Trifluoromethanesulfonylimides of arenehydroxamic acids and their aza Lossen rearrangement

Article abstract of DOI:10.1016/j.jfluchem.2007.01.002

Trifluoromethanesulfonylimides of arenehydroxamic acids ArC({double bond, long}NSO₂CF₃)NHOH (1), analogues of arenehydroxamic acids, in which sp² hybridized oxygen atom is replaced by the much stronger electron-withdrawing

Full text of DOI:10.1016/j.jfluchem.2007.01.002

Journal of Fluorine Chemistry 128 (2007) 515–523
www.elsevier.com/locate/fluor
Trifluoromethanesulfonylimides of arenehydroxamic acids and
their aza Lossen rearrangement
*
Lev M. Yagupolskii , Svetlana V. Shelyazhenko, Irina I. Maletina, Liubov V. Sokolenko,
Alexander N. Chernega 1, Eduard B. Rusanov 1, Ivan F. Tsymbal 2
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 02660, Murmanskaya Str. 5, Kiev, Ukraine
Received 21 November 2006; received in revised form 4 January 2007; accepted 5 January 2007
Available online 13 January 2007
Dedicated to Professor Dr. Alois Haas on his 75th birthday.
Abstract
Trifluoromethanesulfonylimides of arenehydroxamic acids ArC( NSO2CF3)NHOH (1), analogues of arenehydroxamic acids, in which sp2
hybridized oxygen atom is replaced by the much stronger electron-withdrawing group NSO2CF3, have been synthesized, and the abilities of these
compounds to undergo transformations similar to the Lossen rearrangement have been studied.
At heating O-trimethylsilyl or O-tosyl derivatives of acids 1 rearrange to carbodiimides ArN C NSO2CF3 or products of their hydration, the
corresponding carbamides. Interaction of acids 1 with sulfinyl chloride or phosphorus pentachloride results in formation of N-trifluoromethyl-
sulfonyl-N0-arenechloroformamidines, ArNHC(Cl) NSO2CF3, which were transformed into their morpholine derivatives and thus characterized.
# 2007 Elsevier B.V. All rights reserved.
Keywords: Hydroxamic acids; Rearrangements; X-ray structure; Formamidines
1. Introduction
We have also established that the replacement of oxygen in
the chloranhydride of a carboxylic acid by the NSO2CF3
group enabled an aza-Curtius rearrangement to be carried out,
and, in addition, to perform the reaction in more mild
conditions. This rearrangement resulted in the formation of the
carbodiimide RN C NSO2CF3 [6].
Rearrangements of organic compounds via migration of a
substituent with its electron pair from carbon atom to nitrogen
atom are widely used in synthetic organic chemistry for
preparation of isocyanates and amines from amides of
carboxylic acids (Hofmann rearrangement), azides (Curtius),
hydroxamic acids or their derivatives (Lossen), amides from
oximes (Beckmann) [1].
We have found earlier that replacement of an sp2-hybridized
oxygen atom by the NSO2CF3 group in various substituents
enhances their electron-withdrawing power, resulting in a
dramatic change in the properties of corresponding organic
compounds, e.g., their acidity increases significantly [2,3],
halogen atoms in the corresponding aromatic compounds
become more active in reactions of nucleophilic substitution
[4], and dyestuffs are coloured more intensively [5].
Taking into account these observations, it would be of
interest to study the effect of replacement of carbonyl oxygen in
hydroxamic acids by NSO2CF3 group on the course of a
Lossen-type rearrangement.
2. Results and discussion
Trifluoromethanesulfonylimides of arenehydroxamic acids
havenotbeendescribedintheliterature. Wetriedtopreparethese
compounds by reaction of hydroxylamine hydrochloride with N-
trifluormethylsulfonylarencarboximidoyl chlorides at the pre-
sence of triethylamine or sodium hydride (similarly to
corresponding azides [6]), but a mixture of products was
formed. Positive results were finally achieved by reaction of
chloranhydridesofarenehydroxamicacidswiththemonosodium
salt of trifluormethanesulfonamide in dimethylformamide
* Corresponding author. Tel.: +38 44 559 0349; fax: +38 44 573 2643.
E-mail address: Yagupolskii@bpci.kiev.ua (L.M. Yagupolskii).
1
Crystal structure analysis.
2
IR-spectra.
0022-1139/$ – see front matter # 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2007.01.002

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L.M. Yagupolskii et al. / Journal of Fluorine Chemistry 128 (2007) 515–523
Scheme 1.
Scheme 2.
(DMF) solution (similarly to arenesulfonamide monosodium
salts [7]). Trifluoromethanesulfonylimides of arenehydroxamic
acids 1a–f were isolated with good yields (Scheme 1).
