Synthesis of 4-amino-5H-1,2-oxathiole 2,2-dioxides by cyclization of cyanohydrin mesylates. New routes to β-amino and β-keto sulfonic acids

Full text of DOI:10.1021/jo9707242

J . Org. Chem. 1997, 62, 7021-7023
7021
Sch em e 1
Syn th esis of 4-Am in o-5H-1,2-oxa th iole
2,2-Dioxid es by Cycliza tion of Cya n oh yd r in
Mesyla tes. New Rou tes to â-Am in o a n d
â-Keto Su lfon ic Acid s
La´szlo´ Posza´va´cz and Gyula Simig*
Chemical Research Division, EGIS Pharmaceuticals Ltd.,
P.O. Box 100, H-1475 Budapest, Hungary
Received April 22, 1997
Alkanesulfonamides and alkanesulfonates can be con-
veniently deprotonated at the R-position and the reac-
tions of the R-metalated species with electrophiles provide
a wide variety of substituted alkanesulfonic acid deriva-
tives.1-4 Intramolecular alkylation or acylation of sul-
fonate group-stabilized carbanions has been reported to
lead to 1,2-oxathiolane 2,2-dioxides (sultones, eq 1)5 and
the corresponding 4-ones6 (eq 2), respectively.
enamine tautomer in the presence of an unsaturated
electron-withdrawing group attached to the â-carbon.8
The formation of compound 3a in this reaction can be
rationalized by assuming sodium borohydride promoted
deprotonation of the sulfonate ester moiety at the R-posi-
tion and subsequent addition to the nitrile group. The
electron-withdrawing effect of the trifluoromethyl group
prevents the replacement of the mesylate by the hydride
anion, resulting in the unexpected reaction pathway. We
reasoned, however, that the discovered cyclization reac-
tion should not be limited to trifluoromethyl derivatives
when using the weakly nucleophilic sodium hydride as
the base. Indeed, treatment of cyanohydrin mesylates
2a -d with sodium hydride in THF afforded 1,2-oxa-
thioles 3a -d in good yield. To the best of our knowledge,
compounds 3 are the first 4-amino substituted 1,2-
oxathioles, which may find interesting applications in
organic synthesis.
In the current work we hydrogenated compounds 3b-d
in the presence of palladium-charcoal catalyst, produc-
ing â-amino sulfonic acids (2,2-disubstituted taurines)
4b-d in good yields. The only known alternative general
synthetic route to 2-substituted taurines applies R-amino
acids as the starting compounds.9,10 Surprisingly, similar
hydrogenation of enamine 3a did not produce the corre-
sponding 4a as the single product, but a mixture of 4a
diastereomers and 6a as indicated by the 1H NMR
spectrum.
We report here the preparation of 4-amino-5H-1,2-
oxathiole 2,2-dioxides (3) from cyanohydrin mesylates (2)
based on the intramolecular addition of an R-sulfonate
ester carbanion to the nitrile group. Compounds 3 are
useful intermediates for the synthesis of â-amino and
â-ketosulfonic acids 4 and 6 (Scheme 1).
We have recently described the anomalous reactions
of R-(tosyloxy)-R-(trifluoromethyl)phenylacetonitrile with
sodium borohydride in different solvents.7 The formation
of unexpected products (decyanation, reduction of the
nitrile group) has been attributed to the presence of the
trifluoromethyl group. In continuation of these studies
we observed that the reaction of the corresponding
mesyloxy derivative (2a ) with sodium borohydride in tert-
butyl alcohol afforded 1,2-oxathiole 3a . Both 1H NMR
and 13C NMR data provide the chemical shift, multiplic-
ity, and integration for the assigned structure and it was
also confirmed by single crystal X-ray diffraction. The
enamine structure of compound 3a is in agreement with
earlier observations demonstrating the dominance of the
(1) Tanaka, K. In The Chemistry of Sulphonic Acids, Esters and
Their Derivatives; Patai, S., Rappoport, Z., Eds; J ohn Wiley & Sons,
New York, 1991; p 408-412.
(2) Corey, E. J .; Durst, T. J . Am. Chem. Soc. 1968, 90, 5548.
(3) Truce, W. E.; Vrencur, D. J . Can. J . Chem. 1969, 47, 860.
(4) Durst, T.; du Manoir, J . Can. J . Chem. 1969, 47, 1230.
