Indium trifluoromethanesulfonate as a mild and chemoselective catalyst for the conversion of carbonyl compounds into 1,3-oxathiolanes

Article abstract of DOI:10.1055/s-2002-33541

An efficient method for the preparation of 1,3-oxathiolanes from aldehydes and ketones with 2-mercaptoethanol in the presence of a catalytic amount of indium trifluoromethanesulfonate is reported.

Full text of DOI:10.1055/s-2002-33541

LETTER
1535
Indium Trifluoromethanesulfonate as a Mild and Chemoselective Catalyst for
the Conversion of Carbonyl Compounds into 1,3-Oxathiolanes
I
ndium Trifluorom
i
ethanes
y
ulfonate oshi Kazahaya, Nao Hamada, Shinya Ito, Tsuneo Sato*
Department of Chemistry and Bioscience, Kurashiki University of Science and the Arts, Kurashiki 712-8505, Japan
Fax +81(86)4401062; E-mail: sato@chem.kusa.ac.jp
Received 24 May 2002
Table In(OTf)3 Catalyzed Formation of 1,3-Oxathiolanes
Abstract: An efficient method for the preparation of 1,3-oxathi-
olanes from aldehydes and ketones with 2-mercaptoethanol in the
presence of a catalytic amount of indium trifluoromethanesulfonate
is reported.
Entry
Substrate
Conditions
[°C/min (h)]
Yield
(%)a
1b
2b
PhCHO
15/1
82
70
75
89
72
71
73
72c
88
96
81
71
84
92e
80
82
Key words: chemoselectivity, indium trifluoromethanesulfonate,
Lewis acids, 1,3-oxathiolanes, protecting groups
p-MeC6H4CHO
p-ClC6H4CHO
p-NO2C6H4CHO
2,4,6-Me3C6H2CHO
n-C7H15CHO
15/1
3b
15/5
1,3-Oxathiolanes have long been used as carbonyl pro-
tective groups1 and intermediates2 in organic synthesis.
Although a variety of methods for their formation are
reported employing HCl,3 HClO4,4 p-MeC6H4SO3H,5
LiBF4,6 BF3 OEt2,7 BF3 OEt2–CaCl2,8 Bu4NBr3,9 TMSCl–
NaI,2e TMSOTf,10 i-Pr3SiOTf,11 SO2,12 ZnCl2–
4b
15/50
15/1
5b
6b
15/1
7b
cyclo-C6H11CHO
(E)-PhCH=CHCHO
n-C6H13(Me)C=O
cyclo-C6H11(Me)C=O
(PhCH2)2C=O
(CH2)4C=O
15/1
Na2SO4,2e,13
ZrCl4,14
[(dppb)Pt( -OH)]2(BF4)2-
8b
15/1
Mg(ClO4)2 2H2O,15 polystyryl diphenyl phosphonium io-
dide,16 natural kaolinitic clay,17 Amberlyst® 1518 a large
number of these methods employ rather harsh conditions
or are inconvenient to use. Accordingly, there is still a
need for more general pathways of 1,3-oxathiolanes
synthesis. In this paper we wish to disclose an efficient
method for preparing 1,3-oxathiolanes from aldehydes
and ketones by reaction with 2-mercaptoethanol (1.5–2.0
9d
25/(6)
25/(5)
25/(4.5)
25/90
15/30
15/60
25/(3.5)
25/60
10d
11d
12d
13d
14d
15d
16d
(CH2)5C=O
equiv) using
a
catalytic amount of indium
trifluoromethanesulfonate19,20 (5 mol%) under mild reac-
tion conditions (Scheme 1).
menthone
(CH2)6C=O
O
O
R1
R2
HO
HS
R1
R2
O
S
In(OTf)3 (5 mol%)
CH2Cl2, 15-25 °C
O
+
OMe
OMe
17d
25/60
76
O
Scheme 1
O
Table summarizes some results and illustrates the effi-
ciency of the present method.21 Both activated and deacti-
vated aromatic aldehydes including a sterically hindered
one such as mesitaldehyde (entries 1–5), aliphatic alde-
hydes (entries 6 and 7), and cinnamaldehyde (entry 8) re-
acted rapidly with 2-mercaptoethanol (1.5 equiv) in
dichloromethane as the solvent at 15 °C to afford the cor-
responding 1,3-oxathiolanes in good to excellent yields.
The case of p-nitrobenzaldehyde (entry 4) is worth men-
tioning as this gives a high yield by our method, in con-
trast to a low yield (35%) of the product in an earlier
18d
19d
20d
PhMeC=O
25/(21)
25/(21.5)
25/(22)
79
71
71
Ph(i-C3H7)C=O
Ph2C=O
a Isolated yields.
b HO(CH2)2SH (1.5 equiv) was used.
c E/Z = 100/0.
d HO(CH2)2SH (2.0 equiv) was used.
e As 46:54 mixture of diastereomers.
Synlett 2002, No. 9, Print: 02 09 2002.
Art Id.1437-2096,E;2002,0,09,1535,1537,ftx,en;U00902ST.pdf.
© Georg Thieme Verlag Stuttgart · New York
ISSN 0936-5214

