Convenient route to thiocarbonates from alcohols, thiols, and triphosgene

Article abstract of DOI:10.1080/00397910903457258

An efficient and simple one-pot, three-component procedure has been introduced for the preparation of various thiocarbonates from thiols, alcohols, and triphosgene in dichloromethane. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910903457258

Synthetic Communications1, 40: 3467–3471, 2010
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910903457258
CONVENIENT ROUTE TO THIOCARBONATES FROM
ALCOHOLS, THIOLS, AND TRIPHOSGENE
Barahman Movassagh1 and Mohammad Soleiman-Beigi1,2
1Department of Chemistry, K. N. Toosi University of Technology,
Tehran, Iran
2Department of Chemistry, Ilam University, Ilam, Iran
An efficient and simple one-pot, three-component procedure has been introduced for
the preparation of various thiocarbonates from thiols, alcohols, and triphosgene in
dichloromethane.
Keywords: Alcohols; thiocarbonates; thiols; triphosgene
INTRODUCTION
Thiocarbonates have been used as protecting group for thiols,[1] synthetic inter-
mediates in the preparation of other valuable substances,[2,3] heat stabilizers for poly-
mers,[4] polymerization inhibitors,[5] bioactive compounds,[6] radiographic contrast
agents,[7] precursors to polymercaptanes,[8] and as biological toxicants, particularly
as mematocides.[9] The usual syntheses of thiocarbonates involve reactions of
primary and benzyl alcohols with carbon dioxide, methanesulfonic anhydride, and
thiols under basic conditions,[10] the treatment of thiols and disulfides with chloro-
formates,[7b] the reaction of b-nitroalcohols and 2,2,2-trihaloethanols with ethyl
chlorothiolformate,[11] nucleophilic addition of potassium monothiocarbonates to
epoxides or alkyl halides,[12] the rearrangement of diaryl thiocarbonates,[13] the reac-
tion of aryloxide salts, carbonyl sulfide, and alkyl halides,[14] the reaction of tri-
methylsilyl enol ethers with phenyl thiofluoroformate in the presence of a naked
fluoride ion catalyst,[15] selenium-catalyzed reaction of alcohols, carbon monoxide,
sulfur, and alkyl halides,[16] and sulfur-assisted O-carbonylation of alcohols with car-
bon monoxide in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).[17]
However, most of the reported procedures suffer from serious drawbacks such as
the use of poisonous phosgene and carbonyl sulfide, difficult-to-obtain reagents,
poor yields, the use of moisture-sensitive chlorothioformate, preparation of certain
thiocarbonate derivatives, and multistep procedures. Very recently, Nishiyama and
coworkers[18] introduced a novel selenium-catalyzed reaction of alcohols with carbon
monoxide and diaryl disulfides for synthesis of S-aryl-O-alkyl thiocarbonates.
Received June 3, 2009.
Address correspondence to Barahman Movassagh, Department of Chemistry, K. N. Toosi
University of Technology, P.O. Box 16315-1618, Tehran, Iran. E-mail: bmovass1178@yahoo.com
3467

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B. MOVASSAGH AND M. SOLEIMAN-BEIGI
RESULTS AND DISCUSSION
Bis(trichloromethyl)carbonate (BTC, triphosgene) is a phosgene substitute
that combines the high reactivity of phosgene with the safety of a stable crystal-
line solid. The use of BTC as a synthetic auxiliary in the preparation of many
important classes of organic compounds has been investigated in the past two
decades.[19]
We report herein a simple method for the synthesis of various thiocarbonates
via a one-pot multicomponent reaction (MCR) of alcohols=phenol and thiols with
triphosgene in dry dichloromethane (Scheme 1).
In a typical general experimental procedure, a solution of thiols 1, alcohols or
phenol 2, and pyridine in dry dichloromethane was cooled to 5 ꢀC. This was fol-
lowed by addition of triphosgene 3 to the solution at that temperature, which gave,
after workup, the desired thiocarbonates 4. We found that the reactants were con-
verted readily to the corresponding thiocarbonate, with no other by-product, with
a molar ratio of thiol=alcohol=triphosgene of 1:1:1. The structures of the products
1
were confirmed from physical and spectroscopic [infrared (IR), H and 13C NMR]
data.
A series of thiols and various alcohols (methyl, primary, secondary,
tertiary, benzylic, and phenol) were reacted with triphosgene. The results sum-
marized in Table 1 show that the reaction is amenable to the synthesis of various
thiocarbonates. The reaction of aromatic thiols with methyl-, ethyl-, and benzyl
alcohol are in general fast (10–30 min) and clean, and thiocarbonates are
obtained as the sole product in good to excellent yields. In the case of secondary
alcohols (entries 10 and 11, Table 1), longer reaction times are required, giving
the products with lower yields. S-Phenyl-O-tert-butyl thiocarbonate was not
obtained on the reaction of tert-butyl alcohol (entry 12, Table 1). In the case
of phenol, the reaction proceeded efficiently, giving the corresponding S-aryl-
O-phenyl thiocarbonate in good yields (entries 13 and 14, Table 1). Under the
same reaction conditions, an experiment was also conducted with thiophenol,
benzyl alcohol, and triphosgene in a molar ratio of 1:1:0.3; after 4 h, the isolated
yield of the product was 27%. We assume that S,S-diaryl (dialkyl) dithiocarbo-
nates are initially formed by nucleophilic attack of 2 equivalents of thiols to
triphosgene at low temperature, followed by nucleophilic attack of an equivalent
of alcohol or phenol to the dithiocarbonates at room temperature to afford
the final product, thiocarbonates.
In summary, this method provides an efficient one-pot, three-component
approach for the synthesis of various thiocarbonates. This reaction is versatile and
also offers several advantages, such as good yields, shorter reaction times, and simple
experimental and workup procedures.
Scheme 1.

