N,N-dialkyl (N′-chlorosulfonyl)chloroformamidines in heterocyclic synthesis. I. The preparation of [1,2,3,5]thiatriazole and [1,3,2,4] oxathiadiazole derivatives

Article abstract of DOI:10.1071/CH04295

N,N-Dialkyl (N′-chlorosulfonyl)chloroformamidines 1 react regiospecifically with hydrazine derivatives to give [1,2,3,5]thiatriazole dioxides. Reaction of 1 with hydroxamic acids and N-methyl hydroxylamine gave derivatives of [ 1,3,2,4]oxathiadiazole diox

Full text of DOI:10.1071/CH04295

Full Paper
CSIRO PUBLISHING
Aust. J. Chem. 2005, 58, 332–338
www.publish.csiro.au/journals/ajc
N,N-Dialkyl (Nꢀ-Chlorosulfonyl)chloroformamidines in Heterocyclic
Synthesis. I. The Preparation of [1,2,3,5]Thiatriazole
and [1,3,2,4]Oxathiadiazole Derivatives
Gary D. Fallon,A Saba Jahangiri,B Andris J. Liepa,B,C and Ruth C. J. WoodgateB
A School of Chemistry, Monash University, Clayton VIC 3800, Australia.
B CSIRO Molecular Science, Clayton South VIC 3169, Australia.
C Corresponding author. Email: andy.liepa@csiro.au
N,N-Dialkyl (Nꢀ-chlorosulfonyl)chloroformamidines 1 react regiospecifically with hydrazine derivatives to give
[1,2,3,5]thiatriazole dioxides. Reaction of 1 with hydroxamic acids and N-methyl hydroxylamine gave derivatives
of [1,3,2,4]oxathiadiazole dioxide 7, a new heterocycle.
Manuscript received: 16 December 2004.
Final version: 23 March 2005.
Introduction
R
Naturally occurring and synthetic heterocyclic compounds
often exhibit important activity in biology as pharmaceuticals
and agrochemicals, and in the areas of optics, electronics,
and material sciences.[1,2] Accordingly, considerable effort
continues to be directed towards the synthesis of novel, low-
molecular-weight heterocyclic compounds.[3]
Me2N
Et2N
1a
1b
R
Cl
SO2Cl2
R
N
1c
1d
NSO2Cl
N
1
N
In this context, it was of interest to note that certain
readily accessible N,N-dialkylated (Nꢀ-chlorosulfonyl)-
chloroformamidines 1 (Scheme 1) have been treated with
benzamidines[4] to form derivatives of novel six-membered
heterocycles 2 and 3 (Scheme 2). Reaction with some simple
hydrazines[5] was shown to generate a five-membered ring 4.
In each instance a small number of examples were described,
and the regiochemistry of the products was adduced from the
premise that the initial reaction occurred at the chlorosulfonyl
group of 1.
Scheme 1.
R2N
N
SO2
N
RN
R2N
PhN
N
SO2
NPh
S
X
2
3
It appeared to us that these studies might have overlooked
much of the potential offered by a versatile intermediate,
which allows many additional opportunities for the synthe-
sis of uncommon heterocycles. In particular, the original
publication[5] describing thesynthesisof the[1,2,3,5]thiatria-
zole ring 4 only included some simple condensation products
from the reaction of 1 with hydrazine, N-methylhydrazine,
and1,2-dimethylhydrazine. Initiallyitwasofinteresttodeter-
mine whether the scope of the original condensation could
be broadened to deliver a wider variety of [1,2,3,5]thia-
triazole dioxides simply by extending the choice of (1,2-
dinucleophilic) hydrazine component.
R ϭ H, C6H5
X ϭ O, Ar-SO2N, Alk-SO2N
Et2N
N
R3
R4
NR4
2 NR3
4
3
H
H
5
1
CH3
H
CH3
CH3
H
S
O
O
CH3
4
Scheme 2.
thereof) from sulfuryl chloride and the corresponding dialkyl
cyanamide. A variety of hydrazine derivatives were then
allowed to react with 1a–c, usually in the presence of a mild
base. This procedure readily provided the thiatriazoles 5a–e
and 5h–l regioselectively in modest yield (Scheme 3 and
Table 1).
Results and Discussion
The dichlorides 1a–c were readily prepared according to
procedures in the literature[6,7] (or minor modification
© CSIRO 2005
10.1071/CH04295
0004-9425/05/050332

Preparation of [1,2,3,5]Thiatriazole and [1,3,2,4]Oxathiadiazole Derivatives
333
R
R
from an initial attack by the CH3NH moiety upon the sulfonyl
chloride group.[5] On the other hand, an opposite regioselec-
tivity in the reaction of 1 with secondary amines has also
been proposed[8] (from an analysis of mass spectrometric
fragmentation).
R
Cl
NRЉ
NRЈ
3NRЈ
4
RЉ-NH-NH-RЈ
ϩ
N 5 2 NRЉ
N
O
1
S
NSO2Cl
S
O
O
O
1
5
6
To ensure an unequivocal assignment of structure, X-ray
crystallographic analyses were carried out on compounds 5b
and 5i derived from an aryl and an acyl hydrazine respectively
(Fig. 1).The results showed that, in each instance, the cycliza-
tion had proceeded so that the unsubstituted nitrogen atom
of the hydrazine reacted at the amidine carbon atom of 1,
while the substituted nitrogen atom reacted with the sul-
fonyl chloride. In general, monosubstituted acyl and aryl
hydrazines react with most electrophiles at the unsubstituted
amino group.[9,10] Thus, it appears that, in the present work at
least, the thiatriazole heterocycles are formed by a sequence
of reactions which are the result of a regioselectivity contrary
to some previous predictions.[4,5]
Scheme 3.
Table 1. [1,2,3,5]Thiatriazole products
R
Rꢀ
Rꢀꢀ
H
Product
Me2N 1a
CO2But
5a
H
H
5b
5c
Cl
Cl
Cl
Compounds derived from monosubstituted hydrazine
derivatives [such as 4-chlorophenylhydrazine, 2,6-dichloro-
phenylhydrazine, and t-butyloxycarbonyl (t-Boc) hydrazine]
exhibit a significant broadening, or in some cases a virtual
absence, of the 13C NMR resonance attributable to the methyl
or methylene groups flanking the nitrogen substituent at the
C4 position. This is accompanied by a broadening of the cor-
H
5d
Cl
Ph
COMe
COMe
5e
5f
Cl
1
responding signals in the H NMR spectrum. These effects
Cl
may be a consequence of relatively slow (on the NMR time
scale) tautomerism as well as contribution from zwitterionic
resonance structures that restrict free rotation of the sub-
stituent at the C4 position (Scheme 4). Variable-temperature
NMR spectroscopic studies on analogue 5d supported this
F
5g
Cl
N
N
Et2N 1b
H
H
5h
5i
1
conclusion. The H NMR spectrum showed a sharpening
Cl
of the (CH3)2N signal at higher temperatures (55◦C), and
resolution into two distinct singlets upon cooling (−13◦C).
