Metal Free, Direct and Selective Deoxygenation of α-Hydroxy Carbonyl Compounds: Access to α,α-Diaryl Carbonyl Compounds

Article abstract of DOI:10.1002/ejoc.202000142

An efficient, metal free, direct and selective deoxygenation of α-hydroxy carbonyl compounds is achieved with the aid of catalytic amount of aqueous HClO₄ (70 %) and triethylsilane as hydride source. A variety of α-hydroxy-α,α-diaryl carbonyl compounds are selectively deoxygenated to give α,α-diaryl carbonyl compounds in good to excellent yields. Intermediacy of α-keto carbenium ion is proposed on the basis of some control experiments and atmospheric pressure chemical ionization mass spectral analysis.

Full text of DOI:10.1002/ejoc.202000142

A Journal of
Accepted Article
Title: Metal Free, Direct and Selective Deoxygenation of α-
Hydroxy Carbonyl Compounds: Access to α,α-Diaryl Carbonyl
Compounds
Authors: Sandeep ., Paloth Venugopalan, and Anil Kumar
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.202000142
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10.1002/ejoc.202000142
European Journal of Organic Chemistry
Metal Free, Direct and Selective Deoxygenation of α-Hydroxy Carbonyl
Compounds: Access to α,α-Diaryl Carbonyl Compounds
Mr. Sandeep,[a,b] Prof. Paloth Venugopalan,[b] Dr. Anil Kumar*[a]
[a] Department of Applied Sciences, University Institute of Engineering and Technology,
Panjab University, Chandigarh-160014, India. E-mail: akumar13@pu.ac.in
http://uiet.puchd.ac.in/?page_id=484
[b] Department of Chemistry, Panjab University, Chandigarh-160014, India
Abstract:
An efficient, metal free, direct and selective deoxygenation of α-hydroxy carbonyl
compounds is achieved with the aid of catalytic amount of aqueous HClO4 (70%) and
triethylsilane as hydride source. A variety of α-hydroxy-α,α-diaryl carbonyl compounds are
selectively deoxygenated to give α,α-diaryl carbonyl compounds in good to excellent yields.
Intermediacy of α-keto carbenium ion is proposed on the basis of some control experiments
and atmospheric pressure chemical ionization mass spectral analysis.
Introduction
Efficient strategies for the deoxygenation of alcohols have become a cardinal
endeavour in organic synthesis, as defunctionalisation rather than functionalization has come
to a centre stage due to its extreme importance in “best from the worst” policy.[1] For
example, biomass, which is a waste and nuisance (but abundant in –OH due to major
carbohydrate content) is getting great thrust as an alternate to fossil based fuels and a clear-
cut focus has been laid on the conversion of high-volume, low-value biomass into low-
volume, high-value chemicals and fuel.[2] Besides this massive futuristic application,
deoxygenation also plays a vital role in the total syntheses of natural products,
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European Journal of Organic Chemistry
pharmaceutically active compounds and their synthetic modifications.[3] Since the pioneer
protocol given by Barton-McCombie on radical deoxygenation of alcohols,[4] today’s
scenario has witnessed deoxygenation of oxygen present in almost all organic functional
groups.[5-7] Nevertheless, such deoxygenation reactions have been mostly studied on
substrates carrying one type of oxygen functionality. Deoxygenation of hydroxyl and keto
group, for example, has been achieved separately using PdCl2 or InCl3 as Lewis acids and
hydrosilane as the hydride source (Scheme 1a).[8]
Considering the diverse nature of molecules bearing hydroxyl group, its selective
deoxygenation in the presence of other oxygen bearing functional groups (>C=O, –CHO, –
COOH, –O–, –COOR etc) becomes an arduous task demanding careful attention.
Commendable strides have been achieved in this direction.[9] Presence of another oxygen
functionality such as a >C=O moiety at the immediate vicinity of –OH makes the removal
much more demanding as there are many naturally occurring compounds and key synthetic
intermediates that contain this α-hydroxy carbonyl moiety.[10] Being important, many
research groups have achieved such deoxygenations.[11] For example, Speckmeier et al. have
reported visible light mediated deoxygenation of O-acetyl benzoin and acyloin derivatives
(Scheme 1b, i).[11b] Very recently, in a seminal paper, Yang and Xu have realized iridium
catalyzed site selective deoxygenation of a variety of alcohols with a single example of α-
keto alcohol.[11a] In all these reports, hydroxyl group is first converted to other functional
groups or good leaving groups or activators are required prior to selective deoxygenation.[11]
Though selective deoxygenation is achieved, the downside is that a stoichiometric amount of
chemical-waste is also generated. In addition, in many of the conversions, environmentally
harmful toxic metal derivatives are used as catalyst. The realization of the limitations such as
high-cost, environmental pollution and associated toxicity of the metallic reagent has
prompted researchers to approach deoxygenation through metal-free pathways and there are
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European Journal of Organic Chemistry
significant success stories reported in the current decade.[12] Compain and co-workers have
made an important break-through while exploring the use of iodine in the deoxygenation of
hydroxyl group present at the carbon bearing electron withdrawing carbonyl group (Scheme
1b, ii).[12b] Selective deoxygenation of α-hydroxy carbonyl compounds has been achieved via
the formation of corresponding α-iodo carbonyl intermediates. This iodine mediated
deoxygenation of alcohols is not applicable in the case of tertiary α-hydroxy carbonyl
compounds.
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Scheme 1. Different Approaches Toward Deoxygenation
Despite these advances, the development of mild, cheaper and greener methods for
the direct and selective deoxygenation is highly desirable. Deoxygenation of alcohols
containing electron withdrawing group (EWG) at the carbon bearing –OH group is even more
challenging when carbocations are the intermediates. This is because EWG tends to
destabilize the carbocations. Our previous experience of replacing –OH group with a variety
of substituents in tertiary α-hydroxy carbonyl compounds[13] gave us the hope that another
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typical Brønsted acid such as HClO4, if used in conjunction with an appropriate hydride
source should effect, efficient deoxygenation. If this hypothesis is validated affirmative, then
it will provide an efficient strategy, which is metal free to remove –OH group alpha to
carbonyl functionality. Thus, herein, we wish to report for the first time a metal-free, direct
and selective approach for the deoxygenation of α-hydroxy-α,α-diaryl carbonyl compounds
using much cheaper aqueous HClO4 (70%) as catalyst and triethylsilane (Et3SiH) as soluble
hydride source (Scheme 1b, iii). There is an added advantage to this strategy. The
deoxygenation of –OH group in α-hydroxy-α,α-diaryl carbonyl compounds can furnish α,α-
diaryl carbonyl compounds, which are an important class themselves.[14]
1,2,2-
Triarylethanones, for example, are very important precursors for the synthesis of
dibenzo[a,c]phenanthridine, analogues of biologically active benzo[c]phenanthridine
alkaloids.[15] In addition, 1,2,2-triarylethanones are also useful synthons for tamoxifen, the
most widely used drug for the treatment of breast cancer.[16] The synthetic methodology that
result in α,α-diaryl carbonyl compounds are mostly metal assisted.[14]
Results and Discussion
Our careful choice of a substrate to test the above mentioned hypothesis resulted in 2-
hydroxy-1,2,2-triphenylethanone (1a, Table 1). 1a has the essential requisites, the requited α-
hydroxy ketone moiety, but devoid of any influencing electron withdrawing group (EWG) or
electron donating group (EDG) attached to the phenyl ring(s). The lead to select InBr3 and
aqueous HClO4 (70%) is based on the previous reports.[13b,17] A solution of α-hydroxy ketone
1a in CH2Cl2 containing InBr3 (10 mol %) and Et3SiH (1.5 equiv) was stirred at room
temperature (Table 1, entry 1). After usual work up, the product was purified by flash
chromatography. To our delight, the isolated compound was identified as 1,2,2-
triphenylethanone (2a) in which selective deoxygenation of –OH took place, retaining >C=O.
