A facile S-transalkylation of 2,2′-bipyridine alkyl sulfides - A new tool for the synthesis of annulated biheterocycles

Article abstract of DOI:10.1016/j.tetlet.2005.07.062

A simple and efficient synthesis of annulated 2,2′-bipyridinium salts with attached dihydrothiazole or dihydro-1,3-thiazine rings has been developed through tandem S-transalkylation/intramolecular ring closure of 2,2′-bipyridine alkyl sulfides. The structures were confirmed by X-ray crystallographic analysis.

Full text of DOI:10.1016/j.tetlet.2005.07.062

Tetrahedron
Letters
Tetrahedron Letters 46 (2005) 6223–6226
0
A facile S-transalkylation of 2,2 -bipyridine alkyl sulfides—a
new tool for the synthesis of annulated biheterocycles
q
*
Danuta Branowska, Andrzej Rykowski and Waldemar Wysocki
University of Podlasie, Department of Chemistry, ul. 3 Maja 54, 08-110 Siedlce, Poland
Received 20 May 2005; revised 6 July 2005; accepted 14 July 2005
0
Abstract—A simple and efficient synthesis of annulated 2,2 -bipyridinium salts with attached dihydrothiazole or dihydro-1,3-thi-
0
azine rings has been developed through tandem S-transalkylation/intramolecular ring closure of 2,2 -bipyridine alkyl sulfides.
The structures were confirmed by X-ray crystallographic analysis.
ꢀ
2005 Elsevier Ltd. All rights reserved.
0
2
,2 -Bipyridine and its fused analogues have been shown
dines (2a,b) and symmetrical or unsymmetrical cycloal-
0
to exhibit important applications in coordination and
keno[c]fused 2,2 -bipyridines (5a–e) and (7a–d) contain-
1
0
0
supramolecular chemistry. Also the diquaternary 2,2 -
bipyridinium salts such as diquat dibromide (Fig. 1,
R = H) have aroused much interest owing to their valu-
ing alkylsulfanyl functionalities at the a and a
positions, and 1,2-dibromoethane or 1,3-dibromopro-
pane takes a different course, not leading to the forma-
2
able herbicidal activity.
tion of the corresponding diquat derivatives (Fig. 1,
0
R = SCH ), but to annulated 2,2 -bipyridinium salts 4,
3
Although a great variety of substituted diquaternary
6 and 8 in synthetically useful yields (see Scheme 1).
0
2
,2 -bipyridinium salts have been prepared and tested
3
0
as herbicides, the chemistry of their condensed deriva-
tives with attached cycloalkene rings has received little
attention. During the course of our investigations into
symmetrical and unsymmetrical cycloalkeno[c]fused
The required 2,2 -bipyridines 2a,b, 5a–e and 7a–d are
directly available from the Diels–Alder reaction of
0
0
3,3 -dimethylsulfanyl-5,5 -bi-1,2,4-triazine 1, and nor-
bornadiene or cyclic enamines according to our pub-
0
4a–g
4c,g
2
,2 -bipyridine alkyl sulfides,
we became interested
lished methods.
When 2a (R = CH ) was treated
3
in the synthesis of their bridged diquaternary salts by
reaction with 1,2- or 1,3-dihalides. Herein, we wish to re-
port the finding that the reaction between 2,2 -bipyri-
with an excess of 1,2-dibromoethane (3a) under reflux
0
0
0
for 25 h, 2,2 ,3,3 -tetrahydro-5,5 -bithiazolo[3,2-a]pyri-
dinium dibromide 4a (n = 1) was obtained in 69% yield.
The formation of 4a by the reaction of 2b [R =
CH(CH ) ] with 3a was less favourable, and needed
0
3
2
more time (90 h) for completion. The reaction of 2a with
,3-dibromopropane (3b) proceeded in the same manner
1
0
0
0
+
+
giving the corresponding 3,3 4,4 -tetrahydro-2H,2H -
-
N
N
2
Br
0
6,6 -bipyrido-[2,1-b][1,3]thiazinium dibromide (4b) (n = 2).
