The aza Curtius rearrangement

Article abstract of DOI:10.1002/1099-0690(200104)2001:7<1225::AID-EJOC1225>3.0.CO;2-6

On interaction of N-(trifluoromethylsulfonyl)carboximidoyl chlorides (analogs of acyl chlorides in which the carbonyl oxygen atom is substituted by the more strongly electron-withdrawing =NSO₂CF₃ group) with sodium azide in glyme or acetonitrile at -5 to +10 °C, dinitrogen is eliminated quantitatively and carbodiimides RN=C=NSO₂CF₃ are formed in high yield. In other words, an aza Curtius rearrangement occurs. The carbodiimides react with water, alcohols, and secondary amines to give corresponding ureas, isoureas, and guanidine derivatives. Imidoyl chlorides with substituents other than SO₂R_F do not enter into the aza Curtius reaction.

Full text of DOI:10.1002/1099-0690(200104)2001:7<1225::AID-EJOC1225>3.0.CO;2-6

FULL PAPER
The Aza Curtius Rearrangement
Lev M. Yagupolskii,*[a] Svetlana V. Shelyazhenko,[a] Irina I. Maletina,[a] Vitalij N. Petrik,[a]
Eduard B. Rusanov,[a][‡] and Alexander N. Chernega[a][‡]
Keywords: Azides / Fluorine / Heterocycles / Imidoyl chlorides / Rearrangements
On interaction of N-(trifluoromethylsulfonyl)carboximidoyl
chlorides (analogs of acyl chlorides in which the carbonyl
oxygen atom is substituted by the more strongly electron-
withdrawing =NSO2CF3 group) with sodium azide in glyme
or acetonitrile at −5 to +10 °C, dinitrogen is eliminated quant-
itatively and carbodiimides RN=C=NSO2CF3 are formed in
high yield. In other words, an aza Curtius rearrangement oc-
curs. The carbodiimides react with water, alcohols, and sec-
ondary amines to give corresponding ureas, isoureas, and
guanidine derivatives. Imidoyl chlorides with substituents
other than SO2RF do not enter into the aza Curtius reaction.
Introduction
We have established previously that replacement of an
sp2-hybridized oxygen atom (bonded to various elements)
with the ϭNSO2CF3 group enhances the electron-with-
drawing capability, which makes it possible to change the
properties of organic compounds radically. Hence, for ex-
ample, it is possible to increase the acidity strongly,[6,7] or
to activate halogen atoms in nucleophilic substitution reac-
tions of aromatic substances.[8]
The Curtius reaction is one of the most important
methods for the transformation of carboxylic acids into iso-
cyanates and amines (Scheme 1).
Scheme 1. Curtius reaction
Having considered the available data on the mechanism
of the Curtius reaction, we conjectured that substitution of
the carbonyl oxygen atom in acyl chlorides with the much
stronger electron-acceptor group ϭNSO2CF3 would make
it possible to conduct Curtius-type rearrangements under
mild conditions.
However, when the carbonyl oxygen atom in acyl chlor-
ides is substituted by an imino group ϭNRЈ, cyclization
into tetrazole occurs, rather than a Curtius reaction
(Scheme 2).[1Ϫ3]
The necessary prerequisite for the Curtius rearrangement
is a large cationic charge on the carbonyl carbon atom.
This, in particular, is increased by the addition of a proton
onto the oxygen atom during acid catalysis. This charge
weakens the N1ϪN2 bond in the azido group, renders the
adjacent nitrogen atom electron-deficient, and promotes the
anionotropic migration of the group R to this site
(Scheme 4).
Scheme 2. Cyclization to tetrazole
A few cases are known in which imidoyl azides formally
undergo Curtius rearrangements to give carbodiimides
RNϭCϭNRЈ, but these products are formed only at ex-
tremely high temperatures (Scheme 3).[4,5]
Scheme 4. Curtius reaction mechanism
The ϭNSO2CF3 group is so much stronger as an electron
acceptor that there is no need for acid catalysis, and the
aryl group easily migrates to the electron-deficient nitrogen
atom. At the same time, tetrazole ring closure is hampered
because of the drawing off of electron density from the im-
ine nitrogen atom by the SO2CF3 group (Scheme 5).
Scheme 3. High-temperature reactions
[a]
Institute of Organic Chemistry, Ukrainian National Academy
of Sciences,
Murmanskaya Str. 5, Kiev 02094, Ukraine
Fax: (internat.) ϩ 38-44/573-2643
E-mail: Lev@fluor-ukr.kiev.ua
[‡]
Crystal structure analysis.
Scheme 5. Aza Curtius reaction mechanism
Eur. J. Org. Chem. 2001, 1225Ϫ1233
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
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1225

L. M. Yagupolskii et al.
FULL PAPER
Results and Discussion
The starting compounds, N-perfluoroalkylsulfonylcar-
boximidoyl chlorides 2, were obtained from the correspond-
ing acyl chlorides by the sequence of transformations shown
in Scheme 6 (Table 1).
Scheme 6. Synthesis of carboximidoyl chlorides 2
Table 1. N-Perfluoroalkylsulfonylbenzamides and N-trifluorome-
thylsulfonylpivalamide 1a؊g, and N-perfluoroalkylsulfonylcarbox-
imidoyl chlorides 2a؊g
R
RF
Compound Yield [%] Compound Yield [%]
Scheme 8. Formation of triazinetrione 4
Ph
CF3 1a
82
97
83
84
83
80
75
2a
2b
2c
2d
2e
2f
94
89
95
81
78
83
76
4-MeC6H4 CF3 1b
4-FC6H4
4-ClC6H4
CF3 1c
CF3 1d
4-NO2C6H4 CF3 1e
CMe3
CF3 1f
C4F9 1g
4-FC6H4
2g
On treatment of imidoyl chlorides 2 with sodium azide
in a glyme solution without any catalyst, it was found that
dinitrogen was evolved quantitatively even at temperatures
of Ϫ5 to ϩ 10 °C, and carbodiimides 3 were formed in high
yield (Scheme 7).
Scheme 7. Synthesis of carbodiimides 3
Carbodiimides 3 are viscous, undistillable liquids. They
are very reactive and unstable. Elemental analysis data and
1
19F and H NMR parameters for the compounds 3a and
3f, obtained as crude products after separation of inorganic
salts and solvent evaporation, confirmed their purities and
the completeness of conversion. Accordingly, the yields of
transformation products based on compounds 3 have been
calculated on the assumption of complete conversion of
compounds 2. All reactions with carbodiimides 3 were car-
ried out at 0 to ϩ20 °C immediately after their preparation.
