Self-Catalyzed Rapid Synthesis of N-Acylated/ N-Formylated α-Aminoketones and N-Hydroxymethylated Formamides from 3-Aryl-2 H-Azirines and 2-Me/Ph-3-Aryl-2 H-Azirines

Article abstract of DOI:10.1021/acs.orglett.0c01206

A rapid and effective method has been established for the synthesis of N-acylated α-aminoketone derivatives by the reaction of 3-aryl-2H-azirines and highly substituted 2-Me/Ph-3-aryl-2H-azirines with various carboxylic acids under ambient air within 10 min at room temperature. N-Trifluoroacetylated α-aminoketones with different substituents have been reported in the presence of trifluoroacetic acid. This protocol is equally effective to synthesize N-formylated α-aminoketone and N-hydroxymethylated formamide derivatives.

Full text of DOI:10.1021/acs.orglett.0c01206

pubs.acs.org/OrgLett
Letter
Self-Catalyzed Rapid Synthesis of N‑Acylated/N‑Formylated
α‑Aminoketones and N‑Hydroxymethylated Formamides from
3‑Aryl‑2H‑Azirines and 2‑Me/Ph-3-Aryl‑2H‑Azirines
Aramita De, Sougata Santra, Grigory V. Zyryanov, and Adinath Majee*
Cite This: https://dx.doi.org/10.1021/acs.orglett.0c01206
Read Online
sı
*
Metrics & More
Article Recommendations
Supporting Information
ACCESS
ABSTRACT: A rapid and effective method has been established for the synthesis of N-acylated α-aminoketone derivatives by the
reaction of 3-aryl-2H-azirines and highly substituted 2-Me/Ph-3-aryl-2H-azirines with various carboxylic acids under ambient air
within 10 min at room temperature. N-Trifluoroacetylated α-aminoketones with different substituents have been reported in the
presence of trifluoroacetic acid. This protocol is equally effective to synthesize N-formylated α-aminoketone and N-
hydroxymethylated formamide derivatives.
Accordingly, the synthesis of these molecules has become
very significant to synthetic organic chemists for important
biological activities. So far, on the basis of the literature, only
three strategies are available to synthesize the N-trifluoroacety-
lated aminoketone derivatives using two different strategies
(Scheme 1a).9 Using the first strategy, in 1996, Carreira et al.
reported the synthesis of N-trifluoroacetyl α-aminoketone
derivatives by the reaction between silyl enol ethers and
trifluoroacetic anhydride in the presence of nitridomanganese-
(V) salen-derived complexes.9a Whereas Takemoto et al.
developed a photoinduced reaction between silyl enol ethers
and the iminoiodinanes at 0 °C for 4 h,9b in the second
strategy, Beier’s group synthesized N-trifluoroacetyl amides via
the reaction of N-pentafluoroethyl-substituted triazole using
rhodium catalyst and water as the solvent under microwave
irradiation.9c
he derivatives of N-acylated α-aminoketones are consid-
Tered biologically important compounds, and they serve a
significant role in organic chemistry.1 The incorporation of
CF3 groups in drug moieties increases the selectivity on
binding, the lipophilicity, as well as the metabolic stability in
medicinal chemistry.2 As a result, those molecules have
enormous significance in agrochemical and pharmaceutical
chemistry as well as in functional materials.3 In the N-acylated
α-aminoketone derivatives, CF3-containing N-trifluoroacetyl
aminoketone moieties are very useful in pharmaceutical
chemistry because the N-trifluoroacetamido group offers
improved biological activities.4 Interestingly, these N-trifluor-
oacetyl-based aminoketone compounds show biological
activities, like plant disease control,5 microbicide activity,6
treatment of allergy, inflammation, and asthma, and so on.7 A
few biologically active N-trifluoroacetyl-aminoketone-contain-
ing molecules are shown in Figure 1. In addition, the N-
trifluoroacetamido group is very effective for easy handling and
deprotection to synthesize complex molecules; therefore, the
direct introduction of this N-trifluoroacetamido group is very
useful.8
Several important natural products contain 2H-azirine
moieties, which show different biological activities.10 Different
N-heterocycles are synthesized using the 2H-azirine moiety
because it is a small ring system with high strain and can be
easily opened.11,12 Very recently, Xu et al. reported another
strategy to synthesize functionalized α-amido ketones. The
Received: April 4, 2020
Figure 1. A few representative biologically active N-trifluoroacetyl-
containing molecules.