CONVENIENT ROUTE TO THIOCARBONATES
3469
Table 1. One-pot synthesis of thiocarbonates
Entry
R1
R2
Product
Time (min)
Yield (%)a,b
1
2
Ph
4-ClC6H4
4-MeC6H4
4-MeOC6H4
4-BrC6H4
Ph
Et
Et
PhSCOOEt
15
15
10
30
15
10
10
45
10
50
120
60
10
10
94[18]
98[18]
90[18]
87[18]
96[18]
80[7b]
86[7b]
60[7b]
80[18]
46[18]
18[7b]
Trace
72[7b]
60[7b]
4-ClC6H4SCOOEt
4-MeC6H4SCOOEt
4-MeOC6H4SCOOEt
4-BrC6H4SCOOEt
PhSCOOCH2Ph
4-ClC6H4SCOOCH2Ph
PhCH2SCOOCH2Ph
PhSCOOMe
3
Et
Et
4
5
Et
6
PhCH2
PhCH2
PhCH2
Me
7
4-ClC6H4
PhCH2
Ph
8
9
10
11
12
13
14
Ph
Ph
Me2CH
Ph2CH
Me3C
Ph
PhSCOOCHMe2
PhSCOOCHPh2
PhSCOOCMe3
Ph
Ph
PhSCOOPh
4-ClC6H4SCOOPh
4-ClC6H4
Ph
aYields refer to those of pure isolated products characterized by IR, 1H NMR, and 13C NMR
spectroscopy.
bReferences for known compounds.
EXPERIMENTAL
Chemicals were purchased from Merck and Aldrich chemical companies.
Yields refer to isolated products. Melting points were determined by a Buchi
¨
1
B-540 apparatus. IR spectra were run on an ABB FTLA 2000 instrument. The H
NMR (300-MHz) and 13C NMR (75-MHz) spectra were recorded on a Bruker
AQS-300 Avance NMR spectrometer. The progress of the reaction was followed
by thin-layer chromatography (TLC) using silica-gel SILG=UV 254 plates. Products
were characterized by comparing their physical and spectral data with the authentic
samples.[7b,18]
General Experimental Procedure
A stirred solution of thiol (1.0 mmol), alcohol=phenol (1.0 mmol), and pyridine
(4.0 mmol) in dry CH2Cl2 (25 mL) was cooled to 5 ꢀC, and triphosgene (1.0 mmol)
was added in one portion. Then, the solution was allowed to stir for the appropriate
time (Table 1) at room temperature (25 ꢀC). The progress of the reaction was
monitored by TLC. After completion of the reaction, the mixture was washed
with water (2 ꢁ 20 mL); the combined organic extracts were dried (Na2SO4) and
concentrated in vacuo. The crude product was purified by preparative TLC
(silica gel, eluent, n-hexane=EtOAc ¼ 15:1).
SUPPLEMENTARY DATA
O-Ethyl-S-(4-methylphenyl)thiocarbonate (T1-3)[18]
Colorless oil; IR (neat): nmax ¼ 1137, 1728 cmꢂ1; 1H NMR (CDCl3): d ¼ 1.35 (t,
J ¼ 7.2 Hz, 3H), 2.41 (s, 3H), 4.33 (t, J ¼ 7.2 Hz, 2H), 7.24 (d, J ¼ 8.3 Hz, 2H), 7.46