Starting from O-alkylated hydroxylamines we have
prepared O-alkylated trifluoromethanesulfonylimides of are-
nehydroxamic acids 2a–c in high yield by reaction with N-
trifluoromethylsulfonylarenecarboximidoyl chlorides [6] in the
presence of sodium hydride (Scheme 2).
tautomerism is impossible a band at 1565–1590 cmꢀ1 is typical
for vibrations of the fragment C N in the C NSO2CF3 group.
In the IR-spectra of 1a–f compounds (in CHCl3) absorption
bands at 1590–1595 cmꢀ1 are observed, which correspond to
tautomeric form A and agree with the 19F NMR data of these
compounds. The results of X-ray analysis for 1a confirm the
existence of the 1a–f compounds in the form A (Fig. 1).
The perspective view of the molecule 1a and selected
geometrical parameters are given in Fig. 1 from a single crystal
Trifluoromethanesulfonylimides of arenehydroxamic acids
1a–f and O-alkylated trifluoromethanesulfonylimides of are-
nehydroxamic acids 2a–c are colorless (except yellow
nitrocompound 1f) crystalline materials.
Trifluoromethanesulfonylimides of arenehydroxamic acids
may exist in two tautomeric forms (A and B).
1
On the basis of H and 19F NMR spectra, IR spectra and
X-ray analysis of the compounds 1, we have established that
they have the structure of hydroxamic acid A in both solution
and in solid.
The analysis of 19F NMR spectra of the compounds with
fixed C NSO2CF3 and C–NHSO2CF3 groups has confirmed
that a signal of the NSO2CF3 group is in the range ꢀ78 to
ꢀ80 ppm, and that of NHSO2CF3 group—at ꢀ75 to ꢀ77 ppm
[6]. In 19F NMR spectra of the compounds 1a–f signals at ꢀ79
to ꢀ80 ppm are observed, which correspond to the structure A.
In their IR-spectra (both in KBr tablets and in chloroform or
methylene chloride solutions) of the compounds in which
Fig. 1. Perspective view and labelling scheme for the molecule 1a. Selected
˚
bond lengths (A) and angles (8): S(1)–O(1) 1.426(2), S(1)–O(2) 1.432(1), S(1)–
N(1) 1.562(2), S(1)–C(1) 1.825(2), O(3)–N(2) 1.381(2), N(1)–C(2) 1.315(2),
N(2)–C(2) 1.307(2), C(2)–C(3) 1.482(2); S(1)N(1)C(2) 129.5(1), O(3)N(2)C(2)
120.8(2), N(2)O(3)H(3) 100(2).

L.M. Yagupolskii et al. / Journal of Fluorine Chemistry 128 (2007) 515–523
517
comparison with the standard value for the N(sp2)–C(sp2)
˚
single bonds of 1.43–1.45 A [8,9]. In the solid state the
molecules of 1 are joined in nets by the N(2)–Hꢁ ꢁ ꢁO(2) (Nꢁ ꢁ ꢁO
˚
2.878(2), Oꢁ ꢁ ꢁH 2.04(3) A, NHO 165(2)8) and O(3)-Hꢁ ꢁ ꢁO(1)
˚
˚
(Oꢁ ꢁ ꢁO 2.759(2) A, Oꢁ ꢁ ꢁH 1.94(2) A, OHO 175(2)8) hydrogen
bonds (Fig. 2).
Our attempts to carry out rearrangement of compounds 1
under the conditions of the classic Lossen rearrangement,
thermolysis of the sodium salt of the O-acyl derivative, were
unsuccessful. Trifluoromethanesulfonylimide of 4-chlorophe-
nylhydroxamic acid 1e, acylated by acetic anhydride in
dichloromethane, to form acetyl derivative 3, was chosen as
a model compound (Scheme 3).
However, on further heating, the sodium salt of 3, obtained
in situ by its reaction with sodium hydride in anhydrous DMF,
was probably transformed into a rearrangement product,
namely, a carbodiimide which decomposed at high tempera-
ture. As a result, trifluoromethanesulfonamide and tarry
products only were obtained from reaction mixture.
An attempt to use an ester of a stronger acid, namely
trifluoroacetic, for this reaction was also unsuccessful. A
positive result was achieved after tosyl chloride was chosen as
an esterification agent (similarly to [10]). The tosyl residue is
a good leaving group, so rearrangement with formation of
carbamide 4a occurs under the action of aqueous alkali
(Scheme 4).