https://dx.doi.org/10.1021/acs.orglett.0c01206
© XXXX American Chemical Society
Org. Lett. XXXX, XXX, XXX−XXX
A

Organic Letters
pubs.acs.org/OrgLett
Letter
a
Scheme 1. Reported Strategies to Synthesize N-
Trifluoroacetylated α-Aminoketone Derivatives
Table 1. Optimization of the Reaction Conditions
entry
TFA (equiv)
solvent (3 mL)
yields (%)
1
2
3
4
5
6
7
8
1
1
1
1
1
1
1
1
1
1
1
1
0.5
2
1
1
1
1
1
DCM
1,2-DCE
DCB
DMSO
DMF
CH3CN
acetone
THF
1,4-dioxane
benzene
chlorobenzene
toluene
toluene
toluene
methanol
ethanol
water
78
65
55
nd
nd
70
30
nd
20
88
86
94
40
75
b
b
b
9
10
11
12
13
14
15
16
17
18
b
nd
nd
nd
nd
b
b
b
neat
toluene
c
19
93
a
Reaction conditions: 1.0 mmol of 1a, TFA (different equiv amount),
b
solvent (3 mL), room temperature, time: 10 min. nd = not detected
in TLC. Argon atmosphere.
c
found to be the best choice and afforded 94% yield (Table 1,
entry 12). No reaction has been observed under the neat
conditions (Table 1, entry 18). Reducing TFA (0.5 equiv)
afforded less yield; in addition, more TFA (2 equiv) also
decreased the yield (Table 1, entries 12−14). Thus the
optimized yield (94%) was achieved by treating TFA (1 equiv)
in toluene at room temperature for only 10 min under aerobic
conditions (Table 1, entry 12).
reaction proceeded by ring-opening of 2H-azirines in the
presence of AgOAc and the additive DMAP (4-dimethylami-
nopyridine) using Pd(OAc)2 in dioxane as a solvent at 110 °C
within 18 h.13
We are actively engaged in developing various method-
ologies involving azirines and aziridine heterocycles.14 On the
basis of the current working practice, our target is to simplify
methodologies, reducing the solvent additive and even the
catalyst, the so-called neat conditions.15 As a combination of
these two targets, herein, we report a simple protocol for N-
trifluoroacetylated α-aminoketones synthesis by a simple ring-
opening reaction of various aryl 2H-azirines with trifluoroacetic
acid (TFA) (Scheme 1b). In addition, this method is also
effective to synthesize N-acylated α-aminoketones by using
other carboxylic acid derivatives. The reaction takes 10 min for
completion at room temperature.