(5) Durst, T.; Tin, K.-C. Can. J . Chem. 1970, 48, 845.
(6) Stachel, H.-D.; Drasch, G.; Kunze, J .; Peh, J . Ger. Offen.
2,431,734 (to BASF AG., filed 2 J uly 1974), Chem. Abstr. 1975, 84,
135626p.
Hydrolysis of compounds 3 furnished 1,2-oxathiolan-
4-ones 5. Synthesis of 1,2-oxathiolan-4-ones by cycliza-
(8) Huang, Z.-T.; Wang, M.-X. In The Chemistry of Enamines;
Rappoport, Z., Ed.; J ohn Wiley & Sons: New York, 1994; Part 2, p
890-891.
(9) Higashiura, K.; Morino, H.; Matsuura, H.; Toyomaki, Y.; Ienaga,
K. J . Chem. Soc. Perkin Trans. 1 1989, 1479.
(7) Ne´meth, G.; Posza´va´cz, L.; Bo´zsing, D.; Simig Gy. J . Fluorine
Chem. 1996, 78, 87.
(10) Higashiura, K.; Ienaga, K. J . Org. Chem. 1992, 57, 764.
S0022-3263(97)00724-X CCC: $14.00 © 1997 American Chemical Society

7022 J . Org. Chem., Vol. 62, No. 20, 1997
Notes
water (150 mL) and extracted with CH2Cl2 (2 × 100 mL). After
drying (MgSO4) the solvent was evaporated and the residual
was distilled to give 2b (17.8 g, 55%) as a pale yellow oil: bp
113-115 °C (10 mmHg); 1H NMR (CDCl3, 250 MHz) δ 3.19
(3H, s), 1.91 (6H, s); 13C NMR (CDCl3, 62.9 MHz) δ 118.1, 74.8,
39.8, 28.0. Anal. Calcd for C5H9NO3S: C, 36.80; H, 5.56; N,
8.58; S, 19.65. Found: C, 36.76; H, 5.54; N, 8.59; S, 19.82.
2-Eth yl-2-(m esyloxy)bu tyr on itr ile (2c). This compound
was prepared analogously to 2a , starting from 2-ethyl-2-
hydroxybutyronitrile17 (1c, 22.6 g, 200 mmol), mesyl chloride
(17.0 mL, 25.2 g, 220 mmol), and pyridine (50 mL). The
reaction mixture was kept at rt for 3 days. The resulting cude
oil was distilled to give 2c (20.1 g, 53%) as a pale yellow oil:
bp 119-121 °C (2.6 mmHg); 1H NMR (CDCl3, 200 MHz) δ 3.19
(3H, s), 2.15 (4H, q, J ) 7.3 Hz), 1.13 (6H, t, J ) 7.3 Hz). 13C
NMR (CDCl3, 50.3 MHz) δ 116.5, 83.5, 39.4, 30.5, 7.4. Anal.
Calcd for C7H13NO3S: C, 43.96; H, 6.85; N, 7.32; S, 16.77.
Found: C, 44.02; H, 7.03; N, 7.37; S, 16.76.
1-Cya n o-1-(m esyloxy)-cycloh exa n e (2d ). This com-
pound was prepared analogously to 2a , starting from 1-cy-
anocyclohexanol (1d , 25.0 g, 200 mmol),18 mesyl chloride (17.0
mL, 25.2 g, 220 mmol), and pyridine (50 mL). The reaction
mixture was kept at 0-5 °C for 3 days. The resulting crude
oil was purified by distillation to give 2d (22.9 g, 56%) as a
colorless oil: bp 139-140 °C (2.6 mmHg); 1H NMR (CDCl3,
200 MHz) δ 3.20 (3H, s), 2.45-2.25 (2H, m), 2.18-1.50 (7H,
m), 1.50-1.20 (1H, m); 13C NMR (CDCl3, 50.3 MHz) δ 117.5,
79.8, 40.2, 36.7, 23.8, 22.2. Anal. Calcd for C8H13NO3S: N,
6.89; S, 15.77. Found: N, 6.86; S, 15.91.
4-Am in o -5-p h e n yl-5-(t r iflu or om e t h yl)-5H -1,2-o x a -
th iole 2,2-Dioxid e (3a ). A solution of 2a (8.38 g, 30 mmol)
in THF (20 mL) was added to a suspension of NaH (1.33 g,
59.8%, 33 mmol) in THF (30 mL) at -15 °C, during 30 min.
The mixture was stirred at 0 °C for further 30 min. It was
poured into ice-water (50 mL) and extracted with EtOAc (3
× 40 mL). After drying (MgSO4) the solvent was evaporated
and the resulting crude powder was recrystallized from
2-propanol to give 3a (5.95 g, 71%) as a colorless solid: mp
105-107 °C; 1H NMR (CDCl3, 250 MHz) δ 7.70-7.60 (2H, m),
7.55-7.45 (3H, m), 5.78 (1H, s), 4.55 (2H, bs); 13C NMR (CDCl3,
50.3 MHz) δ 151.9, 131.0, 130.8, 129.9, 129.4, 126.4, 122.2, (q,
J ) 286.5 Hz), 87.0, 86.3 (q, J ) 31.3 MHz). Anal. Calcd for
C10H8F3NO3S: C, 43.01; H, 2.89; N, 5.02; S, 11.48. Found: C,
43.15; H, 3.10; N, 4.92; S, 11.84. [The reduction of 2a (1.12 g,
4 mmol) with NaBH4 (0.31 g, 8 mmol) in tert-butyl alcohol at
60 °C for 3 h gave 3a in 62% yield.].
4-Am in o-5,5-dim eth yl-5H-1,2-oxath iole 2,2-Dioxide (3b).
This compound was prepared analogously to 3a , starting from
2b (9.79 g, 60 mmol) in THF (20 mL) and NaH (1.98 g, 80%,
66 mmol) in THF (20 mL). The crude crystalline product was
recrystallized from 2-propanol to give 3b (8.52 g, 87%) as a
colorless solid: mp 179-180 °C; 1H NMR (CDCl3, 250 MHz) δ
6.71 (2H, bs), 5.32 (1H, s), 1.53 (6H, s); 13C NMR (DMSO-d6,
62.9 MHz) δ 161.1, 87.4, 84.0, 25.7. Anal. Calcd for
C5H9NO3S: C, 36.80; H, 5.56; N, 8.58; S, 19.65. Found: C,
37.00; H, 5.77; N, 8.35; S, 19.74.
tion of (R-carboxyethyl)alkyl alkanesulfonates (e.g. eq 2)
has been described in the patent literature.6 The results
obtained in the course of hydrogenation of compounds 3
promted us to attempt the reductive ring opening of
derivatives 5. Thus, catalytic hydrogenation of â-keto
γ-sultones 5 afforded â-keto sulfonic acids 6 (isolated as
ammonium salts) in good yields. Alternative methods
for the synthesis of â-keto sulfonic acids involve sulfona-
tion of ketones11 or R-halo ketones.12
Our results show the synthetic usefulness of 1,2-
oxathioles 3a -d . The overall transformations 1 f 4 and
1 f 6 can be regarded as the addition of methanesulfonic
acid R-carbanion to a nitrile (R1R2CHCN) corresponding
to the starting cyanohydrin 1, followed by the reduction
or hydrolysis of the resulting imine, respectively. Fur-
ther work is in progress to explore the chemistry of these
versatile intermediates.
Exp er im en ta l Section
Melting points are uncorrected. Infrared spectra were
recorded as KBr pellets. 1H NMR spectra were recorded at
200, 250, or 400 MHz and 13C NMR spectra at 50.3, 62.9, or
100.6 MHz, as indicated. All unspecified reagents were from
commercial resources.
Str u ctu r e Deter m in a tion of 3a by X-r a y Cr ysta l-
logr a p h y. The X-ray measurements were carried out by Prof.
A. Ka´lma´n and Mr. Gy. Argay (Central Research Institute for
Chemistry, Hungarian Academy of Sciences). C10H8F3NO3S;
Mr ) 279.233; crystallized from ethyl acetate as colorless
crystals. The orthorombic cell parameters and calculated cell
volume are a ) 16.605 (2) Å, b ) 9.594 (1) Å, c ) 7.462 (1) Å,
V ) 1188.8 (5) Å3. The acentric space group is Pna21.
Intensity data were collected on an Enraf Nonius CAD4
diffractrometer. The structure was solved by direct methods
and refined on Fo2 values to R1 ) ∑|Fo - |Fc||/∑Fo ) 0.0306 for
2396 observations.13
3,3,3-Tr iflu or o-2-(m esyloxy)-2-ph en ylpr opion itr ile (2a).
To a cold (-10 °C) solution of 3,3,3-trifluoro-2-hydroxy-2-
phenylpropionitrile (trifluoroacetophenone cyanohidrin, 1a ,
10.1 g, 50 mmol)14 in pyridine (50 mL) was added mesyl
chloride (11.6 mL, 17.0 g, 150 mmol) dropwise. After 2 days
at rt the mixture was poured into ice-water (200 mL), acidified
with 9 N aqueous H2SO4 solution, and extracted with CH2Cl2
(3 × 150 mL). After drying (MgSO4) the solvent was evapo-
rated and the resulting crude oil was purified by distillation
to give 2a (9.1 g, 65%) as a pale yellow oil: bp 119-121 °C
(4.0 mmHg); 1H NMR (CDCl3, 250 MHz) δ 7.80-7.70 (2H, m),
7.65-7.45 (3H, m), 3.27 (3H, s); 13C NMR (CDCl3, 62.9 MHz)
δ 131.9, 129.2, 127.9, 127.0, 122.0, 120.2 (q, J ) 287.1 Hz),
117.9, 40.5. Anal. Calcd for C10H8F3NO3S: C, 43.01; H, 2.89;
N, 5.02; S, 11.48. Found: C, 43.16; H, 2.93; N, 5.07; S, 11.47.
2-Met h yl-2-(m esyloxy)p r op ion it r ile (2b ). (The com-
pound is mentioned in the patent literature,15 no data avail-
able.) To a cold (-10 °C) solution of 2-hydroxy-2-methylpro-
pionitrile16 (acetone cyanohydrin, 1b, 17.0 g, 200 mmol) and
triethylamine (55.8 mL, 40.5 g, 400 mmol) in CH2Cl2 (100 mL)
was added mesyl chloride (31.0 mL, 45.8 g, 400 mmol) over a
period of 30 min. The reaction was completed by stirring for
an additional 2 h at rt. The mixture was poured into ice-
4-Am in o-5,5-d ieth yl-5H-1,2-oxa th iole 2,2-Dioxid e (3c).
This compound was prepared analogously to 3a , starting from
2c (11.48 g, 60 mmol) and NaH (2.65 g, 59.8%, 66 mmol) in
THF (40 mL). The resulting crude powder was purified by
recrystallization from 2-propanol to give 3c (9.51 g, 83%) as a
colorless solid: mp 162-164 °C; 1H NMR (DMSO-d6, 200 MHz)
δ 6.62 (2H, bs), 5.42 (1H , s), 2.00-1.60 (4H, m), 0.84 (6H, t,
J ) 7.4 Hz); 13C NMR (DMSO-d6, 50.3 MHz) δ 157.26, 94.17,
87.00, 29.82, 7.28. Anal. Calcd for C7H13NO3S: C, 43.96; H,
6.85; N, 7.32; S, 16.77. Found: C, 43.76; H, 6.76; N, 7.23; S,
16.53.
(11) Hofmann, K.; Simchen, G. Synthesis 1979, 699 and the refer-
ences cited.
(12) Pu¨schel, F.; Kaiser, C. Chem. Ber. 1964, 97, 2903.
(13) The author has deposited atomic coordinates for 3d with the
Cambridge Crystallographic Data Centre. The coordinates can be
obtained, on request, from the Director, Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge, CB2 1EZ, UK.
(14) Kanagasabapathy, V. W.; Sawyer, J . F.; Tidwell, T. T. J . Org.
Chem. 1985, 50, 503.
4-Am in o-1-oxa -2-t h ia sp ir o[4.5]d ec-3-en e 2,2-Dioxid e
(3d ). This compound was prepared analogously to 3a , starting
from 2d (12.20 g, 60 mmol) and NaH (2.65 g, 59.8%, 66 mmol)
in THF (40 mL) at rt. The resulting crude powder was purified
(15) Masahiro, N.; Hidetoshi, K. J pn. Kokai J P 03,240,764 (to
Idemitsu Kosan Co., Ltd., filed on 19 Feb 1990); Chem. Abstr. 1992,
116, 105644e.
(16) Cox, R. F. B.; Stormont, R. T. Organic Synthesis; Wiley: New
York, 1943; Collect. Vol. 2, pp 7-8.
(17) Zahorszky, U. I.; Schulze, P. Org. Mass Spectrom. 1989, 24,
759.
(18) Tchoubar, B.; Collin, C. Bull. Soc. Chim. Fr. 1947, 680; Chem.
Abstr. 1948, 42, 2582i.

Notes
J . Org. Chem., Vol. 62, No. 20, 1997 7023
by recrystallization from 2-propanol to give 3d (8.15 g, 67%)
as a colorless solid: mp 200-201 °C; 1H NMR (DMSO-d6, 50.3
MHz) δ 6.67 (2H, bs), 5.29 (1H, m), 2.10-1.80 (2H, m), 1.80-
1.35 (7H, m), 1.35-1.03 (1H, m); 13C NMR (DMSO-d6, 50.3
MHz) δ 160.91, 89.25, 83.95, 33.37, 23.76, 21.52. Anal. Calcd
for C8H13NO3S: N, 6.89; S, 15.77. Found: N, 6.78; S, 15.57.
mL) to give 5c (2.68 g, 70%) as a yellow oil: IR (KBr) 1767
cm-1
;
1H NMR (CDCl3, 200 MHz) δ 3.89 (2H, s), 2.15-1.85
(4H, m), 1.03 (6H, t, J ) 7.5 Hz); 13C NMR (CDCl3, 100.6 MHz)
δ 201.07, 102.45, 53.37, 28.30, 7.49. Anal. Calcd for
C7H12O4S: C, 43.74; H, 6.29; S, 16.68. Found: C, 43.30; H,
6.31; S, 16.77.
(()-2-Am in o-3-m eth ylbu ta n esu lfon ic Acid (4b).9-10
A
1-Oxa -4-oxo-2-th ia sp ir o[4.5]d eca n e 2,2-Dioxid e (5d ).
This compound was prepared analogously to 5a , starting from
3d (4.07 g, 20 mmol), concentrated HCl (3.0 mL), and MeOH
(20 mL). The crude solid was triturated with water (20 mL)
to give 5d (3.53 g, 86%) as a colorless solid: mp 82-83 °C
solution of 3b (1.63 g, 10 mmol) in MeOH (20 mL) was
hydrogenated in the presence of 10% Pd/C (0.3 g) at rt under
2.5 × 105 Pa H2 for 8 h. After removal of the catalyst by
filtration and evaporation of the solvent, the residue was
recrystallized from a mixture of 2-propanol and isopropyl ether
to give 4b (1.30 g, 78%) as a colorless compound: mp >250
1
(aqueous 2-propanol); IR (KBr) 1763 cm-1; H NMR (CDCl3,
200 MHz) δ 3.95 (2H, s), 2.20-2.00 (2H, m), 1.90-1.50 (7H,
m), 1.50-1.20 (1H, m); 13C NMR (CDCl3, 50.3 MHz) δ 200.57,
98.32, 52.22, 32.09, 24.03, 20.80. Anal. Calcd for C8H12O4S:
C, 47.05; H, 5.92; S, 15.70. Found: C, 46.82; H, 5.94; S, 15.74.
Am m on iu m 4,4,4-Tr iflu or o-2-oxo-3-p h en ylbu ta n esu l-
fon a te (6a ). This compound was prepared by hydrogenation
analogously to 4b, starting from 5a (2.80 g, 10 mmol). The
resulting crude oil was dissolved in ether and a solution of
NH3 in EtOH was added. Crystalline ammonium salt sepa-
rated which was recrystallized from a mixture of EtOH and
Et2O to give 6a (2.71, 91%): mp 193-194 °C; IR (KBr) 1718
1
°C; H NMR (DMSO-d6, 250 MHz) δ 7.78 (3H, bs), 3.20 (1H,
ddd, J ) 10.9 Hz, J ) 2.1 Hz, J ) 5.6 Hz), 2.83 (1H, dd, J )
2.1 Hz, J ) 14.2 Hz), 2.62 (1H, dd, J ) 10.9 Hz, J ) 14.2 Hz),
1.92 (1H, m), 0.91 (3H, d, J ) 6.9 Hz), 0.88 (3H, d, J ) 6.9
Hz); 13C NMR (DMSO-d6, 50.3 MHz) δ 54.08, 49.42, 30.06,
18.47, 17.42. Anal. Calcd for C5H13NO3S: C, 35.91; H, 7.84;
N, 8.38; S, 19.17. Found: C, 35.89; H, 7.86; N, 8.28; S, 18.87.
(()-2-Am in o-3-eth ylp en ta n esu lfon ic Acid (4c). This
compound was prepared analogously to 4b, starting from 3c
(1.91 g, 10 mmol). The resulting crude powder was recrystal-
lized from a mixture of 2-propanol and isopropyl ether to give
4c (1.43 g, 73%) as a colorless compound: mp >250 °C; 1H
NMR (DMSO-d6, 200 MHz) δ 7.71 (3H, bs), 3.51-3.40 (1H,
m), 2.71 (1H, dd, J ) 2.4, 14.5 Hz), 2.58 (1H, dd, J ) 10.6,
14.5 Hz), 1.60-0.95 (4H, m), 0.86 (3H, t, J ) 7.2 Hz), 0.84
(3H, t, J ) 7.2 Hz); 13C NMR (DMSO-d6, 50.3 MHz) δ 50.47,
49.16, 43.01, 21.40, 11.47, 11.28. Anal. Calcd for
C7H17NO3S: C, 43.05; H, 8.77; N, 7.17; S, 16.42. Found: C,
42.92; H, 8.70; N, 7.14; S, 16.34.
cm-1 1H NMR (D2O, 400 MHz) δ 7.60-7.50 (3H, m), 7.50-
;
7.40 (2H, m), 5.23 (1H, q , J ) 8.5 Hz), 4.15 (1H, d, J ) 14
Hz), 3.88 (1H, d, J ) 14 Hz); 13C NMR (D2O, 50.3 MHz) δ 192.7,
127.7, 127.3, 127.0, 125.0, 121.4 (q, J ) 279.7 Hz), 58.2, 57.4
(q, J ) 25.6 Hz). Anal. Calcd for C10H12F3NO4S: N, 4.68; S,
10.71. Found: N, 4.76; S, 10.83.
Am m on iu m 3-Meth yl-2-oxo-bu ta n esu lfon a te (6b). This
compound was prepared by hydrogenation analogously to 4b,
starting from 5b (1.64 g, 10 mmol). The resulting ammonium
salt was recrystallized from a mixture of 2-propanol and
isopropyl ether to give 6b (1.75, 90%): mp >130 °C (slow
decomposition). IR (KBr) 1701 cm-1; 1H NMR (D2O, 400 MHz)
δ 4.15 (2H, s), 3.05-2.90 (1H, m), 1.11 (3H, d, J ) 7.0 Hz),
1.09 (3H, d, J ) 7.0 Hz); 13C NMR (D2O, 50.3 MHz) δ 211.71,
61.93, 42.98, 18.89. Anal. Calcd for C5H13NO4S: C, 32.78;
H, 7.15; N, 7.64; S, 17.50. Found: C, 32.44; H, 7.06; N, 7.52;
S, 17.61.
(()-2-Am in o-2-cycloh exyleth an esu lfon ic Acid (4d). This
compound was prepared analogously to 4b, starting from 3d
(2.03 g, 10 mmol). Water (40 mL) was added to the reaction
mixture in order to dissolve the solid precipitate. After
removal of the catalyst by filtration and evaporation of the
solvent the residue was triturated with petroleum ether (10
mL, bp 80-100 °C) to give 4d (1.84 g, 89%) as a colorless
compound: mp >250 °C; 1H NMR (DMSO-d6, 400 MHz) δ 7.79
(3H, bs), 3.19 (1H, ddd, J ) 1.9, 5.9, 11.1 Hz), 2.79 (1H, dd, J
) 1.9, 14.3 Hz), 2.57 (1H, dd, J ) 11.1, 14.1 Hz), 1.80-1.65
(3H, m), 1.65-1.50 (3H, m), 1.25-0.80 (5H, m); 13C NMR
(DMSO-d6, 50.3 MHz) δ 53.32, 50.83, 40.35, 28.22, 27.70, 25.79,
25.70, 25.38. Anal. Calcd for C8H17NO3S: N, 6.76; S, 15.47.
Found: N, 6.83; S, 15.34.
Am m on iu m 3-Eth yl-2-oxo-p en ta n esu lfon a te (6c). This
compound was prepared by hydrogenation analogously to 4b,
starting from 5c (1.91 g, 10 mmol). The resulting ammonium
salt was purified by trituration with isopropyl ether (15 mL)
to give 6c (1.74, 83%): mp >100 °C (slow decomposition). IR
1
(KBr) 1702 cm-1; H NMR (DMSO-d6, 400 MHz) δ 7.08 (4H,
5-(Tr iflu or om eth yl)-4-oxo-5-ph en yl-1,2-oxath iolan e 2,2-
Dioxid e (5a ). A solution of 3a (5.60 g, 20 mmol) in a mixture
of MeOH (20 mL) and concentrated HCl (3.0 mL) was stirred
for 2 h at rt. After evaporation to dryness the residue was
triturated with water (20 mL) and the crystalline precipitate
filtered and washed with water to give 5a (4.01 g, 71%) as a
colorless solid: mp 152-154 °C (aqueous 2-propanol); IR (KBr)
bs), 3.58 (2H, s), 3.10-2.90 (1H, m), 1.60-1.45 (2H, m), 1.42-
1.30 (2H, m), 0.76 (6H, t, J ) 7.4 Hz); 13C NMR (DMSO-d6,
50.3 MHz) δ 206.49, 64.28, 51.79, 22.58, 11.34. Anal. Calcd
for C7H17NO4S: C, 37.79; H, 8.11; N, 6.63; S, 15.18. Found:
C, 38.06; H, 8.22; N, 6.57; S, 15.38.
Am m on iu m 2-Cycloh exyl-2-oxoeth a n esu lfon a te (6d ).
This compound was prepared by hydrogenation analogously
to 4b, starting from 5d (2.04 g, 10 mmol). The resulting
ammonium salt was crystallized from a mixture of 2-propanol
and isopropyl ether to give 6c (1.68, 75%): mp 182-183 °C;
IR (KBr) 1698 cm-1; 1H NMR (DMSO-d6, 400 MHz) δ 7.09 (4H,
t, J ) 51.2 Hz, +NH4), 3.61 (2H, s), 3.00-2.85 (1H, m), 1.90-
1.75 (2H, m), 1.75-1.55 (3H, m), 1.30-1.05 (5H, m); 13C NMR
(DMSO-d6, 100.6 MHz) δ 206.13, 63.15, 48.18, 28.12, 25.76,
25.36. Anal. Calcd for C8H17NO4S: C, 43.03; H, 7.67; N, 6.27;
S, 14.36. Found: C, 42.72; H, 7.62; N, 6.16; S, 14.54.
1
1781 cm-1; H NMR (CDCl3, 250 MHz) δ 7.77-7.70 (2H, m),
7.60-7.40 (3H, m), 4.14 (1H, d, J ) 17.5 Hz), 4.04 (1H, d, J )
17.5 Hz); 13C NMR (DMSO-d6, 100.6 MHz) δ 162.00, 130.76,
130.60, 130.22, 129.10, 126.18, 122.08 (q, J ) 286.1 Hz), 93.58,
85.74 (q, J ) 30.9 MHz). Anal. Calcd for C10H7F3O4S: C,
42.86; H, 2.52; S, 11.44. Found: C, 42.83; H, 2.50; S, 11.50.
5,5-Dim eth yl-4-oxo-1,2-oxa th iola n e 2,2-Dioxid e (5b).
This compound was prepared analogously to 5a , starting from
3b (9.80 g, 60 mmol), MeOH (30 mL), and concentrated HCl
(5.0 mL). The solid residue was triturated with petroleum
ether (25 mL, bp 80-100 °C) to give 5b (6.50 g, 66%) as a
colorless solid: mp 59-60 °C (diethyl ether); lit.6 mp 59 °C;
Su p p or tin g In for m a tion Ava ila ble: 1H NMR and 13C
NMR spectra for compounds 2, 3, 4b-d , 5, and 6 (39 pages).
This material is contained in libraries on microfiche, im-
mediately follows this article in the microfilm version of the
journal, and can be ordered from the ACS; see any current
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1
IR (KBr) 1763 cm-1; H NMR (CDCl3, 250 MHz) δ 3.94 (2H,
s), 1.67 (6H, s); 13C NMR (CDCl3, 62.9 MHz) δ 200.7, 95.4, 51.7,
24.0. Anal. Calcd for C5H8O4S: C, 36.58; H, 4.91; S, 19.53.
Found: C, 36.60; H, 5.02; S, 19.21.
5,5-Dieth yl-4-oxo-1,2-oxath iolan e 2,2-Dioxide (5c). This
compound was prepared analogously to 5a , starting from 3c
(3.83 g, 20 mmol), concentrated HCl (3.0 mL), and MeOH (20
J O9707242