On long storage at room temperature or on heating in
glyme solutions, compounds 3 converted into high-melting from the least-squares plane do not exceed 0.027 A; the C(4)ϪC(9),
dimers or trimers. In the course of recrystallization and col-
umn chromatography on silica gel, the trimer of 3c was hy-
drolyzed by atmospheric moisture into triazinetrione 4,
which was identified by X-ray diffraction analysis
(Scheme 8, Figure 1).
Figure 1. A perspective view and labelling scheme for molecule
˚
4; selected bond lengths [A] and angles [°]: N(1)ϪC(1) 1.379(3),
N(1)ϪC(3) 1.398(3), N(1)ϪC(4) 1.454(3), N(2)ϪC(1) 1.384(3),
N(2)ϪC(2) 1.386(3), N(2)ϪC(10) 1.452(3), N(3)ϪC(2) 1.382(3),
N(3)ϪC(3) 1.391(3), N(3)ϪC(16) 1.454(3), O(1)ϪC(1) 1.212(3),
O(2)ϪC(2) 1.204(3), O(3)ϪC(3) 1.197(3), C(1)ϪN(1)ϪC(3)
124.8(2), C(1)ϪN(2)ϪC(2) 124.3(2), C(2)ϪN(3)ϪC(3) 124.8(2),
N(1)ϪC(1)ϪN(2)
115.6(2),
N(2)ϪC(2)ϪN(3)
115.7(2),
N(1)ϪC(3)ϪN(3) 114.5(2); the central 6-membered ring of com-
pound 4 N(1)ϪN(2)ϪN(3)ϪC(1)ϪC(1)ϪC(3) is planar, deviations
˚
C(10)ϪC(15), and C(16)ϪC(17) benzene rings are twisted out of
this plane by 66.5, 66.7, and 65.3°; the main bond lengths and
angles in
4
are virtually the same as in the previ-
ously studied[9] C3N3O3(C6H5)3
On heating at reflux with 85% orthophosphoric acid, car- N-acetyl derivative (Scheme 9). Trifluoromethylsulfonamide
bodiimide 3a gave aniline, which was characterized as the liberated in this reaction could be regenerated and reused.
1226
Eur. J. Org. Chem. 2001, 1225Ϫ1233

The Aza Curtius Rearrangement
FULL PAPER
Scheme 9. Hydrolysis of carbodiimide 3a
Treatment of 3f with water in a glyme solution resulted
in the corresponding urea 5. Compound 5 was also ob-
tained by treatment of tert-butylamine with trifluorome-
thylsulfonyl isocyanate[10] (Scheme 10). It was identified by
elemental analysis, spectral characteristics, and X-ray dif-
fraction analysis (Figure 2).
Scheme 11. Reactions between carbodiimide 3a and alcohols and
secondary amines
Compound 7 had previously been obtained by an altern-
ative route, by treatment of the reaction product of di-
methylcyanamide and trifluoromethylsulfonic anhydride
with aniline[16] (Scheme 12). The spectral characteristics of
7 prepared by the two methods were identical.
Scheme 10. Synthesis of urea 5
Scheme 12. Alternative pathway to 7 (see also ref.[16]
)
All the compounds 3 obtained by the aza Curtius reac-
tion added morpholine to form easily recrystallizable prod-
ucts of type 8, which were used for identification of the
carbodiimides (Table 2).
Table 2. 4-[N-Aryl(alkyl)-NЈ-perfluoroalkylsulfonylamidino]mor-
pholines 8a؊g
R
RF
Compound
Yield [%]
Ph
CF3
CF3
CF3
CF3
CF3
CF3
C4F9
8a
8b
8c
8d
8e
8f
54
50
58
44
47
48
44
4-MeC6H4
4-FC6H4
4-ClC6H4
4-O2NC6H4
CMe3
Figure 2. A perspective view and labelling scheme for molecule
˚
5; selected bond lengths [A] and angles [°]: S(1)ϪO(1) 1.413(2),
S(1)ϪO(2) 1.409(2), S(1)ϪN(1) 1.596(2), S(1)ϪC(1) 1.809(3),
O(3)ϪC(2) 1.225(2), N(1)ϪC(2) 1.421(3), N(2)ϪC(2) 1.310(3),
N(2)ϪC(3) 1.485(2), O(1)···N(2) 2.837(3); O(1)ϪH(2)ϪN(2)
142(3), S(1)ϪN(1)ϪC(2)ϪO(3) Ϫ168.2, N(1)ϪC(2)ϪN(2)ϪC(3)
178.3, O(3)ϪC(2)ϪN(2)ϪC(3) Ϫ1.7
4-FC6H4
8g
The morpholine derivative 8a was also prepared from the
carbodiimide 3a, synthesized by Wittig reaction
(Scheme 13). The samples of 8a obtained by both methods
showed no mixed melting point depression and had ident-
˚
The S(1)ϪN(1) bond [1.596(2) A] in 5 is noticeably
[11]
ical spectral characteristics (IR, H and 19F NMR), which
˚
1
shorter than in Me2NSO2Me [1.645(10) A]
(Me2N)2SO2 [1.651(3) A],
and
[12]
˚
reflecting the electron-with-
fully confirmed the structure of carbodiimide 3a.
drawing influence of the CF3 group. Because of nNϪπCϭO
˚
conjugation, the N(2)ϪC(2) bond [1.310(3) A] is signific-
antly shorter than the standard N(sp2)ϪC(sp2) single bond
value of 1.45 A.[13] The geometric parameters of the intram-
˚
olecular hydrogen bond O(1)···N(2) in 5 are unexcep-
tional.[14,15]
Scheme 13. Alternative pathway to 8a
Carbodiimide 3a reacts with alcohols and secondary
amines to give the corresponding isoureas and guanidine
derivatives (Scheme 11).
On treatment with morpholine in the presence of an ex-
cess of sodium azide, carbodiimide 3a also gave, in addition
Eur. J. Org. Chem. 2001, 1225Ϫ1233
1227

L. M. Yagupolskii et al.
FULL PAPER
to the major product 8a, the by-product 9, containing a A).[12] In this regard, one may suppose significant delocaliz-
tetrazole ring. Its formation can be explained by the addi- ation of the negative charge over the whole tetrazolimidate-
tion of a morpholine molecule to the intermediate azide, sulfonyl system.
˚
increasing the electron density on the aniline nitrogen atom
It should be noted that the solvent plays a very important
and thus assisting the tetrazole ring closure. The morpholi- role in the aza Curtius reaction. Thus, on treating imidoyl
nium salt 9 was isolated by column chromatography on sil- chloride 2a with sodium azide in diethyl ether, tetrahydrofu-
ica gel and identified by X-ray diffraction analysis ran, or dioxane for a few hours under the same conditions
(Scheme 14, Figure 3).
as in glyme (at Ϫ5 to ϩ 20 °C), no evolution of dinitrogen
occurred. Inorganic salts isolated from the reaction mixture
by filtration did not contain chloride ions. After the addition
of morpholine to any one of the above solutions, only the
substitution product of chlorine in 2a with morpholine Ϫ
that is, compound 10 Ϫ was isolated (Scheme 15). It is likely
that glyme activates the substitution of the azido group for
a chlorine atom in 2 by complexation with sodium azide. In
acetonitrile, the aza Curtius reaction proceeded readily at
even lower temperatures than in glyme, owing to the higher
solubility of sodium azide in this solvent.