In compounds where there is no proton present on N3, as
in analogues 5e–g and 5l–n, strong and distinct resonances
for the methyl or methylene groups adjacent to the nitrogen
substituent at C4 were observed.
1c
S
N
O
H
5j
The thiatriazoles formed from
a monosubstituted
O
hydrazine lead to a product with an NH in the 3-position, and
thus have potential for the introduction of various substituents
at this site. The nucleophilic nature of such thiatriazoles was
confirmed by acylation and alkylation of several analogues.
This resulted in the expected products 5e–g,m,n shown in
Scheme 5 andTable 1. The structural assignments were made
on the basis of literature precedent,[5] where methylation of
closely related compounds was reported to occur exclusively
at N3.
Ph
CO2Et
H
CO2Et
5k
5l
Me
5m
5n
S
O
O
Ph
S
Cl
O
The above ring closure to give a five-membered het-
erocycle is predicated upon a 1,2-dinucleophilic species
( NH NH ), and it was evident that a similar ring clo-
sure might be effected with the alternative 1,2-dinucleophile
NH OH.Additional interest in such an approach was intro-
duced when a search of the chemical literature indicated that
one of the two possible alternative products of ring closure
would embody a previously unknown heterocyclic ring. In the
event, it was found that the scope of the coupling reaction can
indeed be extended by using hydroxylamine derivatives, in
The heterocycles 5a–n may also be plausibly formulated
as the regioisomers 6a–n. Some literature precedent suggests
(on the basis of infrared spectroscopy) a greater susceptibil-
ity of the sulfonyl chloride moiety in 1, relative to the vinyl
chloride, towards nucleophilic attack by secondary amines
(such as morpholine and piperidine),[4] hydrazine, and also
N,Nꢀ-dimethylhydrazine.[5] Similarly, with the asymmetric
methylhydrazine, the major product was presumed to arise

334
G. D. Fallon et al.
C5
C4
C9
N4
C6
C8
C7
N4
C9
C10
C3
S2
C1
N2
C7
C10
N2
N1
C1
C6
C5
C11
N1
C2
C2
N3
O1
N3
O1
C11
C4
S1
C3
C8
S1
O2
O3
O2
5b
5i
Fig. 1. ORTEP drawing of the molecular structures of thiatriazoles 5b and 5i.
CH3
Nϩ
CH3
N
CH3
N
CH3
Nϩ
H3C
H3C
H3C
H3C
3NϪ
Cl
Cl
Cl
Cl
NH
NH
N
N
4
Ϫ N
N
N
O
HN
O
N
HN 5 2 N
1
S
S
S
S
O
O
O
O
O
O
Cl
Cl
Cl
Cl
Scheme 4. Tautomeric and resonance structures of thiatriazole 5d.
R
R
Table 2. [1,3,2,4]Oxathiadiazole products
NH
NRЈ
NRЉ
NRЈ
R
R
N
O
N
O
O
NRЈ
R
Cl
S
S
RЈNHOH ϩ
N
NRЈ
N
O
O
O
NSO2Cl
S
S
O
O
O
O
5
5f,g,m,n
1
7
8
Scheme 5.
R
Rꢀ
Product
particular hydroxamic acids, as dinucleophiles. These gener-
ated derivatives of a new heterocycle, [1,3,2,4]oxathiadiazole
7 (Table 2). Hydroxamic acids have been reported[11] to
react with sulfonyl chlorides to yield O-sulfonylhydroxamic
acids. On this basis, it was expected that the above reac-
tion would have formed derivatives of the uncommon, but
known,[12] [1,2,3,5]oxathiadiazole ring system 8. However,
X-ray crystallographic analysis of 7c (Fig. 2) revealed that
attack by oxygen had in fact occurred at the amidine car-
bon atom, while the nitrogen atom of the hydroxamic acid
reacted with the sulfonyl chloride moiety to produce deriva-
tives of [1,3,2,4]oxathiadiazole 7a–h. On the other hand, the
N-methyl derivative 8a was obtained without difficulty from
the condensation between 1c and N-methylhydroxylamine.
Deprotection of the N-Boc derivatives 7c and 7g to
deliver the parent oxathiadiazoles proved more difficult
than expected. Surprisingly, bubbling anhydrous hydrogen
chloride gas through a solution of 7c in dichloromethane
only returned starting material, while use of concentrated
hydrochloric acid led to N-Boc deprotection with additional
decomposition. When neat formic acid or trifluoroacetic acid
was used with 7c and 7g, conversion into the correspond-
ing 2-N-t-butyl analogues 7f and 7h occurred, probably as a
result of trapping of the t-butyl cation during deprotection.[13]
The use of 4-t-butylthiophenol as a scavenger was found
to eliminate the formation of these products. Finally, the
use of methanesulfonic acid appeared to result in N-Boc
Me2N 1a
7a
Cl
O
7b
7c
7d
O
Cl
1c
CO2But
N
O
O
But
Me
OPh
H
N
7e
7f
8a
CO2But
But
7g
7h
1d
N
deprotection, as suggested by NMR spectroscopy and elec-
trospray mass spectrometry, but on treatment of this product
with 4-t-butylbenzyl bromide and potassium carbonate in
N,N-dimethylformamide, no alkylated product was obtained.

Preparation of [1,2,3,5]Thiatriazole and [1,3,2,4]Oxathiadiazole Derivatives
335
under nitrogen and used without further purification. δH (CDCl3) 3.79–
3.76 (2H, m, CH2NH), 3.70–3.66 (2H, m, CH2NH), 2.11–2.03 (4H, m,
2 × CH2). δC (CDCl3) 148.2, 52.1, 52.0, 25.0, 24.7.
