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An efficient synthesis of 1,3-dithiol-2-thiones from propargyl halides and sodium tert-butyltrithiocarbonate
Tetrahedron Letters NO. 52, PP 5161 - 5162. @Perwon Ress Ltd. 1978. Rinted in Great Britain.
AN EFFICIENT FROM PROPARGYL
SYNTHESIS
OF 1,3-DITHIOL-2-THIONES
HALIDES AND SODIUM
TERT-BUTYLTRITHIOCARBONATE
N. F. Haley Research
Recently, fulvalenes,
Laboratories,
1,3-dithiol-2-thiones
a class of compounds
new high-yield
synthesis
if not impossible
(L).
procedure
is outlined
yield.
After
3_a (bp 78-BO'C/O.l
fluoroacetic
acid
by comparison
thioester
with an authentic
isobutylene
yield
after
after
is filtered
of propargyl
by extraction
the formation
during
Treatment
the
by pro-
of tri-
gives 2-tert-butylthio-4-methylene-1,3-
lH), 5.43(multiplet, causes
acid is added, whereupon
(100°C) for a few minutes.
lH), 4.52(triplet,
the exocyclic
double
salt 52, NMR(TFA, 9H).
dithol
bond to
6) 7.75
Elimination
6_a is produced
6_a is isolated
2H),
by dilution
of in with
(Et20).
bromo alcohols occurs
into 6_ (7_c-e).
temperature
of tri-
(62) (identified
was evolved
manner.
(2a)
evaporated,
4_a and 5_a can be observed
3H, J = 1.2 Hz), 1.43(singlet,
until acetic
bromide
gives trithioester
and the acetone
Isobutylene
4_a at 100°C for a few minutes
heating
a 1,4-dehydration
substituent
Treatment
in the following
5.65(multiplet,
one-
that were difficult
(lOO'C, 15 min) with one equivalent
in 96% yield.
sequence
(2) and sodium
benzyl).2
2-tert-butyl-4-methyl-1,3-dithiolylium
is not observed
followed
bromide
groups
at 0°C instantaneously
The intermediates
TFA at ambient
NMR(TFA,S)
yielding
When acetylenic
occurs
sample3)
lH, J = 1.2Hz), 2.42(doublet,
quantitative
Scheme)
the sodium
halides
being facile and essentially
(e.g., vinyl,
in acetone
torr) is heated
the reaction
Heating
9H).
internally
(quartet,
water
through
salt G,
1.45 (singlet, migrate
besides
ring of functional
in the scheme.
(2
as its dibromide).
3_a with excess
dithiolanium
(&) from acetylenic
(TFA) in acetic acid, giving 4-methyl-1,3-dithiol-2-thione
(identified stepwise
New York 14650
as precursors for tetrathia1,2 We describe here a properties.
electrical
into the dithiol
by older methods
trithioester
ceeding
with interesting
tert-butyltrithiocarbonate
32 in quantitative
Rochester,
have been used extensively
This new synthesis,
introduction
to introduce
The synthetic with sodium
Kodak Company,
of 1,3-dithiol-2-thiones
tert-butyltrithiocarbonate step, allows direct
reaction
Eastman
Z&d,
Following of$(R
or g are employed
spontaneously
resulting
the reaction
= CH20H).
5161
in the reaction
in the introduction
by NMR indicates
sequence
(see
of a vinyl
that the dehydration
step
5162
NO.
52
Mechanistically, the acid-catalyzed ring closure of 3_ to b is reminiscent of the wellknown formation of a heterocyclic carbonium ion via neighboring-groupparticipation by various functions.4 A close analogy would be the regio specific neighboring-groupparticipation by the dithiocarbamate function during protonation of a-substituted S-ally1 N,N-dimethyldithiocarbamates as reported by Nakai and co-workers.5 However, we found no evidence of six-membered ring formation (i.e. g) as did Nakai for his allyl-dithiocarbamates. We also found the ring closure Ring closure of 32 in deu-
of 2 to 3 is stereospecific about the resulting double bond in 1.
terated TFA gave only 2; NMR(TFA,b) 5.43(triplet, lH, J = 1.8 Hz), 4.5l(doublet, ZH, J = 1.8 Hz), 1.45(singlet, 9H). The stereochemistryshown for2 was determined by an NOE experiment on 4_afrom which the chemical shifts of the exocyclic methylene protons were assigned (see Scheme). We are currently pursuing the unsymmetricaltetrathiafulvalenesderived from fi and z 7
aS Well as the chemistry of the ring closure of Lwith reagents other than acids. References and notes 1.
