Hydrogen peroxide/dimethyl carbonate: A green system for epoxidation of: N -alkylimines and N -sulfonylimines. One-pot synthesis of N -alkyloxaziridines from N -alkylamines and (hetero)aromatic aldehydes

Article abstract of DOI:10.1039/c6gc01394e

A green method for epoxidation of imines using an environmentally benign oxidant system, H₂O₂/dimethyl carbonate, was developed. N-Alkyloxaziridines were prepared in high yields from N-alkylamines and (hetero)aromatic aldehydes in one-pot fashion, whereas N-sulfonyloxaziridines have been prepared by using the same oxidant system and 5 mol% of Zn(OAc)₂·2H₂O as catalyst.

Full text of DOI:10.1039/c6gc01394e

View Article Online
View Journal
Green
Chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: J. Kraiem, D.
Ghedira and T. Ollevier, Green Chem., 2016, DOI: 10.1039/C6GC01394E.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
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.
www.rsc.org/greenchem

Please do not adjust margins
Page 1 of 6
Green Chemistry
View Article Online
DOI: 10.1039/C6GC01394E
Green Chemistry
COMMUNICATION
Hydrogen peroxide/dimethyl carbonate: a green system for
epoxidation of N-alkylimines and N-sulfonylimines. One-pot
synthesis of N-alkyloxaziridines from N-alkylamines and
(hetero)aromatic aldehydes
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Jamil Kraïem,a,b Donia Ghedirab and Thierry Olleviera*
www.rsc.org/
A
green method for epoxidation of imines using an corresponding perfluoro-imines with H2O2 in the presence of a
26
environmentally benign oxidant system, H2O2/dimethyl base.25 These methods usually use toxic solvents
such as
carbonate, was developed. N-Alkyloxaziridines were prepared in CH3CN 11,17 and CH2Cl2.19b Furthermore, most of them generate
high yields from N-alkylamines and (hetero)aromatic aldehydes in stoichiometric amounts of undesirable waste, and require
one-pot fashion, whereas N-sulfonyloxaziridines have been tedious work-up and purification.
prepared by using the same oxidant system and 5 mol % of
Zn(OAc)2·2H2O as catalyst.
Recently, such synthetic routes utilizing hazardous solvents
and reagents and generating toxic waste have become
discouraged and there have been much efforts to develop
safer and environmentally-benign alternatives. This green
chemistry approach was introduced in 1990 with the aim at
developing cleaner processes through the design of innovative
and environmentally benign chemical reactions. In recent
years, increasingly stringent environmental requirements have
led to a great interest in the application of sustainable and
green oxidations. The concept of green chemistry has been
rapidly expanding and important advances have been achieved
in this field.27 Interest in new synthetic methods has also been
extended to many relevant classes of chemical compounds,
such as oxaziridines. In this case, two attempts of eco-friendly
synthesis of N-alkyloxaziridines were described in the
literature. The first one consisted in the oxidation of imines
with H2O2 in acetonitrile, catalyzed by 2 mol % of sodium
Oxaziridines, first reported by Emmons in 1957,1 exhibit
unusual and distinctive reactivity, which is linked to the nature
of their N-substituent. For example, N-sulfonyloxaziridines
have been used as electrophilic oxygenating agents for
3
enolates,2 alkenes and sulfides.4 N-alkyloxaziridines undergo
cycloaddition reactions with a variety of heterocumulenes,5,6
9
10
alkenes,7 alkynes,8 nitriles and arynes leading to various
five-membered ring heterocycles. In addition, oxaziridines are
useful as precursors of nitrones,1 amides,11 secondary amines
12
and N,N-disubstituted hydroxylamines.1,13 Within the past
decade, the chemistry of oxaziridines has been significantly
expanded and now encompasses some new interesting
reaction types, among which the enantioselective
oxyamination of alkenes with N-sulfonyloxaziridines, catalyzed
by Cu(II)14 and Fe(II)15 complexes, and the enantioselective
Lewis-base catalyzed cycloaddition of N-sulfonyloxaziridines
with ketenes can be mentioned.16
tungstate,11,27b and the other one described
a chemo-
enzymatic synthesis of N-alkyloxaziridines using H2O2/octanoic
acid system as oxidant of N-alkylimines.17 In both cases, the
conversions of imines to oxaziridines did not reach completion
and tedious work-up and further purification were needed.