1536
K. Kazahaya et al.
LETTER
report.4 Application of this method was then extended
for the protection of different types of aliphatic (entries
9–11), cyclic (entries 12–15), and aromatic ketones (en-
tries 18–20) including a -keto ester (entry 17) in the pres-
ence of 2-mercaptoethanol (2.0 equiv) at ambient
temperatures.22 The 1,3-oxathiolanes were formed in
good yields, although the time required for the completion
of the reaction was found to be longer compared to alde-
hydes. Interestingly, a -keto ester (entry 16) was smooth-
ly monothioacetalized in 82% yield under the above
conditions without formation of a transesterification prod-
uct, which was obtained in substantial amounts when the
reaction was carried out by using natural kaolinitic clay.17
It is important to point out that in contrast to the previous
method which required stoichiometric amount of cata-
lyst,2e,7a,b,8,12,13a,16 in our method a catalytic amount of
In(OTf)3 is enough for the reaction to proceed smoothly.
Moreover, neither using of dehydrating agent2e,8,13a,15 nor
the azeotropic removal of water2a,c,d,3a,5a,d,12 is necessary in
our procedure.
References
(1) (a) Loewenthal, H. J. E. Protective Groups in Organic
Chemistry; McOmie, J. F. W., Ed.; Plenum: London, 1973,
Chap. 9. (b) Greene, T. W.; Wuts, P. G. M. Protective
Groups in Organic Synthesis, 3rd ed.; Wiley: New York,
1999, Chap. 4.
(2) (a) Eliel, E. L.; Pilato, L. A.; Badding, V. G. J. Am. Chem.
Soc. 1962, 84, 2377. (b) Pettit, G. R. Org. React. 1962, 12,
356. (c) Karmas, G. J. Org. Chem. 1968, 33, 2436.
(d) Eliel, E. L.; Doyle, T. W. J. Org. Chem. 1970, 35, 2716.
(e) Yadav, V. K.; Fallis, A. G. Tetrahedron Lett. 1988, 29,
897. (f) Ioannou, M.; Porter, M. J.; Saez, F. Chem. Commun.
2002, 346.
(3) (a) Kipnis, F.; Ornfelt, J. J. Am. Chem. Soc. 1949, 71, 3555.
(b) Musavirov, R. S.; Nedogrei, E. P.; Larionov, V. I.; Zlot-
Skii, S. S.; Kantor, E. A.; Rakhmankulov, D. L. J. Gen.
Chem. 1982, 52, 1229.
(4) Mondal, E.; Sahu, P. R.; Khan, A. T. Synlett 2002, 463.
(5) (a) Djerassi, C.; Gorman, M. J. Am. Chem. Soc. 1953, 75,
3704. (b) Ref. 2a (c) Ref. 2c (d) Ref. 2d (e) Vainiotalo, P.;
Nevalainen, V. Org. Mass Spectrom. 1986, 21, 467.
(6) Yadav, J. S.; Reddy, B. V. S.; Pandey, S. K. Synlett 2001,
238.
Because the conversion of aldehydes is faster than ketones
as shown in Table, the chemoselective protection of alde-
hydes in the presence of ketone function could be
achieved with the present method in good yields and with
excellent chemoselectivities (Scheme 2).
(7) (a) Fieser, L. F. J. Am. Chem. Soc. 1954, 76, 1945.
(b) Wilson, G. E. Jr.; Huang, M. G.; Schloman, W. W. Jr. J.
Org. Chem. 1968, 33, 2133.
(8) Fujita, E.; Nagao, Y.; Kaneko, K. Chem. Pharm. Bull. 1978,
26, 3743.
(9) Mondal, E.; Sahu, P. R.; Bose, G.; Khan, A. T. Tetrahedron
Lett. 2002, 43, 2843.
(10) Ravindranathan, T.; Chavan, S. P.; Dantale, S. W.
Tetrahedron Lett. 1995, 36, 2285.
O
S
CHO
(11) Streinz, L.; Koutek, B.; Šaman, D. Coll. Czech. Chem.
Commun. 1997, 62, 665.
(12) Burczyk, B.; Kortylewicz, Z. Synthesis 1982, 831.
(13) (a) Romo, J.; Rosenkranz, G.; Djerassi, C. J. Am. Chem. Soc.
1951, 73, 4961. (b) Ref.2e
(14) Karimi, B.; Seradj, H. Synlett 2000, 805.
(15) Battaglia, L.; Pinna, F.; Strukul, G. Can. J. Chem. 2001, 79,
621.
(16) Caputo, R.; Ferreri, C.; Palumbo, G. Synthesis 1987, 386.
(17) Ponde, D. E.; Deshpande, V. H.; Bulbule, V. J.; Sudalai, A.;
Gajare, A. S. J. Org. Chem. 1998, 63, 1058.
O
67%
+
In(OTf)3 (5 mol%)
O
96:4
+
O
CH2Cl2, 15 °C
6 min
HO
SH
S
(1.5 equiv)
O
S
3%
(18) Ballini, R.; Bosica, G.; Maggi, R.; Mazzacani, A.; Righi, P.;
Sartori, G. Synthesis 2001, 1826.
(19) Chauhan, K. K.; Frost, C. G. J. Chem. Soc., Perkin Trans. 1
2000, 3015.
O
O
S
CHO
O
67%
In(OTf)3 (5 mol%)
O
94:6
+
+
(20) For the use of In(OTf)3 in other types of reactions, see:
(a) Chauhan, K. K.; Frost, C. G.; Love, I.; Waite, D. Synlett
1999, 1743. (b) Miyai, T.; Onishi, Y.; Baba, A. Tetrahedron
1999, 55, 1017. (c) Ali, T.; Chauhan, K. K.; Frost, C. G.
Tetrahedron Lett. 1999, 40, 5621. (d) Gadhwal, S.; Sandhu,
J. S. J. Chem. Soc., Perkin Trans. 1 2000, 2827.
(e) Prajapati, D.; Laskar, D. D.; Sandhu, J. S. Tetrahedron
Lett. 2000, 41, 8639. (f) Friestad, G. K.; Ding, H. Angew.
Chem. Int. Ed. 2001, 40, 4491. (g) Loh, T.-P.; Hu, Q.-Y.;
Tan, K.-T.; Cheng, H.-S. Org. Lett. 2001, 3, 2669.
(h) Yadav, J. S.; Reddy, B. V. S.; Sadashiv, K.; Harikishan,
K. Tetrahedron Lett. 2002, 43, 2099. (i) Muthusamy, S.;
Babu, S. A.; Gunanathan, C. Tetrahedron Lett. 2002, 43,
3133. (j) Loh, T.-P.; Feng, L.-C.; Yang, J.-Y. Synthesis
2002, 937.
CH2Cl2, 15 °C
2 min
HO
SH
S
(1.5 equiv)
O
S
4%
Scheme 2
In conclusion, we have provided a facile and efficient
method for the synthesis of 1,3-oxathiolanes of aldehydes
and ketones catalyzed by indium trifluoromethane-
sulfonate as a mild Lewis acid catalyst.23
(21) The experimental procedure for the reaction of cyclohexyl
methyl ketone with 2-mercaptoethanol is representative. To
a mixture of cyclohexyl methyl ketone (252 mg, 2.0 mmol)
and In(OTf)3 (56 mg, 0.1 mmol) in CH2Cl2 (5.5 mL) 2-
mercaptoethanol (313 mg, 4.0 mmol) in CH2Cl2 (0.5 mL)
Synlett 2002, No. 9, 1535–1537 ISSN 0936-5214 © Thieme Stuttgart · New York