Very similar and highly desired metal free deoxygenation of 1a to 2a was also achieved with
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European Journal of Organic Chemistry
the use of aq. HClO4 (20 mol %) as the catalyst in 55% yield (Table 1, entry 2). The reaction
conditions were then optimized for the deoxygenation of 2-hydroxy-1,2,2-triphenylethanone
(1a) using both InBr3 (entries 3-5) and HClO4 (entries 6-10) as metal and metal free catalyst
respectively by varying mol% of the catalyst, temperature, reaction time etc. (Table 1,
optimal conditions are shown in bold font).
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Table 1. Optimization of the Reaction Conditions
Yield[b]
Temperature
Catalyst
(mol %)
Et3Si-H
(equiv)
Entry[a]
Time
(%)
(C)
25
25
40
25
40
25
25
25
40
40
1
2[c]
3
InBr3 (10)
HClO4 (20)
InBr3 (10)
InBr3 (5)
1.5
1.5
1.5
1.5
1.5
2.0
3.0
2.0
1.5
2.0
40 min
2 h
93
55
95
88
94
74
85
27
96
96
10 min
1.5 h
30 min
2 h
4
5
InBr3 (5)
6[c]
7[c]
8[c]
9[c]
10[c]
HClO4 (20)
HClO4 (20)
HClO4 (10)
HClO4 (10)
HClO4 (10)
2 h
2 h
2.5 h
1.5 h
[a] Reactions were performed on 0.35 mmol of 2-hydroxy-1,2,2-
triphenylethanone (1a) in CH2Cl2 (3 mL). [b] Isolated yields. [c] Aqueous
HClO4 (70%) is used.
Conversion of the α-hydroxy ketone 1a to 2a in excellent yield (96%) using aq. HClO4
(70%) can offer a convenient metal free pathway to generate these family of triarylketones
through deoxygenation if the reaction is amenable (i.e. feasibility) and sustainable (yield) for
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European Journal of Organic Chemistry
a wide range of substrates. To test this scope, a variety of α-hydroxy ketones 1b-l were
treated under the optimized reaction conditions using aq. HClO4 (10 mol %) and Et3SiH (1.5
equiv) in CH2Cl2 to give 1,2,2-triarylethanones in good to excellent yields (Scheme 2). The
formation of the by-product, 2,3-diphenylnaphtho[1,2-b]furan (3) from 1k needs a mention
here (see experimental section and page S2 of the Supporting Information). Such derivatives
are known and can result from intramolecular rearrangement (4π cyclization) of α-keto
carbenium ion.[18] Indeed, the isolation of 3 (even though in minor yield), indirectly sheds
light upon the proposed mechanism involving the formation of α-carbonyl carbenium ion
(vide infra).[18] It is worth to note that the substrate 1l carrying electron withdrawing fluorine
also deoxygenated to give the desired product 2l in excellent yield.
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European Journal of Organic Chemistry
Scheme 2. Deoxygenation of Various α-Hydroxy Ketones[a]
[a] Reactions were performed on 0.35-0.66 mmol scale of 2-hydroxy-1,2,2-triarylylethanone
(1a-l) in CH2Cl2 (3 mL) using aq. HClO4 (70%). [b] 2,3-diphenylnaphtho[1,2-b]furan (3, 7%)
was also formed in this case.
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Extension of this metal free selective deoxygenation to other representative examples
such as acids and esters was also undertaken to showcase the utility of the reaction to related
α-hydroxy carbonyl compounds (Scheme 3). α-Hydroxy acid such as benzilic acid (1m) and
α-hydroxy ester such as methyl benzilate (1n) are typical and can serve as model compounds
as they lack any extra EWG or EDG moieties that can impart secondary influences. Both
gave desired deoxygenated product in excellent yield under the optimized reaction
conditions. The scope of selective deoxygenation, therefore, can be extended to α-hydroxy
acids and α-hydroxy esters as well.
Scheme 3. Deoxygenation of α-Hydroxy Acid and α-Hydroxy Ester
To understand the mechanistic necessities of the deoxygenation of α-hydroxy ketone,
our model compound 1a (phenyl benzoin) can be bifurcated to a diphenyl methanol moiety
and a bonded benzoyl group. A series of probing questions can be raised, such as; a) does the
reaction happen without the presence of this electron withdrawing benzoyl moiety? b) what
would the consequences of alkyl/phenyl substitution at C-OH moiety? etc. To answer the first
question, reaction of 1,1-diphenylmethanol (4) with Et3SiH (1.5 equiv) and aq. HClO4 (10
mol %) in CH2Cl2 was performed and it gave 1,1-diphenylmethane (5) within 15 minutes in
88% yield (Scheme 4). This experiment suggests that the presence of an electron withdrawing
keto group at the carbon bearing -OH group in 1a has no (at least very minimal) role in
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European Journal of Organic Chemistry
realizing deoxygenation. Similarly, in order to explore the prerequisite of two phenyl groups
at the carbon bearing –OH, deoxygenation of simple benzoin under identical reaction
conditions was carried out. TLC of this reaction showed a number of spots and isolation of
any deoxygenated product did not succeed. This demarcates the difference in the reactivity
pattern of benzoin and phenyl benzoin (1a), and the decisive role played by the second
phenyl moiety in the deoxygenation of α-hydroxy-α,α-diaryl carbonyl compounds.
Mechanistically, the α-carbonyl carbenium ion gets more stability due the presence of an
additional electron donating phenyl group.
Scheme 4. Deoxygenation of 1,1-Diphenylmethanol
To cross-check the deciding influence of the phenyl group, three α-hydroxy ketones
1o-q with alkyl groups have been subjected to deoxygenation reactions under the prevailing
reaction conditions (Scheme 5). α-Hydroxy ketones 1o and 1p failed to react, and in the case
of 1q having methoxy group at para position, deoxygenation did occur, though with poor
yield. A combined analysis of the results of benzoin, phenyl benzoin and scheme 5 clearly
indicates that subtle electronic factors play crucial role in driving the deoxygenation reaction
and α-carbonyl carbenium ions become progressively stable as more EDGs are bonded to the
C-OH moiety.