Furthermore, these methods did not avoid the use of toxic
solvents, such as CH3CN, and are limited to the synthesis of N-
alkyloxaziridines rather than other types of oxaziridines.
Oxaziridines can be readily prepared from imines, through
a number of methods including oxidation with peracids,17
particularly m-chloroperbenzoic acid (MCPBA),18,19 oxidation
with O2 in the presence of transition metals,20 oxidation with
H2O2 in combination with acetic anhydride,1 nitriles,21,22 and
23
urea
and oxidation with buffered oxone.24 Perfluoro-
Among environmentally-friendly oxidation reagents,
hydrogen peroxide is particularly attractive, both for its high
oxygen content and the nature of its by-products (water and
O2). Moreover, diluted aqueous solutions of hydrogen
peroxide are stable and they can be easily handled and stored.
On the other hand, dimethyl carbonate (DMC) is an interesting
green solvent and reagent alternative in organic synthesis due
to its high biodegradability and low toxicity defined as the
absence of associated irritating or mutagenic effects.28
oxaziridines have also been prepared by the oxidation of the
This journal is © The Royal Society of Chemistry 20xx
Green Chemistry., 2016, 00, 1-5 | 1
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 2 of 6
View Article Online
DOI: 10.1039/C6GC01394E
COMMUNICATION
Green Chemistry
Furthermore, its industrial production does not require solution of H2O2 (30%, 5 mmol) in 1 mL of DMC for 15 h,
phosgene but only methanol and CO.29 As reported by Klaass furnishing quantitatively oxaziridine 3a (Table 1, entry 3). We
and Warwel, using DMC with large excess of hydrogen assume that the active oxidant is the monoperoxycarbonic
peroxide solution (60%) under chemo-enzymatic catalysis, acid methyl ester (MeO–CO–OOH) generated by the reaction
alkenes were epoxidized with moderate to high yields.30 These of H2O2 with DMC for the following reasons: i) O-
authors assume that the active oxidant is the monoperoxy alkylperoxycarbonic acids have already been reported in the
carbonic acid methyl ester (MeO-CO-OOH) generated by the literature,31–34 among which O-benzylperoxycarbonic acid,
reaction of hydrogen peroxide with DMC, and decomposes to prepared from dibenzyl dicarbonate and H2O2, was isolated
CO2 and methanol after epoxidation of alkenes. In general, O- and characterized;34 ii) H2O2 itself is not sufficiently reactive
alkylmonoperoxycarbonic acids (RO–CO–OOH) are known to for epoxidation; this hypothesis is supported by the results
be effective epoxidizing reagents of olefins.31–34 They are given in Table 1 (entries 8– 11).
generated in situ by the reaction of ethyl chloroformiate,31
Table 1 Investigation of solvents on the model reactiona
alkoxycarbonyl-1,2,4-triazoles,32 alkoxycarbonylimidazoles
or dialkyl carbonates using hydrogen peroxide solution,30,34
and they could be utilized without isolation because of their
33
instability. In some cases, O-alkylmonoperoxycarbonic acids
34
have been isolated
or detected.32 We think that the
H2O2/DMC system is still underinvestigated in synthetic
chemistry. Indeed, since the report of Klaass and Warwel in
1999, no other reactions using this green oxidant system have
been described in the literature.
equiv.
H2O2
5
3
5
5
5
5
5
5
5
5
5
Time
(h)
24
24
15
20
24
24
18
10
10
10
10
Conversion
Entry
equiv. t-BuNH2
Solvent
3a (%)b
88
1
2
3
4
5
6
7
8
9
1
DMC
DMC
DMC
CH3CN
EtOAc
CH3OH
PCc
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
85
100
98
61
50
In this paper we describe a simple, efficient and eco-
friendly synthesis of oxaziridines by use of the green 30%
H2O2/DMC system. N-Alkyloxaziridines have been prepared
quantitatively in one-pot synthetic route from the
corresponding alkylamines and aldehydes, under mild and
neutral conditions, whereas N-sulfonyloxaziridines have been
prepared with high yields from the corresponding N-
sulfonylimines under basic conditions, in the presence of
Zn(OAc)2·2H2O as a catalyst.
