Convenient synthesis of optically active 1,2-diol monosulfonates and terminal epoxides via oxazaborolidine-catalyzed asymmetric borane reduction of α-sulfonyloxy ketones

Article abstract of DOI:10.1039/b010155i

A very convenient asymmetric synthesis of 1,2-diol monosulfonates and terminal epoxides with high optical purity via oxazaborolidine-catalyzed asymmetric borane reduction of α-sulfonyloxy ketones using N-ethyl-N-isopropylaniline-borane complex as borane carrier has been developed.

Full text of DOI:10.1039/b010155i

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Convenient synthesis of optically active 1,2-diol monosulfonates
and terminal epoxides via oxazaborolidine-catalyzed asymmetric
borane reduction of ꢀ-sulfonyloxy ketones
1
Byung Tae Cho,* Weon Ki Yang and Ok Kyung Choi
Department of Chemistry, Hallym University, Chunchon, Kangwondo 200-702,
Republic of Korea
Received (in Cambridge, UK) 14th December 2000, Accepted 23rd March 2001
First published as an Advance Article on the web 3rd May 2001
A very convenient asymmetric synthesis of 1,2-diol monosulfonates and terminal epoxides with high optical purity
via oxazaborolidine-catalyzed asymmetric borane reduction of α-sulfonyloxy ketones using N-ethyl-N-isopropyl-
aniline–borane complex as borane carrier has been developed.
reagents. Secondly, α-halo ketones suffer from severe draw-
Introduction
backs to commercial applications, such as causing irritation to
skin and eyes and their instability to light. In contrast, it is
known that the amine–borane complexes offer the advan-
tages of being soluble in most common solvents at high concen-
tration and they have lower sensitivity to air and moisture.17 In
fact, we18 and others17b have reported efficient oxazaborolidine-
catalyzed reductions of prochiral ketones using N-phenyl-
amine–borane complexes as a reductant. On the other hand,
α-sulfonyloxy ketones can be used as starting materials for
large-scale applications more readily than α-halo ketones,
because they are not only stable and non-irritant, but also the
sulfonyloxy groups appear to be much better leaving groups
than do halogens.1–3 Therefore, in order to develop a practical
method useful for the large-scale synthesis of optically
active aromatic, aliphatic and heterocyclic 1,2-diol mono-
sulfonates and terminal epoxides, we studied oxazaborolidine-
catalyzed asymmetric reduction of α-sulfonyloxy ketones using
N-phenylamine–borane complexes as borane carriers. Very
recently, we reported briefly on an efficient synthesis of
enantiopure 3-chlorostyrene oxide using this methodology.19
We report here, the details, scope, and limitations of such a
reduction.
Optically active 1,2-diol monosulfonates have been widely used
as precursors for the synthesis of chiral epoxides,1 chiral
ligands2 and chiral solvating agents.3 For the synthesis of these
compounds, biological methods such as enzymatic esterifi-
cation4a,b or hydrolysis1,4c of the racemic mixtures and selective
monosulfonylation2,3,5 of optically active 1,2-diols have been
reported. One of the most convenient methods for obtaining
the compounds may be asymmetric reduction of α-sulfonyloxy
ketones. However, to the best of our knowledge, no report on
this reduction has been published.