3470
B. MOVASSAGH AND M. SOLEIMAN-BEIGI
(d, J ¼ 8.3 Hz, 2H) ppm; 13C NMR (CDCl3): d ¼ 14.3, 21.3, 63.9, 124.4, 130.0, 134.9,
139.8, 169.9 ppm.
O-Ethyl-S-(4-bromophenyl)thiocarbonate (T1-5)[18]
Colorless oil; IR (neat): nmax ¼ 1142, 1728 cmꢂ1; 1H NMR (CDCl3): d ¼ 1.32 (t,
J ¼ 7.0 Hz, 3H), 4.29 (q, J ¼ 7.0 Hz, 2H), 7.38 (d, J ¼ 8.5 Hz, 2H), 7.52 (d, J ¼ 8.5 Hz,
2H) ppm; 13C NMR (CDCl3): d ¼ 14.3, 64.3, 124.2, 127.0, 132.3, 136.2, 168.9 ppm.
O-Benzyl-S-(4-chlorophenyl)thiocarbonate (T1-7)[7b]
Colorless oil; IR (neat): nmax ¼ 1717 cmꢂ1; 1H NMR (CDCl3): d ¼ 5.29 (s, 2H),
7.37–7.42 (m, 7H), 7.49 (d, J ¼ 8.7 Hz, 2H) ppm; 13C NMR (CDCl3): d ¼ 69.7, 126.2,
128.6, 128.70, 128.73, 129.5, 129.7, 134.9, 136.1, 136.4, 169.2 ppm.
O-Methyl-S-phenyl Thiocarbonate (T1-9)[18]
Colorless oil; IR (neat): nmax ¼ 1726 cmꢂ1; 1H NMR (CDCl3): d ¼ 3.89 (s, 3H),
7.46–7.48 (m, 3H), 7.58–7.60 (m, 2H) ppm; 13C NMR (CDCl3): d ¼ 54.9, 128.1,
129.7, 130.1, 135.3, 170.7 ppm.
O-(1,1-Diphenyl)methyl-S-phenyl Thiocarbonate (T1-11)[7b]
Colorless oil; IR (neat): nmax ¼ 1138, 1724 cmꢂ1; 1H NMR (CDCl3): d ¼ 5.47 (s,
1H), 7.31–7.59 (m, 15H) ppm; 13C NMR (CDCl3): d ¼ 80.4, 127.5, 127.7, 127.9,
128.8, 129.7, 130.6, 135.7, 142.6, 188.8 ppm.
ACKNOWLEDGMENT
This work was supported by the K. N. Toosi University of Technology
Research Council and the Iranian National Science Foundation (INSF, Grant
No. 86063=21).
REFERENCES
1. Wuts, P. G. M.; Greene, T. W. Greene’s Protective Groups in Organic Synthesis, 4th ed.;
Wiley: Hoboken, NJ, 2007; pp. 706–771.
2. (a) Harusawa, S.; Kurihara, T. [3,3]-Sigmatropic rearrangement of cyclic thionocarbo-
nates of medium ring size. Rev. Heteroatom. Chem. 1997, 16, 137–169; (b) Harusawa,
S.; Kurihara, T. [3,3]-Sigmatropic ring expansion of cyclic thionocarbonates of medium
ring size. J. Synth. Org. Chem. Jpn. 1995, 53, 712–723.
3. (a) Harusawa, S.; Osaki, H.; Fujii, H.; Yoneda, R.; Kurihara, T. [3,3]-Sigmatropic ring
expansion of cyclic thionocarbonates, 8: Highly stereoselective synthesis of (Z- or
E-)-double bonds by controlling chair-like–boat-like transition states in the [3,3]-
sigmatropic rearrangement of eight-membered thionocarbonates. Tetrahedron 1992, 48,
9433–9450; (b) Harusawa, S.; Takemura, S.; Osaki, H.; Yoneda, R.; Kurihara, T.
[3,3]-Sigmatropic ring expansion of cyclic thionocarbonates, 9: Total synthesis of