C4
C5
C6
C3
N3
tert-Butyl 4-Dimethylamino-1,1-dioxo-1,3-dihydro-1λ6-
[1,2,3,5]thiatriazole-2-carboxylate 5a
O1
O2
C2
C11
C1
The dichloro compound 1a (2.04 g, 10 mmol) was added in portions
over 15 min to a stirred mixture of t-butyl carbazate (2.0 g, 15 mmol),
dichloromethane (10 mL), water (8 mL), and sodium carbonate (3.6 g,
34 mmol) which was maintained at 0◦C for 1 h and then at room temper-
ature for 48 h. The mixture was diluted with water (10 mL) and adjusted
to pH 6 by the addition of 2 M hydrochloric acid. After 8 h, the precip-
itate was collected by filtration and washed lightly with water to give
the title compound 5a (1.33 g, 50%). A portion was recrystallized from
ethanol to give colourless cubes, mp 129◦C (dec.) (Found: C 36.4, H 6.2,
N 21.2, S 12.1. C8H16N4O4S requires C 36.4, H 6.1, N 21.1, S 12.1%).
δH (CDCl3) 8.05 (1H, br s, NH), 3.07 (6H, br s, (CH3)2N), 1.54 (9H, s,
But). δC (CDCl3) 156.8, 150.2, 85.8, 39.5, 36.2, 27.9.
C7
N1
S1
C8
C10
C9
N2
O3
O4
O5
Fig. 2. ORTEP drawing of the molecular structure of oxathiadia-
zole 7c.
Conclusions
{2-(4-Chloro-2-methylphenyl)-1,1-dioxo-2,3-dihydro-1H-1λ6-
[1,2,3,5]thiatriazol-4-yl}dimethylamine 5b
The dichloro compounds 1a–d embody readily available
1,3-dielectrophiles which react regioselectively with some
hetero 1,2-dinucleophiles to form five-membered heterocy-
cles. It is apparent that this methodology may be extended
to include reactions with 1,3-dinucleophiles to provide six-
membered heterocycles. While amidines, which contain a
1,3-dinucleophilic moiety ( HN C(R) NH), have already
been shown[4] to cyclize easily, numerous other opportuni-
ties are likely to exist. An extensive array of readily available
substrates possessing 1,3-dinucleophilic properties can be
envisaged. For example, the necessary attributes are easily
recognized within 2-amino-1-aza heterocycles and similarly
within numerous 2-hydroxy- and 2-thio-1-aza heterocycles.
The results from exploration of these domains and some
related cyclizations will be the subject of further papers.
Triethylamine (2.0 g, 19.8 mmol) was added dropwise to a mix-
ture of dichloro compound 1a (1.0 g, 4.9 mmol) and 4-chloro-2-
methylphenylhydrazine hydrochloride (0.95 g, 4.9 mmol) in dichloro-
methane (15 mL) maintained at 0◦C for 1 h and then left at room
temperature. The next day, the solution was poured into aqueous citric
acid (5%, 100 mL), the organic phase was separated, and the aqueous
phase was extracted with another portion of dichloromethane (20 mL).
The combined organic phase was evaporated as completely as possible
and the residue was boiled briefly with propan-2-ol (5 mL). After being
cooled, the product 5b was collected (1.2 g, 85%), and a portion was
recrystallized from ethanol to give colourless cubes, mp 110◦C (dec.)
(Found: C 41.4, H 4.5, N 19.3, S 11.2. C10H13ClN4O2S requires C 41.6,
H 4.5, N 19.4, S 11.1%). δH (CDCl3) 9.44 (1H, br s, NH), 7.13 (1H, br
s, ArH), 7.09–7.04 (2H, m, ArH), 3.04 (6H, br s, N(CH3)2), 2.37 (3H,
s, Ar–CH3). δC (CDCl3) 161.3, 139.7, 136.3, 132.0, 126.4, 121.9, 36.0,
39.0 (2 × CH3N).
Experimental
X-Ray Structure Determination of 5b
Crystal Data
Materials and Methods
Light petroleum refers to the fraction with a bp of 40–60◦C. Unless
otherwise specified, all 1H and 13C NMR spectra were recorded for
CDCl3 solutions on a BrukerAv400 spectrometer at 400 and 100.6 MHz
respectively. Chemical shifts (δ) are measured in ppm. Carbon res-
onances reported in italics are approximations and were determined
from the HSQC spectrum. Microanalyses were performed by Campbell
Microanalytical Laboratory, University of Otago, New Zealand. Melting
points were recorded on a Reichert–Kofler hot-stage micro-melting
point apparatus and are uncorrected. Flash column chromatography
was carried out using Merck Kieselgel 60 (230–400 mesh; particle size
0.04–0.63 mm) silica gel. Radial chromatography was performed with
silica gel (60 PF254) coated glass rotors by using a Harrison Research
chromatotron 7924T. Analytical thin-layer chromatography (TLC) was
conducted on Sigma–Aldrich silica gel on polyester sheets containing
UV indicator. Hydroxamic acids were prepared by standard procedures;
other materials were obtained from commercial sources.
C7H13N3O3S, Mr 288.75, monoclinic, P21/c, a 8.5164(1), b
7.8858(1), c 19.1997 (3) Å, β 91.936(1)◦, T 123 K, V 1288.69(3) Å3,
Z 4, Dx 1.488 g cm−3, µ 4.58 cm−1, F(000) 600, 14621 measured
reflections, Rint 0.043 for 3059 unique reflections, 2330 observed
reflections [F2 > 2σ(F2)]. Intensity data were measured for a crystal
0.25 × 0.25 × 0.23 mm3 on a Nonius Kappa CCD fitted with graphite
monochromatized MoKα radiation, λ 0.71073 Å. The structure was
solved by direct methods and refined by a full-matrix, least-squares
procedures based on F2.[14] After the inclusion of a weighting
scheme of the form w = 1/[σ2(Fo2) + (0.0334P)2 + 0.5868P], where
P = (Fo2 + 2Fc2)/3, the refinement was continued until convergence
when R = 0.038 and R2w = 0.098 (CCDC deposition number 265889).