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Scheme 5. Deoxygenation of α-Hydroxy Ketones Bearing Alkyl Groups
Consolidating different aspects of the deoxygenation reactions described above,
intermediacy of the α-carbonyl carbenium ion in the catalytic cycle is proposed (Scheme 6).
Interaction of HClO4 with the –OH group leads the formation of α-carbonyl carbenium ion
and the elimination of a water molecule. The carbenium ion then reacts with the hydride
source (Et3SiH) to give deoxygenated product. This step will regenerate the HClO4 catalyst to
complete the catalytic cycle. It is noteworthy that such an α-carbonyl carbenium ion had been
observed by reacting 2-hydroxy-1,2,2-triphenylethanone with chlorosulphonic acid at -60 C
in CDCl3 or CD2Cl2.[18b]
Scheme 6. Proposed Reaction Mechanism
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We performed two additional experiments to prove the intermediacy of α-carbonyl
carbenium ion. Firstly, the deoxygenation reaction did not happen in the absence of aq.
HClO4 catalyst. Secondly, the trapping of the carbenium ion is possible if an arene is used as
a nucleophile. The reaction of 2-hydroxy-1,2,2-triphenylethanone (1a) with anisole occurred
smoothly in the presence of aq. HClO4 to give 2-(4-methoxyphenyl)-1,2,2-triphenylethanone
(6, Scheme 7). This reaction is similar to the Friedel-Crafts arylation reaction of alcohols
occurring through carbocation under acidic conditions.[19] Isolation of 3 as rearangement
product during deoxygenation of α-hydroxy ketone 1k also suggests the intermediacy of α-
carbonyl carbenium ion.
Scheme 7. Friedel-Crafts Reaction of 1a With Anisole
Based on the nature of the substrate, it was considered logical to utilize atmospheric
pressure chemical ionization mass spectrometry (APCI-MS) to gather further support to the
intermediacy of α-carbonyl carbenium ion. The APCI mass spectra of representative α-
hydroxy ketones 1a, 1e, 1g, 1j showed two prominent base peaks corresponding to two
different fragment ions A and B (Table 2). Fragment B is base peak for 1a and 1e, and A is
for the later two (see the Supporting Information). Occurrence of different base-peaks is due
to the difference in the stability of the respective carbocations that depends upon the nature of
aryl groups and substituents present; nevertheless, the formation of the α-keto carbenium ion
is vouched in both cases.
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Table 2. APCI Mass Spectral Fragments of 2-Hydroxy-1,2,2-triarylethanones
MH+
A
B
m/z (RA)[a]
m/z (RA)
α-Hydroxy Ketone
M
m/z
288
289
271(93)
243(100)
273(100)
318
318
319
319
301(41)
301(100)
273(12)
293(48)
338
339
321(100)
[a] RA = Relative abundance in %.
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Conclusion
In conclusion, we have uncovered a direct, selective and metal free method for the
deoxygenation of α-hydroxy-α,α-diaryl carbonyl compounds to obtain an important class of
α,α-diaryl carbonyl compounds using Et3SiH as a soluble hydride source and catalytic
amount of aqueous HClO4 (70%). Use of much cheaper aq. HClO4 proves to be effective and
environment friendly. The presence of two aryl groups at carbon bearing hydroxyl group
plays a crucial role in the selective deoxygenation. The intermediacy of α-keto carbenium ion
has been proposed for the reaction and is supported by the APCI mass spectral data of few 2-
hydroxy-1,2,2-triarylethanones.
EXPERIMENTAL SECTION
General Information. Melting points were recorded in open capillaries and are uncorrected.
IR spectra (in wavenumber) were recorded with Thermo Scientific (NICOLET IS 50) FT-IR
1
spectrophotometer. H NMR spectra were recorded in CDCl3 with a Bruker Avance II 400
and Bruker Avance NEO 500 NMR spectrometer operating at 400 MHz and 500 MHz
respectively. Proton-decoupled 13C NMR spectra were also recorded in CDCl3 with a Bruker
Avance II 400 and Bruker Avance NEO 500 NMR spectrometer operating at 100.53 MHz
and 125.76 MHz respectively. Chemical shifts (δ) are reported in parts per million downfield
from tetramethylsilane as an internal standard. Coupling constant (J) values are given in hertz
(Hz). Multiplicity of the signal is defined as ‘s’ (singlet), ‘d’ (doublet), ‘t’ (triplet), ‘q’
(quartet), ‘m’ (multiplet). Atmospheric pressure chemical ionization (APCI) mass spectra
were obtained with Finnigan Mat LCQ mass spectrometer equipped with an APCI source.
High resolution mass spectra (HRMS) were obtained with a Waters Alliance 2795 Q-ToF
Micromass spectrometer running under Mass Lynx version 4.0 software and equipped with
an ESI source. TLC analyses were performed using aluminum backed plates pre-coated with
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10.1002/ejoc.202000142
European Journal of Organic Chemistry
silica gel containing fluorescent material and examining them under UV light. Flash
chromatography was performed by using 40–63 μm silica gel (230–400 mesh) and applying
nitrogen pressure from the top of the column.[20]
General experimental procedure for the deoxygenation of α-hydroxy ketones. A solution
of α-hydroxy ketones 1a-l, 1o-q (1.0 equiv.) in CH2Cl2 (3 mL) and Et3SiH (1.5 equiv.) were
placed in a 25 mL two neck round bottom flask (RBF) fitted with a condenser. Aqueous
HClO4 (70%, 10 mol%) was added to this reaction mixture. The contents were stirred at 40
C and progress of the reaction was monitored by TLC analysis. After stirring the contents
for appropriate time period, the product was extracted with CH2Cl2 (3×15 mL), washed with
10% Na2CO3 and dried over anhydrous Na2SO4. The solvent was removed under reduced
pressure and purification was done by flash chromatography using n-hexane and ethyl acetate
(EtOAc) as eluent.
1,2,2-Triphenylethanone (2a).[14a] Following the general procedure and purification by flash
chromatography (n-hexane/EtOAc 9:1), the title compound 2a was obtained as a white solid
(90 mg, 96%) from 1a (100 mg, 0.35 mmol). Rf = 0.40 (n-hexane/EtOAc 9:1); Mp 136-
1
137C; H NMR (CDCl3, 400 MHz): δ = 5.95 (s, 1H; -CH), 7.14-7.25 (m, 10H; ArH), 7.30
(t, J = 7.0 Hz, 2H; ArH), 7.39 (tt, J = 1.8, 1.2 Hz, 1H; ArH), 7.91ppm (dd, J = 7.1, 1.4 Hz,
2H; ArH); 13C NMR (CDCl3, 100.53 MHz): δ = 59.4, 127.2, 128.6, 128.7, 129.0, 129.1,
133.1, 136.8, 139.1, 198.2 ppm; IR (neat): 3088, 3035, 3002, 2921, 1677 (CO), 1593, 1576,
1492, 1446, 1283, 1203 cm-1.
