a/2c.
A mixture of alkynyl-cyclohexadienone 1a/1c (1.0 g; 1.0 equiv) and
Cu(OTf)2 (10 mol %) in THF (25 mL) was taken in a screw-cap sealed
tube. The reaction mixture was heated to 95 °C and stirred overnight.
The progress of the reaction was monitored by thin-layer chromatog-
raphy (TLC) analysis. Upon completion, the reaction mixture was
cooled to room temperature, and the crude residue was purified using
column chromatography on silica gel (100−200 mesh) to provide the
desired α-aryl-α,β-unsaturated ketones 2a and 2c in 90% (0.9 g) and
93% (0.93 g) yields, respectively.
1
hexane/EtOAc) [silica, UV, and I2]; H NMR (400 MHz, CDCl3) δ
8.34 (s, 1H), 7.64−7.58 (m, 1H), 7.52−7.43 (m, 1H), 7.36 (d, J = 7.6
Hz, 1H), 6.84 (dd, J = 8.0, 2.8 Hz, 1H), 6.51−6.44 (m, 1H), 6.31−6.24
(m, 1H), 3.86 (dd, J = 8.4, 4.4 Hz, 1H), 3.56−3.46 (m, 1H), 2.96 (dd, J
= 17.2, 3.6 Hz, 1H), 2.73 (bs, 1H), 2.08 (s, 3H); 13C{1H} NMR (101
MHz, CDCl3) δ 206.4, 155.1, 153.2, 139.0, 136.1, 134.6, 131.0, 127.2,
126.6, 126.2, 123.6, 114.0, 113.7, 50.3, 35.1, 18.6; IR (neat) νmax 3252,
1679, 1603, 1584, 1500, 1462, 1435, 1381, 1279 cm−1; HRMS (ESI)
m/z [M + H]+ calcd for C16H15O2+ 239.1067, found 239.1080.
Synthesis of 2-(5-Hydroxy-2-methylphenyl)-1-(4-
methoxyphenyl)propan-1-one (4). A mixture of compound 2c (0.2
mmol, 54 mg) and NaBH4 (0.4 mmol, 15 mg) was taken in a Schlenk
ASSOCIATED CONTENT
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sı
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.joc.1c00290.
H
https://doi.org/10.1021/acs.joc.1c00290
J. Org. Chem. XXXX, XXX, XXX−XXX

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Article
Detailed spectra (1H, 13C, and 19F NMR) and X-ray
crystallographic data (PDF)
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Accession Codes
CCDC 1947873, 2054259, and 2060957 contains the
supplementary crystallographic data for this paper. These data
can be obtained free of charge via www.ccdc.cam.ac.uk/data_
request/cif, or by emailing data_request@ccdc.cam.ac.uk, or by
contacting The Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: + 44 1223 336033.
AUTHOR INFORMATION
Corresponding Author
Akhila K. Sahoo − School of Chemistry, University of
Hyderabad, Hyderabad, Telangana 500046, India; Advanced
Centre of Research in High Energy Materials (ACRHEM),
University of Hyderabad, Hyderabad 500046, India;
orcid.org/0000-0001-5570-4759;
■
(4) Roy, D.; Tharra, P.; Baire, B. Intercepted Meyer−Schuster
Rearrangements in Organic Synthesis. Asian J. Org. Chem. 2018, 7,
1015.
Email: akhilchemistry12@gmail.com, akssc@uohyd.ac.in
Authors
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Rajendra K. Mallick − School of Chemistry, University of
Hyderabad, Hyderabad, Telangana 500046, India;
orcid.org/0000-0002-9998-6767
Srinivas Vangara − Advanced Centre of Research in High
Energy Materials (ACRHEM), University of Hyderabad,
Hyderabad 500046, India
Nagarjuna Kommu − Advanced Centre of Research in High
Energy Materials (ACRHEM), University of Hyderabad,
Hyderabad 500046, India
Tirumaleswararao Guntreddi − School of Chemistry,
University of Hyderabad, Hyderabad, Telangana 500046,
India
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.joc.1c00290
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This research was supported by the CEFIPRA (5505-2). We
thank the University of Hyderabad (UoH-IoE; UPE-CAS and
PURSE-FIST) for use of the facility. R.K.M., V.S., N.K., and
T.G. thank UGC, ACRHEM, and DST for financial support.
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