LETTER
was added at 25 °C. After the reaction mixture was kept
Indium Trifluoromethanesulfonate
1537
(22) By using InBr3 (5 mol%), benzophenone was converted into
2,2-diphenyl-1,3-oxathiolane under similar reaction
conditions in 40% yield. This result clearly shows the strong
catalytic activity of In(OTf)3 in comparison with InBr3.
(23) Trifluoromethanesulfonic acid (TfOH) arising by hydrolysis
of In(OTf)3 is less effective than In(OTf)3 in our reaction
system. For example, benzophenone was treated with
HO(CH2)2SH and TfOH (15 mol%) at 25 °C for 22 h to
afford the product in 50% yield.
stirring at the same temperature for 5 h, it was quenched by
adding sat. NaHCO3. The resulting mixture was extracted
three times with EtOAc. The combined extracts were dried
over Na2SO4, and concentrated. Silica gel column
chromatography (5% EtOAc–hexane) yielded 2-cyclohexyl-
2-methyl-1,3-oxathiolane (359 mg, 96%) as a colorless oil.
1H NMR (500 MHz, CDCl3) 1.01–1.31 (m, 5 H), 1.51 (s, 3
H), 1.64–1.93 (m, 6 H), 2.94 (m, 1 H), 3.03 (m, 1 H), 4.08
(m, 1 H), 4.21 (m, 1 H); 13C NMR (125 MHz, CDCl3) 25.8,
26.3, 26.4, 28.6, 28.7, 33.3, 49.5, 70.2, 98.9.
Synlett 2002, No. 9, 1535–1537 ISSN 0936-5214 © Thieme Stuttgart · New York