R. D. Hamilton and E. Campaigne in "Special Topics in Heterocyclic Chemistry" Vol. 30, p. p. 271, ed., A. Weissberger and E. C. Taylor, Wiley-Interscience,New York, New York, 1977.
2.
M. Narita and C. U. Pittman, Jr., Synthesis, 489 (1976).
3.
E. Fanghanel, J. Prakt. Chem., 317(l), 123 (1975).
4.
C. U. Pittman, S. P. McManus, and J. W. Larson, Chem. Rev., 72, 357 (1972). K. Tomita and M. Nagano, Chem. Pharm. Bull. II, 2442 (1969) have isolated compounds like 4a from a 3component mixture arising from the reaction of sodium acetylenic alcohols with carbon disulfide.
5.
T. Nakai, K. Hiratani, and M. Okawara, Chem. Lett., 1041 (1974).
6.
Yields of isolated products.
7.
The author thanks M. W. Fichtner for technical assistance and M. J. Bogdanowict and F. Chen for helpful theoretical discussions. H3
CH3
4-
+
EwCHd=CRj+S8SCH~~CFj
s\
2
S4
+
tH3
R
5
HOAc
2
5
P)
*
S=. \'
loo”c
S'\CHZR
s=o \
&
&
A.$\
l
s' \CH=R 2.
s5
75 -
sd
-
ee 7c 7e
‘CsH5 29
R t-5.436 Scheme
(ReceivedinUSB 23 October1978)
2”
%Z $;,
?d
/&356
+
i?l
'n
1
100°C c
- “/*K’
CHOHCsH5 CHOHCHa c-l.2 CsHsCH CH3CH
92 80
55
AN EFFICIENT FROM PROPARGYL
SYNTHESIS
OF 1,3-DITHIOL-2-THIONES
HALIDES AND SODIUM
TERT-BUTYLTRITHIOCARBONATE
N. F. Haley Research
Recently, fulvalenes,
Laboratories,
1,3-dithiol-2-thiones
a class of compounds
new high-yield
synthesis
if not impossible
(L).
procedure
is outlined
yield.
After
3_a (bp 78-BO'C/O.l
fluoroacetic
acid
by comparison
thioester
with an authentic
isobutylene
yield
after
after
is filtered
of propargyl
by extraction
the formation
during
Treatment
the
by pro-
of tri-
gives 2-tert-butylthio-4-methylene-1,3-
lH), 5.43(multiplet, causes
acid is added, whereupon
(100°C) for a few minutes.
lH), 4.52(triplet,
the exocyclic
double
salt 52, NMR(TFA, 9H).
dithol
bond to
6) 7.75
Elimination
6_a is produced
6_a is isolated
2H),
by dilution
of in with
(Et20).
bromo alcohols occurs
into 6_ (7_c-e).
temperature
of tri-
(62) (identified
was evolved
manner.
(2a)
evaporated,
4_a and 5_a can be observed
3H, J = 1.2 Hz), 1.43(singlet,
until acetic
bromide
gives trithioester
and the acetone
Isobutylene
4_a at 100°C for a few minutes
heating
a 1,4-dehydration
substituent
Treatment
in the following
5.65(multiplet,
one-
that were difficult
(lOO'C, 15 min) with one equivalent
in 96% yield.
sequence
(2) and sodium
benzyl).2
2-tert-butyl-4-methyl-1,3-dithiolylium
is not observed
followed
bromide
groups
at 0°C instantaneously
The intermediates
TFA at ambient
NMR(TFA,S)
yielding
When acetylenic
occurs
sample3)
lH, J = 1.2Hz), 2.42(doublet,
quantitative
Scheme)
the sodium
halides
being facile and essentially
(e.g., vinyl,
in acetone
torr) is heated
the reaction
Heating
9H).
internally
(quartet,
water
through
salt G,
1.45 (singlet, migrate
besides
ring of functional
in the scheme.