2-(2-Methylphenyl)-1,2-diphenylethanone (2b).[16] Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2b was
obtained as a colourless oil (175 mg, 92%) from 1b (200 mg, 0.66 mmol). Rf = 0.52 (n-
1
hexane/EtOAc 9:1); H NMR (CDCl3, 500 MHz): δ = 2.32 (s, 3H; CH3), 6.12 (s, 1H; -CH),
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7.04 (dd, J = 7.7, 1.5 Hz, 1H; ArH), 7.11 (dt, J = 7.2, 1.0 Hz, 1H; ArH), 7.16 (dt, J = 7.5, 1.5
Hz, 1H; ArH), 7.20 (m, 3H; ArH), 7.25 (tt, J = 5.0, 1.0 Hz, 1H; ArH), 7.31 (tt, J = 7.5, 1.0
Hz, 2H; ArH), 7.37 (m, 2H; ArH), 7.47 (tt, J = 5.5, 1 Hz, 1H; ArH), 7.92 ppm (dd, J = 8.5,
1.0 Hz, 2H; ArH); 13C NMR (CDCl3, 125.76 MHz): δ = 20.0, 56.6, 126.2, 127.1, 127.3,
128.5, 128.6, 128.7, 128.8, 129.6, 130.8, 132.9, 135.8, 136.7, 137.5, 137.8, 198.5 ppm; IR
(neat): 3064, 3027, 1683 (CO), 1593, 1580, 1491, 1446, 1274, 1203 cm-1.
2-(3-Methylphenyl)-1,2-diphenylethanone (2c).[16] Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2c was
obtained as a white solid (180 mg, 95%) from 1c (200 mg, 0.66 mmol). Rf = 0.50 (n-
hexane/EtOAc 9:1); Mp 86-87 C; 1H NMR (CDCl3, 500 MHz): δ = 2.29 (s, 3H; CH3), 5.99
(s,1H; -CH), 7.03-7.09 (m, 3H; ArH), 7.17-7.31 (m, 6H; ArH), 7.37 (t, J = 6.5 Hz, 2H; ArH),
7.47 (tt, J = 6.5, 1.0 Hz, 1H; ArH), 7.99 ppm (dd, J = 8.5, 1.0 Hz, 2H; ArH); 13C NMR
(CDCl3, 125.76 MHz): δ = 21.5, 59.4, 126.2, 127.1, 128.0, 128.6, 128.7, 129.0, 129.1, 129.8,
133.0, 136.9, 138.4, 138.9, 139.2, 198.3 ppm; IR (neat): 3060, 3023, 2917, 1682 (CO), 1605,
1576, 1495, 1446, 1274, 1200, 1184 cm-1.
2-(4-Methylphenyl)-1,2-diphenylethanone (2d).[16] Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2d was
obtained as a white solid (160 mg, 84%) from 1d (200 mg, 0.66 mmol). Rf = 0.50 (n-
hexane/EtOAc 9:1); Mp 95-97 C; 1H NMR (CDCl3, 500 MHz): δ = 2.29 (s, 3H; CH3), 5.99
(s, 1H; -CH), 7.17 (d, J = 8.0, 2H; ArH), 7.15 (d, J = 8.0, 2H; ArH), 7.21-7.31 (m, 5H; ArH),
7.38 (t, J = 7.5 Hz, 2H; ArH), 7.47 (tt, J = 6.5, 1.0 Hz, 1H; ArH), 7.99 ppm (dd, J = 8.5, 1.0
13
Hz, 2H; ArH); C NMR (CDCl3, 125.76 MHz): δ = 21.0, 59.1, 127.0, 128.6, 128.7, 128.9,
129.0, 129.1, 129.5, 132.9, 136.0, 136.8, 136.9, 139.3, 198.3 ppm; IR (neat): 3064, 3027,
2917, 1679 (CO), 1593, 1492, 1446, 1282, 1202 cm-1.
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1-(4-Methoxyphenyl)-2,2-diphenylethanone (2e).[14a] Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2e was
obtained as a white solid (70 mg, 74%) from 1e (100 mg, 0.31 mmol). Rf = 0.37 (n-
1
hexane/EtOAc 9:1); Mp 123-124 C; H NMR (CDCl3, 500 MHz): δ = 3.81 (s, 3H; OCH3),
5.99 (s, 1H; -CH), 6.87 (td, J = 6.5, 2.5 Hz, 2H; ArH), 7.21-7.32 (m, 10H; ArH), 7.99 ppm
(dd, J = 7.0, 2.0 Hz, 2H; ArH); 13C NMR (CDCl3, 125.76 MHz): δ = 55.4, 59.1, 113.8, 127.0,
128.7, 129.1, 129.8, 131.3, 139.4, 163.4, 196.7 ppm; IR (neat): 3064, 3031, 2978, 2900, 1673
(CO), 1594, 1493, 1452, 1311, 1266, 1211, 1154 cm-1.
2-(2-Methoxyphenyl)-1,2-diphenylethanone (2f).[16] Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2f was
obtained as a white solid (130 mg, 68%) from 1f (200 mg, 0.63 mmol). Rf = 0.48 (n-
1
hexane/EtOAc 9:1); Mp 117-118 C; H NMR (CDCl3, 500 MHz): δ = 3.72 (s, 3H; OCH3),
6.33 (s, 1H; -CH), 6.83-6.86 (m, 2H; ArH), 6.92 (dd, J = 6.5, 1.5 Hz, 1H; ArH), 7.19-7.21 (m,
1H; ArH), 7.22-7.25 (m, 1H; ArH), 7.29-7.32 (m, 4H; ArH), 7.34-7.37 (m, 2H; ArH), 7.44
13
(tt, J = 6.0, 1.5 Hz, 1H; ArH), 7.99 ppm (dd, J = 8.5, 1.0 Hz, 2H; ArH); C NMR (CDCl3,
125.76 MHz): δ = 53.1, 55.4, 110.4, 120.6, 127.1, 128.3, 128.4, 128.67, 128.70, 129.7, 132.6,
137.1, 137.6, 156.3, 198.8 ppm; IR (neat): 064, 2933, 2835, 1678 (CO), 1596, 1489, 1465,
1446, 1307, 1244, 1165, 1108 cm-1.