Initially, we started the reaction by taking 3-phenyl-2H-
azirine (1a, 1 mmol) in dichloromethane (DCM) at room
temperature using TFA (1 equiv). To our delight, the desired
product 2,2,2-trifluoro-N-(2-oxo-2-phenylethyl)acetamide
(2a) was formed within 10 min in 78% yield (Table 1, entry
1). This observation encouraged us for the optimization of the
reaction conditions, as reported in Table 1. No improvement
in yield has been observed by increasing the reaction time up
to 15 to 30 min. To interpret the solvent effects, we have tested
several polar aprotic solvents such as 1,2-dichloroethene (1,2-
DCE), dichlorobenzene (DCB), dimethyl sulfoxide (DMSO),
dimethylformamide (DMF), CH3CN, acetone, tetrahydrofuran
(THF), 1,4-dioxane, benzene, and chlorobenzene (Table 1,
entries 2−11) and polar protic solvents like MeOH, EtOH,
and H2O (Table 1, entries 15−17). Among them, toluene was
We have explored the generality of this TFA-mediated ring-
opening reaction with various substituted aryl 2H-azirines after
optimization, as shown in Scheme 2. Different N-trifluor-
oacetylated α-aminoketone derivatives have been synthesized
(2a−q) in good to excellent yields. Simple 3-phenyl-2H-azirine
(1a) formed the expected 2,2,2-trifluoro-N-(2-oxo-2-
phenylethyl)acetamide (2a) in 94% yield, whereas 3-aryl-2H-
azirines substituted with an electron-donating substituent (like
methyl at the ortho, meta, and para positions in the phenyl
ring) reacted smoothly with TFA, giving the desired products
in satisfactory yields (2b, 80%; 2c, 90%; 2d, 92%). Similarly,
the phenyl ring disubstituted and trisubstituted by an electron-
donating methyl group also underwent a smooth reaction (2e,
88%; 2f, 78%). We have observed that a strong electron-
donating tert-butyl substituent produced the expected product
(2g, 87%) using the same reaction conditions. Similarly, 2H-
azirines containing a substituted phenyl group with electron-
withdrawing groups, such as, chloro, bromo, and fluoro (1h−
m), took part in the reaction and afforded the products in very
good yields (2h, 85%; 2i, 82%; 2j, 74%; 2k, 86%; 2l, 90%; 2m,
85%). Furthermore, aryl-2H-azirine bearing a strong electron-
withdrawing −CF3 group gave an excellent yield (2n, 87%). 4-
Biphenyl-and 1- and 2-naphthyl-containing 2H-azirines gave
the desired products 2o, 2p, and 2q in 75, 80, and 76% yields,
respectively.
B
https://dx.doi.org/10.1021/acs.orglett.0c01206
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
pubs.acs.org/OrgLett
Letter
2H-azirines produced the corresponding products 3l and 3m
in 87 and 74% yields, respectively. This method is also
applicable for highly substituted 2H-azirines such as 2-methyl-
3-phenyl-2H-azirine (1t) and 2,3-diphenyl-2H-azirine (1u),
giving 3n in 88% and 3o in 75% yield, respectively.
Scheme 2. Substrate Scope to Synthesize N-
Trifluoroacetylated α-Aminoketone Derivatives
a
We have used several other acids like difluoroacetic acid,
trichloroacetic acid, bromoacetic acid, propiolic acid, and
phenylpropiolic acid, and we obtained the desired products
(4a−n) in high yields (Scheme 4). However, acetic acid,
benzoic acid, propionic acid, and pivalic acid were unable to
give the desired products.
Scheme 4. Substrate Scope by Varying Other Acids to
a
Synthesize N-Acylated α-Aminoketone Derivatives
a
Reaction conditions: 1 mmol of TFA, 1 mmol of 3-aryl-2H-azirine
(1), toluene (3.0 mL) under ambient air for 10 min, room
temperature.
It is worth noting that formic acid instead of TFA under neat
conditions underwent a smooth reaction to give N-formylated
α-aminoketones. We have synthesized a series of N-formylated
α-aminoketone derivatives (3a−m) by ring-opening of azirines
(Scheme 3). We have noticed the formation of the desired N-
Scheme 3. Substrate Scope for the Synthesis of N-
a
Formylated α-Aminoketones
a
Reaction conditions: 1 mmol of 3-aryl-2H-azirine (1), 1 mmol of
acid, toluene (3.0 mL) for 10 min, ambient air, room temperature.
In addition, the reaction of 2H-azirine with formic acid in
the presence of formaldehyde in a 1:1:1 ratio under similar
reaction conditions gave N-hydroxymethylated formamide
(Scheme 5). A series of desired products have been
Scheme 5. Substrate Scope to Synthesize N-Hydroxymethyl
a
Formamide
a
Reaction conditions: 1 mmol of HCOOH and 1 mmol of 3-aryl-2H-
azirine (1), under neat conditions for 10 min, ambient air, room
temperature.