Also, non-racemic aromatic and aliphatic terminal epoxides
are extremely useful chiral building blocks for the synthesis of
a variety of pharmaceutical products6 and can be used as key
intermediates7 for the synthesis of more complex chiral organic
compounds. In recent years, many chemical and biological
methods for the synthesis of epoxides, such as asymmetric
epoxidation of olefins, resolution of racemic epoxides, and
indirect chemical transformation, have been reported. However,
the direct asymmetric epoxidation of terminal olefins such as
styrene analogues catalyzed by salen and porphyrin ligands,8
or chiral dioxiranes9 has been only moderately successful,
to give products of 50–70% ee,10 although they provide high
enantioselectivity for the epoxidation of conjugated
Z-substituted olefins and non-conjugated E-olefins with >90%
ee.11 The resolution of racemic epoxides with biocatalytic
hydrolysis,12 and chemically hydrolytic resolution methods,13
both suffer from the fact that the theoretical yield is limited to
50%. Among the indirect methods such as chemical trans-
formation of chiral sulfonium ylides,6f halohydrins6c,g,14 and
1,2-diols15 to epoxides, the conversion of chiral halohydrins to
the epoxides may be one of the most simple and convenient
procedures for the synthesis of chiral terminal epoxides, since
halohydrins with high optical purity can be easily obtained
from asymmetric reduction of α-halo ketones.16 Indeed,
Corey et al. reported the preparation of optically active styrene
oxide with high ee using CBS oxazaborolidine-catalyzed asym-
metric borane reduction of 2-chloroacetophenone.14 However,
this procedure has two major problems for large-scale appli-
cations. First, the use of borane–tetrahydrofuran THF, borane–
dimethyl sulfide (BMS) and catechol–borane commonly
employed as borane carriers for the reduction is not free from
certain disadvantages, such as low concentration, thermal
decomposition, high volatility, flammability, unpleasant odor
and high sensitivity to air and moisture of these borane
Results and discussion
The α-sulfonyloxy ketone derivatives 8a–p used as substrates
were prepared by sulfonyloxylation of aryl (or alkyl) methyl
ketones or their trimethyl enol ethers with {hydroxy[aryl(or
methyl)sulfonyloxy]iodo}benzenes in 46–87% yield according
to the literature procedure.20
In order to examine effects of oxazaborolidines and hydride
sources on asymmetric induction, we first compared the asym-
metric borane reduction of 1-phenyl-2-(p-tolylsulfonyloxy)-
ethanone 8b catalyzed by four structurally different chiral
oxazaborolidines, such as a proline-based oxazaborolidine
(Corey’s CBS reagents, 121), an aminodiphenylethanol-based
oxazaborolidine (Pfizer’s reagent, 222), an aminoindanol-
based oxazaborolidine (Sepracor’s reagent, 323) and a valine-
based oxazaborolidine (Itsuno’s reagent, 424) using N-ethyl-
N-isopropylaniline–borane complex 5 as the borane source.
Thus, slow addition of 8b over a period of 1 h to a solution
of 1.0 equiv. of the amine–borane reagent 5 in the presence of
10 mol% of each oxazaborolidine in THF at 25 ЊC afforded
1-phenyl-2-(p-tolylsulfonyloxy)ethanol 9b within 10 min in
almost quantitative yield (Scheme 1). This was easily converted
1204
J. Chem. Soc., Perkin Trans. 1, 2001, 1204–1211
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b010155i

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Table 1 Effect of oxazaborolidine and borane reagents on catalytic asymmetric borane reduction of 1-phenyl-2-(p-tolylsulfonyloxy)ethanone 8ba
9b
Borane
reagent
(1.0 equiv.)
Cat.
(0.1 equiv.)
Yieldb
(%)
[α]D22
(c, CHCl3)
Entry
% ee
Config.
1
2
3
4
5
6
1
2
3
4
1
1
5
5
5
5
6
7
99
98
96
96
94
93
ϩ50.4 (2.4)
99c (99)d
77c
Sd
Sd
Sd
Sd
Sd
e
e
e
e
e
78c
94c
95c
90c
a [8b] : [borane reagent] : [catalyst] = 1 : 1 : 0.1. [7] = 0.5 M. The reaction was carried out in THF at 25 ЊC. The reaction was complete within 10 min to
give the product alcohol 9b. b Isolated and purified yields. c Determined by HPLC analysis of phenyloxirane obtained from 9b by treatment with 2 M
NaOH using a Daicel Chiralcel OD; hexane–iPrOH 99.8 : 0.2. d Based on literature value: ref. 14. e Not measured.
Scheme 1
to phenyloxirane 10 by treatment with 2 M NaOH in diethyl
ether at room temperature in almost quantitative yield. The ee
Scheme 2
of the epoxide 10 was determined by HPLC analysis using a
Chiralcel OD (eluent: hexane–iPrOH = 99.8 : 0.2). Among the
catalysts examined, Corey’s CBS reagent 1 provided the best
enantioselectivity, approaching 100% ee (Table 1, entries 1–4).
The same reduction of 8b with other N-phenylamine–borane
reagents such as N,N-diethylaniline–borane complex 6 and
N-phenylmorpholine–borane complex 7 provided somewhat
low enantioselectivity (entries 5,6).
