Deoxygenation of nitrosoarene by N-heterocyclic carbene (NHC): an elusive Breslow-type intermediate bridging carbene and nitrene

Article abstract of DOI:10.1039/d0cc05192f

N-Heterocyclic carbene (NHC) activates and deoxygenates nitrosoarene (ArNO) to afford arylnitrene (ArN), thereby portraying a fundamental route connecting two 6e^?species. A combination of spectroscopic and computational studies suggests that th

Full text of DOI:10.1039/d0cc05192f

View Article Online
View Journal
ChemComm
Chemical Communications
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. Kundu, B. S.
Anju, R. Bhattacharjee, S. Gupta, S. Ahammad and A. Datta, Chem. Commun., 2020, DOI:
10.1039/D0CC05192F.
Volume 54
This is an Accepted Manuscript, which has been through the
Number
January 2018
Pages 1-112
1
4
Royal Society of Chemistry peer review process and has been
accepted for publication.
ChemComm
Chemical Communications
rsc.li/chemcomm
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 1359-7345
COMMUNICATION
S. J. Connon, M. O. Senge et al.
Conformational control of nonplanar free base porphyrins:
towards bifunctional catalysts of tunable basicity
rsc.li/chemcomm

Please do not adjust margins
Page 1 of 5
ChemComm
View Article Online
DOI: 10.1039/D0CC05192F
COMMUNICATION
Deoxygenation of Nitrosoarene by N-Heterocyclic Carbene (NHC):
Elusive Breslow-type Intermediate Bridging Carbene and Nitrene
Anju B. S.,a Rameswar Bhattacharjee,b Shourya Gupta,a Soniya Ahammad,a Ayan Datta,*b and
Received 00th January 20xx,
Accepted 00th January 20xx
Subrata Kundu*a
DOI: 10.1039/x0xx00000x
N-heterocyclic carbene (NHC) activates and deoxygenates
nitrosoarene (ArNO) to afford arylnitrene (ArN), thereby portraying
a fundamental route connecting two 6e– species. A combination of
spectroscopic and computational studies suggest that the
interaction of ArNO with NHC affords a transient 2,2’-diamino
imine-N-oxide as a key intermediate in ArNO deoxygenation.
Nitrosoarenes (ArNO) are an important class of compounds in
organic synthesis and also involved as intermediates in the
biodegradation routes of nitroaromatics (ArNO2) and aromatic
amines (ArNH2), thus triggering significant research interests
over the decades.1 For instance, ArNO participates in a number
of transformations mediated by coenzymes including thiamine,2
otherwise known as vitamin B1. In the presence of pyruvate,
thiamine dependent enzymes such as transketolase have been
demonstrated to catalyze the transformation of PhNO to N-
phenylhydroxamic acid, a potent mutagen (Scheme 1).3 Inspired
Scheme 1. Proposed mechanism of thiamine dependent transformation of
nitrosobenzene to N-phenylhydroxamic acid in the presence of pyruvate.
by the seminal work by Breslow in 1958,4 the proposed aldehydes have been illustrated over the last decade.7
mechanism for hydroxamic acid formation considers the Moreover, the quest for new umpoled synthons has resulted in
participation of thiamino enol, the so-called Breslow a wide variety of new intermediates such as diamino dienol
intermediate as an acyl anion equivalent which attacks the from a,b
-enals,8 ene-diamine from alkyl bromides,9 diamino
electrophilic site of PhNO (Scheme 1).5 enamine10 (also known as aza-Breslow intermediate) from
The insights gained from the Breslow’s initial reports into iminium salts. It is noteworthy that the principle for generating
the thiamine-catalyzed umpoled reactivity of aldehyde have such an umpoled species considers the primary interactions of
added a new dimension to the field of organocatalysis.6 Since N-heterocyclic carbenes (NHCs) with the electrophilic sites of
then enormous research efforts have been dedicated to shed aldehyde,
light on the structure and reactivity patterns of the Breslow the concept of such interactions with NHCs, umpolungs of
intermediate. Notably, successful generations, in situ Michael acceptors such as -unsaturated esters are
a,b-enal, alkyl bromide, and iminium salts. Employing
a,b
characterizations, X-ray crystallographic analyses as well as generated in situ and depicted to participate in C-C bond
reactivity studies of diamino enols generated from carbene and forming reactions.11
In contrast to the above-mentioned electrophilic substrates,
nitrosoarenes exhibit ambiphilic reactivity.12 Intrigued by the
a. School of Chemistry, Indian Institute of Science Education and Research
ambiphilicity of free ArNO, we are curious to investigate the
interaction of ArNO with NHC. A combination of experimental
and theoretical studies, herein, demonstrate that NHCs activate
Thiruvananthapuram (IISER–TVM), Thiruvananthapuram – 695551, India. E-mail:
skundu@iisertvm.ac.in, skundu.chem@gmail.com
b. School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A
& 2B Raja S. C. Mullick Road, Jadavpur – 700032, Kolkata, India. Email:
spad@iacs.res.in.