Scheme 14. Formation of morpholinium salt 9
It was found that, in the solid state, compound 9 incorp-
orates a sulfonyltetrazolimidate anion and a morpholinium
cation (Figure 3), connected by a strong[15] NH···N hydro-
Scheme 15. Synthesis of substitution product 10
˚
gen bond [N(4)···N(6) 2.822(4) A, N(4)ϪHϪN(6) 168(3)°].
The N(1)ϪN(2)ϪN(3)ϪN(4)ϪC(7) heterocycle is planar
˚
within 0.005 A; the C(1)ϪC(6) benzene ring is twisted out
Particular attention should be paid to the exclusion of
of this plane by 41.4°. The N(5), S(1), and O(1) atoms lie moisture in the solvents, as the hydrolysis rate of imidoyl
almost in the plane of the tetrazole heterocycle, deviating chlorides 2 in polar media is extremely high.
˚
from this plane only by 0.07, Ϫ0.12, and 0.12 A respect-
It was of interest to clear up the course of the reaction of
ively, the torsion angle S(1)ϪN(5)ϪC(7)ϪN(1) being sodium azide with imidoyl chlorides possessing the SO2Ph
Ϫ170.7(2)°. The S(1)ϭO(1), S(1)ϭO(2), and S(1)ϪC(8) substituent Ϫ a close structural analog of the SO2CF3
bond lengths in 9 are similar to those in 5, whereas the group but possessing lesser electron-withdrawing power (its
˚
S(1)ϪN(5) bond [of 1.531(3) A] is significantly shorter than σp value is 0.68 as against 1.04 for SO2CF3) Ϫ at the nitro-
˚
the corresponding bond in 5 [1.596(2) A] and is among the gen atom.
shortest SIVϪN(sp2) bonds.[17,18] In turn, the N(5)ϪC(7)
We found that treatment of imidoyl chloride 11, bearing
˚
bond [1.351(4) A] is noticeably elongated in comparison the SO2Ph group at the nitrogen terminus, with sodium az-
[14]
˚
with the standard NϭC double bond (1.27 A),
but ide in glyme was accompanied by evolution of dinitrogen,
shorter than the standard N(sp2)ϪC(sp2) single bond (1.45 which started at 48Ϫ50 °C and was completed within a few
˚
Figure 3. A perspective view and labelling scheme for molecule 9; selected bond lengths [A] and angles [°]: S(1)ϪO(1) 1.419(2), S(1)ϪO(2)
1.431(2), S(1)ϪN(5) 1.531(3), S(1)ϪC(8) 1.806(4), N(1)ϪC(7) 1.355(4), N(1)ϪN(2) 1.356(4), N(1)ϪC(1) 1.427(4), N(2)ϪN(3) 1.284(4),
N(3)ϪN(4) 1.351(4), N(4)ϪC(7) 1.330(4), N(5)ϪC(7) 1.351(4); N(2)ϪN(1)ϪC(7) 108.5(2), N(1)ϪN(2)ϪN(3) 105.9(3), N(2)ϪN(3)ϪN(4)
112.1(2), N(3)ϪN(4)ϪC(7) 105.9(3), N(1)ϪC(7)ϪN(4) 107.5(3), S(1)ϪN(5)ϪC(7) 123.5(2)
1228
Eur. J. Org. Chem. 2001, 1225Ϫ1233

The Aza Curtius Rearrangement
FULL PAPER
hours. No Curtius-like rearrangement occurred, however, ius-type rearrangement of the compounds possible. This re-
and the intermediate product was transformed into dihy- action offers considerable scope for preparation of various
drotetrazine 12 (Scheme 16). Therefore, the electron-ac- compounds containing the trifluoromethylsulfonylimino
ceptor ability of the ϭNSO2Ph group is sufficient to group.
weaken the NϪN bond in the azido group and to promote
the ejection of dinitrogen, but insufficient to assist the mi-
gration of the phenyl group from the carbon atom to the
Experimental Section
electron-deficient nitrogen atom. The structure of the dihy-
drotetrazine 12 was established by X-ray diffraction ana-
lysis (Figure 4).
General: Moisture-sensitive reactions were carried out under dry
argon, using flame-dried glassware. All chemicals were of reagent
grade or were purified by standard methods before use. Solvents
were distilled from the appropriate drying agents immediately prior
to use. Ϫ All reactions were monitored by thin layer chromato-
graphy (TLC) on precoated Kieselgel 60 F/UV254 silica gel plates
(Merck); spots were viewed with UV light. Purification of most
products was performed by column chromatography (CC) on
Scheme 16. Formation of the dihydrotetrazine 12
70Ϫ230 mesh 60A silica gel (Aldrich). Ϫ H, 19F, and 13C NMR
1
spectra were recorded at 299.5 MHz, 282.2 MHz, and 75.3 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. Ϫ IR
spectra were recorded with a VR-20 instrument (KBr). Ϫ Melting
points were determined in open capillaries and are uncorrected. Ϫ
Elemental analysis was performed in the Analytical Laboratory of
the Institute of Organic Chemistry, NAS of Ukraine, Kiev.
General Procedure for the Synthesis of N-Perfluoroalkylsulfonyl-
benzamides and N-Trifluoromethylsulfonylpivalamide 1a؊g: A solu-
tion of acyl chloride (0.03 mol) in anhydrous diethyl ether (30 mL)
was added dropwise over 20 min to a stirred mixture of perfluoroal-
kanesulfonamide (0.03 mol) and triethylamine (6.1 g, 0.08 mol) in
anhydrous diethyl ether (100 mL) at 0 °C. After stirring for 1 h at
room temperature, the reaction mixture was refluxed for 2 h. After
cooling, the precipitate was filtered off and washed twice with di-
ethyl ether (20 mL). The filtrate was cocnentrated in vacuo and the
resulting oil was treated with 50% H2SO4 at 0 °C. Filtration, air-
drying, and recrystallization (from benzene) of the resultant precip-
itate gave analytically pure 1.