92
H2O
0d
CH2Cl2
Toluene
DMPUe
0d
10
11
0d
0d
a Conditions: 1a, 1 mmol of 1b, H2O2 (30%), solvent (1 mL), rt. b Determined
by 1H NMR analysis of crude product. Propylene carbonate.
The
1,3-
c
d
e
1H
NMR).
With the aim of synthesizing N-alkyloxaziridines in a one-
pot fashion, we investigated the reaction of t-butylamine 1a
(1.0 and 1.5 mmol) with benzaldehyde 1b (1 mmol) and 30%
hydrogen peroxide solution, in the presence of a variety of
solvents, affording 2-t-butyl-3-phenyloxaziridine 3a (Table 1).
We found that, when the one-pot reaction was run in H2O,
CH2Cl2, toluene or DMPU, no transformation into the
oxaziridine was observed (Table 1, entries 8–11). These
solvents are indeed known to be inert towards H2O2.
Accordingly, these results indicate that hydrogen peroxide
itself is not sufficiently reactive to epoxidize the intermediate
imine, whereas, when the reaction was run in DMC,
acetonitrile, ethyl acetate, methanol or propylene carbonate
(Table 1, entries 1–7), a moderate to high conversion into the
oxaziridine was observed. Solvents such as acetonitrile, dialkyl
carbonates or ethyl acetate can react with H2O2. Indeed,
peroxyimidic acids, generated in situ by perhydrolysis of a
nitrile, are known to be effective epoxidizing reagents of
olefins and imines (Payne oxidation).22,35 Perhydrolysis of ethyl
acetate may also generate peracetic acid as the oxidant of the
imine.17,36 In this case, oxaziridine 3a was formed with a
moderate yield after 24 h (Table 1, entry 5). The use of
methanol as solvent provided the oxaziridine 3a in 50 % yield
after 24 h (Table 1, entry 6). As shown in Table 1, the best
result for the one-pot synthesis of oxaziridine 3a was achieved
when the reaction was performed by stirring a mixture of t-
butylamine (1.5 mmol), benzaldehyde (1 mmol) and aqueous
oxaziridine
was
not
detected
(TLC,
Dimethyltetrahydropyrimidin-2(1H)-one.
Scheme 1
One-pot synthesis of N-alkyloxaziridines
The optimized conditions found for the one-pot synthesis
of oxaziridine 3a (Table 1, entry 3) were chosen as model
conditions for our continuing studies. The substrate scope was
then investigated, and a variety of N-alkyloxaziridines were
prepared from the corresponding aldehydes and alkylamines,
using the 30% H2O2/DMC system (Scheme 1). The
condensation of alkylamine
imine intermediate, which underwent epoxidation by the
oxidizing agent to afford oxaziridine . In general, the synthesis
1 with aldehyde 2 provided the
3
of an imine requires removal of water by use of dehydrating
agents, such as molecular sieves,37,38 to shift the equilibrium in
favor of the imine formation. In our case, the total conversion
of amine and aldehyde into the imine is assured by the
2 | Green Chemistry., 2016, 00, 1-5
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 3 of 6
View Article Online
DOI: 10.1039/C6GC01394E
Green Chemistry
consumption of the latter through its oxidation. 1H NMR
COMMUNICATION
Table 2 One-pot preparation of N-alkyloxaziridines from alkylamines and
analysis showed total conversion of alkylamines
aldehydes into oxaziridines . Pure products were obtained
1
and aromatic aldehydesa
2
3
in excellent yields after washing with a saturated solution of
sodium sulfite and extraction with ethyl acetate (Table 2).
Consequently, additional purification methods such as column
chromatography or recrystallization were not needed.
Noteworthy, the present oxidation is scalable as the reaction
with 1 g of benzaldehyde (10 mmol) with 15 mmol of t-
butylamine in 10 mL of DMC, in the presence of 5 mL of 30%
H2O2, reached completion after 18 h and afforded oxaziridine
3a in 97% yield.