(2
as its dibromide).
3_a with excess
dithiolanium
(&) from acetylenic
(TFA) in acetic acid, giving 4-methyl-1,3-dithiol-2-thione
(identified stepwise
New York 14650
as precursors for tetrathia1,2 We describe here a properties.
electrical
into the dithiol
by older methods
trithioester
ceeding
with interesting
tert-butyltrithiocarbonate
32 in quantitative
Rochester,
have been used extensively
This new synthesis,
introduction
to introduce
The synthetic with sodium
Kodak Company,
of 1,3-dithiol-2-thiones
tert-butyltrithiocarbonate step, allows direct
reaction
Eastman
Z&d,
Following of$(R
or g are employed
spontaneously
resulting
the reaction
= CH20H).
5161
in the reaction
in the introduction
by NMR indicates
sequence
(see
of a vinyl
that the dehydration
step
5162
NO.
52
Mechanistically, the acid-catalyzed ring closure of 3_ to b is reminiscent of the wellknown formation of a heterocyclic carbonium ion via neighboring-groupparticipation by various functions.4 A close analogy would be the regio specific neighboring-groupparticipation by the dithiocarbamate function during protonation of a-substituted S-ally1 N,N-dimethyldithiocarbamates as reported by Nakai and co-workers.5 However, we found no evidence of six-membered ring formation (i.e. g) as did Nakai for his allyl-dithiocarbamates. We also found the ring closure Ring closure of 32 in deu-
of 2 to 3 is stereospecific about the resulting double bond in 1.
terated TFA gave only 2; NMR(TFA,b) 5.43(triplet, lH, J = 1.8 Hz), 4.5l(doublet, ZH, J = 1.8 Hz), 1.45(singlet, 9H). The stereochemistryshown for2 was determined by an NOE experiment on 4_afrom which the chemical shifts of the exocyclic methylene protons were assigned (see Scheme). We are currently pursuing the unsymmetricaltetrathiafulvalenesderived from fi and z 7
aS Well as the chemistry of the ring closure of Lwith reagents other than acids. References and notes 1.
R. D. Hamilton and E. Campaigne in "Special Topics in Heterocyclic Chemistry" Vol. 30, p. p. 271, ed., A. Weissberger and E. C. Taylor, Wiley-Interscience,New York, New York, 1977.
2.
M. Narita and C. U. Pittman, Jr., Synthesis, 489 (1976).
3.
E. Fanghanel, J. Prakt. Chem., 317(l), 123 (1975).
4.
C. U. Pittman, S. P. McManus, and J. W. Larson, Chem. Rev., 72, 357 (1972). K. Tomita and M. Nagano, Chem. Pharm. Bull. II, 2442 (1969) have isolated compounds like 4a from a 3component mixture arising from the reaction of sodium acetylenic alcohols with carbon disulfide.
5.
T. Nakai, K. Hiratani, and M. Okawara, Chem. Lett., 1041 (1974).
6.
Yields of isolated products.
7.
The author thanks M. W. Fichtner for technical assistance and M. J. Bogdanowict and F. Chen for helpful theoretical discussions. H3
CH3
4-
+
EwCHd=CRj+S8SCH~~CFj
s\
2
S4
+
tH3
R
5
HOAc
2
5
P)
*
S=. \'
loo”c
S'\CHZR
s=o \
&
&
A.$\
l
s' \CH=R 2.
s5
75 -
sd
-
ee 7c 7e
‘CsH5 29
R t-5.436 Scheme
(ReceivedinUSB 23 October1978)
2”
%Z $;,
?d
/&356
+
i?l
'n
1
100°C c
- “/*K’
CHOHCsH5 CHOHCHa c-l.2 CsHsCH CH3CH
92 80
55