Figure 4. A perspective view and labelling scheme for molecule
˚
12; selected bond lengths [A] and angles [°]: S(1)ϪN(2) 1.667(5),
N-Trifluoromethylsulfonylbenzamide (1a): M.p. 110Ϫ112 °C; ref.[20]
112.5Ϫ114.5 °C.Ϫ 1H NMR ([D6]DMSO): δ ϭ 7.39Ϫ7.93 (m, 5
H, ArH), 9.73 (s, 1 H, NH).Ϫ 19F NMR ([D6]DMSO): δ ϭ Ϫ76.97
(s, 3 F, SO2CF3).
S(1)ϪC(8) 1.763(7), S(2)ϪN(4) 1.708(5), S(2)ϪC(21) 1.749(7),
N(1)ϪC(1) 1.269(7), N(1)ϪN(2) 1.458(6), N(2)ϪC(14) 1.416(7),
N(3)ϪC(14) 1.271(7), N(3)ϪN(4) 1.411(6), N(4)ϪC(1) 1.409(7);
N(2)ϪN(1)ϪC(1)
N(4)ϪN(3)ϪC(14)
113.8(5),
114.4(4),
N(1)ϪN(2)ϪC(14)
N(3)ϪN(4)ϪC(1)
115.4(4),
116.5(4),
N(1)ϪC(1)ϪN(4) 121.0(5), N(2)ϪC(14)ϪN(3) 120.9(5)
N-Trifluoromethylsulfonyl-p-toluamide (1b): M.p. 130Ϫ132 °C. Ϫ
C9H8F3NO3S (267.2): calcd. C 40.45, H 3.02; found C 40.39, H
3.00.
The central N(1)ϪN(2)ϪN(3)ϪN(4)ϪC(1)ϪC(2) hetero-
cycle of molecule 12 is significantly nonplanar and has a
boat conformation, the C(1)ϪN(1)ϪC(14)ϪN(3) ‘‘bottom’’
4-Fluoro-N-(trifluoromethylsulfonyl)benzamide (1c): M.p. 152Ϫ153
1
°C; ref.[20] 148Ϫ150 °C. Ϫ H NMR (CDCl3): δ ϭ 7.22Ϫ7.91 (m,
˚
is planar within 0.035 A, the ‘‘edges’’ C(1)ϪN(3)ϪN(4) and
4 H, ArH), 8.77 (s, 1 H, NH). Ϫ 19F NMR (CDCl3): δ ϭ Ϫ75.37
(s, 3 F, SO2CF3), Ϫ102.35 (s, 1 F, ArF).
N(1)ϪN(2)ϪC(14) form dihedral angles of 30.0 and 28.2°
with this plane. The C(2)ϪC(7) and C(15)ϪC(20) benzene
rings are twisted out of the C(1)ϪN(1)ϪC(14)ϪN(3) plane
by 86.6 and 21.8°. Geometrical parameters of the 6-mem-
bered heterocycle in 12 are similar to the corresponding
Tablevalues in 1,4-dihydro-1,2,4,5-tetrazine.[19]
4-Chloro-N-(trifluoromethylsulfonyl)benzamide (1d): M.p. 156Ϫ158
°C; ref.[20] 156.5Ϫ158 °C.
4-Nitro-N-(trifluoromethylsulfonyl)benzamide (1e): Obtained ac-
cording to the general procedure, but in acetone solution and treat-
ment with 96% H2SO4. Ϫ M.p. 144Ϫ145 °C; ref.[20] 140Ϫ145 °C.
Ϫ IR (KBr): ν˜ ϭ 1730 (CϭO), 3250 cmϪ1 (NH).
N-Trifluoromethylsulfonylpivalamide (1f): M.p. 74Ϫ75 °C. Ϫ 1H
NMR ([D6]DMSO): δ ϭ 1.10 (s, 9 H, Me3C), 7.80 (s, 1 H, NH).
Conclusion
Ϫ
19F NMR ([D6]DMSO): δ ϭ Ϫ75.74 (s, 3 F, SO2CF3). Ϫ IR
In summary, the substitution of the ϭNSO2CF3 group
for the carbonyl oxygen atom in acyl azides makes a Curt- (KBr): ν˜ ϭ 1730 (CϭO), 3250 cmϪ1 (NH). Ϫ C6H10F3NO3S
Eur. J. Org. Chem. 2001, 1225Ϫ1233
1229

L. M. Yagupolskii et al.
FULL PAPER
(233.2): calcd. C 30.90, H 4.32, N 6.01; found C 30.89, H 4.44,
N 6.13.
ing oligomerization products on long storage at room temperature
or on heating.
N-Phenyl-NЈ-(trifluoromethylsulfonyl)carbodiimide (3a): Oil. Ϫ 1H
NMR (CD3CN): δ ϭ 7.59Ϫ7.62 (m, 5 H, ArH). Ϫ 19F NMR
(CD3CN): δ ϭ Ϫ78.48 (s, 3 F, SO2CF3). Ϫ C8H5F3N2O2S (250.2):
calcd. C 38.40., H 1.99, N 11.19; found C 38.21., H 2.28, N 11.25.
4-Fluoro-N-(nonafluorobutylsulfonyl)benzamide (1g): M.p. 180Ϫ182
°C. Ϫ H NMR ([D6]DMSO): δ ϭ 7.13Ϫ7.97 (m, 4 H, ArH), 9.64
1
(s, 1 H, NH). Ϫ 19F NMR ([D6]DMSO): δ ϭ Ϫ80.30 (m, 3 F, CF3),
Ϫ110.16 (s, 1 F, ArF), Ϫ113.62 (m, 2 F, CF2), Ϫ120.93 (s, 2 F,
CF2), Ϫ125.59 (s, 2 F, CF2). Ϫ IR (KBr): ν˜ ϭ 1705 (CϭO), 3370
cmϪ1 (NH). Ϫ C11H5F10NO3S (421.2): calcd. C 31.35, H 1.19, N
3.33; found C 31.60, H 1.42, N 3.38.
N-tert-Butyl-NЈ-(trifluoromethylsulfonyl)carbodiimide (3f): Oil. Ϫ
1H NMR (CD3CN): δ ϭ 1.54 (s, 9 H, Me3C). Ϫ 19F NMR
(CD3CN): δ ϭ Ϫ78.16 (s, 3 F, SO2CF3). Ϫ C6H9F3N2O2S (230.2):
calcd. C 31.30., H 3.94, N 12.17; found C 31.15., H 3.76, N 11.82.
General Procedure for the Synthesis of N-Perfluoroalkylsulfonylcar-
boximidoyl Chlorides 2a؊g: A mixture of carboxamide 1 (0.03
mol), PCl5 (6.56 g, 0.0315 mol), and POCl3 (15 mL) was stirred
and heated to reflux until evolution of HCl ceased (ca. 2 h). Once
the reaction was complete, POCl3 was distilled off in vacuo
(20 Torr) at 50 °C and the residue was purified by vacuum distilla-
tion (except for 2e, which was recrystallized).