It was found earlier that trimethylsilyl esters of arenehy-
droxamic acids underwent the Lossen rearrangement [11]. We
have obtained trimethylsilyl esters of trifluoromethanesulfo-
nylimides of 4-fluoro- and 4-chlorophenylhydroxamic acids
(5a, b) by reaction of compounds 1d, e with hexamethyldi-
silazane (HMDS) in acetonitrile solution. In this case, in
contrast to silylation of usual hydroxamic acids, resulting in
O,O0-bis-trimethylsilyl derivatives [11], only monosilylation
Fig. 2. Crystal packing of the compound 1a.
1
occurs, which was confirmed by H and 19F NMR spectra.
Compounds 5 underwent thermal decomposition in boiling
toluene. Morpholine was then added to the reaction mixture in
order to obtain stable derivatives. As a result, mixture of
carbamide 4 and trifluoromethylsulfonylamidinomorpholine 6
is formed, obviously due to competitive bonding of not only
morpholine, but also water to the resulting carbodiimide
(Scheme 5).
Scheme 3.
X-ray study. The central O(3)N(1)N(2)C(2)C(3) bond system is
planar (deviations from the least-square plane do not exceed
The low yields of key products obtained within Schemes 4
and 5 may be rationalized by the fact that transient formed
carbodiimides ArN C NSO2CF3 were unstable at the tem-
perature necessary for the rearrangement realization.
It is known that hydroxamic acids and their derivatives
undergo a Lossen rearrangement by the action of acid
dehydration agents, e.g. sulfinyl chloride. When heating the
˚
˚
0.004 A). The S(1) atom is 0.237 A above this plane. The
benzene ring C(3–8) is twisted out of this plane by 29.58. The
N(2) atom has a trigonal–planar bond configuration (sum of
the bond angles 359.68). Due to the nN(2)–pC(2)=N(1) conjugation
˚
the N(2)–C(2) bond of 1.307(2) A is significantly shortened in
Scheme 4.

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L.M. Yagupolskii et al. / Journal of Fluorine Chemistry 128 (2007) 515–523
Scheme 5.
solutions of compounds 1 in glyme with sulfinyl chloride
or phosphorus pentachloride the rearrangement occurs to
form N-trifluoromethylsulfonyl-N0-arenechloroformamidines 7.
Chloroformamidines 7 are found to be compounds unstable at
storage or to hydrolysis, therefore, only three of them, namely,
7a, 7d, and 7f were isolated and characterized by NMR-spectra
and elemental analysis. All 7a–f were characterized in the
form of their morpholine derivatives 6 (Scheme 6).
We first assumed, that this transformation proceeded by the
classical mechanism of triplet rearrangements [1] with
formation of a carbodiimide, as shown in Scheme 5, with
further addition of HCl. In order to check this assumption we
obtained carbodiimide 8 from N-trifluoromethylsulfonyl-(4-
fluorophenyl)carboximidoyl chloride, with the use of aza
Curtius reaction [6], and passed the dry HCl flow through its
boiling solution in glyme. It was found, however, that under
these conditions hydrogen chloride did not add to carbodiimide
8 with formation of N-trifluormethylsulfonyl-N0-(4-fluorophenyl)
chloroformamidine 7d (Scheme 7).
This result suggests that under the action of sulfinyl chloride
or phosphorus pentachloride the trifluoromethanesulfonyli-
mides of arenehydroxamic acids 1a–f undergo a Lossen-type
rearrangement which includes a five-membered cyclic transi-
tion complex (Scheme 8).
Scheme 6.

L.M. Yagupolskii et al. / Journal of Fluorine Chemistry 128 (2007) 515–523
519
Scheme 7.
Scheme 8.
Chloroformamidines 7, formed in the course of this
reactions were found to be thermally much more stable then
corresponding carbodiimides, that enabled to obtain products
up to Scheme 6 with good yields.
reagent grade or were purified by standard methods before
use. Solvents were distilled from the appropriate drying
agents immediately prior to use. Some reactions were
monitored by thin-layer chromatography (TLC) on precoated
silica gel Kieselgel 60 F/UV254 plates (Merck); spots
were visualized with UV light. Purification of most products
was performed by column chromatography (CC) on silica
O-Alkylated trifluoromethanesulfonylimides of arenehy-
droxamic acids 2 do not enter into rearrangements under the
action of sulfinyl chloride and phosphorous pentachloride.
We have earlier established [6], that Curtius reaction for
the compounds, in which sp2 oxygen atom is replaced by
the group NSO2CF3, proceeds under more mild conditions
(ꢀ5 to 0 8C) than for azides of carboxylic acids. It can be
accounted for by the weakening of the N–N bond in azides
due to the strong electron-withdrawing affect of the
NSO2CF3 group. In the case of trifluoromethanesulfonyli-
mides of arenehydroxamic acids 1 Lossen rearrangement
proceeds under more severe conditions. This can be explained
by the strengthening of the N–O bond in hydroxyaminogroup.