We found that excess of N-alkylamines and H2O2 is
necessary to ensure complete consumption of the starting
aldehydes in a reasonable time. The reaction time is attractive
if we consider that the one-pot route to N-alkyloxaziridines
allows avoiding prior imine synthesis and related work-up. As
described in the literature, N-alkylimines were prepared in 18
h at room temperature using CH2Cl2 as a solvent, activated
molecular sieves and 2 equiv. of alkylamines with regard to
aldehydes,37 and in 48 h by heating an equimolecular mixture
of amine and aldehyde in dry toluene, in the presence of
activated molecular sieves.38
a
Reaction conditions: alkylamine (1.5 mmol), aldehyde (1 mmol), H2O2
(30%) (5 mmol), DMC (1 mL), rt, 15 h (reaction monitored by TLC). b Isolated
It was demonstrated that commercial aqueous H2O2
solution in moderate concentration (30%) can be used
successfully instead of more concentrated solutions.30
Moreover, this oxidation does not require a catalyst to take
yields (trans/cis selectivity determined by 1H NMR analysis).
Encouraged by the excellent results obtained using the
place. No significant amount of by-products, resulting from the H2O2/DMC system for the synthesis of N-alkyloxaziridines, we
oxidation of aldehydes and amines with the DMC/H2O2 system, investigated the preparation of other synthetically important
were formed in this reaction. Indeed, the oxidation of oxaziridines, such as N-sulfonyloxaziridines. Our initial
aldehydes with hydrogen peroxide requires the presence of attempts to perform the oxidation of N-sulfonylimines into N-
selenium oxychloride as catalyst.39 As for alkylamines, they can sulfonyloxaziridines under the same conditions previously
40
be easily oxidized by peracids
or by the H2O2/Na2WO4 described (H2O2/DMC system, neutral conditions and without
system.27b,41 Consequently, the one-pot route from aldehydes catalysis) were unsuccessful (no conversion of the N-
and amines to N-alkyloxaziridines probably cannot be achieved sulfonylimine was observed). Therefore, a systematic study
by the use of peracids or H2O2/Na2WO4. Thus, the present was undertaken to define the best reaction conditions for the
work represents the first example of a one-pot route to N- synthesis of these oxaziridines (Table 3). We investigated the
alkyloxaziridines from N-alkylamines and aldehydes.42
influence of basic medium and that of catalysis with
In this work, N-t-butyloxaziridines were formed exclusively Zn(OAc)2·2H2O and TBAB (tetra-n-butyl ammonium bromide)
in the trans-isomer form (Table 2). The less stable cis-isomer is on the model reaction, based on the following precedents: i)
less favoured because of the bulkiness of the t-butyl group. the epoxidation of N-sulfonylimines with MCPBA,18a,19
22
24
Oxaziridines with smaller N-substituents were produced as CCl3CN/H2O2 and Oxone® requires basic medium; ii) the
mixtures of trans and cis-isomers though. These epoxidation of N-sulfonylimines with CCl3CN/H2O2 requires the
stereoselectivity results are in agreement with the other use of TBAB as a phase transfer catalyst;22 iii) Zn(OAc)2 is a
methods described in the literature.17,22,43,44 The one-pot non-toxic compound (food additive E650) that showed high
synthesis of N-alkyloxaziridines, described in this work, catalytic activity in the methoxycarbonylation of aromatic
provided a high stereoselectivity, affording the trans-isomer as diamines with DMC.45
a major product (100:0–90:10, Table 2). The cis/trans ratio was
determined by 1H NMR analysis. Indeed, cis and trans-
Table 3 Optimization of the conditions on the model reactiona
oxaziridines isomers are known to give different 1H and 13C
NMR spectra.17,22,43,44 NMR data of cis and trans-oxaziridines
isomers is provided in SI.
This journal is © The Royal Society of Chemistry 20xx
Green Chemistry., 2016, 00, 1-5 | 3
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 4 of 6
View Article Online
DOI: 10.1039/C6GC01394E
COMMUNICATION
Green Chemistry
equiv.