Hydrolysis of Carbodiimide 3a: Carbodiimide 3a (0.005 mol), ob-
tained after concentration of the glyme solution in vacuo, was
treated with 85% orthophosphoric acid (10 mL) at 0 °C. After stir-
ring at 150 °C for 1 h, the reaction mixture was poured onto
crushed ice and extracted with diethyl ether (3ϫ 10 mL). The or-
ganic phase was dried with magnesium sulfate and concentrated to
dryness, to give CF3SO2NH2 (0.34 g, 45%). Ϫ M.p. 118Ϫ120 °C.
Ϫ The aqueous phase was treated with 30% NaOH until pH ϭ 10
was reached, and extracted with diethyl ether (3 ϫ 10 mL). The
mixture was concentrated at atmospheric pressure to 3 mL volume
and treated with a mixture of acetic anhydride (1 mL), sodium acet-
ate (0.25 g), and water (10 mL). After stirring at 25 °C for 1 h, the
precipitate formed was filtered off. The crude product was recrys-
tallized from ethanol to give acetanilide (0.25 g, 36%); m.p.
110Ϫ112 °C.
N-Trifluoromethylsulfonylbenzimidoyl Chloride (2a): M.p. 83Ϫ85
°C. Ϫ B.p. 111Ϫ113 °C (0.06 Torr). Ϫ 19F NMR (CDCl3): δ ϭ
Ϫ79.84 (s, 3 F, SO2CF3). Ϫ C8H5ClF3NO2S (271.7): calcd. Cl
13.05; found Cl 13.10.
N-Trifluoromethylsulfonyl-p-toluimidoyl Chloride (2b): M.p. 67Ϫ68
°C. Ϫ B.p. 120Ϫ121 °C (0.05 Torr). Ϫ 19F NMR (CDCl3): δ ϭ
Ϫ79.26 (s, 3 F, SO2CF3). Ϫ C9H7ClF3NO2S (285.7): calcd. Cl
12.40; found Cl 11.98.
4-Fluoro-N-(trifluoromethylsulfonyl)benzimidoyl Chloride (2c): M.p.
87Ϫ 88 °C. Ϫ B.p. 93Ϫ94 °C (0.03 Torr). Ϫ 19F NMR (CDCl3):
1,3,5-Tris(4-fluorophenyl)-2,4,6-trioxoperhydro-s-1,3,5-triazine (4):
A glyme solution of carbodiimide 3c was stirred and heated at re-
flux for 5 h and then concentrated to dryness. Purification of the
crude product by recrystallization failed. Column chromatography
(eluent: benzene/ethyl acetate, 2:1) afforded 4 (0.39 g, 57%). Ϫ M.p.
265Ϫ267 °C.
δ
ϭ Ϫ79.11 (s, 3 F, SO2CF3), Ϫ98.38 (s, 1 F, ArF). Ϫ
C8H4ClF4NO2S (289.6): calcd. Cl 12.24, N 4.84; found Cl 12.22,
N 5.12.
4-Chloro-N-(trifluoromethylsulfonyl)benzimidoyl Chloride (2d): M.p.
55Ϫ56 °C. Ϫ B.p. 125Ϫ127 °C (0.03 Torr). Ϫ 19F NMR (CDCl3):
δ ϭ Ϫ78.92 (s, 3 F, SO2CF3). Ϫ C8H4Cl2F3NO2S (306.1): calcd. Cl
23.16; found Cl 22.96.
N-(tert-Butyl)-NЈ-trifluoromethylsulfonylurea (5).
؊ Method A:
Water (5 mL) was added dropwise over 20 min to a stirred glyme
solution of carbodiimide 3f at 0 °C. After stirring for 2 h at room
temperature, the reaction mixture was extracted with diethyl ether
(3 ϫ 10 mL). The organic phase was dried with magnesium sulfate
and concentrated to dryness. The crude product was recrystallized
from benzene to afford 5 (0.53 g, 43%). Ϫ Method B: A solution
of trifluoromethylsulfonyl isocyanate[10] (0.87 g, 0.005 mol) in an-
hydrous dichloromethane (10 mL) was added dropwise over 20 min
to a stirred solution of tert-butylamine (0.36 g, 0.005 mol) in an-
hydrous dichloromethane (10 mL) at Ϫ50 °C. After stirring for 1 h
at Ϫ50 °C and for 2 h at room temperature, the precipitate formed
was filtered off. The crude product was recrystallized from benzene
to give the desired product (0.62 g, 50%). Ϫ M.p. 110Ϫ111 °C. Ϫ
1H NMR (CDCl3): δ ϭ 1.35 (s, 9 H, Me3C), 6.46 (s, 1 H, NH). Ϫ
19F NMR (CDCl3): δ ϭ Ϫ76.11 (s, 3 F, SO2CF3). Ϫ 13C NMR
([D6]DMSO): δ ϭ 28.3 (s, CH3), 50.6 (s, CMe3), 119.6 (d, J ϭ
322 Hz, CF3), 150.7 (s, CϭO). Ϫ IR (KBr): ν˜ ϭ 1720 (CϭO), 3415
cmϪ1 (NH). Ϫ C6H11F3N2O3S (248.2): calcd. C 29.03, H 4.47, N
11.29; found C 28.98, H 4.44, N 11.20.
4-Nitro-N-(trifluoromethylsulfonyl)benzimidoyl Chloride (2e): M.p.
124Ϫ126 °C (hexane). Ϫ 19F NMR (CDCl3): δ ϭ Ϫ78.80 (s, 3 F,
SO2CF3). Ϫ C8H4ClF3N2O4S (316.6): calcd. Cl 11.19, N 8.84;
found Cl 10.88, N 8.78.
N-Trifluoromethylsulfonylpivalimidoyl Chloride (2f): B.p. 90Ϫ91 °C
1
(0.5 Torr). Ϫ H NMR (CDCl3): δ ϭ 1.10 (s, 9 H, Me3C). Ϫ 19F
NMR (CDCl3): δ ϭ Ϫ79.45 (s, 3 F, SO2CF3). Ϫ C6H9ClF3NO2S
(251.7): calcd. C 28.63, H 3.60, Cl 14.08; found C 28.60, H 3.61,
Cl 14.14.
4-Fluoro-N-(nonafluorobutylsulfonyl)benzimidoyl Chloride (2g): B.p.
128Ϫ129 °C (0.06 Torr). Ϫ 19F NMR (CDCl3): δ ϭ Ϫ81.19 (m, 3
F, CF3), Ϫ98.28 (s, 1 F, ArF), Ϫ113.53 (m, 2 F, CF2), Ϫ121.22 (s,
2 F, CF2), Ϫ126.40 (m, 2 F, CF2). Ϫ C11H4ClF10NO2S (439.7):
calcd. C 30.05, H 0.92, Cl 8.06; found C 29.79, H 1.17, Cl 8.14.