Subsequently, the influence of different sulfonyl groups on
the selectivity in the same reduction of 1-phenyl-2-sulfonyloxy-
ethanones having mesyl and p-nitrobenzenesulfonyl (p-nosyl)
groups was examined. As shown in Table 2, no differences in
selectivity among mesyl, p-tosyl and p-nosyl groups were
observed (entries 1–3). Next, we examined generality and
limitations of such reactions by carrying out the same asym-
metric reduction for other aromatic, aliphatic and heterocyclic
α-sulfonyloxy ketone derivatives (Scheme 2). All the sulfonyl-
oxy ketones 8 examined were reduced to the corresponding
1,2-diol monosulfonates 9 in almost quantitative yield. Also, all
the product alcohols obtained except 9p were easily converted
into the corresponding terminal epoxides 10–22 by treatment
with 2 M NaOH in high yield with no racemization. In the
case of 9p, it was observed that polymerization occurred
during product isolation by silica gel column chromatography.
With respect to enantioselectivity, the reduction of aromatic
analogues 8g–l bearing 3,4-dichlorophenyl, 4-fluorophenyl,
4-tolyl, 4-nitrophenyl, 4-biphenylyl and 2-naphthyl groups
afforded the epoxides 14–19 with very high enantioselectivites
(94–99% ee) (entries 7–12). Interestingly, the reduction of
1-(2-chlorophenyl)-2-(p-tosyloxy)ethanone 8d provided 80% ee
in contrast to 99% ee for 1-(3-chlorophenyl)-2-(p-tosyloxy)-
ethanone 8e and 1-(4-chlorophenyl)-2-(p-tosyloxy)ethanone
8f (entries 4–6). These results indicate that the asymmetric
induction was sensitive to steric effects of the substituent
proximal to the carbonyl group. This is a common phenomenon
in oxazaborolidine-catalyzed reductions.18,25 For aliphatic
analogues 8m,n, the asymmetric reduction of the sulfonyloxy
ketones 8n having a branched alkyl group such as cyclohexyl
provided high enantioselectivity, whereas 8m containing an
unbranched alkyl group afforded low enantioselectivity (entries
13,14). The reduction of heterocyclic analogues 9o,p bearing
2-pyridyl and 2-thienyl groups afforded moderate to low
enantioselectivities (entries 15,16). All the product epoxides
10–22 obtained are consistently enriched in the S-enantiomer.
The stereochemical course of the asymmetric reduction showed
that the α-sulfonyloxy ketones were attacked by hydride on
their Re faces in the transition states 23.18,25
J. Chem. Soc., Perkin Trans. 1, 2001, 1204–1211
1205

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Table 2 Asymmetric reduction of α-sulfonyloxy ketones 8 in the presence of 0.1 equiv. of 1 with 1.0 equiv. of 5 in THF at 25 ЊCa
1,2-Diol monosulfonates 9 Chiral epoxides 10–22
Entry
Cpd
Yieldb
[α]D22 (c, solvent)
Cpd
Yieldc
[α]D22 (c, solvent)
% ee
Config.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
9a
9b
9c
9d
9e
9f
9g
9h
9i
9j
9k
9l
9m
9n
9o
9p
ϩ53.8 (1.12, CHCl3)
ϩ50.4 (2.41, CHCl3)
ϩ40.0 (1.00, MeCOMe)
ϩ43.8 (1.08, CHCl3)
ϩ39.6 (1.32, CHCl3)
ϩ45.5 (1.00, CHCl3)
ϩ39.6 (1.04, CHCl3)
ϩ47.0 (1.05, CHCl3)
ϩ56.7 (1.01, CHCl3)
ϩ30.3 (1.02, MeCOMe)
ϩ50.0 (1.01, CHCl3)
ϩ57.2 (1.00, CHCl3)
ϩ3.5 (1.20, CHCl3)
ϩ12.10 (1.02, CHCl3)
ϩ4.5 (1.01, CHCl3)
ϩ34.2 (1.05, CHCl3)w
10
10
10
11
12
13
14
15
16
17
18
19
20
21
22