Entry
Time
Conversion
Time
(h)
Catalyst
Base
5a (%)b
0 c
Entry
1
Oxaziridine 5
Yield 5 (%)
H2O2
(h)
10
24
10
24
24
10
24
10
24
10
14
1
2
3
5
10
5
–
–
–
Na2CO3
–
62
0 c
14
13
91
Zn(OAc)2·2H2O
TBAB
4
5
Na2CO3
Na2CO3
Na2CO3
Na2CO3
AcONa
NaOH
23
5
5
5
10
5
Zn(OAc)2·2H2O
Zn(OAc)2·2H2O
Zn(OAc)2·2H2O
Zn(OAc)2·2H2O
Zn(OAc)2·2H2O
Zn(OAc)2·2H2O
Zn(OAc)2·2H2O
86
6d
7e
8
0 c
2
86
86
0 c
9
5
66
0 c
3
4
16
14
88
94
10
11
5
10
Imidazole
Na2CO3
99
a
Conditions: 0.5 mmol of 4a, catalyst (5 mol %), base (1.2 equiv.), H2O2
(30%), DMC (1.5 mL), rt. b Determined by 1H NMR analysis of crude product.
c The oxaziridine was not detected by TLC. d Reaction carried out in MeOH or
e
in CH2Cl2 instead of DMC. 0.5 equiv. of Na2CO3 was used instead of 1.2
equiv.
5b
17
18
87
89
Optimization studies led us to conclude that the basic
medium is essential for the epoxidation of N-sulfonylimine 4a
(Table 3, entries 1 and 2), but it is not sufficient for completion
of the reaction in less than 24 h. The reaction did not work
when using bases that are soluble in DMC, such as sodium
acetate and imidazole (Table 3, entries 8 and 10). To improve
the efficiency of this reaction, we tried two catalysts, i.e. TBAB
as a phase transfer catalyst and Zn(OAc)2·2H2O as an activating
reactant of DMC. The use 5 mol % of TBAB did not lead to any
improvement of the reaction (Table 3, entry 4), whereas 5 mol
% of Zn(OAc)2·2H2O would work best for this reaction (Table 3,
entries 5 and 11). Thereafter, the reaction reached completion
in 14 h when 10 equiv of H2O2 were used (Table 3, entry 11).
Hence, the optimized conditions found for the synthesis of
N-sulfonyloxaziridines starting from N-sulfonylimines (1.2
equiv. of Na2CO3, 5 mol % of Zn(OAc)2·2H2O, 10 equiv. of 30%
H2O2, DMC, rt) were chosen as model conditions for our
continuing studies. The substrate scope was then investigated.
A variety of N-sulfonylimines 4a-k were tested under the
optimized conditions, and representative results are
summarized in Table 4. N-Sulfonyloxaziridines 5a-k were
6
7b
15
88
8b
9b
18
15
90
85
10
11
14
14
83
93
a
Reaction conditions: N-sulfonylimine (0.5 mmol),46 Zn(OAc)2·2H2O (5 mol
b
obtained in high yields after washing with sodium sulfite, %), Na2CO3 (1.2 equiv.), H2O2 (30%, 10 equiv.), DMC (1.5 mL), rt. Reaction
carried out in 3 mL of DMC instead of 1.5 mL to solubilize the imine.
extraction with ethyl acetate and filtration through a short pad
of silica gel. There was not much difference in reaction time
and yields with various functional groups on the benzene ring
of the imine system. In all cases, the reaction produced only
In order to demonstrate the applicability of the present
method, a gram scale oxidation of imine 4f was carried out,
using 2 g of 4f (7.2 mmol), 10 mL of DMC, 0.9 g of Na2CO3, 7
mL of H2O2 (30%) and 80 mg of Zn(OAc)2·2H2O (5 mol %). The
reaction reached completion in 12 h and afforded oxaziridine
5f in 92% yield.
As for epoxidation of imines with peracids,18a we
postulated that the reaction proceeds in two steps according
to a Baeyer-Villiger type mechanism, rather than the concerted
one
N-sulfonyloxaziridine
isomer,
namely,
the
thermodynamically favored trans-oxaziridine, as for the
existing methods.18a,19,22
Table 4 Synthesis of N-sulfonyloxaziridinesa
oxygen transfer (epoxidation of olefins).
A
plausible
mechanism illustration is proposed in Fig. 1. The addition of
H2O2 to DMC, in the presence of Na2CO3, would generate the
methoxy carbonyl peroxydate
6 as an active oxidant, which
would react with the electrophilic N-sulfonylimine to give
4 | Green Chemistry., 2016, 00, 1-5
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 5 of 6
View Article Online
DOI: 10.1039/C6GC01394E
Green Chemistry
intermediate
COMMUNICATION
7.