ArNO and cleave the N
elusive 2,2’-diamino imine-N-oxide,
=
O double bond of ArNO by involving
Breslow-type
Electronic Supplementary Information (ESI) available. CCDC 1976500 contain the
supplementary crystallographic data. For ESI and crystallographic data (CIF), See
DOI: 10.1039/x0xx00000x
a
intermediate and a spiro-oxaziridine species. Unlike the
previously known reactivity patterns of the Breslow
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 5
COMMUNICATION
Journal Name
intermediate,6 diamino imine-N-oxide rapidly decomposes to
yield a urea-derivative and a transient arylnitrene (ArN) species.
View Article Online
DOI: 10.1039/D0CC05192F
Scheme 3. Postulated mechanistic routes for the deoxygenation of nitrosoarenes
(ArNO, Ar = Ph, 2,4,6-Br3C6H2, Mes) by IMes considering the different possible initial
interactions between IMes and ArNO.
Scheme 2. (A) Deoxygenation of PhNO by IMes and trapping of singlet phenyl nitrene
(1PhN). (B) N-heterocyclic carbenes employed in PhNO deoxygenation.
An equimolar reaction of 1,3-dimesitylimidazol-2-ylidene
Deoxygenation of PhNO by oxophilic reagents such as
(
IMes) with PhNO in anhydrous tetrahydrofuran at room trialkyl phosphites, carbon atom, organosilicon reagents have
temperature leads to an immediate formation of a brown been illustrated to generate transient singlet PhN.16 Moreover,
solution. NMR analysis on the crude brown solution reveals the phosphite/ phosphine mediated deoxygenation of ArNOx (x = 1,
formation of a urea-derivative IMes=O (1) in a near quantitative 2) has been previously utilized in Cadogan-Sundberg
yield along with azoxybenzene, as a trace byproduct (Scheme reactions.17 The mechanism of PhNO deoxygenation, however,
2A, Figures S1-S2). The UV-vis absorption features of the brown remains undisclosed. The deoxygenation of PhNO by IMes
solution in tetrahydrofuran depicts a very intense broad band yielding IMes=O and 1PhN presumably involves the initial
extending from ultraviolet region to ~650 nm (Figure S3), which formation of metastable diamino imine-N-oxide 2a-Ph and/or
is similar to that of the previously reported poly-1,2-azepine, an spiro-oxaziridine 2b-Ph from the primary interactions of IMes
end-product generated through the ring expansion of transient with PhNO (Scheme 3). It is noteworthy that the analogous
singlet phenyl nitrene (1PhN).13 We therefore postulate that the reactions between NHCs and benzaldehyde have been depicted
trace amount of azoxybenzene in the equimolar reaction of to afford diamino enol as well as spiro-epoxide depending on
IMes and PhNO originates from the reaction between transient the nature of NHC.7,18 The viability of 2a-Ph or 2b-Ph has been
1PhN and unreacted PhNO. Indeed, a reaction of IMes with 5 probed by UV-vis, HRMS, and theoretical analyses.