(2-oxo-2-phenylethyl)formamide (3a) in 90% yield from 3-
phenyl-2H-azirine (1a). Substituted 3-aryl-2H-azirines with an
electron-donating methyl substituent at the ortho, meta, and
para positions of the phenyl ring reacted with formic acid and
provided the corresponding products in excellent yields (3b,
88%; 3c, 85%; 3d, 91%). For disubstituted and trisubstituted
electron-donating substituents (e.g., methyl) in 3-aryl-2H-
azirines, the reactions also proceeded efficiently (3e, 81%; 3f,
78%). Furthermore, 2H-azirines substituted with chloro,
bromo, fluoro, and nitro were also shown to give the desired
products smoothly (3g, 80%; 3h, 76%; 3i, 87%; 3j, 84%; 3k,
83%). In addition, 4-biphenyl- and 1-naphthyl-substituted aryl-
a
Reaction conditions: HCOOH (1 mmol), HCHO (1 mmol), and 3-
aryl-2H-azirine (1, 1 mmol) under neat conditions for 10 min,
ambient air, room temperature.
C
https://dx.doi.org/10.1021/acs.orglett.0c01206
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
pubs.acs.org/OrgLett
Letter
synthesized using this protocol and were obtained (5a−g) in
satisfactory yields. The desired product N-(hydroxymethyl)-N-
(2-oxo-2-phenylethyl) formamide (5a) has been isolated in
78% yield for simple 3-phenyl-2H-azirine (1a). 3-Aryl-2H-
azirines with a methyl substituent at the ortho and meta
positions as well as a trimethyl-substituted phenyl ring afforded
the products very smoothly (5b, 72%; 5c, 74%; 5d, 68%). Also,
an electron-withdrawing group (fluoro) at the phenyl moiety
was found to be efficient to give the desired N-hydroxymethyl
formamide 5e (70%). Aryl-2H-azirines substituted with
biphenyl and naphthyl moieties also afforded the products 5f
in 62% yield and 5g in 65% yield, respectively.
In this reaction, no external additives or oxidants have been
used. None of these reactions are sensitive to air and moisture.
It is worth mentioning that an inert atmosphere was not
necessary, and the reaction was carried out under an open
atmosphere. No decomposition of the product, polymerization,
or byproducts has been observed. In addition, the
regioselectivity and high yields are also very important for
this reaction protocol. The structural confirmation of the
known compounds was done by the comparison of spectral
data. Those compounds that are new were characterized by
spectral as well as analytical data. Finally, the crystal analysis of
N-(2-(2,4-dimethylphenyl)-2-oxoethyl)-2,2,2-trifluoroaceta-
mide (2e) was performed to confirm the structure.
azirine, giving intermediate (A), as shown in Scheme 8. This
particular intermediate is not stable, and the lone pair of
Scheme 8. Proposed Reaction Mechanism
nitrogen atoms attacks the carbonyl carbon of ester to give the
1,3-oxazitidine ion (B). This 1,3-oxazitidine ion (B) gives the
stable desired product 2a via aziridine ring-opening.
In conclusion, an efficient and regioselective method to
synthesize N-acylated α-aminoketones including N-trifluoro-
methylated α-aminoketone derivatives has been developed by
the reaction of aryl 2H-azirines with various carboxylic acid
derivatives, including TFA, under ambient air at room
temperature without using any catalyst or additive. A library
of N-trifluoromethylated α-aminoketone derivatives with
different substituents has been obtained in excellent yields.