The latter undergoes intramolecular
Based on the previous control experiments, we assume
cyclisation by attack of the sulfonamide anion on the that the basic media is not crucial for the one-pot synthesis of
electrophilic oxygen of the methoxy carbonyl peroxide moiety. N-alkyloxaziridines because the N–H group in the intermediate
The role of Na2CO3 may be explained by the generation of the
8 may be sufficiently nucleophilic for the cyclisation step (Fig.
sulfonylamide anion instead of the N–H sulfonamide in 7, 2). The excess of N-alkylamine used in the optimized
which would not be nucleophilic enough because of the conditions (1.5 equiv.) is believed to be necessary to ensure
adjacent electron-withdrawing sulfonyl group. On the other the complete consumption of the aldehyde by shifting the
hand, the role of Zn(OAc)2·2H2O may be explained by its ability equilibrium towards the imine formation and ensure,
to activate the carbonyl group of the DMC and intermediates
6
accordingly, the total conversion of the imine into the
corresponding oxaziridine. This hypothesis is in agreement
with the following results: i) in the presence of 1 equiv. of t-
BuNH2, the conversion of benzaldehyde into the oxaziridine
was not complete after 24 h of reaction (Table 1, entry 1), ii)
the oxidation of N-propylimine, in the presence of t-BuNH2 (1
equiv.), furnished a mixture of N-propyloxaziridine 3l (64%)
and N-t-butyloxaziridine 3a (33%) (Table 3, entry 4),
demonstrating the equilibrium taking place in the reaction
conditions (Fig. 2).
and 7 to increase the rate of the oxidation.
Fig. 1 Postulated reaction mechanism for the Baeyer-Villiger-type oxidation of
N-sulfonylimines in basic medium under Zn(OAc)2·2H2O catalysis
Fig. 2 Proposed reaction mechanism for the one-pot Baeyer-Villiger-type
oxidation of N-alkylimines in neutral medium without catalyst
The influence of the pH of the reaction media was studied
in the synthesis of N-alkyloxaziridines, in order to get more
insight into the mechanism of the oxidation of the alkylimine.
The oxidation of isolated N-alkylimines was investigated under
different pH conditions (Table 5). When the pH was adjusted
to 8.5 by adding 1.2 equiv. of Na2CO3, or to 7.0 by adding 0.5
equiv. of t-BuNH2, the obtained results were quite similar to
those observed without addition of a base, in both reaction
time and conversion (Table 5, entries 1–3). A similar trend was
reported for the epoxidation of olefins with the O-
ethylperoxycarbonic acid in acidic and basic media.31
For the first time, an eco-friendly one-pot synthesis of N-
alkyloxaziridines from the corresponding N-alkylamines and
aldehydes has been developed. In this approach, only green
DMC is used as solvent and reagent in the presence of an
aqueous solution of hydrogen peroxide (30%). Monoperoxy
carbonic acid methyl ester, generated in situ by perhydrolysis
of DMC, is the active oxidant, which decomposes, after
epoxidation of the imine intermediate, to carbon dioxide and
methanol. The method has been expanded to the preparation
of N-sulfonyloxaziridines from the corresponding N-
sulfonylimines. In this case, the reaction was carried out in
basic medium under catalysis with 5 mol % of Zn(OAc)2·2H2O.
All oxaziridines were obtained in high yields and high purity
under simple and minimum manipulation. This procedure
appears to be better than the existing methods on cost, ease
of manipulation and greenness, and will provide a novel
approach to an environmentally benign process for the
preparation of oxaziridines.
Table 5 Influence of the pH on the oxidation of N-alkyliminesa
Time
(h)
Conversion
By-product
(%)b
Entry
R
Additive
–
(%) 3b
PhCHO
(4%)
PhCHO
(< 1%)
–
1
2
3
4
t-Bu
t-Bu
t-Bu
n-Pr
12
12
10
10
96
>99
Na2CO3
(1.2 equiv.)
t-Bu-NH2
(0.5 equiv.)
t-Bu-NH2
100
3a (33%),
PhCHO (3%)
64 (3l)
(1 equiv.)
a Conditions: imine (1 mmol), H2O2 (30%, 5 mmol), DMC (1 mL), additive, rt.
b Determined by 1H NMR analysis of crude product.