equivalents of PhNO leads to increase in the yield of
azoxybenzene (71%) but no detectable azobenzene, thereby 2,4,6-Br3C6H2, Mes) in tetrahydrofuran at –40
Monitoring of the reaction of IMes with ArNO (Ar = Ph,
C by UV-vis
°
demonstrating the efficient trapping of the in situ generated spectroscopic analyses show the generation of a transient
1PhN by excess PhNO (Scheme 2A, Figure S4). Furthermore, the intermediate. Reaction of IMes with PhNO (1 equiv) at –40
°
C
1
in situ generated PhN can be trapped by excess diethylamine yields a dark solution with absorption features (
l
max) centered
where 1PhN undergoes ring expansion to 1-azacyclohepta- at 450 and 575 nm (Figure S8). The HRMS spectrum of a sample
1,2,4,6-tetraene and reacts with diethylamine to afford 2- generated from an equimolar reaction of IMes and PhNO at –
diethylamino-3H-azepine in 52% yield (Scheme 2A, Figures S5- 35 °C depicts signals at mass-to-charge ratio (m/z) of 412.2382
S6).14 To assess the generality of PhNO deoxygenation by other and 396.2440 congruent with the respective formulations as
NHCs, we reacted triazolium-based NHCs with PhNO in [{IMes(PhNO)}H]+ (calc. m/z 412.2383) and [{IMes(PhNO)}H–
tetrahydrofuran which affords corresponding urea derivatives O]+ (calc. m/z 396.2434) (Figure S9). Similarly, the reaction of
and azoxybenzene (Scheme 2B). Moreover, the high-resolution IMes with 2,4,6-tribromonitrosobenzene (Br3ArNO) in
mass spectroscopic (HRMS) analysis on a sample generated tetrahydrofuran at –40 °C leads to a spontaneous generation of
from a triazolium-based NHC mediated deoxygenation reaction a metastable orange species with absorption maxima centered
in the presence of diethylamine shows the formation of 2- at λmax/nm = 425, 505, and 545 (Figures 1A, S12). The HRMS
diethylamino-3H-azepine (observed m/z 165.1385, calc. m/z sample generated by employing 2,4,6-tribromonitrosobenzene
165.1386 for [MH]+) (Figure S7). Notably, previously reported15 (Br3ArNO) at –35
°C exhibits the m/z peaks at 647.9676 and
NHC-catalyzed reactions of substituted arylaldehydes (ArCHO) 631.9721 with the appropriate mass and isotope distribution
in the presence of ArNO are shown to involve a preferential patterns corresponding to [{IMes(Br3ArNO)}H]+ (calc. m/z
interaction of NHC with the aldehyde presumably due to the 647.9678 for 79Br isotope) and [{IMes(Br3ArNO)}H–O]+ (calc.
higher electrophilicity of ArCHO relative to ArNO. However, the m/z 631.9729 for 79Br isotope), respectively (Figures 1B, S13-
formation of azoxybenzene side product during the NHC- 14). Similarly, an analogous sample prepared using MesNO
catalyzed amidation reaction of benzaldehyde with PhNO is shows the m/z peaks at 454.2842 and 438.2894, which can be
indicative of a competitive interaction of NHC with PhNO.15a
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 5
ChemComm
Please do not adjust margins
Journal Name
COMMUNICATION
assigned to [{IMes(MesNO)}H]+ (calc. m/z 454.2853) and
[{IMes(MesNO)}H–O]+ (calc. m/z 438.2904), respectively
(Figures S15-16). Notably, observation of m/z peaks for [M–O]+
and [MH–O]+ fragments in mass spectroscopic analyses are
previously reported for N-oxide molecules.19 Thus, the HRMS
studies corroborate the involvement of diamino imine-N-oxide
2a-Ar and/or spiro-oxaziridine 2b-Ar as the adduct compound
formed from the interaction of IMes with ArNO (Scheme 3).
However, the transient natures of the intermediate compounds
hinder the further NMR spectroscopic characterizations,
thereby hampering the unambiguous assignment.
View Article Online
DOI: 10.1039/D0CC05192F
Figure 2. Calculated Gibbs free energy profiles for the interconversion of intermediates
and generation of PhN from IMes and PhNO at 298.15 K employing M062X/6-31G(d,p)
level of theory in gas phase. For the structural drawings of all intermediates, reactant-
and product-complexes, see Scheme 3, Figures S19 and S20.