{2-(4-Chlorophenyl)-1,1-dioxo-2,3-dihydro-1H-1λ6-
[1,2,3,5]thiatriazol-4-yl}dimethylamine 5c
The dichloride 1a (2.1 g, 10 mmol) in dichloromethane (2 mL)
was added dropwise over 5 min to a cooled (0–5◦C) mixture of
4-chlorophenylhydrazine hydrochloride (1.79 g, 10 mmol) and potas-
sium carbonate (4.2 g, 30.4 mmol) in a mixture of ether (12 mL) and
water (12 mL). The reaction mixture was warmed to room temperature,
stirred for 1 h, and then water (10 mL), citric acid (4.2 g), and ether
(95 mL) were added. Stirring was continued for a further 1 h. The pre-
cipitate was filtered off and washed with ether. Recrystallization from
ethanol gave the title compound as colourless needles (0.63 g, 23%), mp
110◦C (dec.) (Found: C 39.2, H 4.2, N 20.3, S 11.6. C9H11ClN4O2S
N-(Chlorosulfonyl)-Nꢀ,Nꢀ-tetramethylenechloroformamidine 1d
Pyrrolidine-1-carbonitrile (25 g, 0.26 mol) was added dropwise over
20 min to sulfuryl chloride (41.8 mL, 0.52 mmol) cooled with a water
bath maintained at room temperature. After 2 h the mixture was cau-
tiously warmed and maintained under gentle reflux for 10 min. Stirring
was continued at room temperature for 1.5 days. The excess sulfuryl
chloride was removed under reduced pressure to yield the title com-
pound as a pale yellow solid (60 g, 100%). The product was stored

336
G. D. Fallon et al.
requires C 39.4, H 4.0, N 20.4, S 11.7%). δH (CDCl3/CD3OD) 7.28–
7.26 (2H, m, ArH), 7.18–7.15 (2H, m, ArH), 3.07 (6H, s, N(CH3)2). δC
(CDCl3) 160.5, 140.4, 131.3, 128.9, 121.3, ∼39 (2 × CH3).
CH3N), 2.32 (3H, s, CH3C=O). δC (CDCl3) 172.2, 159.8, 139.5, 132.9,
129.5, 121.8, 40.6, 40.2, 23.1.
{2-(2,6-Dichlorphenyl)-3-(4-fluorobenzyl)-1,1-dioxo-2,3-dihydro-
1H-1λ6-[1,2,3,5]thiatriazol-4-yl}dimethylamine 5g
{2-(2,6-Dichlorophenyl)-1,1-dioxo-2,3-dihydro-1H-1λ6-
[1,2,3,5]thiatriazol-4-yl}dimethylamine 5d
To a stirred solution of the thiatriazole 5d (0.3 g, 1 mmol) in ethyl acetate
(5 mL) was added p-fluorobenzyl chloride (0.13 mL, 1.1 mmol) fol-
lowed by potassium carbonate (0.14 g, 1 mmol), tetrabutylammonium
bromide (0.032 g, 0.01 mmol), and a catalytic amount of anhydrous
sodium iodide. Stirring was continued at room temperature for 16 h.
The reaction mixture was diluted with ethyl acetate (20 mL), and washed
with dilute citric acid (10 mL) and aqueous sodium metabisulfite (10%,
10 mL) before being dried and concentrated under reduced pressure
to afford an orange solid. Recrystallization from ethanol gave the title
compound 5g ascolourlessplates(0.28 g, 67%), mp176–177◦C(Found:
C 45.9, H 3.5, N 13.4, S 7.7. C16H15Cl2FN4O4S requires C 46.1, H 3.6,
N 13.4, S 7.7%). δH (CDCl3) 7.20 (2H, m, ArH), 7.19 (2H, m, ArH),
7.06 (1H, m, ArH), 6.83 (2H, m, ArH), 4.55 (2H, s, CH2), 3.21 [6H,
br s, (CH34)2N]. δC (CDCl3) 166.7, 162.5 (d, 1JCF 247.1), 135.0, 134.8,
To a stirred solution of 2,6-dichlorophenylhydrazine hydrochloride
(2.1 g, 10 mmol) in ethyl acetate (50 mL) were added caesium car-
bonate (12.5 g, 38.4 mmol) and tetrabutylammonium bromide (0.32 g,
1 mmol) followed by dichloride 1a (2.46 g, 12 mmol). Stirring was con-
tinued at room temperature for 7 days. The reaction mixture was then
diluted with additional ethyl acetate, washed with 5% citric acid solu-
tion, dried (sodium sulfate), and the organic extract was concentrated
under reduced pressure. The crude product was washed with ether and
recrystallized from ethanol to afford the title compound 5d as colourless
needles (1.85 g, 50%), mp 140◦C (dec.) (Found: C 35.1, H 3.1, N 18.2,
S 10.3. C9H10Cl2N4O2S requires C 35.0, H 3.3, N 18.1, S 10.4%). δH
[500 MHz; (CD3)2SO] 10.49 (1H, br s, NH), 7.54–7.52 (2H, m, ArH),
7.38–7.35 (1H, m, ArH), 3.00 (6H, br s, N(CH3)2); at −13◦C, two dis-
tinct NCH3 peaks are seen at δH 3.0 and 3.19. δC (CDCl3) 160.9, 135.1,
134.1, 129.7, 129.6, 37.0 (2 × CH3).
3
2
129.9 (d, JCF 8.3), 129.8 (d, JCF 3.2), 129.4, 129.2, 115.2 (d, JCF
21.6), 60.3, 39.6.
{2-(6-Chloropyridazin-3-yl)-1,1-dioxo-2,3-dihydro-1H-1λ6-
[1,2,3,5]thiatriazol-4-yl}diethylamine 5h
1-(4-Dimethylamino-1,1-dioxo-2-phenyl-1,2-dihydro-1λ6-
[1,2,3,5]thiatriazol-3-yl)ethanone 5e
This was prepared as in 5b from 1b (0.6 g, 2.6 mmol) and 3-chloro-
6-pyridazinylhydrazine (0.29 g, 2 mmol) to afford the title compound
(0.33 g, 61%) as pale orange cubes from 1,2-dichloroethane, mp 152◦C
(dec.) (Found: C 35.6, H 4.1, N 27.9, S 10.3. C9H13N6ClO2S requires
C 35.5, H 4.3, N 27.6, S 10.5%). δH (2% CD3OD/CDCl3) 7.57–7.55
(2H, m, ArH), 7.49–7.47 (2H, m, ArH), 3.47 (4H, q, J 7.2, CH2CH3),
1.24 (6H, t, J 7.2, CH2CH3). δC (CDCl3) 157.1, 154.0, 152.9, 129.8,
121.0, ∼43 (2 × CH2), 12.7.