As a result of coupling with the NSO2CF3 group an electron
pair of nitrogen atom N(2) shifts to form a partial double
bonding. It is confirmed by X-ray analysis, namely, length of
1
gel, 70–230 mesh 60A (Aldrich). H and 19F NMR spectra
were recorded at 299.5 MHz and 282.2 MHz, respectively,
with a Varian VXR-300 spectrometer, and chemical shifts
are given in ppm relative to Me4Si and CCl3F, respectively,
as internal standards. Coupling constants are given in Hz.
IR spectra were recorded with a Spekord M 40 instrument
(KBr tablet or solution in CHCl3). Melting points were
determined in open capillaries and are uncorrected.
Elemental analysis was performed in the Analytical
Laboratory of the Institute of Organic Chemistry, NAS of
Ukraine, Kiev.
3.2. General procedure for the synthesis of
trifluoromethanesulfonylimides of arenehydroxamic acids
(1a–f)
˚
˚
N(2)–C(2) bond is 1.307 A instead of 1.43–1.45 A in the
compounds with the typical N(sp2)–C(sp2) bond. Emergence
of a partial positive charge on N(2) atom strengthens
N(2)–O(3) bond because of withdrawing the electron density
from O(3) atom.
A solution of arenehydroxamic acid chloranhydride
(0.003 mol) in anhydrous DMF (10 mL) was added dropwise
to a stirred mixture of monosodium salt of trifluoro-
methanesulfonamide (0.006 mol) in anhydrous DMF
(10 mL) at 0 8C in 20 min. After stirring for 24 h at room
temperature, the reaction mixture was poured into ice. The
product was extracted with diethyl ether (3 ꢂ 15 mL), ether
layer was washed with water (2 ꢂ 15 mL), and dried with
Na2SO4. Distillation of ether, and recrystallization (from
3. Experimental
3.1. General
Moisture-sensitive reactions were carried out under dry
argon using flame-dried glassware. All chemicals were of

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L.M. Yagupolskii et al. / Journal of Fluorine Chemistry 128 (2007) 515–523
chloroform/hexane) of resultant precipitate gave analytically
pure 1.
3.3. General procedure for the synthesis of O-substituted
trifluoromethanesulfonylimides of arenehydroxamic acids
(2a–c)
3.2.1. Phenylhydroxamic acid
trifluoromethanesulfonylimide (1a)
A solution of 4-fluoro-N-(trifluoromethylsulfonyl)benzi-
midoyl chloride [6] (0.57 g, 0.002 mol) in anhydrous
THF (10 mL) was added dropwise to a stirred mixture of
O-alkylhydroxylamine hydrochloride (0.002 mol) and
sodium hydride (0.15 g, 0.006 mol) in anhydrous THF
(25 mL) at 0 8C in 20 min. After stirring for 72 h at room
temperature and refluxing for 30 min, the solvent was
evaporated in vacuo. The residue was dissolved in water
and filtered, filtrate was acidified with conc. HCl at 0 8C. The
precipitate formed was filtered off, washed with water and
dried. Recrystallization(frombenzene/hexane)gaveanalytically
pure 2.
mp 126–128 8C (dec.). 1H NMR ([D6]acetone): d 7.51–7.78
(5H, m, ArH), 10.00–10.60 (1H, w s, NH), 11.00–12.00 (1H, w
s, OH); 19F NMR ([D6]acetone): d–79.4 (s, 3F, SO2CF3); IR
(KBr): n 3400, 3285, 3240 (O–H), 1608 (C N), 943 cmꢀ1 (N–
O). Anal. calcd for C8H7F3N2O3S: C 35.82, H 2.63, N 10.44.
Found: C 35.90, H 2.54, N 10.48.
3.2.2. 4-Methoxyphenylhydroxamic acid
trifluoromethanesulfonylimide (1b)
mp 138–140 8C (dec.). 1H NMR ([D6]acetone): d 3.65 (3H,
s, OCH3), 6.76–7.30 (4H, dd, ArH), 7.94–8.06 (1H, w s, NH),
8.45 (1H, s, OH); 19F NMR ([D6]acetone): d ꢀ79.6 (s, 3F,
SO2CF3); IR (KBr): n 3310 (O–H), 1606 (C N), 943 cmꢀ1 (N–
O). Anal. calcd for C9H9F3N2O4S: C 36.24, H 3.04, N 9.39.
Found C 35.92, H 2.87, N 9.07.