2-(4-Methoxyphenyl)-1,2-diphenylethanone (2g).[14a] Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2g was
obtained as a white solid (145 mg, 76%) from 1g (200 mg, 0.63 mmol). Rf = 0.42 (n-
1
hexane/EtOAc 9:1); Mp 86-87 C; H NMR (CDCl3, 500 MHz): δ = 3.75 (s, 3H; OCH3),
5.98 (s, 1H; -CH), 6.84 (dd, J = 6.5, 1.5 Hz, 2H; ArH), 7.18 (dd, J = 6.5, 1.5 Hz, 2H; ArH),
7.22-7.26 (m, 3H; ArH), 7.30 (t, J = 7.5 Hz, 2H; ArH), 7.38 (t, J = 7.5 Hz, 2H; ArH), 7.48 (t,
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13
J = 7.0 Hz, 1H; ArH), 7.99 ppm (dd, J = 8.5, 1.0 Hz, 2H; ArH); C NMR (CDCl3, 125.76
MHz): δ = 55.2, 58.6, 114.1, 127.0, 128.58, 128.67, 128.93, 129.03, 130.2, 131.1, 133.0,
136.8, 139.5, 158.6, 198.5 ppm; IR (neat): 3027, 2962, 2896, 2839, 1685 (CO), 1597, 1511,
1445, 1255, 1169 cm-1.
1,2-bis(3-Methoxyphenyl)-2-phenylethanone (2h). Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2h was
obtained as a colourless oil (150 mg, 79%) from 1h (200 mg, 0.57 mmol). Rf = 0.44 (n-
1
hexane/EtOAc 9:1); H NMR (CDCl3, 500 MHz): δ = 3.74 (s, 3H; -OCH3), 3.79 (s, 3H; -
OCH3), 5.98 (s, 1H; -CH), 6.77-6.79 (m, 1H; ArH), 6.81-6.82 (m, 1H; ArH), 6.86 (d, J = 7.5
Hz, 1H; ArH), 7.03-7.06 (m, 1H; ArH), 7.21-7.32 (m, 7H; ArH), 7.52-7.53 (m, 1H; ArH),
13
7.57 ppm (dd, J = 7.0, 2.0 Hz, 1H; ArH); C NMR (CDCl3, 125.76 MHz): δ = 55.2, 55.3,
59.5, 112.4, 113.3, 115.0, 119.5, 121.54, 121.57, 127.1, 128.7, 129.1, 129.6, 129.7, 138.2,
138.9, 140.5, 159.7, 159.8, 197.9 ppm; IR (neat): 3060, 3002, 2937, 2839, 1682 (CO), 1594,
1580, 1486, 1451, 1426, 1253, 1193, 1160 cm-1; HRMS (ESI): m/z [M + H]+ calcd for
C22H21O3: 333.1486; found: 333.1414.
1,2-bis(4-Methylphenyl)-2-phenylethanone (2i).[16] Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2i was
obtained as a white solid (180 mg, 95%) from 1i (200 mg, 0.63 mmol). Rf = 0.46 (n-
hexane/EtOAc 9:1); Mp 64-65 C; 1H NMR (CDCl3, 500 MHz): δ = 2.28 (s, 3H; CH3), 2.34
(s, 3H; CH3), 5.97 (s, 1H; -CH), 7.11 (d, J = 8.0 Hz, 2H; ArH), 7.14-7.18 (m, 4H; ArH), 7.21-
13
7.23 (m, 1H; ArH), 7.24-7.31 (m, 4H; ArH), 7.89 ppm (d, J = 8.0 Hz, 2H; ArH); C NMR
(CDCl3, 125.76 MHz): δ = 21.0, 21.6, 58.9, 127.0, 128.6, 129.0, 129.08, 129.09, 129.3,
129.4, 134.3, 136.2, 136.7, 139.5, 143.8, 197.9 ppm; IR (neat): 3027, 2921, 1678 (CO), 1603,
1511, 1450, 1406, 1276, 1201, 1176 cm-1.
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2-(Naphthalen-1-yl)-1,2-diphenylethanone (2j).[14a] Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2j was
obtained as a white solid (160 mg, 84%) from 1j (200 mg, 0.59 mmol). Rf = 0.57 (n-
1
hexane/EtOAc 9:1); Mp 110-111 C; H NMR (CDCl3, 500 MHz): δ = 6.73 (s, 1H; -CH),
7.20-7.38 (m, 9H; ArH), 7.45-7.49 (m, 3H; ArH), 7.77 (d, J = 8.0 Hz, 1H; ArH), 7.86-7.87
(m, 1H; ArH), 7.96-7.98 (m, 2H; ArH), 7.99-8.01 ppm (m, 1H; ArH); 13C NMR (CDCl3,
125.76 MHz): δ = 55.9, 123.2, 125.4, 125.8, 126.7, 127.1, 127.3, 128.1, 128.7, 128.79, 128.9,
129.1, 129.6, 131.3, 133.1, 134.2, 135.0, 136.6, 138.1, 198.3 ppm; IR (neat): 3060, 3035,
1682 (CO), 1597, 1449, 1291, 1210, 1177 cm-1.
2-(Naphthalen-2-yl)-1,2-diphenylethanone (2k). A solution of α-hydroxy ketone 1k (200
mg, 0.59 mmol) in CH2Cl2 (3 mL) and Et3SiH (1.5 equiv.) were placed in a 25 mL round
bottom flask (RBF). Aqueous HClO4 (70%, 10 mol%) was added to this reaction mixture.
The contents were stirred at 40 C. After stirring the contents for 70 minute, the product was
extracted with CH2Cl2 (3×15 mL), washed with 10% Na2CO3 and dried over anhydrous
Na2SO4. The solvent was removed under reduced pressure. The purification was done by
flash chromatography (n-hexane/EtOAc 9:1) to obtain the title compound 2k and a by-
product 2,3-Diphenylnaphtho[1,2-b]furan (3).
2-(Naphthalen-2-yl)-1,2-diphenylethanone (2k).[21] White solid (141 mg, 74%); Rf = 0.60
(n-hexane/EtOAc 9:1); Mp 105-106 C; 1H NMR (CDCl3, 500 MHz): δ = 6.19 (s, 1H; -CH),
7.24-7.44 (m, 10H; ArH), 7.48 (tt, J = 7.5, 1.5 Hz, 1H; ArH), 7.69-7.80 (m, 4H; ArH), 8.02-
13
8.04 (m, 2H; ArH); C NMR (CDCl3, 125.76 MHz): δ = 59.5, 126.0, 126.1, 127.2, 127.3,
127.6, 127.8, 127.9, 128.5, 128.6, 128.7, 129.0, 129.3, 132.5, 133.1, 133.4, 136.6, 136.8,
139.0, 198.3 ppm; IR (neat): 3056, 2925, 1686 (CO), 1593, 1499, 1445, 1360, 1282, 1198
cm-1.