General Procedure for the Synthesis of N-Aryl(Alkyl)-NЈ-perfluoro-
alkylsulfonylcarbodiimides 3a؊g: Finely powdered sodium azide 2-Isopropyl-1-phenyl-3-(trifluoromethylsulfonyl)isourea (6): A solu-
(0.36 g, 0.0055 mol) was added to a vigorously stirred solution of
imidoyl chloride 2 (0.005 mol) in anhydrous glyme (15 mL) at Ϫ5
°C. The reaction mixture was stirred at Ϫ5 to ϩ10 °C until nitrogen
tion of 2-propanol (0.60 g, 0.01 mol) in anhydrous glyme (3 mL)
was added dropwise over 20 min to a stirred glyme solution of car-
bodiimide 3a at 0 °C. After stirring for 1 h at room temperature
evolution (110Ϫ115 mL) ceased (ca. 0.5Ϫ1 h). The precipitate of and for 4 h at 70 °C, the solvent was evaporated in vacuo. Column
inorganic salts was filtered off under dry argon and washed with
anhydrous glyme (5 mL). The filtrate was a solution of 3, pure
enough for the next step. After concentration in vacuo (0.05 Torr)
at 15 °C, it afforded pure, undistillable oil 3, which gave high-melt-
chromatography (eluent: benzene) of the residue and recrystalliza-
tion from hexane gave 6 (0.93 g, 60%). Ϫ M.p. 60Ϫ61 °C. Ϫ 1H
NMR (CD3CN): δ ϭ 1.33 (d, J ϭ 6 Hz, 6 H, 2 CH3), 5.28 (sept,
1 H, CH), 7.30Ϫ7.41 (m, 5 H, ArH), 9.04 (s, 1 H, NH). Ϫ 19F
1230
Eur. J. Org. Chem. 2001, 1225Ϫ1233

The Aza Curtius Rearrangement
FULL PAPER
NMR (CD3CN): δ ϭ Ϫ78.91 (s, 3 F, SO2CF3). Ϫ IR (KBr): ν˜ ϭ F, SO2CF3). Ϫ IR (KBr): ν˜ ϭ 1580 (CϭN), 3300 cmϪ1 (NH). Ϫ
1595 (CϭN), 3290 cmϪ1 (NH). Ϫ C11H13F3N2O3S (310.3): calcd.
C 42.58, H 4.22, N 9.03; found C 42.29, H 4.08, N 9.21.
C12H13ClF3N3O3S (371.8): calcd. C 38.77, H 3.52, N 11.30; found
C 38.59, H 3.42, N 11.19.
1,1-Dimethyl-3-phenyl-2-(trifluoromethylsulfonyl)guanidine (7):
A
4-[N-(4-Nitrophenyl)-NЈ-trifluoromethylsulfonylamidino]morpholine
(8e): M.p. 217Ϫ219 °C. Ϫ H NMR (CD3CN): δ ϭ 3.61 (m, 4 H,
2CH2), 3.73 (m, 4 H, 2CH2), 7.32Ϫ8.22 (dd, 4 H, ArH), 8.17 (s, 1
H, NH). Ϫ 19F NMR (CD3CN): δ ϭ Ϫ79.15 (s, 3 F, SO2CF3). Ϫ
IR (KBr): ν˜ ϭ 1590 (CϭN), 3285 cmϪ1 (NH). Ϫ C12H13F3N4O5S
(382.3): calcd. C 37.69, H 3.42, N 14.65; found C 37.61, H 3.50,
1
solution of dimethylamine (0.23 g, 0.005 mol) in anhydrous glyme
(5 mL) was added dropwise over 20 min to a stirred glyme solution
of carbodiimide 3a at 0 °C. After stirring for 8 h at room temper-
ature, the solvent was evaporated in vacuo. Column chromato-
graphy (eluent: benzene/ethyl acetate, 20:1) of the residue afforded
7 (0.78 g, 53%). Ϫ M.p. 133Ϫ135 °C. Ϫ 1H NMR (CDCl3): δ ϭ N 14.64.
2.91 (br.s, 6 H, CH3), 6.99 (m, 2 H, ArH), 7.21 (m, 1 H, ArH),
4-(N-tert-Butyl-NЈ-trifluoromethylsulfonylamidino)morpholine (8f):
7.37 (m, 2 H, ArH), 8.44 (s, 1 H, NH) [ref. [16] 1H NMR (CDCl3):
δ ϭ 2.91 (br.s, 6 H, CH3), 7.00 (m, 2 H, ArH), 7.21 (m, 1 H, ArH),
7.37 (m, 2 H, ArH), 8.41 (s, 1 H, NH)]. Ϫ 19F NMR (CDCl3): δ ϭ
Ϫ79.31 (s, 3 F, SO2CF3). Ϫ C10H12F3N3O2S (295.3): calcd. C 40.67,
H 4.10, N 14.23; found C 40.24, H 3.87, N 13.99.
M.p. 132Ϫ133 °C. Ϫ 1H NMR (CD3CN): δ ϭ 1.38 (s, 9 H, Me3C),
3.50 (m, 4 H, 2CH2), 3.72 (m, 4 H, 2CH2), 5.61 (s, 1 H, NH). Ϫ
19F NMR (CD3CN): δ ϭ Ϫ78.24 (s, 3 F, SO2CF3). Ϫ IR (KBr):
ν˜ ϭ 1590 (CϭN), 3360 cmϪ1 (NH). Ϫ C10H18F3N3O3S (317.3):
calcd. C 37.85, H 5.71, N 13.24; found C 37.92, H 5.80, N 13.06.
General Procedure for the Synthesis of 4-[N-Aryl(Alkyl)-NЈ-per-
fluoroalkylsulfonylamidino]morpholines 8a؊g: A solution of mor-
pholine (0.44 g, 0.005 mol) in anhydrous glyme (5 mL) was added
dropwise over 20 min to a stirred solution of carbodiimide 3, ob-
tained according to the general procedure, at 0 °C. After stirring
for 5 h at room temperature (TLC monitoring; eluent: benzene/
ethyl acetate, 20:1), the solvent was evaporated in vacuo and the
crude product was purified by column chromatography (eluent:
benzene/ethyl acetate, 20:1).