3.3.1. 4-Fluorophenyl-O-methylhydroxamic acid
trifluoromethanesulfonylimide (2a)
1
mp 105–107 8C. H NMR (CDCl3): d 4.03 (3H, s, OCH3),
7.07–7.13 (2H, m, ArH), 7.58–7.62 (2H, m, ArH), 7.85 (1H, s,
NH); 19F NMR (CDCl3): d ꢀ76.8 (s, 3F, SO2CF3), ꢀ108.7 (s,
1F, ArF); IR (KBr): n 3225 (N–H), 1610 cmꢀ1 (C N). Anal.
calcd for C9H8F4N2O3S: C 36.01, H 2.69, N 9.33. Found C
36.23, H 2.83, N 9.57.
3.2.3. 4-Difluoromethoxyphenylhydroxamic acid
trifluoromethanesulfonylimide (1c)
mp 134–135 8C (dec.). 1H NMR ([D6]acetone): d 7.19 (1H, t,
J
H,F = 73 Hz, OCHF2), 7.28–7.83 (4H, dd, ArH), 10.20–10.60
(1H, w s, NH), 11.00–11.80 (1H, w s, OH); 19F NMR
([D6]acetone): d ꢀ79.2 (s, 3F, SO2CF3), ꢀ82.9 (d, JH,F = 73 Hz,
2F, OCHF2); IR (KBr): n 3325 (O–H), 1606 (C N), 943 cmꢀ1
(N–O). Anal. calcd for C9H7F5N2O4S: C 32.34, H 2.11, N 8.38.
Found C 32.51, H 1.98, N 8.46.
3.3.2. 4-Fluorophenyl-O-ethylhydroxamic acid
trifluoromethanesulfonylimide (2b)
mp 92–93 8C. 1H NMR (CDCl3): d 1.34 (3H, t, OCH2CH3),
4.28 (2H, quart, OCH2CH3), 7.06–7.12 (2H, m, ArH), 7.58–
7.63 (2H, m, ArH), 7.80 (1H, s, NH); 19F NMR (CDCl3): d
ꢀ77.0 (s, 3F, SO2CF3), ꢀ111.6 (s, 1F, ArF). Anal. calcd for
C10H10F4N2O3S: C 38.22, H 3.21, N 8.91. Found C 38.09, H
2.77, N 9.16.
3.2.4. 4-Fluorophenylhydroxamic acid
trifluoromethanesulfonylimide (1d)
mp 139–141 8C (dec.). 1H NMR ([D6]acetone): d 7.29–7.37
(2H, m, ArH), 7.82–7.87 (2H, m, ArH), 9.84–10.32 (1H, w s,
NH), 11.48–11.93 (1H, w s, OH); 19F NMR ([D6]acetone): d
ꢀ76.8 (s, 3F, SO2CF3), ꢀ108.8 (s, 1F, ArF); IR (KBr): n 3220
(O–H), 1600 cmꢀ1 (C N). Anal. calcd for C8H6F4N2O3S: C
33.57, H 2.11, N 9.79. Found C 33.70, H 2.05, N 9.68.
3.3.3. 4-Fluorophenyl-O-allylhydroxamic acid
trifluoromethanesulfonylimide (2c)
mp 82–83 8C. 1H NMR ([D6]acetone): d 4.71 (2H, d, OCH2–
CH CH2), 5.32–5.50 (2H, m, OCH2–CH CH2), 6.03–6.16
(1H, m, OCH2–CH CH2), 7.27–7.33 (2H, m, ArH), 7.81–7.86
(2H, m, ArH), 10.00–12.00 (1H, w s, NH); 19F NMR
([D6]acetone): d ꢀ78.5 (s, 3F, SO2CF3), ꢀ108.2 (s, 1F, ArF).
Anal. calcd for C11H10F4N2O3S: C 40.49, H 3.09, N 8.58.
Found C 40.70, H 2.89, N 8.56.
3.2.5. 4-Chlorophenylhydroxamic acid
trifluoromethanesulfonylimide (1e)
mp 157 8C (dec). 1H NMR ([D6]acetone): d 7.58–7.79 (4H,
dd, ArH), 10.50–11.50 (2H, w s, NH + OH); 19F NMR
([D6]acetone): d ꢀ79.7 (s, 3F, SO2CF3); IR (KBr): n 3315
(O–H), 1616 (C N), 943 cmꢀ1 (N–O). Anal. calcd for
C8H6ClF3N2O3S: C 31.75, H 2.00, N 9.25. Found C 31.85,
H 2.05, N 9.30.