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2,3-Diphenylnaphtho[1,2-b]furan (3).[22] Light yellow solid (14
1
mg, 7%); Rf = 0.80 (n-hexane/EtOAc 9:1); Mp 97-98 C; H NMR
(CDCl3, 500 MHz): δ = 7.29 (tt, J = 7.5, 1.5 Hz, 1H; ArH), 7.33-7.36
(m, 2H; ArH), 7.43 (tt, J = 7.5, 1.5 Hz, 1H; ArH), 7.48-7.52 (m, 3H; ArH), 7.55-7.57 (m, 3H;
ArH), 7.62 (dt, J = 8.0, 1 Hz, 1H; ArH), 7.58 (d, J = 8.5 Hz, 1H; ArH), 7.73-7.75 (m, 2H;
ArH), 7.93 (d, J = 8 Hz, 1H; ArH), 8.43 ppm (d, J = 8 Hz, 1H; ArH); 13C NMR (CDCl3,
125.76 MHz): δ = 118.5, 118.8, 120.2, 121.2, 123.6, 125.3, 125.6, 126.4, 126.8, 127.7, 128.1,
128.4, 128.5, 129.0, 129.9, 130.9, 131.8, 133.0, 149.6, 150.0 ppm; IR (neat): 3056, 3032,
2938, 1638, 1597, 1577, 1446, 1375, 1274, 1197, 1160, 1068 cm-1; HRMS (ESI) m/z [M +
H]+ calcd for C24H17O: 321.1274; found: 321.1225.
1,2-bis(2-Fluorophenyl)-2-phenylethanone (2l). Following the general procedure and
purification by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2l was
obtained as a white solid (175 mg, 92%) from 1l (200 mg, 0.62 mmol). Rf = 0.62 (n-
1
hexane/EtOAc 9:1); Mp 105-106 C; H NMR (CDCl3, 500 MHz): δ = 5.95 (s, 1H; -CH),
7.00 (tt, J = 8.5, 2.0 Hz, 2H; ArH), 7.05-7.08 (m, 2H; ArH), 7.19-7.27 (m, 5H; ArH), 7.31-
7.34 (m, 2H; ArH), 7.99-8.02 ppm (m, 2H; ArH); 13C NMR (CDCl3, 125.76 MHz): δ = 58.6,
115.5 (d, J = 21.2 Hz), 115.7 (d, J = 21.2 Hz), 127.4, 128.92, 128.96, 130.7 (d, J = 7.5 Hz),
131.7 (d, J = 8.8 Hz), 132.9 (d, J = 3.8 Hz), 134.7 (d, 2.5 Hz), 138.7, 162.0 (d, J = 255.3 Hz),
165.7 (d, J = 246.5 Hz), 196.5 ppm; IR (neat): 3031, 1681 (CO), 1592, 1506, 1413, 1211,
1159 cm-1; HRMS (ESI): m/z [M + H]+ calcd for C20H15F2O: 309.1086; found: 309.1104.
2,2-Diphenylethanoic acid (2m).[23] A solution of α-hydroxy acid 1m (500 mg, 2.19 mmol)
in CH2Cl2 (3 mL) and Et3SiH (1.5 equiv.) were placed in a 25 mL two neck RBF fitted with a
condenser. Aqueous HClO4 (70%, 10 mol%) was added to this reaction mixture. The contents
were stirred at 40 C and progress of the reaction was monitored by TLC analysis. After
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10.1002/ejoc.202000142
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stirring the contents for 20 h, the product was extracted with CH2Cl2 (3×15 mL) and dried
over anhydrous Na2SO4. The solvent was removed under reduced pressure and purification
was done by flash chromatography (n-hexane/EtOAc 8:2) to give the title compound 2m as a
1
white solid in 94% yield (435 mg). Rf = 0.60 (n-hexane/EtOAc 7:3); Mp 152-153 C; H
NMR (CDCl3, 500 MHz): δ = 4.94 (s, 1H; -CH), 7.14-7.17 (m, 2H; ArH), 7.19-7.23 (m, 8H;
ArH), 10.93 ppm (s, 1H; -COOH); 13C NMR (CDCl3, 125.76 MHz): δ = 57.1, 127.6, 128.75,
128.76, 137.9, 179.0 ppm; IR (neat): 3076, 3019, 2900, 2815, 2700, 1698 (CO), 1495, 1413,
1315, 1221 cm-1.
Methyl 2,2-diphenylacetate (2n).[24] A solution of α-hydroxy ester 1n (500 mg, 2.06 mmol)
in CH2Cl2 (3 mL) and Et3SiH (1.5 equiv.) were placed in a 25 mL two neck RBF fitted with a
condenser. Aqueous HClO4 (70%, 10 mol%) was added to this reaction mixture. The contents
were stirred at 40 C and progress of the reaction was monitored by TLC analysis. After
stirring the contents for 24 h, the product was extracted with CH2Cl2 (3×15 mL), washed with
10% Na2CO3, and dried over anhydrous Na2SO4. The solvent was removed under reduced
pressure and purification was done by flash chromatography (n-hexane/EtOAc 9:1) to give
the title compound 2n as a white solid in 90% yield (420 mg). Rf = 0.68 (n-hexane/EtOAc
1
9:1); Mp 63-64 C; H NMR (CDCl3, 500 MHz): δ = 3.66 (s, 3H; -CH3), 5.02 (s, 1H; -CH),
7.19-7.22 (m, 2H; ArH), 7.25-7.30 ppm (m, 8H; ArH); 13C NMR (CDCl3, 125.76 MHz): δ =
52.4, 57.1, 127.4, 128.73, 128.74, 138.8, 173.0 ppm; IR (neat): 3092, 3068, 3023, 2998,
2949, 1722 (CO), 1605, 1491, 1454, 1428, 1359, 1194 cm-1.
3-(4-Methoxyphenyl)butan-2-one (2q).[25] Following the general procedure and purification
by flash chromatography (n-hexane/EtOAc 9:1), the title compound 2q was obtained as a
colourless liquid (70 mg, 38%) from 1q (200 mg, 1.03 mmol). Rf = 0.48 (n-hexane/EtOAc
9:1); 1H NMR (CDCl3, 400 MHz): δ=1.36 (d, J = 7.0 Hz, 3H; -CH3), 2.03 (s, 3H; -CH3), 3.69
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(q, J = 7.0 Hz, -1H; CH), 3.79 (s, 3H; -OCH3), 6.86-6.88 (m, 2H; ArH), 7.11-7.14 ppm (m,
2H; ArH); 13C NMR (CDCl3, 100.53 MHz): δ = 17.2, 28.2, 52.8, 55.2, 114.3, 128.8, 132.6,
158.7, 209.2 ppm; IR (neat): 2974, 2937, 2835, 1708 (CO), 1605, 1508, 1454, 1353, 1301,
1244, 1177 cm-1.
1,1-Diphenyl methane (5).[26] Following the general procedure and purification by flash
chromatography (n-hexane), the title compound 5 was obtained as a colourless liquid (160
mg, 88%) from 4 (200 mg, 1.08 mmol). Rf = 0.86 (n-hexane); 1H NMR (CDCl3, 500 MHz): δ
= 3.97 (s, 2H; CH2), 7.17-7.20 (m, 6H; ArH), 7.25-7.28 ppm (m, 4H; ArH); IR (neat): 3035,
2962, 2904, 2876, 1605, 1503, 1454, 1241, 1069 cm-1.