The formation of N-formylated α-aminoketones in the
presence of formic acid instead of TFA is a very meaningful
extension of this protocol. In addition, we have also
synthesized N-hydroxymethylated formamides under the
same reaction conditions by the reaction of azirines, formic
acid, and formaldehyde. A mechanistic pathway has also been
proposed for the construction of N-trifluoromethylated α-
aminoketones. The fast and clean reaction, easily available
reactants, simple product isolation, and usual purification in
the absence of metals, catalysts, and additives are the notable
advantages of the present methodology. It is our expectation
that this developed methodology will be applicable to
synthesize N-acylated α-aminoketones including N-trifluoro-
methylated α-aminoketones, N-formylated α-amino ketones,
and N-hydroxymethylated formamides, which are considered
as very important building blocks in the organic synthetic
community.
Using our laboratory setup, the gram-scale synthesis for the
model reaction was investigated to synthesize N-trifluorome-
thylated α-aminoketones and N-formylated α-aminoketones.
We observed 1.04 g of 2a in 90% yield and 1.43 g of 3a in 88%
yield, which shows a demanding application of our method-
ology in the large-scale synthesis of the compounds N-
trifluoromethylated α-aminoketone and N-formylated α-
aminoketone derivatives (Scheme 6).
Scheme 6. Gram-Scale Synthesis
ASSOCIATED CONTENT
* Supporting Information
■
sı
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.orglett.0c01206.
As an extension, a cyclization reaction was carried out, taking
N-trifluoroacetyl α-aminoketone (2a) with hydrazine hydrate,
and we obtained substituted 1,2,4-triazine derivative (6) in
excellent yield (Scheme 7). These 1,2,4-triazine derivatives
exhibit biological activities with antiinflammatory, antibacterial,
antitumor, anticonvulsant, as well as antiviral properties.16
The mechanism of the formation of N-trifluoromethylated
α-aminoketone derivatives has been explained based on the
literature.13,17 Here the strong TFA plays a role in the
activation of azirine by the proton. On the contrary, the
trifluoro acetate acts as a nucleophile and attacks the activated
X-ray crystallographic data of compound 2e, exper-
1
imental details, and scanned copies of H, 13C, and 19F
NMR spectra of the synthesized compounds (PDF)
Accession Codes
CCDC 1978555 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 Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
Scheme 7. Further Transformation of the Synthesized
Compound (2a)
AUTHOR INFORMATION
Corresponding Author
■
Adinath Majee − Department of Chemistry, Visva-Bharati (A
Central University), Santiniketan 731235, India; orcid.org/
0000-0002-5439-6851; Email: adinath.majee@visva-
bharati.ac.in
D
https://dx.doi.org/10.1021/acs.orglett.0c01206
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Authors
pubs.acs.org/OrgLett
Letter
(10) (a) Skepper, C. K.; Molinski, T. F. J. Org. Chem. 2008, 73,
2592. (b) Skepper, C. K.; Dalisay, D. S.; Molinski, T. F. Bioorg. Med.
Chem. Lett. 2010, 20, 2029.
(11) (a) Palacios, F.; de Retana, A. M. O.; de Marigorta, E. M.; de
los Santos, J. M. Eur. J. Org. Chem. 2001, 2401. (b) Balme, G. Angew.
Chem., Int. Ed. 2004, 43, 6238. (c) Huang, C.-Y.; Doyle, A. G. Chem.
Rev. 2014, 114, 8153. (d) Ouyang, K.; Hao, W.; Zhang, W.-X.; Xi, Z.
Chem. Rev. 2015, 115, 12045.
Aramita De − Department of Chemistry, Visva-Bharati (A
Central University), Santiniketan 731235, India
Sougata Santra − Department of Organic and Biomolecular
Chemistry, Chemical Engineering Institute, Ural Federal
University, 620002 Yekaterinburg, Russian Federation;
orcid.org/0000-0002-4186-6105
(12) (a) Xuan, J.; Xia, X.-D.; Zeng, T.-T.; Feng, Z.-J.; Chen, J.-R.;
Lu, L.-Q.; Xiao, W.-J. Angew. Chem., Int. Ed. 2014, 53, 5653.
(b) Mueller, J. O.; Schmidt, F. G.; Blinco, J. P.; Barner-Kowollik, C.