Scheme 3, path a). TDDFT analysis of 2a-Ph predicts the
electronic transitions at 430 nm primarily originating from
transitions from the HOMO (Figure S24), which involves p-type
Figure 1. (A) Changes in the absorption features of IMes (blue trace) (2.0 mM, in
tetrahydrofuran) upon addition of one equivalent 2,4,6-tribromonitrosobenzene
(Br3ArNO) at –40 °C. (B) HRMS of the adduct compound IMes(Br3ArNO) (2a-/2b-Br3Ar)
experimentally observed (black) and the calculated (red) mass and isotopic distribution
patterns for [{IMes(Br3ArNO)}H–O]+ and [{IMes(Br3ArNO)}H]+ species.
orbital interaction between NHC and PhNO. Subsequently, the
isomerization of diamino imine-N-oxide 2a-Ph affording spiro-
oxaziridine 2b-Ph is predicted to involve a free energy barrier of
12.5 kcal/mol via a transition state TS‡2a-2b (Figures 2, S20, and
S25). Finally, the computational analysis suggests that
phenylnitrene generation from spiro-oxaziridine 2b-Ph
Density functional theory (DFT)20 calculations at M062X/6-
31G(d,p) level of theory are employed to predict the structures
of the intermediates and investigate the energy profile diagram
for the formation and deoxygenation of IMes(PhNO)
intermediates leading to the generation of PhN (Figure 2). The
structural parameters obtained from the DFT calculations of 2a-
Ph and 2b-Ph (Figures S17-18) are similar to those of the closely
related, structurally characterized diamino enol and spiro-
epoxide compounds, respectively (Tables S1-S2).7,18
Mechanistically following the initial formation of IMes×××PhNO
reactant complex (RC), three possible interactions between
IMes and PhNO may be envisioned prior to the formation of
proceeds either through a TS‡
or a TS‡
transition state
triplet
singlet
to afford open-shell singlet phenylnitrene (1PhN) or triplet
phenylnitrene (3PhN), respectively (Figures 2, S19, S27-S30).
While the previously reported theoretical studies on
phenylnitrene unambiguously depict that the triplet state is
relatively more stable as compared to the singlet state, the spin
state of the in situ generated phenylnitrene and interconversion
between singlet and triplet spin-isomers of PhN largely depend
on the experimental conditions.22
Interestingly, an alternative decomposition of spiro-
oxaziridine 2b-Ph does not afford any guanidine-derivative
IMes=NPh (3-Ph) (Scheme 3, path e), an anticipated end-
product via an oxygen-atom transfer from 2b-Ph. Notably, the
nature of substituent on the N-site of oxaziridine is known to
dictate the reactivity pattern.23 For instance, an electron
withdrawing substituent on the N-site significantly favours the
oxygen-atom transfer rather than the loss of nitrene from the
oxaziridine. Hence, we attempt to investigate the room
temperature reactions of IMes with different nitrosoarenes
with varied electronic properties. Notably, a room temperature
reaction of IMes and MesNO in tetrahydrofuran cleanly
nitrene. First, a k
1-N interaction of PhNO with the carbene leads
to the formation of diamino imine-N-oxide 2a-Ph via transition
state TS‡2a with a free energy barrier of 9.9 kcal/mol (Scheme 3,
path a; Figure S21). Prompted by a previous mechanistic study
illustrating the formation of a related spiro-epoxide from the
reaction N,N’-diamidocarbene and aldehyde proceeds through
a concerted asynchronous (2+1) cycloaddition route,21 we
considered a concerted h
2-O,N interaction of PhNO with the
carbene directly affording spiro-oxaziridine 2b-Ph (Scheme 3,
path b). A viable transition state, however, was not identified
considering the concerted
another alternative route involving a
h
2-O,N interaction. Furthermore,
k
1-O interaction of PhNO
provides IMes=O (1) but no detectable IMes=NMes (Figure
S31), thereby demonstrating that the spiro-oxaziridines 2b with
electron rich N-Aryl substituents function as the source of
arylnitrene selectively. Interestingly, an equimolar reaction of
IMes with electron deficient 2,4,6-tribromonitrosobenzene
(Br3ArNO) in tetrahydrofuran at room temperature affords urea
with the carbene leading to an intermediate 2c-Ph is estimated
to involve a transition state TS‡ with a higher free energy
2c
barrier of 20.5 kcal/mol (Figures 3 and S22-S23). While the
relative energies of 2a-Ph (0 kcal/mol), 2b-Ph (2.3 kcal/mol),
and 2c-Ph (4.5 kcal/mol) are comparable, the energy barrier
profiles suggest that the transformation of IMes×××PhNO
reactant complex to 2a-Ph is kinetically controlled (Figure 2 and
IMes=O (1) as well as the guanidine-derivative IMes=NArBr3 (3-
Br3Ar) in 2:3 ratio with 49% isolated yield of 3-Br3Ar (Figure
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 4 of 5
COMMUNICATION
Journal Name
There are no conflicts to declare.
View Article Online
DOI: 10.1039/D0CC05192F
Notes and references
1
(a) J. Lee, L. Chen, A. H. West, G. B. Richter-Addo, Chem. Rev.
2002, 102, 1019. (b) B. G. Gowenlock, G. B. Richter-Addo,
Chem. Rev. 2004, 104, 3315.
2
3
4
R. Tatsunami, T. Yoshioka, J. Agric. Food Chem. 2006, 54, 590.
M. D. Corbett, Bioorg. Chem. 1974, 3, 361.
(a) R. Breslow, J. Am. Chem. Soc. 1957, 79, 1762. (b) R.
Breslow, J. Am. Chem. Soc. 1958, 80, 3719.
Figure 3. X-ray crystal structure of IMes=NArBr3 (3-Br3Ar) (CCDC 1976500).
5
6
M. D. Corbett, B. R. Chipko, Bioorg. Chem. 1980, 9, 273.
(a) X. Bugaut, F. Glorius, Chem. Soc. Rev. 2012, 41, 3511. (b) H.
Ohmiya, ACS Catal., 2020, 10, 6862. (c) T. Ishii, K. Nagao and
H. Ohmiya, Chem. Sci., 2020, 11, 5630.
S32). In addition to the NMR and mass spectroscopic
characterizations of 3-Br3Ar (Figures S33-S35), single crystal X-
ray diffraction confirms the molecular structure of 3-Br3Ar
(Figures 3 and S36). Thus, the distribution of the products
comprising a mixture of IMes=O and IMes=NArBr3, indeed,
demonstrates that the metastable spiro-oxaziridine
7
(a) A. Berkessel, S. Elfert, V. R. Yatham, J.-M. Neudörfl, N. E.
Schlörer, J. H. Teles, Angew. Chem. Int. Ed. 2012, 51, 12370.
(b) M. Paul, P. Sudkaow, A. Wessels, N. E. Schlörer, J.-M.
Neudörfl, A. Berkessel, Angew. Chem. Int. Ed. 2018, 57, 8310.
(a) S. S. Sohn, E. L. Rosen, J. W. Bode, J. Am. Chem. Soc. 2004,
126, 14370−14371. (b) C. Burstein, F. Glorius, Angew. Chem.
Int. Ed. 2004, 43, 6205.
8
9
intermediate 2b
tribromoaryl substituent decomposes through two competitive
pathways: (A) loss of arylnitrene to yield (Scheme 3, path d);
-Br3Ar with electron deficient 2,4,6-
C. E. I. Knappke, J. M. Neudörfl, A. J. Von Wangelin, Org.
Biomol. Chem. 2010, 8, 1695.
1
and (B) oxygen-atom transfer to provide 3-Br3Ar (Scheme 3, 10 D. A. DiRocco, K. M. Oberg, T. Rovis, J. Am. Chem. Soc. 2012,
134, 6143.
path e). Illustrating the trapping of oxygen-atom, a reaction of
IMes with Br3ArNO in the presence of excess thioanisole at 78
C results in the formation of methyl phenyl sulfoxide (Figure
11 (a) C. Fischer, S. W. Smith, D. A. Powell, G. C. Fu, J. Am. Chem.
Soc. 2006, 128, 1472. (b) A. T. Biju, M. Padmanaban, N. E.
Wurz, F. Glorius, Angew. Chem. Int. Ed. 2011, 50, 8412. (c) S.
I. Matsuoka, Y. Ota, A. Washio, A. Katada, K. Ichioka, K. Takagi,
M. Suzuki, Org. Lett. 2011, 13, 3722.
12 P. Zuman, B. Shah, Chem. Rev. 1994, 94, 1621.
13 E. W. Meijer, S. Nijhuis, F. C. B. M. Van Vroonhoven, J. Am.
Chem. Soc. 1988, 110, 7209.