2-(4-Methoxyphenyl)-1,2,2-triphenylethenone (6).[13a] A solution of α-hydroxy ketone 1a
(200 mg, 0.69 mmol) in CH2Cl2 (3 mL) and anisole (1.5 equivalents) were placed in a 25 mL
two neck RBF fitted with a condenser. Aqueous HClO4 (70%, 10 mol%) was added to this
reaction mixture. The contents were stirred at 40 C and progress of the reaction was
monitored by TLC analysis. After stirring the contents for 2 h, the product was extracted with
CH2Cl2 (3×15 mL), washed with 10% Na2CO3 and dried over anhydrous Na2SO4. The
solvent was removed under reduced pressure. After purification by flash chromatography (n-
hexane/EtOAc 9:1), the title compound 6 was obtained as a white solid in 74% yield (195
mg). Rf = 0.54 (n-hexane/EtOAc 9:1); Mp 138-140 C; 1H NMR (CDCl3, 500 MHz): δ = 3.75
(s, 3H; OCH3), 6.77 (m, 2H; ArH), 7.12-7.14 (m, 4H; ArH), 7.15-7.24 (m, 9H; ArH), 7.25-
7.29 (m, 2H; ArH), 7.66 ppm (dd, J = 8.0, 1.5 Hz, 2H; ArH); IR (neat): 3056, 3031, 2949,
2839, 1675(CO), 1609, 1581, 1507, 1443, 1299, 1250, 1214, 1180 cm-1.
Supporting Information
1H NMR spectra and 13C NMR spectra of final products. APCI mass spectra of 1a, 1e, 1g and
1j (PDF).
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10.1002/ejoc.202000142
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ACKNOWLEDGMENTS
Sandeep thanks CSIR, New Delhi for JRF (09/135(0842)/2019-EMR-1). AK thanks Prof. Tej
Vir Singh for useful discussions while preparing this manuscript.
Keywords: • deoxygenation • α,α-diaryl carbonyl compounds • α-hydroxy carbonyl
compounds • α-keto carbenium ion
REFERENCES
[1] a) R. C. Larock, Comprehensive Organic Transformations. Wiley-VCH, New York.
1999, 49‒52; b) A. G. Sergeev, J. F. Hartwig, Science. 2011, 332, 439‒443; c) J. M.
Herrmann, B. König, Eur. J. Org. Chem. 2013, 7017‒7027; d) W. Hartwig,
Tetrahedron 1983, 39, 2609‒2645.
[2] a) S. Kim, E. E. Kwon, Y. T. Kim, S. Jung, H. J. Kim, G. W. Huber, J. Lee, Green.
Chem. 2019, 21, 3715‒3743; b) Y. Seo, J. M. Lowe, M. R. Gagné, ACS Catal. 2019
,
9, 6648‒6652; c) L. L. Adduci, T. A. Bender, J. A. Dabrowski, M. R. Gagné, Nat.
Chem. 2015, 7, 576‒581.
[3] a) M.-M. Li, Y. Wu, B. Liu, Org. Lett. 2019, 21, 575‒578; b) S. P. Chavan, A. L.
Kadam, R. G. Gonnade, Org. Lett. 2019, 21, 9089‒9093; c) D. H. Dethe, S.
Mahapatra, S. K. Sau, Org. Lett. 2018, 20, 2766‒2769; d) T. A. Bender, J. A.
Dabrowski, M. R. Gagné, Nat. Rev. 2018, 2, 35‒46; e) T. A. Bender, P. R. Payne, M.
R. Gagné, Nat. Chem. 2018, 10, 85‒90; f) X.-J. Dai, C.-J. Li, J. Am. Chem. Soc.
2017, 138, 5433‒5440; g) P. A. Jordan, S. J. Miller, Angew. Chem. Int. Ed. 2012, 51,
2907‒2911; h) D. S. Palacios, T. M. Anderson, M. D. Burke, J. Am. Chem. Soc.
2007, 129, 13804‒13805.
[4] a) D. H. R. Barton, S. W. McCombie, J. Chem. Soc., Perkin Trans. 1, 1975, 16,
1574‒1585; b) D. H. R. Barton, D. O. Jang, J. C. Jaszberenyi, Tetrahedron Lett.
1992, 33, 5709‒5712.
[5] For some selected examples on deoxygenation of alcohols, see: a) M. Isomura, D. A.
Petrone, E. M. Carreira, J. Am. Chem. Soc. 2019, 141, 4738‒4748; b) M. Sai, Adv.
Synth. Catal. 2018, 360, 4330–4335; c) B. Ciszek, I. Fleischer, Chem. Eur. J. 2018
,
24, 12259–12263; d) E. Steffensmeier, K. M. Nicholas, Chem. Commun. 2018, 54,
790‒793; e) O. J. Bauer, S. Chakraborty, D. Milstein, ACS Catal. 2017, 7, 4462‒4466;
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202000142
European Journal of Organic Chemistry
f) G. R. Kasner, C. Boucher-Jacobs, J. M. McClain II, K. M. Nicholas, Chem.
Commun. 2016, 52, 7257‒7260; g) D. Rackl, V. Kais, P. Kreitmeier, O. Reiser,
Beilstein J. Org. Chem. 2014, 10, 2157–2165; h) M.-L. Yao, A. B. Pippin, G. W.
Kabalka, Tetrahedron Lett. 2010, 51, 853–855; k) V. Gevorgyan, M. Rubin, S.
Benson, J.-X. Liu, Y. Yamamoto, J. Org. Chem. 2000, 65, 6179‒6186.
[6] For aldehyde and ketones, see; a) G. Argouarch, New J. Chem. 2019, 43,
11041‒11044; b) Z. Dong, J. Yuan, Y. Xiao, P. Mao, W. Wang, J. Org. Chem. 2018
,
83, 11067−11073; c) J. R. Bernardo, A. C. Fernandes, Green Chem. 2016, 18, 2675–
2681; d) T. Mahdi, D. W. Stephan, Angew. Chem. Int. Ed. 2015, 54, 8511‒8514.
[7] For acid, ester and amide see; a) S. Das, H. Karmaker, J. Bhattacharjee, T. K. Panda,
Dalton Trans. 2019, 48, 11978‒11984; b) J. Chen, Z. Zhang, D. Liu, W. Zhang,
Angew. Chem. Int. Ed. 2016, 55, 8444‒8447; c) N. Sakai, K. Kawana, R. Ikeda, Y.
Nakaike, T. Konakahara, Eur. J. Org. Chem. 2011, 3178‒3183.
[8] H. Wang, L. Li, X.-F. Bai, J.-Y. Shang, K.-F. Yang, L.-W. Xu, Adv. Synth. Catal.
2013, 355, 341‒347; b) M. Yasuda, Y. Onishi, M. Ueba, T. Miyai, A. Baba, J. Org.