4-[N-(4-Fluorophenyl)-NЈ-nonafluorobutylsulfonylamidino]-
morpholine (8g): M.p. 127Ϫ129 °C. Ϫ 1H NMR (CD3CN): δ ϭ
3.43 (m, 4 H, 2CH2), 3.66 (m, 4 H, 2CH2), 6.99Ϫ7.45 (m, 4 H,
ArH), 8.95 (s, 1 H, NH). Ϫ 19F NMR (CD3CN): δ ϭ Ϫ80.28 (m,
3 F, CF3), Ϫ113.20 (m, 2 F, CF2), Ϫ117.44 (s, 1 F, ArF), Ϫ120.67
˜
(s, 2 F, CF2), Ϫ125.61 (m, 2 F, CF2). Ϫ IR (KBr): ν ϭ 1590 (Cϭ
N), 3290 cmϪ1 (NH). Ϫ C15H13F10N3O3S (505.3): calcd. C 35.65,
H 2.59, N 8.32; found C 35.46, H 2.45, N 8.16.
Morpholinium 1-Phenyl-5-(trifluoromethylsulfonylimino)tetrazolide
(9): Morpholine (0.2 g, 0.0022 mol) was added dropwise to the re-
action mixture obtained as described for 3a, but without filtration
of inorganic salts, from 1a (0.54 g, 0.002 mol), sodium azide (0.26 g
0.004 mol), and glyme (3 mL). After stirring at room temperature
for 48 h, the precipitated inorganic salts were filtered off and
washed with glyme (3 mL). The filtrate was concentrated in vacuo.
Column chromatography (eluent: benzene/ethyl acetate, 20:5)
yielded 8a (0.18 g, 26%) and the desired salt (0.32 g, 42%); m.p.
171Ϫ172 °C. Ϫ 1H NMR (CD3CN): δ ϭ 3.29 (m, 4 H, 2 CH2),
3.93 (m, 4 H, 2 CH2), 7.48Ϫ7.79 (m, 5 H, ArH), 8.10 (br. s, 2 H,
H2Nϩ). Ϫ 19F NMR (CD3CN): δ ϭ Ϫ77.50 (s, 3 F, SO2CF3). Ϫ
C12H15F3N6O3S (380.4): calcd. C 37.89, H 3.97, N 22.09; found C
38.15, H 3.83, N 21.90.
4-(N-Phenyl-NЈ-trifluoromethylsulfonylamidino)morpholine (8a). ؊
Method A: According to general procedure. Ϫ Method B: Triphen-
yl(phenylimino)phosphorane (0.35 g, 0.001 mol) in anhydrous
dichloromethane (5 mL) was added to a stirred solution of trifluor-
omethylsulfonyl isocyanate (0.18 g, 0.001 mol) in anhydrous dichlo-
romethane (5 mL) at 0 °C. After stirring at 0 °C for 4 h, the reac-
tion mixture was treated with morpholine (0.17 g, 0.002 mol) in
anhydrous dichloromethane (3 mL). After stirring at room temper-
ature for 8 h, the solvent was evaporated in vacuo and the crude
product was dissolved in benzene (10 mL) and Ph3PO removed by
filtration through Al2O3. Column chromatography (eluent: ben-
zene/ethyl acetate, 20:1) afforded 8a (0.24 g, 71%). Ϫ M.p. 112Ϫ114
°C. Ϫ 1H NMR (CD3CN): δ ϭ 3.51 (m, 4 H, 2CH2), 3.67 (m, 4
H, 2CH2), 7.18Ϫ7.42 (m, 5 H, ArH), 8.21 (s, 1 H, NH). Ϫ 19F
NMR (CD3CN): δ ϭ Ϫ78.94 (s, 3 F, SO2CF3). Ϫ IR (KBr): ν˜ ϭ
1590 (CϭN), 3360 cmϪ1 (NH). Ϫ C12H14F3N3O3S (337.3): calcd.
C 42.72, H 4.18, N 12.45; found C 42.60, H 4.26, N 12.18.
N-Trifluoromethylsulfonylbenzimidoyl Morpholide (10): Finely pow-
dered sodium azide (0.14 g, 0.0022 mol) was added to a vigorously
stirred solution of imidoyl chloride 2a (0.54 g, 0.002 mol) in anhyd-
rous THF (10 mL) at 0 °C. The reaction mixture was stirred for
2 h at room temperature and for 1 h at 40 °C, but no evolution of
nitrogen occurred. After cooling, the precipitate of inorganic salts
was filtered off under dry argon and washed with anhydrous THF
(3 mL). The filtrate was treated with morpholine (0.4 g, 0.0045
mol) at 0 °C. After stirring at room temperature for 2 h, precipit-
ated morpholine hydrochloride was filtered off, the filtrate was con-
centrated to dryness, and the residue was recrystallized from ben-
zene/hexane (1:1) to give the desired product (0.48 g, 75%). Ϫ M.p.
136Ϫ138 °C. Ϫ 1H NMR (CD3CN): δ ϭ 3.31 (m, 2 H, CH2), 3.62
4-(N-Tolyl-NЈ-trifluoromethylsulfonylamidino)morpholine (8b): M.p.
1
117Ϫ118 °C. Ϫ H NMR (CD3CN): δ ϭ 2.34 (s, 3 H, CH3), 3.51
(m, 4 H, 2CH2), 3.63 (m, 4 H, 2CH2), 7.07Ϫ7.20 (dd, 4 H, ArH),
8.16 (s, 1 H, NH). Ϫ 19F NMR (CD3CN): δ ϭ Ϫ78.93 (s, 3 F,
SO2CF3). Ϫ IR (KBr): ν˜ ϭ 1585 (CϭN), 3375 cmϪ1 (NH). Ϫ
C13H16F3N3O3S (351.4): calcd. C 44.43, H 4.59, N 11.96; found C
44.52, H 4.67, N 11.89.
4-[N-(4-Fluorophenyl)-NЈ-trifluoromethylsulfonylamidino]-
morpholine (8c): M.p. 142Ϫ144 °C. Ϫ 1H NMR (CD3CN): δ ϭ
3.51 (m, 4 H, 2CH2), 3.66 (m, 4 H, 2CH2), 7.09Ϫ7.29 (m, 4 H, (m, 2 H, CH2), 3.81 (m, 2 H, CH2), 3.93 (m, 2 H, CH2), 7.46Ϫ7.56
ArH), 8.14 (s, 1 H, NH). Ϫ 19F NMR (CD3CN): δ ϭ Ϫ79.06 (s, 3
(m, 5 H, ArH). Ϫ 19F NMR (CD3CN): δ ϭ Ϫ78.64 (s, 3 F,
F, SO2CF3), Ϫ116.8 (s, 1 F, ArF). Ϫ IR (KBr): ν˜ ϭ 1585 (CϭN), SO2CF3). Ϫ IR (KBr): ν˜ ϭ 1565 cmϪ1 (CϭN). Ϫ C12H13F3N2O3S
3310 cmϪ1 (NH). Ϫ C12H13F4N3O3S (355.3): calcd. C 40.56, H (322.3): calcd. C 44.72, H 4.06, N 8.69; found C 44.58, H 3.98,
3.68, N 11.83; found C 40.26, H 3.55, N 11.52.