R
R
Also symmetrical and unsymmetrical cycloalkeno[c]-
fused 2,2 -bipyridines (5a–e) reacted efficiently with 3a
0
Figure 1. Diquat and its annulated analogues.
and 3b giving dimeric dihydrothiazolopyridinium dibro-
mides 6a–e (n = 1) or pyridodihydro-1,3-thiazinium
dibromides 6f–j (n = 2) in excellent yields. Extending
0
Keywords: S-Transalkylation; Annulated diquaternary 2,2 -bipyridi-
nium salts.
q
0
this study by using mixed 2,2 -bipyridines 7a–d consist-
Part 31 in Ô1,2,4-Triazines in Organic SynthesisÕ. For part 30,
ing of two different heterocyclic units, clearly showed the
generality of this reaction, since unsymmetrical diqua-
ternary bipyridinium salts 8a–d were obtained in good
yields (Scheme 1 and Table 1).
see Branowska, D.; Rykowski, A. Tetrahedron, submitted for
publication.
*
0
Corresponding author. Tel.: +48 25 643 11 16; fax: +48 25 644 20
5; e-mail: dankab@ap.siedlce.pl
4
040-4039/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2005.07.062

6224
D. Branowska et al. / Tetrahedron Letters 46 (2005) 6223–6226
R
S
N
N
N
S
N
N
N
1
R
S
R
S
R
S
R
N
N
N
Y"(
)
Y"( )
R
(
)Y'
N
N
N
R
S
2a-b
R
S
5a-e
S
7a-d
( )n
(
)n
( )n
Br
Br
Br
Br
Br
Br
3
a,b
n=1,2
3a,b
3a,b
(
)n
( )n
( )
n
n=1,2
n=1,2
S
S
S
+
+
+
N
N
N
Y"(
)
Y"( )
(
)Y'
+
N
+
+
N
N
-
2Br
-
2
Br
S
S
4a,b
S
8a-d
2Br-
( )
n
(
)n
( )n
6a-j
0
Scheme 1. Synthesis of annulated 2,2 -bipyridinium salts.
0
Table 1. Synthesis of 2,2 -bipyridinium salts with attached dihydro-
thiazole or dihydro-1,3-thiazine rings
0
No.
Y
Y
n
Time (h)
Yield (%)
Mp (ꢁC)
a
4
4
6
6
6
6
6
6
6
6
6
6
8
8
8
8
a
b
a
b
c
d
e
f
—
—
1
2
3
4
3
3
1
2
3
4
3
4
1
2
—
—
1
2
3
4
4
4
1
2
3
4
—
—
—
—
1
2
1
1
1
1
1
2
2
2
2
2
1
1
2
2
25
13
6
69
64
84
94
86
82
96
94
90
89
96
89
95
96
88
96
360
a
313
a
274
a
14
10
14
21
21
12
16
12
12
36
37
32
32
315
a
289
a
252
a
235
a
285
a
g
h
i
304
a
266
a
291
a
j
244
a
a
b
c
d
334
a
0
0
0
339
Figure 2. X-ray of 2,2 3,3 -tetrahydro-[5,5 ]bithiazolo[3,2-a]pyridinium
dibromide 4a.
a
240
a
235
a
Decomposition.
Evidence for the structures of 4a,b and their condensed
1
analogues 6a–j and 8a–d was provided by H NMR and
5
HR-ESI spectroscopy. The structures of 4a,b were fully
6
determined by X-ray crystallographic analysis. The X-
ray investigation suggested that the positive charges in
4
a and 4b are strongly localized at the N1 atoms and
rather slightly delocalized in the N11–C16–S17 areas.
The pyridine rings in both molecules are twisted relative
to each other by 69.7(2)ꢁ and 75.1(2)ꢁ for 4a and 4b,
respectively (Figs. 2 and 3). This conformation is con-
strained by electrostatic repulsion between positive
charges at the adjacent pyridine rings and steric interac-
tion of the hydrogen atoms from the methylene groups.
Distortions of the ring geometries are comparable with
0
0
0
0
Figure 3. X-ray of 3,3 ,4,4 -tetrahydro-2H,2H -[6,6 ]-bipyrido[2,1-b]-
1,3-thiazinium dibromide 4b.
0
7
those in other 2,2 -bipyridinium compounds.
0
Mechanistically, the formation of the 2,2 -bipyridinium
dibromides 4a,b and their annulated analogues by the
reaction of 2a with 1,2-dibromoethane (3a) or 1,3-di-
bromopropane (3b) is thought to proceed via the reac-
tive sulfonium salts 9a,b followed by demethylation of

D. Branowska et al. / Tetrahedron Letters 46 (2005) 6223–6226
6225
to Mrs. Ewa Olender of the University of Podlasie for
technical assistance.
+
N
Br
Br
S
Br ( )
n
2
X
10a,b
References and notes
1
. (a) Steel, P. J. Adv. Heterocycl. Chem. 1997, 67, 1; (b)
Charboniere, L. J.; Ziessel, R.; Guardigli, M.; Rode, A.;
Sabbatini, N.; Cesario, M. J. Am. Chem. Soc. 2001, 123,
2
a
3
a,b
CH Br
3
N
N
+
4a,b
S
Br
S
Br
2
436; (c) Charbonniere, L. J.; Weibel, N.; Ziessel, R.
(
)n
( )n
2
2
Tetrahedron Lett. 2001, 42, 659; (d) Ziessel, R. Coord.
Chem. Rev. 1998, 171, 331, and references cited therein; (e)
Elghayoury, A.; Douce, L.; Skoulios, A.; Ziessel, R. Angew.
Chem., Int. Ed. 1998, 37, 2205.
9
a,b
1
1a,b
Scheme 2. A proposed mechanism for the S-transalkylation reaction.
2
. (a) Summers, L. A. The Bipyridinium Herbicides; Academic
Press, 1980; (b) Summers, L. A. In Adv. Heterocycl. Chem.;
Academic Press, 1984; Vol. 35, pp 282–372.
3
. (a) Balasubramanian, M.; Keay, J. G. In Comp. Heterocycl.
Chem. II; Katritzky, A. R., Rees, C. W., Eds.; Pergamon:
Oxford, 1996; Vol. 5, pp 245–299; (b) Warning, J. F.;
Ciurliokis, R. I.; Jolly, R. A.; Heindel, M.; Ulrich, R. G.
Toxicol. Lett. 2001, 120, 359–368.
Ph
Br
Ph
N
N
S
S
S
1
2a
Ph
2
a
4
. (a) Rykowski, A.; Branowska, D.; Kielak, J. Tetrahedron
Lett. 2000, 41, 3657; (b) Branowska, D.; Rykowski, A.
Synlett 2002, 1892; (c) Branowska, D. Synthesis 2003, 2096;
+
+
N
N
S
(
d) Branowska, D.; Kielak, J. Polish J. Chem. 2003, 77,
1149; (e) Branowska, D. Tetrahedron 2004, 60, 6021–6027;
f) Branowska, D. Molecules 2005, 10, 247; (g) Branowska,
1
2b
Ph
Ph
(
0
Scheme 3. S-Transalkylation of 2,2 -bipyridine methylsulfide with
D. Molecules 2005, 10, 265.
. General procedure for the synthesis of compounds 4a–b,
6
benzyl bromide.
5
0
a–j and 8a–d. A solution of the 2,2 -bipyridine derivative
(
(
1 mmol) in 1,2-dibromoethane or 1,3-dibromopropane
2 ml) was heated at 136–140 ꢁC for a number of hours as
8
0
0
the resulting intermediates. This leads to 6,6 -bis(2-
0
bromoethylsulfanyl)-2,2 -bipyridine (11a) or 6,6 -bis(3-
bromopropylsulfanyl)-2,2 -bipyridine (11b). Cyclization
of the latter compounds involving nucleophilic replace-
ment of the bromine by the ring nitrogen afforded 4a
and 4b, respectively (see Scheme 2).
indicated in Table 1. After cooling, the precipitated solid
was filtered off and washed with diethyl ether. The crude
products 4a–b were recrystallized from methanol to give
light yellow solids. The crude products 6a–j and 8a–d were
recrystallized from dichloromethane/methanol mixtures.
0
ꢀ
1
Compound 4a mp 360 ꢁC; IR (KBr) cm 1107, 1455, 1560,
1
2
2
2
8
5
2
970, 3403. H NMR (D O, 200 MHz) d (ppm) 3.95 (t,
It is reasonable to assume that the formation of the sul-
fonium salts 9a,b occurs in preference to the pyridinium
salts 10a,b as a consequence of the enhanced nucleo-
philicity of sulfur and the higher affinity of a sulfide
group for soft electrophiles in comparison with the ring
· 2H, J = 8.3 Hz), 4.99–5.14 (m, 2 · 2H), 7.95 (dd,
· 1H, J = 1.0, 7.7 Hz), 8.28 (dd, 2 · 1H, J = 1.0,
13
2
.0 Hz), 8.49 (t, 2 · 1H, J = 8.1 Hz); C NMR (D O,
0 MHz) d (ppm) 31.77, 62.48, 127.54, 128.61, 143.47,
147.37, 167.78; HR-ESI calcd for C H N S 274.0587;
found 274.0562.
Compound 4b mp 313 ꢁC; IR (KBr) cm 1107, 1455, 1560,
2
2
(m, 2 · 2H), 7.79 (dd, 2 · 1H, J = 1.4, 7.4 Hz), 8.10 (dd,
2
2
NMR (D O, 50 MHz) d (ppm) 20.91, 27.41, 53.36, 126.00,
1
4
14
2 2
9
nitrogen. To prove this, compound 2a (R = CH3)
ꢀ
1
was refluxed with benzyl bromide for 2 h. Under these
conditions no trace of bipyridinium dibromide 12b was
observed; compound 2a formed the corresponding
1
970, 3406. H NMR (D
2
O, 200 MHz) d (ppm) 2.48 (quin,
· 2H, J = 6.0 Hz), 3.46 (t, 2 · 2H, J = 6.3 Hz), 4.22–4.45
0
0
6
,6 -bis-(benzylsulfanyl)-2,2 -bipyridine 12a, exclusively
1
3
· 1H, J = 1.6, 8.6 Hz), 8.26 (t, 2 · 1H, J = 7.6 Hz);
C
(
Scheme 3).
1
31.10, 141.80, 143.90, 162.10; HR-ESI calcd for
In summary we have prepared several annulated diqua-
ternary, 2,2 -bipyridinium salts containing dihydrothi-
16 18 2 2
C H N S
302.0900; found 302.0902.
0
ꢀ1
Compound 6a mp 274 ꢁC; IR (KBr) cm 1207, 1459, 1557,
1601, 2943, 3445. H NMR (D O, 200 MHz) d (ppm) 2.45
1
azine and dihydro-1,3-thiazole rings by tandem
2
0
reactions between the corresponding 2,2 -bipyridine
(quin, 2 · 2H, J = 7.7 Hz), 3.13 (t, 2 · 2H, J = 7.6 Hz), 3.30
alkyl sulfides and 1,2- or 1,3-dihalides. The ease and effi-
ciency of this approach makes it an attractive process
for the preparation of functionalized biheterocycles
and macrocycles.
(t, 2 · 2H, J = 7.6 Hz), 3.92 (t, 2 · 2H, J = 7.5 Hz), 4.80–
5
.05 (m, 2 · 2H), 7.79 (s, 2 · 1H); HR-ESI calcd for
C H N S 354.1213 found 354.1222.
2
0
22
2 2
ꢀ
1
Compound 6b mp 315 ꢁC; IR (KBr) cm 1211,1447, 1556,
1
1
1
2
2
596, 2937, 3443. H NMR (D O, 200 MHz) d (ppm) 1.72–
.96 (m, 4 · 2H), 2.68 (t, 2 · 2H, J = 7.4 Hz), 2.93 (t,
· 2H, J = 7.5 Hz), 3.77 (t, 2 · 2H, J = 7.6 Hz), 4.72–4.98
Acknowledgements
(
3
m, 2 · 2H), 7.51 (s, 2 · 1H); HR-ESI calcd for C22
H
26
N S
2 2
82.1526 found 382.1552.
ꢀ
1
The authors are very grateful to Dr. Zbigniew
Karczmarzyk for the interpretation of X-ray data and
Compound 6c mp 289 ꢁC; IR (KBr) cm 1221, 1444, 1553,
1595, 2926, 3400. H NMR (D O, 200 MHz) d (ppm)
2
1

6226
D. Branowska et al. / Tetrahedron Letters 46 (2005) 6223–6226
1
2
2
3
2
4
.05–2.15 (m, 2 · 2H), 2.15–2.21 (m, 2 · 2H), 2.65–2.80 (m,
· 2H), 3.22–3.36 (m, 2 · 2H), 3.42 (t, 2 · 2H, J = 4.5 Hz),
.61 (t, 2 · 2H, J = 5.5 Hz), 4.18–4.28 (m, 2 · 2H), 7.07 (s,
2
Compound 8b mp 339 ꢁC; H NMR (D O, 200 MHz) d
(ppm) 1.30–1.45 (m, 2 · 2H), 1.68–1.89 (m, 2 · 2H), 2.85–
3.00 (m, 2 · 2H), 3.72 (t, 2H, J = 7.7 Hz), 3.85 (t, 2H,
J = 7.8 Hz), 4.81–4.98 (m, 2 · 2H), 7.61 (s, 1H), 7.80 (dd,
1H, J = 1.0, 8.2 Hz), 8.15 (dd, 1H, J = 1.1, 8.4 Hz), 8.37 (t,
30 2 2
· 1H); HR-ESI calcd for C24H N S 438.2128; found
38.2168.
ꢀ1
Compound 6d mp 252 ꢁC; IR (KBr) cm 1235, 1453, 1552,
24 2 2
1H, J = 8.5 Hz); HR-ESI calcd 356.1370 for C20H N S
1
1559, 2921, 3400. H NMR (D O, 200 MHz) d (ppm) 1.15–
found 356.1354.
2
1
1
.28 (m, 4 · 2H), 1.78–2.15 (m, 4 · 2H), 3.07 (q, 4 · 2H,
Compound 8c mp 240 ꢁC; H NMR (D
2
O, 200 MHz) d
J = 6.2 Hz), 3.88 (t, 2 · 2H, J = 7.5 Hz), 4.82–5.15 (m,
2
4
(ppm) 2.30–2.50 (m, 3 · 2H), 3.09 (t, 2H, J = 7.6 Hz), 3.25
(t, 2H, J = 7.4 Hz), 3.45 (t, 2 · 2H, J = 7.0 Hz), 4.20–4.41
(m, 2 · 2H), 7.68 (s, 1H), 7.77 (dd, 1H, J = 1.5, 7.5 Hz),
8.10 (dd, 1H, J = 1.5, 8.7 Hz), 8.26 (t, 1H, J = 8.6 Hz); HR-
· 2H), 7.73 (s, 2 · 1H); HR-ESI calcd for C H N S
2
6
34
2 2
38.2152; found 438.2150.
ꢀ
1
Compound 6e mp 235 ꢁC; IR (KBr) cm 1205, 1453, 1550,
1
1
1
4
559, 2920, 3405. H NMR (D
.25 (m, 2 · 2H), 1.30–1.45 (m, 5 · 2H), 2.48–2.58 (m,
2
O, 200 MHz) d (ppm) 1.10–
ESI calcd 342.1213 for C19
H
22
N S
2 2
found 342.1208.
1
Compound 8d mp 235 ꢁC; H NMR (D O, 200 MHz) d
2
· 2H), 3.28–3.43 (m, 2 · 2H), 4.40–4.58 (m, 2 · 2H), 7.22
(ppm) 1.78–2.05 (m, 2 · 2H), 2.35–2.58 (m, 2 · 2H), 2.80 (t,
2H, J = 5.7 Hz), 2.98 (t, 2H, J = 6.2 Hz), 3.46 (t, 2H,
J = 6.2 Hz), 3.44 (t, 2H, J = 6.4 Hz), 4.15–4.42 (m, 2 · 2H),
7.55 (s, 1H), 7.77 (dd, 1H, J = 1.6, 7.5 Hz), 8.10 (dd, 1H,
J = 1.5, 8.6 Hz), 8.27 (t, 1H, J = 7.4 Hz); HR-ESI calcd
(
32 2 2
s, 1H), 7.25 (s, 1H); HR-ESI calcd for C25H N S
4
24.1996; found 424.2010.
ꢀ1
Compound 6f mp 285 ꢁC; IR (KBr) cm 1235, 1450, 1552,
1
1
1
2
3
2
559, 2921, 3400. H NMR (D O, 200 MHz) d (ppm) 1.12–
.22 (m, 2 · 2H), 1.30–1.55 (m, 5 · 2H), 1.95–2.05 (m,
· 2H), 2.45–2.55 (m, 2 · 2H), 2.57–2.70 (m, 2 · 2H), 2.90–
.05 (m, 2 · 2H), 3.80–4.05 (m, 2 · 2H), 7.23 (s, 1H), 7.35
24 2 2
356.137 for C20H N S found 356.1354.
Compound 12a mp 143 ꢁC; IR (KBr) cm 1138, 1417,
1556, 2927, 3057. H NMR (CDCl , 200 MHz) d (ppm)
ꢀ1
1
3
(
s, 1H); HR-ESI calcd for C27
H
36
N
2
S
2
452.2309; found
4.58 (s, 2 · 2H), 7.17–7.34 (m, 2 · 5H), 7.44 (dd, 2 · 1H,
452.2326.
J = 1.4, 7.6 Hz), 7.60 (t, 2 · 1H, J = 7.6 Hz), 8.16 (dd,
ꢀ
1
13
Compound 6g mp 304 ꢁC; IR (KBr) cm 1206, 1429, 1559,
2 · 1H, J = 1.2, 7.8 Hz). C NMR (CDCl , 50 MHz) d
3
1
1
2
2
563, 2932, 3487. H NMR (D
.39 (m, 4 · 2H), 2.99 (t, 2 · 2H, J = 7.6 Hz), 3.15 (t,
2
O, 200 MHz) d (ppm) 2.20–
(ppm) 34.27, 116.80, 122.12, 127.06, 2 · C 128.49, 2 · C
128.76, 136.81, 138.23, 155.26, 157.80. HR-ESI calcd for
+
· 2H, J = 7.6 Hz), 3.35 (t, 2 · 2H, J = 6.2 Hz), 4.08–4.22
C
H
24 21
N
2
S
2
(M+H) 401.1141; found 401.1164. Anal.
Calcd for C H N S : C 71.78; H 5.27; N 6.97. Found:
(
3
m, 2 · 2H), 7.56 (s, 2 · 1H); HR-ESI calcd for C H N S
2
2
26
2
2
24 20 2 2
82.1526; found 382.1552.
C 71.87; H 5.23; N 7.13.
ꢀ1
Compound 6h mp 266 ꢁC; IR (KBr) cm 1248, 1420, 1556,
6. X-ray measurements were performed on an Enraf-Nonius
MACH 3 four-circle diffractometer at the Institute of
Organic Chemistry Polish Academy of Sciences in Warsaw.
1
1602, 2934, 3441. H NMR (D O, 200 MHz) d (ppm) 1.75–
2
1
.90 (m, 2 · 4H), 2.27–2.33 (m, 2 · 2H), 2.70 (t, 2 · 2H,
J = 6.0 Hz), 2.88 (t, 2 · 2H, J = 6.0 Hz), 3.34 (t, 2 · 2H,
J = 6.4 Hz), 4.01–4.18 (m, 2 · 2H), 7.42 (s, 2 · 1H); HR-
ESI calcd for C H N S 410.1815; found 410.1848.
Crystal data of 4a: monoclinic, space group P2
1
/n,
˚
˚
˚
a = 13.2170(5) A, b = 7.1624(3) A, c = 16.5787(9) A, b =
˚
3
96.945(4)ꢁ, V = 1557.9(1) A , Z = 4. Crystal data of 4b:
2
4
30
2 2
ꢀ
1
˚
Compound 6i mp 291 ꢁC; IR (KBr) cm 1206, 1429, 1566,
monoclinic, space group P2 /n, a = 14.1037(10) A, b =
1
1
˚
˚
˚
1
1
2
3
2
4
604, 2989, 3431. H NMR (D
2
O, 200 MHz) d (ppm) 1.50–
7.4756(6) A, c = 16.7277(14) A, b = 96.961(6)ꢁ, V =
3
.70 (m, 4 · 2H), 1.75–1.90 (m, 2 · 2H), 2.20–2.30 (m,
· 2H), 2.85–2.98 (m, 2 · 2H), 3.07 (t, 2 · 2H, J = 5.8 Hz),
.27 (t, 2 · 2H, J = 6.8 Hz), 4.02–4.20 (m, 2 · 2H), 7.44 (s,
1750.7(2) A , Z = 4.3244 for 4a and 3692 reflections for
4b were collected at room temperature. Both structures
were solved by direct methods and refined by full-matrix
least-squares methods, final R of 0.0496 and 0.0506 for
2376 and 2584 reflections with I > 2r(I) for 4a and 4b,
respectively. More crystallographic data for the structures
in this letter have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication
numbers CCDC 278673 and CCDC 278666. Copies of the
data can be obtained, free of charge, on application to
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK [fax:
+44(0)-1223-336033 or e-mail: deposit@ccdc.cam.ac.uk].
7. (a) Dorner, H.; Dehnicke, K.; Massa, W.; Schmidt, R. Z.
Naturforsch., B: Chem. Sci. 1983, 38, 437; (b) Degani, Y.;
Willner, I. J. Am. Chem. Soc. 1983, 105, 6228.
· 1H); HR-ESI calcd for C26
H
34
N
2
S
2
438.2152; found
38.2160.
ꢀ
1
Compound 6j mp 244 ꢁC; IR (KBr) cm 1125, 1453, 1552,
1
1
1
2
2
599, 2920, 3458. H NMR (D O, 200 MHz) d (ppm) 1.21–
.43 (m, 4 · 2H), 1.58–1.85 (m, 4 · 2H), 2.28–2.38 (m,
· 2H), 2.94 (t, 2 · 2H, J = 5.6 Hz), 3.11 (t, 2 · 2H,
J = 5.2 Hz), 3.34 (t, 2 · 2H, J = 6.6 Hz), 4.10–4.25 (m,
2
4
Compound 8a mp 334 ꢁC; IR (KBr) cm
38 2 2
· 2H), 7.55 (s, 2 · 1H); HR-ESI calcd for C28H N S
66.2465; found 466.2490.
ꢀ1 1
H NMR (D O,
2
2
2
2
00 MHz) d (ppm) 1.71–1.80 (m, 2 · 2H), 1.90–2.10 (m,
H), 3.00–3.13 (m, 2 · 2H), 3.38 (t, 2H, J = 7.5 Hz), 3.91 (t,
H, J = 7.5 Hz), 4.95–5.15 (m, 2 · 2H), 7.70 (s, 1H), 7.88
8. Labuschagne, A. J.; Malherbe, J. S.; Meyer, C. J.; Schnei-
der, D. F. J. Chem. Soc., Perkin Trans. 1 1978, 955.
9. Press, J. B.; McNally, J. J.; Hajos, Z. G.; Sawyers, R. A.
J. Org. Chem. 1992, 57, 6335–6339.
(
dd, 1H, J = 1.2, 7.5 Hz), 8.23 (dd, 1H, J = 1.2, 8.6 Hz),
8.45 (t, 1H, J = 8.6 Hz); HR-ESI calcd 342.1212 for
19 22 2 2
C H N S
found 342.1206.