14 N. P. Gritsan, M. S. Platz, Chem. Rev. 2006, 106, 3844.
15 (a) T. W. Fong, P. K. Patra, J. Seayad, Y. Zhang and J. Y. Ying,
Org. Lett., 2008, 10, 2333. (b) Z. X. Sun and Y. Cheng, Org.
Biomol. Chem., 2012, 10, 4088.
16 (a) R. A. Odum, M. Brenner, J. Am. Chem. Soc. 1966, 88, 2074.
(b) B. M. Armstrong, P. B. Shevlin, J. Am. Chem. Soc. 1994, 116,
4071. (c) E. Łukasik, Z. Wróbel, Synlett 2014, 25, 217.
17 A. W. Freeman, M. Urvoy and M. E. Criswell, J. Org. Chem.,
2005, 70, 5014.
-
°
S37). The oxygen-atom transfer from diamino imine-N-oxide 2a-
Ph to a model substrate Me2S is estimated to proceed via a
transition state TS‡
with an activation barrier of 34.6
OAT
kcal/mol (Figures S38-S42). However, a feasible transition state
for the direct oxygen-atom transfer from spiro-oxaziridine 2b-
Ph to Me2S was not detected computationally.
In summary, the present work demonstrates the activation
and deoxygenation of nitrosoarene by N-heterocyclic carbene.
A combination of spectroscopic and computational studies
reveals that NHC interacts with ArNO to yield Breslow-type 2,2’-
diamino imine-N-oxide 2a and spiro-oxaziridine 2b
intermediates, which subsequently decays to generate
18 J. P. Moerdyk, C. W. Bielawski, Nat. Chem. 2012, 4, 275–280.
19 R. Ramanathan, A.-D. Su, N. Alvarez, N. Blumenkrantz, S. K.
Chowdhury, K. Alton, J. Patrick, Anal. Chem. 2000, 72, 1352.
20 See Electronic Supplementary Information for the details.
21 D. T. Chase, J. P. Moerdyk, C. W. Bielawski, Org. Lett. 2012, 14,
5510.
22 W. T. Borden, N. P. Gritsan, C. M. Hadad, W. L. Karney, C. R.
Kemnitz, M. S. Platz, Acc. Chem. Res. 2000, 33, 765–771.
23 K. S. Williamson, D. J. Michaelis, T. P. Yoon, Chem. Rev. 2014,
114, 8016.
24 S. Kundu, S. C. E. Stieber, M. G. Ferrier, S. A. Kozimor, J. A.
Bertke, T. H. Warren, Angew. Chem. Int. Ed. 2016, 55, 10321.
25 J. M. Fukuto, S. J. Carrington, Antioxid. Redox Signal. 2011, 14,
1649.
26 F. Doctorovich, D. E. Bikiel, J. Pellegrino, S. A. Suárez, M. A.
Martí, Acc. Chem. Res. 2014, 47, 2907.
arylnitrene. Interestingly, this report portrays
a
new
fundamentally significant route establishing a connection
between two 6e– species, namely carbene and nitrene. Notably,
ArNO is often considered as the stable analog of relatively more
reactive nitroxyl (HNO),24 an important species in NO signalling
pathways.25 Thus, this reactivity pattern of ArNO towards NHCs
offers a view towards a possible interaction between HNO and
thiamine in the biological milieu. Insights gained from this work
will be extended in our laboratory to trap HNO employing
suitable NHC compounds which, in turn, may enable a new
method26 to sense transient HNO species in different
biochemical transformations of NO.
S.K. gratefully acknowledges ECR/2017/003200 from SERB.
S.K., A.B.S., and S.G. are thankful to the supports from IISER-
TVM. The authors thank Amanda Ben for her support in
preparing one of the carbene precursors and Prof. Yashwant D.
Vankar (Emeritus Professor, IISER-TVM) for valuable comments.
Conflicts of interest
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 5
ChemComm
View Article Online
DOI: 10.1039/D0CC05192F
Figure for table of contents entry:
Text for table of contents entry:
Interaction of N-heterocyclic carbene (NHC) with nitrosoarene (ArNO) affords
arylnitrene (ArN) through the deoxygenation of ArNO.