Chem. 2001, 66, 7741‒7744; c) T. Miyai, M. Ueba, A. Baba, Synlett. 1999, 2,
182‒184.
[9] W. Yang, L. Gao, J. Lu, Z. Song, Chem. Commun. 2018, 54, 4834‒4837; b) I.
Chatterjee, D. Porwal, M. Oestreich, Angew. Chem. Int. Ed. 2017, 56, 3389‒3391; c)
T. McCallum, E. Slavko, M. Morin, L. Barriault, Eur. J. Org. Chem. 2015, 81‒85; d)
V. J. Meyer, M. Niggemann, Chem. Eur. J. 2012, 18, 4687–4691.
[10] a) T. Tanaka, M. Kawase, S. Tani, Bioorg. Med. Chem. 2004, 12, 501‒505; b) B.
Plietker, Tetrahedron: Asymmetry. 2005, 16, 3453‒3459; c) G. Olack, H. Morrison, J.
Org. Chem. 1991, 56, 4969‒4971; d) H. B. Rasmussen, J. K. MacLeod, J. Nat. Prod.
1997, 60, 1152.
[11] a) S. Yang, W. Tang, Z. Yang, J. Xu, ACS Catal. 2018, 8, 9320−9326; b) E.
Speckmeier, C. Padi , K. Zeitler, Org. Lett. 2015, 17, 4818−4821; c) M. Dobmeier, J.
M. Herrmann, D. Lenoir, B. König, Beilstein J. Org. Chem. 2012, 8, 330–336; d) J. E.
Milne, J. A. Murry, A. King, R. D. Larsen, J. Org. Chem. 2009, 74, 445–447.
[12] a) M. M. Pichon, D. Hazelard, P. Compain, Eur. J. Org. Chem. 2019, 6320–6332; b)
M. M. Pichon, F. Stauffert, L. G. Addante-Moya, A. Bodlenner, P. Compain, Eur. J.
Org. Chem. 2018, 1538–1545.
[13] a) A. Kumar, T. V. Singh, S. P. Thomas, P. Venugopalan, Eur. J. Org. Chem. 2015
,
1226–1234; b) A. Kumar, R. K. Sharma, T. V. Singh, P. Venugopalan, Tetrahedron
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202000142
European Journal of Organic Chemistry
2013, 69, 10724–10732; c) A. kumar, A. K. Pal, R. D. Anand, T. V. Singh, P.
Venugopalan, Tetrahedron 2011, 67, 8308‒8313.
[14] a) Y.-J. Hao, X.-S. Hu, Y. Zhou, J. Zhou, J.-S. Yu, ACS Catal. 2020, 10, 955−993;
b) I. Astarloa, R. SanMartin, M. T. Herrero, E. Domínguez, Adv. Synth. Catal. 2018
,
360, 1711‒1718; c) T. Chen, Y.-F. Li, Y. An, F.-M. Zhang, Org. Lett. 2016, 18,
4754‒4757; d) C. C. C. Johansson, T. J. Colacot, Angew. Chem. Int. Ed. 2010, 49, 676
–707; e) D. A. Culkin, J. F. Hartwig, Acc. Chem. Res. 2003, 36, 234‒245; f) M.
Palucki, S. L. Buchwald, J. Am. Chem. Soc. 1997, 119, 1110811109.
[15] F. Churruca, R. SanMartin, M. Carril, M. K. Urtiaga, X. Solans, I. Tellitu, E.
Dominguez, J. Org. Chem. 2005, 70, 3178‒3187.
[16] G. Danoun, A. Tlili, F. Monnier, M. Taillefer, Angew. Chem. Int. Ed. 2012, 51,
12815‒12819.
[17] a) X.-P. Xin, L. Zhu, J. Zhou, Adv. Synth. Catal. 2018, 360, 1116‒1122; b) L. Chen, X.-
P. Yin, C.-H. Wang, J. Zhou, Org. Biomol. Chem. 2014, 12, 60336048; c) F. Zhou, M.
Ding, J. Zhou, Org. Biomol. Chem. 2012, 10, 3178–3181; d) L. Chen, F. Zhou, T.-D. Shi,
J. Zhou, J. Org. Chem. 2012, 77, 4354−4362; e) F. Zhu, F. Zhou, Z.-Y. Cao, C. Wang,
Y.-X. Zhang, C.-H. Wang, J. Zhou, Synthesis 2012, 44, 3129–3144; f) F. Zhou, Z.-Y.
Cao, J. Zhang, H.-B. Yang, J. Zhou, Chem. Asian J. 2012, 7, 233–241.
[18] a) T. Ohwada, K. Shudo, J. Am. Chem. Soc. 1988, 110, 18621870; b) L. H. Dao, M.
Maleki, A. C. Hopkinson, E. Lee-Ruff, J. Am. Chem. Soc. 1986, 108, 5237‒5242; c) X.
Creary, Acc. Chem. Res. 1985, 18, 38; d) X. Creary, C. C. Geiger, J. Am. Chem. Soc.
1983, 105, 71237129; e) P. G. Gassman, T. T. Tidwell, Acc. Chem. Res. 1983, 16,
279285; f) K. Takeuchi, T. Kitagawa, K. Okamoto, J. Chem. Soc., Chem. Commun.
1983, 7; g) X. Creary, C. C. Geiger, J. Am. Chem. Soc. 1982, 104, 41514162.
[19] L. Chen, J. Zhou, Chem. Asian J. 2012, 7, 2510–2515.
[20] W. C. Still, M. Kahn, A. Mitra, J. Org. Chem. 1978, 43, 29232925.
[21] R. Takise, K. Muto, J. Yamaguchi, K. Itami, Angew. Chem. Int. Ed. 2014, 53, 6791–
6794.
[22] J. Y. Liu, S. Jia, L. Xue, D. Li, Y. Tan, W. Qin, H. Yan, Tetrahedron 2018, 74,
433440.
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10.1002/ejoc.202000142
European Journal of Organic Chemistry
[23] D.-T. Yang, M. Zhu, Z. J. Schiffer, K. Williams, X. Song, X. Liu, K. Manthiram, ACS
Catal. 2019, 9, 4699−4705.
[24] J.-M. Yang, Y. Cai, S.-F. Zhu, Q.-L. Zhoua, Org. Biomol. Chem. 2016, 14, 5516–5519.
[25] M. Gao, D. Sun, H. Gong, Org. Lett. 2019, 21, 1645−1648.
[26] Z. Bazyar, M. Hosseini-Sarvari, J. Org. Chem. 2019, 84, 13503−13515.
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10.1002/ejoc.202000142
European Journal of Organic Chemistry
Table of Contents
A variety of α-hydroxy-α,α-diaryl carbonyl compounds are selectively deoxygenated to
give an important class of α,α-diaryl carbonyl compounds using catalytic amount of
aqueous HClO4 (70%) and triethylsilane as hydride source.
Key topic: Deoxygenation
This article is protected by copyright. All rights reserved.