Angew. Chem., Int. Ed. 2015, 54, 10284. (c) Zeng, T.-T.; Xuan, J.;
Ding, W.; Wang, K.; Lu, L.-Q.; Xiao, W.-J. Org. Lett. 2015, 17, 4070.
(d) Jin, L.; Wu, Y.; Zhao, X. J. Org. Chem. 2015, 80, 3547. (e) Li, T.;
Xu, F.; Li, X.; Wang, C.; Wan, B. Angew. Chem., Int. Ed. 2016, 55,
2861. (f) Zhao, M.-N.; Zhang, M.-N.; Ren, Z.-H.; Wang, Y.-Y.; Guan,
Z.-H. Sci. Bull. 2017, 62, 493.
Grigory V. Zyryanov − Department of Organic and
Biomolecular Chemistry, Chemical Engineering Institute, Ural
Federal University, 620002 Yekaterinburg, Russian Federation;
I. Ya. Postovskiy Institute of Organic Synthesis, Ural Division of
the Russian Academy of Sciences, 620219 Yekaterinburg,
Russian Federation
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.orglett.0c01206
(13) Xu, F.; Si, X.-J.; Song, Y.-Y.; Wang, X.-D.; Liu, C.-S.; Geng, P.-
F.; Du, M. J. Org. Chem. 2019, 84, 2200.
Notes
(14) Our references: (a) De, A.; Santra, S.; Hajra, A.; Zyryanov, G.
V.; Majee, A. J. Org. Chem. 2019, 84, 11735. (b) Samanta, S.; Santra,
S.; Chatterjee, R.; Majee, A. Org. Biomol. Chem. 2020, 18, 551.
(c) Chatterjee, R.; Samanta, S.; Mukherjee, A.; Santra, S.; Zyryanov,
G. V.; Majee, A. Tetrahedron Lett. 2019, 60, 276. (d) Chakraborty
Ghosal, N.; Santra, S.; Das, S.; Hajra, A.; Zyryanov, G. V.; Majee, A.
Green Chem. 2016, 18, 565. (e) Ghosal, N. C.; Santra, S.; Zyryanov,
G. V.; Hajra, A.; Majee, A. Tetrahedron Lett. 2016, 57, 3551.
(15) (a) Mahato, S.; Santra, S.; Zyryanov, G. V.; Majee, A. J. Org.
Chem. 2019, 84, 3176. (b) Mahato, S.; Santra, S.; Chatterjee, R.;
Zyryanov, G. V.; Hajra, A.; Majee, A. Green Chem. 2017, 19, 3282.
(16) (a) Khoshneviszadeh, M.; Ghahremani, M. H.; Foroumadi, A.;
Miri, R.; Firuzi, O.; Madadkar-Sobhani, A.; Edraki, N.; Parsa, M.;
Shafiee, A. Bioorg. Med. Chem. 2013, 21, 6708. (b) Yurttas, L.;
Demirayak, S.; Ilgın, S.; Atlı, O. Bioorg. Med. Chem. 2014, 22, 6313.
(c) Culakova, H.; Dzugasova, V.; Gbelska, Y.; Subik, J. Microbiol. Res.
2013, 168, 147. (d) Rusinov, V. L.; Egorov, I. N.; Chupakhin, O. N.;
Belanov, E. F.; Bormotov, N. I.; Serova, O. A. Pharm. Chem. J. 2012,
45, 655.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
A.M. acknowledges the CSIR-Major Research Project (ref. no.
02(0383)/19/EMR-II) for financial support. We are grateful to
the Department of Chemistry, Visva-Bharati and DST-FIST
and UGC-SAP program.
REFERENCES
■
(1) (a) Garcia, J.; Mata, E. G.; Tice, C. M.; Hormann, R. E.; Nicolas,
E.; Albericio, F.; Michelotti, E. L. J. Comb. Chem. 2005, 7, 843.