To a strirred solution of 1-acetyl-2-phenylhydrazine (2.3 g, 15 mmol) in
1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU; 75 mL)
was added dichloride 1a (3.69 g, 18 mmol). The stirred solution was
cooled to 0◦C, N,N-diisopropylethylamine (2.5 equiv.) was added drop-
wise, and the mixture was stirred at room temperature for 24 h before
being stirred into 5% aqueous citric acid and extracted with ethyl
acetate. The solvent was removed under vacuum to give 5e in 41%
crude yield. Purification by chromatography over silica (10% ethyl
acetate/dichloromethane) followed by recrystallization from methanol
gave the title compound as colourless cubes, mp 169–171◦C (Found:
C 46.8, H 5.0, N 19.8, S 11.3. C11H14N4O3S requires C 46.8, H 5.0,
N 19.9, S 11.4%). δH (CDCl3) 7.43–7.39 (2H, m, ArH), 7.32–7.28 (1H,
m, ArH), 7.18–7.15 (2H, m, ArH), 3.28 (3H, s, NCH3), 3.25 (3H, s,
NCH3), 2.35 (3H, s, CH3CO). δC (CDCl3) 172.4, 160.0, 141.0, 129.4,
127.4, 120.6, 40.6, 40.3, 23.2.
(1,1-Dioxo-4-piperidin-1-yl-1,3-dihydro-1λ6-[1,2,3,5]-
thiatriazol-2-yl)thiophen-2-ylmethanone 5i
This was prepared as for compound 5d from 1c (2.52 g, 10 mmol) and
2-thiophenecarboxylic hydrazide (1.42 g, 10 mmol). The product was
partially purified by column chromatography over silica gel (24% crude
yield). Recrystallization from aqueous ethanol afforded the title com-
pound as colourless cubes, mp 179◦C (dec.) (Found: C 42.1, H 4.3, N
18.0, S 20.4. C11H14N4O3S2 requires C 42.0, H 4.5, N 17.8, S 20.4%).
δH (CDCl3) 8.03 (1H, dd, J 1.1, 3.9,ArH), 7.63 (1H, dd, J 1.1, 5.0,ArH),
7.09 (1H, dd, J 3.9, 5, ArH), 3.46 (4H, br s, CH2NCH2), 3.06 (1H, br s,
NH), 1.61 (6H, br s, 3 × CH2). δC (CDCl3) 160.6, 155.7, 134.3, 134.1,
133.9, 128.0, 46.4 (2 × CH2), 24.9 (two overlapping CH2), 23.4.
X-Ray Structure Determination of 5e
Crystal Data
C11H14N4O3S, Mr 282.32, orthorhombic, P212121, a 6.5064(1),
b 11.3714(2), c 17.2182(3) Å, β 90◦, T 123 K, V 1274.92(4) Å3,
Z 4, Dx 1.472 g cm−3, µ 2.65 cm−1, F(000) 592, 14214 measured
reflections, Rint 0.047 for 3022 unique reflections, 2726 observed
reflections (F2 > 2σ(F2)). Intensity data were measured for a crystal
0.51 × 0.24 × 0.08 mm3 on a Nonius Kappa CCD fitted with graphite
monochromatized MoKα radiation, λ 0.71073 Å. The structure was
solved by direct methods and refined by a full-matrix, least-squares
procedures based on F2.[14] After the inclusion of a weighting
scheme of the form w = 1/[σ2(Fo2) + (0.0334P)2 + 0.5868P], where
P = (Fo2 + 2Fc2)/3, the refinement was continued until convergence
when R = 0.036 and R2w = 0.083 (CCDC deposition number 265891).
X-Ray Structure Determination of 5i
Crystal Data
C11H14N4O3S2, Mr 314.38, monoclinic, P21/c, a 9.7622(1),
b 10.0622(1), c 14.2277(2) Å, β 95.131(1)◦, T 123 K, V 1392.98(3) Å3,
Z 4, Dx 1.500 g cm−3, µ 3.95 cm−1, F(000) 656, 14214 measured
reflections, Rint 0.032 for 3311 unique reflections, 2855 observed
reflections [F2 > 2σ(F2)]. Intensity data were measured for a crys-
tal 0.30 × 0.29 × 0.21 mm3 on a Nonius Kappa CCD fitted with
graphite monochromatized MoKα radiation, λ 0.71073 Å. The structure
was solved by direct methods and refined by a full-matrix, least-
squares procedures based on F2.[14] After the inclusion of a weighting
scheme of the form w = 1/[σ2(Fo2) + (0.0334P)2 + 0.5868P], where
P = (Fo2 + 2Fc2)/3, the refinement was continued until convergence
when R = 0.044 and R2w = 0.112 (CCDC deposition number 265890).
1-{2-(4-Chlorophenyl)-4-dimethylamino-1,1-dioxo-1,2-dihydro-
1λ6-[1,2,3,5]thiatriazol-3-yl}ethanone 5f
The thiatriazole 5c (250 mg, 0.9 mmol) was suspended in acetic anhy-
dride (1 mL), cooled to 0◦C, and treated with pyridine (150 mg). After
3 h at room temperature, the solution was stirred into water and the
precipitate (226 mg, 79%) was collected and recrystallized from 1,2-
dichloroethane to give the title compound as colourless needles, mp
184◦C (dec.) (Found: C 41.7, H 4.1, N 17.6, S 9.9. C11H13ClN4O3S
requires C 41.7, H 4.1, N 17.7, S 10.1%). δH (CDCl3) 7.38–7.34 (2H,
m, ArH), 7.11–7.07 (2H, m, ArH), 3.26 (3H, s, CH3N), 3.22 (3H, s,
(1,1-Dioxo-4-piperidin-1-yl-1,3-dihydro-1λ6-[1,2,3,5]thiatriazol-
2-yl)-p-tolylmethanone 5j
A mixture of 4-toluoylhydrazine (0.38 g, 2.5 mmol) and the dichloro
compound 1c (0.7 g, 2.85 mmol) in DMPU (3 mL) was heated at 90◦C
for 2 h. The solution was cooled to room temperature, ether (6 mL)
followed by water (15 mL) was added, and the mixture was stirred for

Preparation of [1,2,3,5]Thiatriazole and [1,3,2,4]Oxathiadiazole Derivatives
337
2 h. The solid which precipitated at the interface was collected (0.36 g,
44%), and a portion was recrystallized from propan-2-ol to give pale
yellow needles of the title compound, mp 161◦C (dec.) (Found: C 52.1,
H 5.8, N 17.2, S 9.7. C14H18N4O3S requires C 52.2, H 5.6, N 17.4, S
10.0%). δH (CDCl3) 8.84 (1H, br s, NH), 7.87–7.85 (2H, m,ArH), 7.30–
7.28 (2H, m, ArH), 3.49 (4H, br s, CH2NCH2), 2.41 (3H, s, CH3Ar),
1.65 (6H, br s, 3 × CH2). δC (CDCl3) 167.8, 155.3, 144.6, 129.3, 129.1,
128.7, 46.3 (2 × CH2), 25.0, 23.4, 21.7.
142.6, 140.8, 131.7, 131.4, 129.6, 129.2, 127.2, 121.1, 52.6, 50.8, 25.8,
24.8, 23.7.
3-Chlorophenyl-(5-dimethylamino-3,3-dioxo-3H-3λ6-
[1,3,2,4]oxathiadiazol-2-yl)methanone 7a
To a stirred solution of 3-chlorobenzhydroxamic acid (0.17 g, 1 mmol) in
ethyl acetate (10 mL) were added caesium carbonate (0.72 g, 2.2 mmol)
and tetrabutylammonium bromide (0.032 g, 0.1 mmol), followed by
dichloride 1a (0.31 g, 1.5 mmol). The mixture was stirred at room tem-
peraturefor7days.Themixturewasdilutedwithadditionalethylacetate,
washed with 5% citric acid solution, dried (sodium sulfate), and con-
centrated under vacuum to give the crude product (0.29 g, 95%). A
portion was recrystallized from propan-2-ol to give the title compound
as colourless cubes, mp 138–139◦C (Found: C 39.6, H 3.2, N 13.65, S
10.4. C10H10ClN3O4S requires C 39.55, H 3.3, N 13.8, S 10.6%). δH
(CDCl3) 7.97–7.96 (1H, m, ArH), 7.93–7.90 (1H, m, ArH), 7.65–7.62
(1H, m, ArH), 7.47 (1H, t, J 8.1, ArH), 3.21 (3H, s, NCH3), 3.19 (3H,
s, NCH3). δC (CDCl3) 166.5, 159.5, 135.2, 134.6, 132.3, 130.2, 129.5,
127.8, 39.6, 35.6.
1-(1,1-Dioxo-2-phenyl-2,3-dihydro-1H-1λ6-[1,2,3,5]thiatriazol-
4-yl)piperidine 5k
Toasolutionofphenylhydrazine(4.3 g, 40 mmol)inether(50 mL)main-
tained at 0◦C was added the dichloride 1c (2.04 g, 10 mmol) in portions
(0.5 g) over 20 min. After 2 h the mixture was stirred at room tempera-
ture for 6 h and then added to chilled hydrochloric acid (1 M, 50 mL),
stirred for 2 h, and the suspended material was collected by filtration to
afford crude 5k (1.1 g, 41%), mp 114◦C (dec.). A portion was recrys-
tallized from ethanol to yield the title compound as pale yellow plates
(Found: C 51.5, H 6.0, N 20.1, S 11.3. C12H16N4O2S requires C 51.4,
H 5.8, N 20.0, S 11.4%). δH (CDCl3) 7.72 (1H, br s, NH), 7.35–7.15
(5H, m, ArH), 3.56 (4H, br s, 2 × CH2N), 1.71 (6H, br s, 3 × CH2). δC
(CDCl3) 159.7, 141.8, 128.9, 126.2, 120.3, ∼46 (2 × CH2), 25.2, 23.6.
2-Chlorophenyl-(5-dimethylamino-3,3-dioxo-3H-3λ6-
[1,3,2,4]oxathiadiazol-2-yl)methanone 7b
This was prepared as for compound 5e from 4a and 2-
chlorobenzhydroxamic acid, followed by purification by radial
chromatography. The material (27% crude yield) eluted with
dichloromethane and was recrystallized from ethanol to give the title
compound as small colourless cubes, mp 128–129◦C (Found: C 39.6,
H 3.3, N 13.8, S 10.5. C10H10ClN3O4S requires C 39.6, H 3.3, N 13.8,
S 10.6%). δH (CDCl3, 500 MHz) 7.80–7.78 (1H, m, ArH), 7.52–7.51
(2H, m, ArH), 7.42–7.37 (1H, m, ArH), 3.164 (3H, s, NCH3), 3.156
(3H, s, NCH3). δC (CDCl3) 164.0, 158.3, 133.8, 133.6, 131.4, 131.2,
129.9, 126.8, 39.4, 35.5.
1,1-Dioxo-4-piperidin-1-yl-1H-1λ6-[1,2,3,5]thiatriazole-
2,3-dicarboxylic Acid Diethyl Ester 5l
This was prepared as for compound 5d from 1c (2.5 g, 12 mmol) and
1,2-dicarbethoxyhydrazine (1.8 g, 10 mmol).The crude product was trit-
urated with chloroform to remove unreacted hydrazine. The residue
was then recrystallized from propan-2-ol to give the title compound
as colourless cubes (0.62 g, 18%), mp 103–104◦C (Found: C 41.4, H
5.8, N 16.1, S 9.1. C12H20N4O6S requires C 41.4, H 5.8, N 16.1, S
9.2%). δH (CDCl3) 4.32 (2H, q, J 7.1, CO2CH2CH3), 4.28 (2H, q, J
7.1, CO2CH2CH3), 3.70–3.48 (2H, m, CH2N), 3.48 (2H, br s, CH2N),
1.67 (6H, br s, 3 × CH2), 1.33 (3H, t, J 7.1, CO2CH2CH3), 1.29 (3H, t,
J 7.1, CO2CH2CH3). δC (CDCl3) 156.1, 151.4, 151.1, 65.3, 64.6, 50.3,
49.5, 25.3, 26.7, 23.3, 14.0, 13.8.
tert-Butyl 3,3-Dioxo-5-piperidin-1-yl-3H-3λ6-
[1,3,2,4]oxathiadiazole-2-carboxylate 7c
This was prepared as for compound 7a from dichloride 1c (2.8 g,
11.3 mmol) and N-tert butoxycarbonylhydroxylamine (1.0 g, 7.5 mmol)
and caesium carbonate (5.4 g, 16.5 mmol). The crude product was
recrystallized from cyclohexane to give the title compound as white
needles, mp 108–109◦C (Found: C 43.3, H 6.1, N 13.9, S 10.3.
C11H19N3O5S requires C 43.3, H 6.3, N 13.8, S 10.5%). δH (CDCl3)
3.56–3.54 (4H, m, CH2NCH2), 1.68 (6H, br s, 3 × CH2), 1.56 (9H, s,
But). δC (CDCl3) 156.9, 149.9, 87.4, 48.4, 44.5, 27.7, 25.3, 24.8, 23.2.
(3-Methyl-1,1-dioxo-4-piperidin-1-yl-1,3-dihydro-1λ6-
[1,2,3,5]thiatriazol-2-yl)thiophen-2-ylmethanone 5m
The thiatriazole 5i (0.3 g, 0.95 mmol) was suspended in acetone
(3 mL) containing sodium carbonate (0.5 g) and methyl iodide (0.25 g,
1.76 mmol), stirred for 24 h, and added to water (20 mL). The precipi-
tate was collected and crystallized from methanol to afford the product
(0.14 g, 45%) as a yellow solid. A portion was recrystallized from
propan-2-ol to give the title compound as pale yellow cubes, mp 137–
142◦C (Found: C 43.9, H 4.8, N 17.0, S 19.8. C12H16N4O3S2 requires
C 43.9, H 4.9, N 17.1, S 19.5%). δH (CDCl3) 8.02–8.01 (1H, m, ArH),
7.68 (1H, dd, J 1.1, 5.1, ArH), 7.16–7.13 (1H, m, ArH), 3.55 (4H, br s,
CH2NCH2), 3.24 (3H, s, NCH3), 1.69 (6H, br s, 3 × CH2). δC (CDCl3)
163.9, 160.1, 135.4, 134.5, 128.4, 49.4, 44.5, 25.6, 24.0.
X-Ray Structure Determination of 7c
Crystal Data
C11H19N3O5S, Mr 305.35, orthorhombic, Pccn, a 17.691(3),
b 15.900(3), c 10.187(2) Å, β 90◦, T 123 K, V 2865 (9) Å3, Z 8, Dx
1.416 g cm−3, µ 2.49 cm−1, F(000) 1296, 41439 measured reflec-
tions, Rint 0.077 for 3402 unique reflections, 2447 observed reflec-
tions [F2 > 2σ(F2)]. Intensity data were measured for a crystal
0.25 × 0.23 × 0.21 mm3 on a Nonius Kappa CCD fitted with graphite
monochromatized MoKα radiation, λ 0.71073 Å. The structure was
solved by direct methods and refined by a full-matrix, least-squares
procedures based on F2.[14] After the inclusion of a weighting
scheme of the form w = 1/[σ2(Fo2) + (0.0334P)2 + 0.5868P], where
P = (Fo2 + 2Fc2)/3, the refinement was continued until convergence
when R = 0.039 and R2w = 0.100 (CCDC deposition number 265888).
1-{3-(4-Chlorobenzenesulfonyl)-1,1-dioxo-2-phenyl-2,3-
dihydro-1H-1λ6-[1,2,3,5]thiatriazol-4-yl}piperidine 5n
Thethiatriazole5k (0.2 g, 0.7 mmol)wassuspendedinbenzene(10 mL),
4-chlorobenzenesulfonyl chloride (0.2 g, 0.9 mmol) and sodium carbon-
ate (0.4 g, 3.8 mmol) were added, and the mixture was stirred for 2 days.
Water was added and the mixture was extracted with dichloromethane.
The extract was evaporated and the residue was purified by radial chro-
matography to afford the title compound as a fawn powder (0.29 g,
91%). Recrystallization from propan-2-ol gave pale yellow needles, mp
149◦C (dec.) (Found: C 47.6, H 4.3, N 27.2, S 13.7. C18H19ClN4O4S2
requires C 47.5, H 4.2, N 12.3, S 14.1%). δH (CDCl3) 7.85–7.83 (2H,
m, ArH), 7.56–7.54 (2H, m, ArH), 7.40–7.36 (2H, m, ArH), 7.28–7.25
(1H, m,ArH), 7.17–7.15 (2H, m,ArH), 4.04–3.90 (2H, m, CH2N), 3.77–
3.60 (2H, m, CH2N), 2.04–1.77 (6H, m, 3 × CH2). δC (CDCl3) 157.1,
(3,3-Dioxo-5-piperidin-1-yl-3H-3λ6-[1,3,2,4]oxathiadiazol-2-yl)-
2-phenoxyphenylmethanone 7d
This was prepared as for compound 5e from 2-phenoxybenzhydroxamic
acid (0.69 g, 3 mmol) and dichloride 1c followed by chromatography to
give a colourless solid (0.41 g, 34%). Recrystallization from methanol
gave the title compound as colourless needles, mp 138–140◦C (Found:
C 56.7, H 4.6, N 10.5, S 7.8. C19H19N3O5S requires C 56.9, H 4.8, N

338
G. D. Fallon et al.
10.5, S 8.0%). δH (CDCl3) 7.84 (1H, dd, J 7.8, 1.4,ArH), 7.49–7.46 (1H,
m, ArH), 7.37–7.33 (2H, m, ArH), 7.18–7.12 (4H, m, ArH), 6.89–6.87
(1H, m, ArH), 3.63–3.59 (4H, m, CH2NCH2), 1.70 (6H, br s, 3 × CH2).
δC (CDCl3) 164.5, 157.72, 157.73, 156.1, 134.7, 131.4, 129.9, 124.3,
122.6, 122.2, 120.3, 118.3, 48.6, 44.8, 26.1, 24.8, 23.3.
1-(5-Methyl-2,2-dioxo-2,5-dihydro-2λ6-[1,2,3,5]oxathiadiazol-
4-yl)piperidine 8a
To a stirred solution of dichloride 1c (3.84 g, 15.9 mmol) in THF
(70 mL) was added a solution of N-methylhydroxylamine hydrochlo-
ride (1.32 g, 15.9 mmol) and potassium carbonate (2.17 g, 15.9 mmol)
in water (15 mL). Additional potassium carbonate (6.52 g, 47.3 mmol)
was slowly added, and the mixture was stirred at room temperature
for 20 min. The mixture was filtered and the filtrate, which consisted
of two phases, was separated. The THF extract was dried and concen-
trated under reduced pressure. Purification of the residue by column
chromatography afforded the title compound as colourless crystals.
Recrystallization from ether yielded 8a as colourless sheets (0.32 g,
9%), mp 79–80◦C (Found: C 38.5, H 6.1, N 16.3, S 14.9. C7H13N3O3S
requires C 38.3, H 6.0, N 19.2, S 14.6%). δH (CDCl3) 3.50 (4H, br s,
2 × NCH2), 3.31 (3H, s, NCH3), 1.69 (6H, br s, 3 × CH2). δC (CDCl3)
166.8, 48.4, 45.8, 25.2, 23.5.
3,3-Dioxo-5-piperidin-1-yl-3H-3λ6-[1,3,2,4]oxathiadiazole-
2-carboxylic Acid Cyclohexylamide 7e
Thiswaspreparedasforcompound 5e (38%yield)from1-cyclohexyl-3-
hydroxy urea and 1c.The crude product was recrystallized from benzene
to give the title compound as colourless needles, mp 155–156◦C (Found:
C 47.3, H 6.4, N 17.1, S 9.5. C13H22N4O4S requires C 47.3, H 6.7, N
17.0, S 9.7%). δH (CDCl3) 3.46 (1H, br d, J 8.1, NH), 3.71–3.63 (1H,
m, CHNH), 3.62–3.57 (4H, m, CH2NCH2), 2.0–1.97 (2H, m, CH2),
1.77–1.70 (9H, m, CH2), 1.43–1.14 (5H, m, CH2). δC (CDCl3) 161.2,
152.0, 50.9, 49.1, 45.06, 32.6, 25.3, 25.2, 24.9, 24.6, 23.4.
X-Ray Structure Determination of 8a
1-(2-tert-Butyl-3,3-dioxo-2,3-dihydro-3λ6-[1,3,2,4]oxathiadiazol-
5-yl)piperidine 7f
Crystal Data
C7H13N3O3S, Mr 219.26, monoclinic, P21/c, a 6.4039(1), b
18.2492(3), c 8.6021(1) Å, β 105.521(1)◦, T 123(2) K, V 969.63(3) Å3,
Z 4, Dx 1.504 g cm−3, µ 3.21 cm−1, F(000) 464, 11315 measured
reflections, Rint 0.036 for 2296 unique reflections, 2032 observed
reflections (F2 > 2σ(F2)). Intensity data were measured for a crys-
tal 0.25 × 0.25 × 0.18 mm3 on a Nonius Kappa CCD fitted with
graphite monochromatized MoKα radiation, λ 0.71073 Å. The structure
was solved by direct methods and refined by a full-matrix, least-
squares procedures based on F2.[14] After the inclusion of a weighting
scheme of the form w = 1/[σ2(Fo2) + (0.0334P)2 + 0.5868P], where
P = (Fo2 + 2Fc2)/3, the refinement was continued until convergence
when R = 0.032 and R2w = 0.079 (CCDC deposition number 265893).
To thiadiazole 7c (0.15 g, 0.5 mmol) was added trifluoroacetic acid
(2 mL), and the solution was stirred at room temperature for 15 h. The
solvent was removed under vacuum to yield the title compound as a
pale yellow oil that slowly crystallized on standing. Recrystallization
from ethanol gave the title compound (0.15 g, 83%) as colourless cubes,
mp 131–133◦C (Found: C 46.2, H 7.6, N 16.2, S 12.1. C13H22N4O4S
requires C 46.0, H 7.3, N 16.1, S 12.3%). δH (CDCl3) 3.553–3.44 (4H,
m, CH2NCH2), 1.67 (6H, br s, 3 × CH2), 1.44 (9H, s, But).
X-Ray Structure Determination of 7f
Crystal Data
C10H19N3O3S, Mr 261.34, monoclinic, P21/c, a 11.5136(2),
b
8.3258(2), c 13.0857(2) Å, β T 123(2) K, V
96.7562(12)◦,
Acknowledgments
1245.68(4) Å3, Z 4, Dx 1.394 g cm−3, µ 2.62 cm−1, F(000) 560, 17004
measured reflections, Rint 0.041 for 2941 unique reflections, 2422
observed reflections [F2 > 2σ(F2)]. Intensity data were measured for
a crystal 0.48 × 0.32 × 0.08 mm3 on a Nonius Kappa CCD fitted with
graphite monochromatized MoKα radiation, λ 0.71073 Å. The structure
was solved by direct methods and refined by a full-matrix, least-
squares procedures based on F2.[14] After the inclusion of a weighting
scheme of the form w = 1/[σ2(Fo2) + (0.0334P)2 + 0.5868P], where
P = (Fo2 + 2Fc2)/3, the refinement was continued until convergence
when R = 0.0.35 and R2w = 0.082 (CCDC deposition number 265892).
We thank E. I. DuPont de Nemours and Co., Agricul-
tural Products Department, for the biological screening of
these compounds. We also thank Ms Katarina Johansson for
technical assistance.
References
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3,3-Dioxo-5-pyrrolidin-1-yl-3H-3λ6-[1,3,2,4]oxathiadiazole-
2-carboxylic Acid tert-Butyl Ester 7g
This was prepared as for compound 7a from 1d (2.78 g, 12 mmol) and
N-tert-butyloxycarbonylhydroxylamine (1.33 g, 1.0 mmol). The crude
product was recrystallized from propan-2-ol to give the title compound
(2.90 g, 83%) as colourless needles, mp 116◦C (dec. with effervescence)
(Found: C 41.3, H 5.6, N 14.6, S 10.8. C10H17N3O5S requires C 41.2,
H 5.9, N 14.4, S 11.0%). δH (CDCl3) 3.57 (4H, t, 6.68, CH2NCH2),
2.08–1.97 (4H, 2 × CH2), 1.58 (9H, s, But). δC (CDCl3) 156.1, 150.0,
87.4, 49.3, 46.1, 27.8, 25.5, 24.8.
2-tert-Butyl-5-pyrrolidin-1-yl-[1,3,2,4]oxathiadiazole
3,3-Dioxide 7h
[10] M. Knollmüller, R. Fauß, Montash. Chem. 1985, 116, 1027.
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[12] F. Eloy, R. Lenaers, Bull. Soc. Chim. Belg. 1965, 74, 129.
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[14] G. M. Sheldrick, SHELXS97 and SHELXL97 1997 (University of
Göttingen: Göttingen).
To thiadiazole 7g (0.1 g, 0.52 mmol) was added trifluoroacetic acid
(0.5 mL), and the solution was stirred at room temperature for 15 h. The
solvent was removed under reduced pressure. Purification by column
chromatography (dichloromethane) yielded the title compound (0.06 g,
50%) as colourless crystals, mp 68–70◦C (Found: C 43.7, H 6.8, N
16.9, S 12.8. C9H17N3O3S requires C 43.7, H 6.9, N 17.0, S 13.0%). δH
(CDCl3) 3.55–3.52 (2H, m, NCH2), 3.48–3.44 (2H, m, NCH2), 2.04–
1.97 (4H, m, 2 × CH2), 1.44 (9H, s, But). δC (CDCl3) 157.3, 62.4, 48.8,
25.5, 24.9.