This journal is © The Royal Society of Chemistry 20xx
Green Chemistry., 2016, 00, 1-5 | 5
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 6 of 6
View Article Online
DOI: 10.1039/C6GC01394E
COMMUNICATION
Green Chemistry
27 (a) Handbook of Green Chemistry, Vol. 1, Green Catalysis,
Homogeneous Catalysis, P. T. Anastas and R. H. Crabtree Eds,
Wiley-VCH, 2013; (b) R. Noyori, M. Aoki and K. Sato, Chem.
Commun., 2003, 1977.
28 (a) F. Aricò and P. Tundo, Russ. Chem. Rev., 2010, 79, 479; (b)
P. Tundo and M. Selva, Acc. Chem. Res., 2002, 35, 706; (c) P.
Tundo, Pure Appl. Chem., 2001, 73, 1117.
29 M. M. Mauri, U. Romano and F. Rivetti, Ing. Chim. Ital. 1985,
21, 1.
30 M. Rüsch gen. Klaas and S. Warwel, Org. Lett., 1999, 1, 1025.
Acknowledgments
This work was financially supported by the Natural Sciences
and Engineering Research Council of Canada (NSERC), the
Centre in Green Chemistry and Catalysis (CGCC) and the
Ministère de l'enseignement supérieur et de la recherche
scientifique tunisien. We thank Marie Gonay for her assistance
in performing control experiments.
31 R. D. Bach, M. W. Klein, R. A. Ryntz and J. W. Holubka, J. Org.
Chem., 1979, 44, 2569.
32 Y. Tsunokawa, S. Iwasaki and S. Okuda, Chem. Pharm. Bull.,
1983, 31, 4578.
33 Y. Tsunokawa, S. Iwasaki and S. Okuda, Tetrahedron Lett.,
1982, 23, 2113.
References and notes
1
2
W. D. Emmons, J. Am. Chem. Soc., 1957, 79, 5739.
D. A. Evans, M. M. Morrissey and R. L. Dorow, J. Am. Chem.
Soc., 1985, 107, 4346.
3
4
5
6
7
8
9
D. Prieur, A. El Kazzi, T. Kato, H. Gornitzka and A. Baceiredo,
Org. Lett., 2008, 10, 2291.
F. A. Davis, S. G. Lal and H. Dupont Durst, J. Org. Chem.,
1988, 53, 5004.
M. Komatsu, Y. Ohshiro, H. Hotta, M. Sato and T. Agawa, J.
Org. Chem. 1974, 39, 948.
J. Kraïem, L. Grosvalet, M. Perrin and B. Ben Hassine,
Tetrahedron Lett., 2001, 42, 9131.
M. Fabio, L. Ronzini and L. Troisi, Tetrahedron, 2007 , 63
12896.
M. Fabio, L. Ronzini and L. Troisi, Tetrahedron, 2008, 64
4979.
L. Troisi, L. Ronzini, F. Rosato and V. Videtta, Synlett, 2009,
34 R. M. Coates and J. W. Williams, J. Org. Chem., 1974, 39
3054.
35 G. B. Payne and P. H. Williams, J. Org. Chem., 1961, 26, 651.
,
36 E. G. Ankudey, H. F. Olivo and T. L. Peeples, Green Chem.,
2006, , 923.
8
37 (a) M. Blümel, P. Chauhan, R. Hahn, G. Raabe and D. Enders,
Org. Lett., 2014, 16, 6012; (b) I. Hachiya, Y. Minami, T.
Aramaki and M. Shimizu, Eur. J. Org. Chem., 2008, 1411.
,
38 C. P. Casey and J. B. Johnson, J. Am. Chem. Soc., 2005, 127
1883.
,
,
39 J. B. Firth and H. H. Gething, J. Chem. Soc., 1936, 633.
40 E. J. Corey and A. W. Gross, Tetrahedron Lett., 1984, 25, 491.
41 D. R. Boyd, D. C. Neill, C. G. Watson and W. B. Jennings, J.
Chem. Soc., Perkin Trans. 2, 1975, 1813.