(b) Tice, C. M.; Hormann, R. E.; Thompson, C. S.; Friz, J. L.;
Cavanaugh, C. K.; Saggers, J. A. Bioorg. Med. Chem. Lett. 2003, 13,
1883. (c) Morwick, T.; Hrapchak, M.; DeTuri, M.; Campbell, S. Org.
Lett. 2002, 4, 2665 and references cited therein..
(2) (a) Muller, K.; Faeh, C.; Diederich, F. Science 2007, 317, 1881.
̈
(17) O’Brien, C. Chem. Rev. 1964, 64, 81.
(b) Purser, S.; Moore, P. R.; Swallow, S.; Gouverneur, V. Chem. Soc.
Rev. 2008, 37, 320. (c) Hagmann, W. K. J. Med. Chem. 2008, 51,
4359.
(3) (a) Qing, F. Youji Huaxue 2012, 32, 815. (b) Liu, T.; Shen, Q.
Eur. J. Org. Chem. 2012, 2012, 6679. (c) Charpentier, J.; Fruh, N.;
̈
Togni, A. Chem. Rev. 2015, 115, 650. (d) Alonso, C.; Martínez de
Marigorta, E.; Rubiales, G.; Palacios, F. Chem. Rev. 2015, 115, 1847.
́
́
(e) Wang, J.; Sanchez-Rosello, M.; Acena, J. L.; del Pozo, C.;
̃
Sorochinsky, A. E.; Fustero, S.; Soloshonok, V. A.; Liu, H. Chem. Rev.
2014, 114, 2432.
(4) (a) Sandomenico, A.; Russo, A.; Palmieri, G.; Bergamo, P.;
Gogliettino, M.; Falcigno, L.; Ruvo, M. J. Med. Chem. 2012, 55, 2102.
(b) Mamidyala, S. K.; Dutta, S.; Chrunyk, B. A.; Preville, C.; Wang,
H.; Withka, J. M.; McColl, A.; Subashi, T. A.; Hawrylik, S. J.; Griffor,
M. C.; Kim, S.; Pfefferkorn, J. A.; Price, D. A.; Menhaji-Klotz, E.;
Mascitti, V.; Finn, M. G. J. Am. Chem. Soc. 2012, 134, 1978.
(5) Ogami, S.; Funamizu, T.; Hohara, S.; Tajino, H.; Murakami, H.;
Ono, H.; Maehara, S.; Ando, M.; Kutsuma, S.; Kondo, S.; Watanabe,
Y. Patent JP2001097959A, 2001.
(6) Okada, I.; Shiga, Y.; Kikutake, K. Patent JP2002205985A, 2002.
(7) Bahl, A.; Perry, M.; Springthorpe, B. Patent GB2373186A, 2002.
́
(8) For a review, see: (a) Lopez, S. E.; Restrepo, J.; Salazar, J. Curr.
Org. Synth. 2010, 7, 414. For selected examples, see: (b) Osorio-
Olivares, M.; Rezende, M. C.; Sepulveda-Boza, S.; Cassels, B. K.;
Fierro, A. Bioorg. Med. Chem. 2004, 12, 4055. (c) Kong, K.; Moussa,
Z.; Lee, C.; Romo, D. J. Am. Chem. Soc. 2011, 133, 19844.
(9) (a) Du Bois, J.; Hong, J.; Carreira, E. M.; Day, M. W. J. Am.
Chem. Soc. 1996, 118, 915. (b) Kobayashi, Y.; Masakado, S.;
Takemoto, Y. Angew. Chem., Int. Ed. 2018, 57, 693. (c) Motornov, V.;
̌
́
̈
Kost’al, V.; Markos, A.; Taffner, D.; Beier, P. Org. Chem. Front. 2019,
6, 3776. (d) Wang, J.; Weng, Z. Eur. J. Org. Chem. 2019, 2019, 1330.
E
https://dx.doi.org/10.1021/acs.orglett.0c01206
Org. Lett. XXXX, XXX, XXX−XXX