N 8.74.
4-[N-(4-Chlorophenyl)-NЈ-trifluoromethylsulfonylamidino]-
morpholine (8d): M.p. 148Ϫ150 °C. Ϫ 1H NMR (CD3CN): δ ϭ
1,4-Dihydro-3,6-diphenyl-1,4-bis(phenylsulfonyl)-1,2,4,5-tetrazine
(12): Finely powdered sodium azide (0.14 g, 0.0022 mol) was added
3.53 (m, 4 H, 2CH2), 3.68 (m, 4 H, 2 CH2), 7.10Ϫ7.42 (dd, 4 H, to a vigorously stirred solution of imidoyl chloride 11[21] (0.55 g,
ArH), 8.16 (s, 1 H, NH). Ϫ 19F NMR (CD3CN): δ ϭ Ϫ79.04 (s, 3 0.002 mol) in anhydrous glyme (10 mL) at 0 °C. After stirring at
Eur. J. Org. Chem. 2001, 1225Ϫ1233
1231

L. M. Yagupolskii et al.
FULL PAPER
Table 3. Crystal data and structure refinement parameters for compounds 4, 5, 9, and 12
4
5
9
12
Empirical formula
Cell parameters:
C21H12F3N3O3
C6H11F3N2O3S
C12H15F3N6O3S
C26H20N4O4S2
˚
a [A]
11.687(3)
7.504(2)
21.278(4)
90
6.291(1)
9.039(1)
9.764(1)
93.50(1)
94.12(1)
92.60(1)
552.03
2
10.550(2)
19.996(4)
8.128(2)
90
10.422(2)
14.892(3)
16.203(3)
90
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
92.05(2)
90
105.85(3)
90
90
90
3
˚
V [A ]
1865.0
1649.5
516.6
Z
4
4
4
Dcalcd. [gcmϪ3
]
1.47
1.49
1.53
1.36
Crystal system
Space group
monoclinic
P21/n
triclinic
monoclinic
P21/c
orthorhombic
P212121
2.52
¯
P1
µ [cmϪ1
]
10.00
29.56
23.04
Radiation
Cu-Kα
Cu-Kα
Cu-Kα
Mo-Kα
1072
0.25ϫ0.31ϫ0.50
0 Ͻ h Ͻ 12
0 Ͻ k Ͻ 17
0 Ͻ l Ͻ 19
25
F(000)
843
812
784
Crystal size [mm]
Index ranges
0.15ϫ0.25ϫ0.44
0 Ͻ h Ͻ 11
0 Ͻ k Ͻ 8
Ϫ24 Ͻ l Ͻ 24
65
0.22ϫ0.28ϫ0.38
0 Ͻ h Ͻ 7
Ϫ10 Ͻ k Ͻ 10
11 Ͻ l Ͻ 11
65
0.06ϫ0.16ϫ0.41
Ϫ3 Ͻ h Ͻ 11
Ϫ13 Ͻ k Ͻ 22
Ϫ9 Ͻ l Ͻ 8
60
θmax [°]
No of reflections:
collected
independent
in refinement
R(int)
3338
2920
2221
1883
2582
2439
2516
2516
1960 [I Ͼ 3σ(I)]
3069 [I Ͼ 3σ(I)]
1820 [I Ͼ 2σ(I)]
1625 [I Ͼ 2σ(I)]
0.023
319
0.018
144
0.061
281
0
325
No. of refined parameters
Final R indices:
R1(F)
0.042
0.044
0.042
0.049
0.046
0.052
Rw(F)
Rw (F2)
0.115
0.950
0.076, 0.759
0.22/Ϫ0.26
0.102
GOF
1.150
1.114
1.018
Weighting coefficients:
1.19, 0.30, 0.93, 0.02, 0.29
0.16/Ϫ0.21
2.82, 2.71, 2.66,0.93, 0.69
0.28/Ϫ0.28
0.055
Largest peak/hole [ecmϪ3
]
0.19/Ϫ0.23
48Ϫ50 °C for 2 h, the calculated amount of nitrogen (45 mL) had
been evolved. The precipitate of inorganic salts was filtered off and
the filtrate was concentrated to dryness. Recrystallization of the
residue from benzene/hexane (1:1) afforded the desired product
(0.31 g, 61%). Ϫ M.p. 168Ϫ170 °C (dec). Ϫ C26H10N4O4S2 (516.6):
calcd. C 60.44, H 3.91, S 12.41; found C 60.00, H 3.87, S 12.35.
Cambridge CB2 1 EZ, U.K. [Fax: (internat.) ϩ 44-1223/336-033;
E-mail: deposit@ccdc.cam.ac.uk].
[1]
G. Schroeter, Chem. Ber. 1909, 42, 3356Ϫ3362.
[2]
V. A. Chervonyi, U. S. Zyabrev, A. V. Kharchenko, B. S. Drach,
Zh. Org. Khim. (Russ.) 1989, 25, 2597Ϫ2602. Chem. Abstr.
1990, 113, 23863z.
X-ray Crystallography: Crystal data, data collection, and pro-
cessing parameters are given in Table 3. All crystallographic meas-
urements were performed at 20 °C with a CAD-4-EnrafϪNonius
diffractometer, using the ω-2θ scan mode (ratio of the scanning
rates ω/2θ ϭ 1.2). All data were corrected for Lorentz and polariza-
tion effects, but not for absorption. All structures were solved by
direct methods. Non-hydrogen atoms were refined by full-matrix,
least-squares technique in the anisotropic approximation. All hy-
drogen atoms in 4, 5, and 9 were located in difference Fourier maps,
in 12 they were placed in calculated positions. In 4 and 9, all
hydrogen atoms were refined isotropically, in 5 only the atoms
H(1) and H(2) were refined, in 12 all hydrogen atoms were included
in the final refinement riding their supporting carbon atoms.
The weighting scheme wϪ1 ϭ σ2(F2o) ϩ (AP)2 ϩ BP with P ϭ
(F2o ϩ 2F2c)/3 was used for 9 and 12. The Chebushev weighting
scheme[22] was used for 4 and 5. For 4 and 5, all structural calcula-
tions were carried out using the CRYSTALS program package,[23]
for 9 and 12 using SHELXS-86[24] and SHELXS-93.[25] Crystallo-
graphic data for the structures reported (excluding structure
factors) have been deposited with the Cambridge Crystallographic
Data Center as supplementary publication no. CCDC-141592 (4),
-146591 (5), -144594 (9), and -146593 (12), and can be obtained
free of charge on application to the CCDC, 12 Union Road,
[3]
J. Xiao, X. Zhang, D. Wang, C. Yuan, J. Fluorine Chem. 1999,
99, 83Ϫ85.
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