CONVENIENT ROUTE TO THIOCARBONATES
3471
(ꢃ)-yellow scale pheromone via 10-membered thiolcarbonate. Tetrahedron 1993, 49,
7657–7666; (c) Furlan, R. L. E.; Mata, E. G. Efficient and simple one-pot conversion
of resin-bound N-Fmoc amino acids and dipeptides into N-Boc derivatives. Arkivok
2003, 32–40; (d) Laak, K. V.; Scharf, H. D. Synthesis of methyl 2,6-dideoxy-4-thio-a-D-
ribohexopyranoxide, a new thio sugar found in calichemicins. Tetrahedron Lett. 1989,
30, 4505–4506; (e) Jones, F. N. Base-catalyzed conversion of thiolcarbonate esters into
sulfides: Reactions of xanthate esters. J. Org. Chem. 1968, 33, 4290–4292.
4. Minagawa, M.; Nakahara, Y.; Kitsukawa, K. Thiolcarbonate ester stabilizers. U.S.
Patent 4199495, 1980.
5. (a) Bafford, R. A.; Mageli, O. L. Peroxy thiolcarbonates. Brit. Patent GB 1171324, 1980;
(b) Bafford, R. A.; Mageli, O. L. Peroxy thiolcarbonates. U.S. Patent 3478080, 1969.
6. Dyer, E.; Bender, H. S. Derivatives of purinethiols: Purine thiolcarbonates and related
compounds. J. Med. Chem. 1964, 7, 10–14.
7. (a) Newton, B. N. Iodinated thiolcarbonates and method for use as radiographic contrast
agents. U.S. Patent 4125554, 1978; (b) Movassagh, B.; Tavoosi, M. Synthesis of S-aryl=
alkyl thiolcarbonates from disulfides and chloroformates in the presence of the Zn=AlCl3
system. Monatsh. Chem. 2008, 139, 251–253.
8. (a) Pinazzi, C. P.; Esnault, J.; Pleurdeau, S. Synthesis of polymers with carbonate–alcohol
functional end groups. Eur. Poly. J. 1980, 16, 283–287; (b) Overberger, C. G.; Ringsdorf,
H.; Weinshenker, N. Preparation and polymerization of S-, O-, and N-vinyl derivatives of
carbonic acid: Unsaturated carbonic acid derivatives II. J. Org. Chem. 1962, 27, 4331–
4337; (c) Overberger, C. G.; Daly, W. H. S-Vinyl-O-t-butyl thiolcarbonate: A new route
to polymercaptans. J. Am. Chem. Soc. 1964, 86, 3402–3403.
9. Grisley, D. W. Methods for preparing S-alkyl-O-aryl thiolcarbonates. U.S. Patent
3151145, 1964.
10. Bratt, M. O.; Taylor, P. C. Synthesis of carbonates and related compounds from carbon
dioxide via methanesulfonyl carbonates. J. Org. Chem. 2003, 68, 5439–5444.
11. Gilligan, W. H.; Stafford, S. L. O-Chlorocarbonylation of b-nitroalcohols and 2,2,2-triha-
loethanols via O-alkyl-S-ethyl thiocarbonates. Synthesis 1979, 600–602.
12. Bean, M.; Kohn, H. Studies on the reaction of mitomycin C with potassium ethyl mono-
thiocarbonate under reductive conditions. J. Org. Chem. 1983, 48, 5033–5041.
13. Al-Kazimi, H. R.; Tarbell, D. S.; Plant, D. A study of the Scho¨nberg rearrangement of
diaryl thioncarbonates to diaryl thiolcarbonates. J. Chem. Soc. 1955, 77, 2479–2482.
14. Chanyshev, N. T.; Kalashnikov, S. M.; Kuramshin, E. M.; Naimushin, A. I.; Imashev,
U. B. Reaction of potassium phenoxide with carbon oxysulfide in the DMSO-1,4-dioxane
system: Synthesis of O-aryl-S-alkylthiocarbonates. Zh. Obshch. Khim. 1990, 60, 2568–
2576; Chem. Abstr. 1991, 115, 28833r.
15. Olofson, R. A.; Cuomo, J. Useful route to alkenyl S-phenyl thiocarbonates: Reagents
for the introduction of the enyloxycarbonyl moiety in synthesis. J. Org. Chem. 1980,
45, 2538–2541.
16. Mizuno, T.; Nishiguchi, I.; Hirashima, T.; Ogawa, A.; Kambe, N.; Sonoda, N. A new
selenium-catalyzed synthesis of S-alkyl carbonothioates from alcohols, carbon monoxide,
sulfur, and alkyl halides. Tetrahedron Lett. 1990, 31, 4773–4776.
17. Mizuno, T.; Nishiguchi, I.; Hirashima, T. Sulfur-assisted O-carbonylation of alcohols
with carbon monoxide in the presence of DBU. Tetrahedron Lett. 1988, 29, 4767–4768.
18. Nishiyama, Y.; Maehira, K.; Nakase, J.; Sonoda, N. A new method for synthesis of
S-aryl-O-alkyl thiolcarbonates: Selenium-catalyzed reaction of alcohols with carbon
monoxide and diaryl disulfides. Tetrahedron Lett. 2005, 46, 7415–7417.
ˇ
´
19. (a) Cotarca, L.; Delogu, P.; Nardelli, A.; Sunjic, V. Bis(trichloromethyl)carbonate in
organic synthesis. Synthesis 1996, 553–576; (b) Eckert, H.; Forster, B. Triphosgene, a crys-
talline phosgene substitute. Angew. Chem., Int. Ed. Engl. 1987, 26, 894–895.

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