1806.
10 A. Kivrak and R. C. Larock, J. Org. Chem., 2010, 75, 7381.
11 C. H. Leung, A. M. Voutchkova, R. H. Crabtree, D. Balcells and
O. Eisenstein, Green Chem., 2007, 9, 976.
12 F. A. Davis, P. A. Mancinelli, K. Balasubramanian and U. K.
Nadir, J. Am. Chem. Soc., 1979, 101, 1044.
13 M. L. Di Gioia, A. Leggio, A. Le Pera, A. Liguori and C.
Siciliano, J. Org. Chem., 2005, 70, 10494.
14 D. J. Michaelis, K. S. Williamson and T. P. Yoon, Tetrahedron,
2009, 65, 5118.
15 K. S. Williamson and T. P. Yoon, J. Am. Chem. Soc., 2012, 134
12370.
16 P.-L. Shao, X.-Y. Chen and S. Ye, Angew. Chem., Int. Ed., 2010,
49, 8412.
17 T. B. Bitencourt and M. da Graça Nascimento, Green Chem.,
2009, 11, 209.
42 The oxaziridines derived from anilines are known to be
unstable and lead to quick decomposition: (a) K. Shinzawa
and I. Tanaka, J. Phys. Chem., 1964, 68, 1205; (b) J. S. Splitter
and M. Calvin, J. Org. Chem., 1965, 30, 3427; (c) H. Ono, J. S.
Splitter and M. Calvin, Tetrahedron Lett., 1973, 4107.
43 D. Mohajer, N. Iranpoor, A. Rezaeifard, Tetrahedron Lett.,
2004, 45, 631.
44 M. Čudić, R. Hermann, Magn. Reson. Chem., 1993, 31, 461.
45 (a) T. Baba, A. Kobayashi, T. Yamauchi, H. Tanaka, S. Aso, M.
Inomata, Y. Kawanami, Catalysis Lett., 2002, 82, 193; (b) T.
Baba, A. Kobayashi, Y. Kawanami, K. Inazu, A. Ishikawa, T.
Echizenn, K. Murai, S. Aso and M. Inomata, Green Chem.,
,
2005, 7, 159.
46 S. Morales, F. G. Guijarro, J. L. García Ruano, M. B. Cid, J. Am.
Chem. Soc. 2014, 136, 1082.
18 (a) F. A. Davis, J. Lamendola Jr., U. Nadir, E. W. Kluger, T. C
Sedergran, T. W. Panunto, R. Billmers, R. Jenkins Jr., I. J.
Turchi, W. H. Watson, J. S. Chen and M. Kimura, J. Am. Chem.
Soc. 1980, 102, 2000; (b) F. A. Davis and O. D. Stringer, J. Org.
Chem., 1982,
19 (a) Y. Usuki, Y. Wang and J. Aubé, J. Org. Chem., 1995, 60
8028; (b) J. L. García Ruano, J. Alemá, C. Fajardo and A. Parra,
Org. Lett., 2005, , 5493.
7, 1774.
,
7
20 L. Martiny and K. A. Jørgensen, J. Chem. Soc., Perkin Trans. 1
1995, 699.
21 J. Kraïem, Y. Kacem, J. Khiari and B. Ben Hassine, Synth.
Commun., 2001, 31, 263.
22 J. Kraïem, R. Othman and B. Ben Hassine, C. R. Chim., 2004,
7, 1119.
23 J. A. Damvandi, B. Karami and M. A. Zolfigol, Synlett, 2002,
933.
24 F. A. Davis, S. Chattopadhyay, J. C. Towson, S. Lal and T.
Reddy, J. Org. Chem., 1988, 53, 2087.
25 (a) W. Navarrini and D. D. DesMarteau, Process for the
preparation of perfluoro-amino oxaziridines, United States
Patent US 5017709-A, 1991; (b) V. A. Petrov and D. D.
DesMarteau, J. Fluorine Chem., 1996, 77, 175.
26 D. Prat, J. Hayler and A. Wells, Green Chem., 2014, 16, 4546.
6 | Green Chemistry., 2016, 00, 1-5
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins