Thianthrene Cation Radical Addition to Cycloalkanes
J . Org. Chem., Vol. 64, No. 25, 1999 9209
Su m m a r y
Ma ter ia l Ba la n ce in th e P r ep a r a tion of 2a . A solution
of 2.48 g (22.1 mmol) of cyclooctene in 10 mL of MeCN was
It is striking, in summary, that monoadducts can be
obtained from these three cycloalkenes. In contrast with
cyclooctene, cyclooctadiene reacted with Th ClO
•+
-
4
added to a stirred solution of 1.03 g (3.26 mmol) of Th ClO
in 10 mL of MeCN. After overnight stirring, volatile compo-
nents of the solution were pumped off at room temperature
and collected in a trap cooled in liquid nitrogen. GC assay of
the trapped solution, with biphenyl as internal standard, gave
•
+
-
4
to give
a bisadduct (details of which will be reported later),
containing only a very small amount of monoadduct, and
this was removable by reprecipitation of the product.
Not many additions to alkenes that result in bissulfo-
nium salts, as described here and earlier, are to be found
in the literature. Very recently, Nenajdenko and co-
1
3.9 mmol (63%) of cyclooctene. The residue of solid and
remaining liquid was dissolved in MeCN, and dry ether was
added to precipitate 2a , which was washed with dry ether and
dried to give 830 mg (1.58 mmol) of 2a . The filtrate was
assayed by GC for Th (1.94 mmol, 59.5%) and cyclooctene (3.59
mmol, 16.2%). Thus, this procedure accounted for 19.1 mmol
86.4%) of the cyclooctyl units and 3.52 mmol (108%) of Th
units.
Stoich iom etr y of Reaction of 2a with Sodiu m Th ioph e-
n oxid e. 2a (33.7 mg, 0.064 mmol) and PhSNa (38.7 mg, 0.293
mmol) were placed in a septum-capped flask into which 10
mL of MeCN was injected. The mixture was stirred overnight
and assayed by GC, with biphenyl as internal standard, giving
0.062 mmol (97%) of cyclooctene, 0.068 mmol (106%) of Th,
and 0.099 mmol (155%, based on 2a ) of DPDS. Following GC
analysis, the solution was poured into 50 mL of 2 M NaOH
solution, which was extracted with 3 × 25 mL of ether. Workup
of the ether solution gave a solid residue which was placed on
a column of silica gel from which a mixture of biphenyl, Th,
and DPDS was eluted with petroleum ether. This mixture was
recovered and dissolved in 5 mL of MeCN. GC assay gave 0.058
mmol (91%) of DPDS.
workers11 reported the reaction of Me
+
+
2
2
S -S Me , and the
(
analogous tetrahydrothiophene dication, with a number
of alkenes and dienes. Addition to alkenes containing an
attached aromatic center gave bissulfonium adducts.
Reaction with simpler alkenes, such as hexene and
cyclohexene, gave a complex mixture of unidentified
sulfonium salts, believed to derive from the propensity
of the adducts to form products of elimination.
Exp er im en ta l Section
Solvent acetonitrile was dried by distillation from P
followed by distillation from CaH . Dimethyl sulfoxide (DMSO)
was dried by boiling over CaH for 4 h and distilling under
2 5
O
2
2
reduced pressure. Cyclopentene, cycloheptene, and cyclooctene
were from commercial sources. The GC column used was 10%
OV-101 on 80-100 mesh Chrom-WHP, 4 ft stainless steel. It
was held at 50 °C for 2 min and ramped to 250 °C at 12 deg/
min. NMR spectra were recorded at 300 MHz and in the mixed
P r ep a r a tion of Ad d u cts 8 a n d 9 of Cyclop en ten e. As
described for 2a , a solution of 1.27 g (18.7 mmol) of cyclopen-
•
+
-
4
tene and a solution of 760 mg (2.41 mmol) of Th ClO
were
solvent CD
3
CN/CDCl
3
, approximately 1:1.
used. The stirred mixture retained a light violet color after
being stirred overnight, and on being poured into ether gave
a light-violet precipitate, mp 146-150 °C dec, a small amount
P r ep a r a t ion of Th ia n t h r en e Ca t ion R a d ica l Sa lt s
•+
-
•+
-
12
(
Th X ). Th ClO
4
was prepared as described earlier. Note
•
+
-
•+
-
1
the warning about explosiveness. Th BF
4
, Th SbF
were prepared by oxidation of Th with the appropri-
ate nitrosonium salt (Aldrich Chemical Co., Strem Chemicals),
as follows. Thianthrene (1.03 g, 4.77 mmol) and NOBF (580
6
, and
of which did not dissolve in the NMR solvent. H NMR: δ (J )
•
+
-
6
Th PF
8.661 (5.77, 3.41), dd, 2H; 8.585 (5.82, 3.36), dd, 2H; 8.235
(7.34, 1.93), dd, 2H; 8.201 (-, 3.37), part of dd, 2H; 8.125 (7.54,
1.02), dd, 2H; 8.105 (-, 3.42), part of dd, 2H; 7.913-7.696,
overlapping sets of dd’s and td’s, 10H; 7.535 (7.29, 1.86) dd,
2H; 4.963, m, 2H; 2.439, m, 2H, 1.949, m, 2H; the remaining
4
mg, 4.96 mmol) were placed side by side in a three-necked
flask, which was flushed with argon while 80 mL of MeCN
was added. The mixture became dark blue very quickly and
was stirred under argon for 1 h, after which 250 mL of dry
ether was added with continued stirring. The dark blue-black
precipitate was filtered, washed with dry ether, and dried
under vacuum for 2 h to give 670 mg (2.21 mmol, 46%) of
C
5
ring multiplet overlapped solvent peaks. 13C NMR attribut-
able to 8: δ 138.376, 138.030, 137.120, 129.071, 58.674, 29.526,
26.551. 13C attributable to 9: δ 137.024, 136.744, 136.613,
136.303, 136.218, 132.461, 131.453, 131.392, 131.064, 116.322,
115.456, 53.953, 30.044, 24.814. A sample (88 mg) of this
mixture containing 0.019 mmol of 8 and 0.112 mmol of 9 (from
NMR data) reacted with 55 mg (0.417 mmol) of PhSNa in 10
mL of DMSO. GC analysis gave 0.025 mmol (19%) of cyclo-
pentene, 0.243 mmol (100%) of Th, and 0.025 mmol of DPDS.
Two other products were obtained, which from GC/MS data
appeared to be either 1- or 3-(phenylthio)cyclopentene (12) and
1,2-bis(phenylthio)cyclopentane (13). In the absence of au-
•
+
-
•+
-
•+
-
6
Th BF
4
. Th SbF
6
(44%) and Th PF
(57%) were prepared
similarly.
P r ep a r a tion of 2a .. A solution of 2.38 g (21.3 mmol) of
cyclooctene in 10 mL of MeCN was added to a solution of 846
mg (2.68 mmol) of Th ClO
the solution turned from purple to light yellow in 15 min.
There was a small amount of white precipitate (possibly Th).
After overnight stirring, the now, light pink solution was
poured into 60 mL of dry ether. The white precipitate that
formed was filtered, washed with dry ether, and crystallized
•
+
-
4
in 10 mL of MeCN. The color of
from hot MeCN-ether solution. Drying under vacuum gave
1
2
50 mg (0.474 mmol, 35.4%) of 2a , mp 125-128 °C dec. H
NMR: δ (J ) 8.635 (5.81, 3.37), dd, 2H; 8.565 (5.81, 3.37), dd,
2
4
H; 8.200 (5.82, 3.37), dd, 2H; 8.151 (5.87, 3.38), dd, 2H;
.598, m, 2H; 2.462, m, 2H; 1.735, m, 2H; 1.623, m, 4H; 1.344,
thentic samples of these compounds, their yields were esti-
mated by comparing GC peak areas with that of the Th that
was formed, giving 0.038 mmol (29%) of 12 and 0.087 mmol
(78%) of 13. The collective data correspond to a recovery of
114% of the cyclopentyl units.
1
3
m, 4H. C NMR (CD
1
Anal. Calcd for C20H22Cl O S : C, 45.7; H, 4.22; Cl, 13.5; S,
2 8 2
3
CN): δ 137.634, 137.333, 137.065,
36.102, 126.848, 123.921, 58.217, 29.938, 28.174, 25.289.
1
1
2.2. Found (Desert Analytics): C, 45.2; H, 4.16; Cl, 13.2; S,
1.7.
The adducts C (2b), mp 118-121 °C dec,
P r ep a r a tion of th e Ad d u cts 10 a n d 11 of Cycloh ep -
ten e. Reaction between 1.41 g (14.7 mmol) of cycloheptene and
-
8
H
14Th2+2BF
(2c), mp 120-125 °C dec, and C
2d ), mp 125-128 °C dec were prepared in the same way, with
4
2
+
-
2+
-
•+
-
4
C
(
8
H
14Th 2SbF
6
8
H
14Th 2PF
6
660 mg (2.09 mmol) of Th ClO
occurred quickly. The pale
yellow solution from overnight stirring gave 550 mg of a 1:1
1
1
the use of the appropriate cation radical salt. Each had
H
mixture (from H NMR data) of 10 and 11, mp 141-143 °C
1
3
dec. 1H NMR: δ (J ) 8.643 (5.81, 3.38), dd, 2H; 8.597 (5.86,
and C NMR spectral data similar to those listed for 2a .
3
2
7
.38), dd, 2H; 8.204 (5.86, 3.34), dd, 2H; 8.143 (5.84, 3.35), dd
H; 8.220-8.127, overlapping sets of dd’s and td’s, 6H; 7.747-
.699, overlapping dd and dd, 2H; 7.632 (7.82, 1.27), dd, 2H;
(
11) Nenajdenko, V. G.; Shevchenko, N. E.; Balenkova, E. S.
Tetrahedron 1998, 54, 5353.
12) Shine, H. J .; Yeuh, W. J . Org. Chem. 1994, 59, 3553.
(
4.740, m, 2H; 2.621, m, 1H; 1.261, m, 3H; the remaining C
7