3.4. 4-Chlorophenyl-O-acetylhydroxamic acid
trifluoromethanesulfonylimide (3)
A solution of acetic anhydride (1 mL) in anhydrous
methylene chloride (10 mL) was added dropwise to a
stirred suspension of 1e (0.3 g, 0.001 mol) in anhydrous
methylene chloride (10 mL) at 5 8C in 20 min. After stirring
for 2 h at room temperature (the completion of reaction
was controlled with FeCl3 probe) the solvent was evaporated
in vacuo (0.05 Torr). The residue afforded spectral pure 3
(0.31 g). mp 120–121 8C. 1H NMR ([D6]acetone): d 2.25
(3H, s, OCOCH3), 7.55–7.65 (4H, dd, ArH), 10.00–12.00
3.2.6. 4-Nitrophenylhydroxamic acid
trifluoromethanesulfonylimide (1f)
mp 152–154 8C (dec.). 1H NMR ([D6]acetone): d 8.03–8.36
(4H, dd, ArH), 10.60–11.80 (2H, w s, NH + OH); 19F NMR
([D6]acetone): d ꢀ75.4 to ꢀ79.7 (w s, 3F, SO2CF3); IR (KBr): n
3285 (O–H), 1626 (C N), 943 cmꢀ1 (N–O). Anal. calcd for
C8H6F3N3O5S: C 30.68, H 1.93, N 13.42. Found C 30.79, H
1.81, N 13.30.

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521
(1H, w s, NH); 19F NMR ([D6]acetone): d ꢀ78.9 (s, 3F,
dryness, residue was dissolved in anhydrous glyme (15 mL)
and treated with solution of morpholine (0.002 mol) in glyme
(5 mL) at 0 8C. After stirring for 24 h at room temperature the
solvent was distilled off. Column chromatography (eluent
hexane/ethylacetate 2:1) afforded compounds 4 and 6.
SO2CF3).
3.5. Aza Lossen rearrangement with tosyl chloride
3.5.1. N-(4-Chlorophenyl)-N0-trifluoromethylsulfonylurea
(4a)
3.8. Aza Lossen rearrangement with sulfinyl chloride
(method A). 4-[N-Arene-N0-
Tosyl chloride (0.19 g, 0.001 mol) was added in portions to a
stirred solution of 1e (0.3 g, 0.001 mol) in 2N aqueous sodium
hydroxide (2 mL) at 0 8C in 20 min. After stirring for 4 h at
room temperature, the reaction mixture was neutrolized with
conc. HCl at 0 8C. The product was extracted with diethyl ether
(3 ꢂ 15 mL), ether layer was washed with water (2 ꢂ 15 mL),
and dried with Na2SO4. Distillation of ether, and recrystalliza-
tion (from chloroform) of resultant precipitate gave 0.05 g of 4a
(from 5a, 0.03 g). mp 220 8C. 1H NMR ([D6]DMSO): d 7.19–
7.53 (4H, dd, ArH), 9.00 (1H, s, NH); 19F NMR ([D6]DMSO): d
ꢀ75.8 (s, 3F, SO2CF3). Anal. calcd for C8H6ClF3N2O3S: C
31.75, H 2.00, N 9.25. Found C 31.83, H 1.96, N 9.31.
trifluoromethylsulfonylamidino]morpholines (6a–f) and
N-trifluoromethylsulfonyl-N0-arenechloroformamidines
(7a, d, f)
A solution of SOCl2 (0.4 g, 0.0033 mol) in anhydrous glyme
(5 mL) was added dropwise to a stirred solution of 1
(0.003 mol) in anhydrous glyme (10 mL) at 5 8C in 20 min.
After refluxing for 1 h, the solvent was evaporated in vacuo
(0.05 Torr). Products 7a, 7d, and 7f were recrystallized from
anhydrous ether/hexane. Others 7 were used without isolation.
Compound 7 was dissolved again in glyme and treated with
morpholine (0.3 g, 0.0033 mol). After stirring for 24 h at room
temperature, precipitated morpholine hydrochloride was
filtered off, the filtrate was concentrated to dryness, and the
residue was purified by column chromatography (eluent
benzene/ethylacetate 20:1) and following crystallization (from
benzene/hexane).
3.5.2. N-(4-Fluorophenyl)-N0-trifluoromethylsulfonylurea
(4b)
1
Yield 0.03 g, mp 136–140 8C. H NMR ([D6]acetone): d
7.10–7.60 (4H, m, ArH), 9.10 (1H, s, NH); 19F NMR
([D6]acetone): d ꢀ79.3 (s, 3F, SO2CF3), ꢀ116.1 (s, 1F, ArF).
Anal. calcd for C8H6F4N2O3S: C 33.57, H 2.11, N 9.78. Found
C 33.61, H 2.08, N 9.83.
3.8.1. 4-[N-Phenyl-N0-
trifluoromethylsulfonylamidino]morpholine (6a)
mp 115–116 8C; Ref. [6] 112–114 8C. 1H NMR (CD3CN): d
3.51 (4H, m, 2CH2), 3.67 (4H, m, 2CH2), 7.15–7.26 (3H, m,
ArH), 7.38–7.44 (2H, m, ArH), 8.15–8.32 (1H, w s, NH);
19F NMR (CD3CN): d ꢀ79.1 (s, 3F, SO2CF3); IR (KBr): n 3405
(N–H), 1611 (C N), 1575 cmꢀ1 (amide II).
3.6. General procedure for the synthesis of O-silylated
trifluoromethanesulfonylimides of arenehydroxamic acids
(5a, b)
The mixture of 1 (0.002 mol), HMDS (0.97 g, 0.006 mol),
and acetonitrile (10 mL) was stirred for 72 h at room
temperature. After evaporation of solvent in vacuo the residue
was pure enough for further reactions.
3.8.2. 4-[N-(4-Methoxyphenyl)-N0-
trifluoromethylsulfonylamidino]morpholine (6b)
mp 142–144 8C. 1H NMR (CD3CN): d 3.50 (4H, m, 2CH2),
3.80 (4H, m, 2CH2), 3.88 (3H, s, OCH3), 6.72–7.68 (4H, dd,
ArH), 8.21–8.35 (1H, w s, NH); 19F NMR (CD3CN): d ꢀ79.5
(s, 3F, SO2CF3); IR (KBr): n 3400 (N–H), 1610 (C N),
1580 cmꢀ1 (amide II). Anal. calcd for C13H16F3 N3O4S: C
42.50, H 4.39, N 11.44. Found C 42.64, H 4.21, N 11.48.
3.6.1. 4-Chlorophenyl-O-trimethylsilylhydroxamic acid
trifluoromethanesulfonylimide (5a)
Yield 0.73 g, 1H NMR ([D6]DMSO): d 0.02 (9H, s,
Si(CH3)3), 5.27 (1H, s, NH), 7.34–7.67 (4H, dd, ArH); 19F
NMR ([D6]DMSO): d ꢀ77.8 (s, 3F, SO2CF3).
3.6.2. 4-Fluorophenyl-O-trimethylsilylhydroxamic acid
trifluoromethanesulfonylimide (5b)
Yield 0.65 g, 1H NMR ([D6]DMSO): d 0.02 (9H, s, Si(CH3)3),
7.23–7.29 (2H, m, ArH), 7.91–7.96 (2H, m, ArH); 19F NMR
([D6]DMSO): d ꢀ77.1 (s, 3F, SO2CF3), ꢀ110.2 (s,1F, ArF).
3.8.3. 4-[N-(4-Difluoromethoxyphenyl)-N0-
trifluoromethylsulfonylamidino]morpholine (6c)
mp 132–134 8C. 1H NMR (CD3CN): d 3.52 (4H, m, 2CH2),
3.67 (4H, m, 2CH2), 6.76 (1H, t, JH,F = 73 Hz, OCHF2), 7.10–
7.30 (4H, m, ArH), 8.17 (1H, s, NH); 19F NMR (CD3CN): d
ꢀ79.1 (s, 3F, SO2CF3), ꢀ81.8 (d, JH,F = 73 Hz, 2F, OCHF2); IR
(KBr): n 3290 (N–H), 1615 (C N), 1583 cmꢀ1 (amide II).
Anal. calcd for C13H14F5N3O4S: C 38.71, H 3.50, N 10.42.
Found C 38.82, H 3.33, N 10.49.
3.7. Aza Lossen rearrangement with O-silylated
trifluoromethanesulfonylimides of arenehydroxamic acids
(5a, b). N-Arene-N0-trifluoromethylsulfonylureas (4a, b)
and 4-(N-arene-N0-
trifluoromethylsulfonylamidino)morpholines (6d, e)
3.8.4. 4-[N-(4-Fluorophenyl)-N0-
trifluoromethylsulfonylamidino]morpholine (6d)
From 5b yield 0.04 g, mp 144–146 8C; Ref. [6] 142–144 8C.
1H NMR ([D6]acetone): d 3.62 (4H, m, 2CH2), 3.78 (4H, m,
Substance 5 (0.002 mol) was refluxed in toluene (15 mL)
solution for 30 min. Reaction mixture was evaporated to

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2CH2), 7.22–7.32 (4H, m, ArH), 8.15–8.30 (1H, w s, NH);
19F NMR ([D6]acetone): d ꢀ78.8 (s, 3F, SO2CF3), ꢀ116.6 (s,
1F, ArF); IR (KBr): n 3330 (N–H), 1575 (C N), 1537 cmꢀ1
(amide II).
ethylacetate 20:1) and following crystallization (from benzene/
hexane) to give 0.72 g 6e.
3.10. X-ray crystallography
3.8.5. 4-[N-(4-chlorophenyl)-N0-
All crystallographic measurements were performed at
293 K on a Bruker SMART 6K CCD diffractometer. The
intensity data were collected within the range 2.7 < u < 29.38
(ꢀ12 < h < 13, ꢀ15 < k < 14, ꢀ12 < l < 12) using graphite
trifluoromethylsulfonylamidino]morpholine (6e)
From 5a yield 0.05 g, mp 150–152 8C; Ref. [6] 148–150 8C.
1H NMR (CD3CN): d 3.53 (4H, m, 2CH2), 3.68 (4H, m, 2CH2),
7.15–7.40 (4H, dd, ArH), 8.09–8.22 (1H, w s, NH); 19F NMR
(CD3CN): d ꢀ79.1 (s, 3F, SO2CF3).
˚
monochromated Mo Ka radiation (l = 0.71073 A). Intensities
of 9418 reflections (28718 unique, Rint = 0.014) were mea-
sured. Data were corrected for Lorentz and polarisation effects
and an absorption correction using the Sadabs procedure [12]
was applied.
3.8.6. 4-[N-(4-Nitrophenyl)-N0-
trifluoromethylsulfonylamidino]morpholine (6f)
mp 218–220 8C; Ref. [6] 217–219 8C. 1H NMR (CD3CN): d
3.63 (4H, m, 2CH2), 3.73 (4H, m, 2CH2), 7.33–8.22 (4H, dd,
ArHH), 8.40–8.60 (1H, w s, NH); 19F NMR (CD3CN): d ꢀ79.1
(s, 3F, SO2CF3).
3.10.1. Structure solution and refinement
The structure was solved by direct methods and refined by
full-matrix least-squares technique in the anisotropic approx-
imation using the CRYSTALS program package [13]. In the
refinement 1710 reflections with I > 3s(I) were used. All
hydrogen atoms were located in the different Fourier maps and
refined isotropically. Convergence was obtained at R = 0.031
and Rw = 0.034, GOF = 1.116 (182 refined parameters; obs./
variabl. 9.4). Chebushev weighting scheme [14] with para-
meters 0.74, 0.88, 0.63, 0.24, and 0.10 was used. Full
crystallographic details have been deposited at Cambridge
Crystallographic Data Centre (CCDC). Any request to the
CCDC for this materials should quote the full literature citation
and reference number CCDC 613386.
3.8.7. N-Trifluoromethylsulfonyl-N0-
phenylchloroformamidine (7a)
1
mp 104–106 8C. H NMR (CDCl3): d 7.25–7.49 (5H, m,
ArH), 8.06 (1H, w s, NH); 19F NMR (CDCl3): d ꢀ79.5 (s, 3F,
SO2CF3). Anal. calcd for C8H6ClF3N2O2S: C 33.52, H 2.11, Cl
12.37. Found C 33.39, H 2.00, Cl 11.98.
3.8.8. N-Trifluoromethylsulfonyl-N0-4-
fluorophenylchloroformamidine (7d)
1
mp 112–114 8C. H NMR (CDCl3): d 7.14 (2H, m, ArH),
7.56 (2H, m, ArH), 7.96 (1H, w s, NH); 19F NMR (CDCl3): d
ꢀ79.0 (s, 3F, SO2CF3), ꢀ116.0 (s, 1F, ArF). Anal. calcd for
C8H5ClF4N2O2S: C 31.54, H 1.65, Cl 11.63. Found C 31.38, H
2.03, Cl 11.32.
3.10.2. Crystal data for 1a
C8H7F3N2O3S, M = 268.2, monoclinic, a = 9.8787(4), b =
˚
11.6982(4), c = 9.4291(3) A, b = 97.966(3)8, V = 1079.14(7)
3
A , Z = 4, d = 1.65 g cmꢀ1, space group P21/c (N 14),
˚
m = 0.34 cmꢀ1, F(0 0 0) = 544, crystal size ca. 0.14 mm ꢂ
3.8.9. N-Trifluoromethylsulfonyl-N0-4-
0.22 mm ꢂ 0.49 mm.
nitrophenylchloroformamidine (7f)
mp 147–149 8C (dec.). 1H NMR (CDCl3): d 7.40–8.21
(4H, dd, ArH), 8.40 (1H, w s, NH); 19F NMR (CDCl3): d
ꢀ77.8 (s, 3F, SO2CF3). Anal. calcd for C8H5ClF3N3O4S:
C 28.97, H 1.52, Cl 10.68. Found C 28.68, H 1.74,
Cl 10.44.
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