96
96
96
94
95
96
94
96
95
96
96
97
99
96
92
Ϫ44.5 (1.15, C6H6)
Not measured
Not measured
99d (99)e
S e
S e
S e
S g
S i
99d
99d
ϩ43.7 (1.42, CHCl3)
ϩ11.15 (1.56, CHCl3)
ϩ25.5 (1.00, CHCl3)
ϩ15.3 (1.18, CHCl3)
ϩ19.2 (1.20, CHCl3)
Ϫ25.9 (1.02, C6H6)
ϩ37.8 (1.34, CHCl3)
ϩ30.0 (1.06, CHCl3)
ϩ11.4 (1.11, CHCl3)
Ϫ3.7 (1.14, CHCl3)
ϩ2.1 (0.88, CHCl3)
ϩ2.9 (0.41, CHCl3)
80f (100)g
99h (100)i
99j (100)k
94j (100)l
98f (100)m
97d (99)n
97o (100)p
98q
S k
S l
S m
S n
S p
S r
S s
S t
S u
S v
(100)s
(40)t
96h
21h
a [8] = 0.5 M. The reaction was complete within 10 min to give the α-sulfonyloxy alcohols 9. b Isolated yields. c Isolated and purified yield of the
corresponding epoxides obtained by treatment of 9 with 2 M NaOH. d Determined by HPLC analysis using a Daicel Chiralcel OD; hexane–iPrOH
99.8 : 0.2. e Based on [α]D23 Ϫ44.9 (c 1.02, C6H6), S; ref. 14. f Determined by capillary GLC analysis using a β-DEX 120 chiral column (Supelco).
g Based on [α]D25 ϩ32.2 (c 1.19, CHCl3), >99%, S; ref. 27. h Determined by capillary GLC analysis using a G-TA chiral column (Astec). i Based on [α]D20
Ϫ11.1 (c 1.23, CHCl3), >99% ee, R, ref. 28. j HPLC analysis using a Daicel Chiralpak OT; hexane–iPrOH 99 : 1. k Based on [α]D20 Ϫ24.0 (c 1.08,
CHCl3), >97% ee, R; ref. 12b. l Based on [α]D Ϫ11 (c 1.00, CHCl3), 96% ee, R; ref. 6f. m Based on [α]D20 Ϫ17 (c 1.03, CHCl3), 97% ee, R; ref. 12b. n Based
on [α]D20 ϩ25.5 (c 1.3, C6H6), 98% ee, R; ref. 29. o Determined by HPLC analysis using a Daicel Chiralpak OT; hexane–iPrOH 40 : 1. p Based on [α]D25
ϩ36.0 (c 1.25, CHCl3), 95% ee, S; ref. 6h. q Determined by HPLC analysis using a Daicel Chiralcel OD; hexane–iPrOH 99 : 1. r Based on the sign of
optical-rotation value, (R)-(Ϫ); ref. 7c. s Based on [α]D Ϫ9 (c 1.2, CHCl3), 92% ee, R; ref. 6f. t Based on [α]2D4 Ϫ8.9 (c 1.14, CHCl3), 97% ee, S; ref. 30;
u Determined by optical-rotation value of 21 obtained from (S)-cyclohexylethane-1,2-diol, ref. 31. v Based on [α]1D9 ϩ14.0 (c 0.56, CHCl3), 99% ee, S;
ref. 32; w 80% ee by comparison with optical-rotation value of 9p obtained from authentic (R)-(2-thienyl)ethane-1,2-diol.
fitted with a 25 cm Chiralcel OD or Chiralpak OT column
(Daicel).
Materials
Most of organic compounds utilized in this study were com-
mercial products of the highest purity. They were further puri-
fied by distillation when necessary. THF was distilled over
sodium benzophenone ketyl and stored in ampoules under
nitrogen atmosphere. The CBS reagent 1, N,N-diethylaniline–
Conclusions
We have established a simple and practical procedure for the
synthesis of 1,2-diol monosulfonates and the corresponding
terminal epoxides with very high optical purity in high yields
via oxazaborolidine-catalyzed borane reduction of α-sulfonyl-
oxy ketones using N-ethyl-N-isopropylaniline–borane complex
as borane carrier. The reduction provided almost enantiopure
epoxides in aromatic analogues. This procedure can be used
as an excellent alternative to synthesis of such compounds.
Further applications using this methodology are now under
investigation.
borane complex, N-ethyl-N-isopropylaniline–borane complex,
N-methylmorpholine–borane complex, (1S,2R)-cis-1-amino-
indan-2-ol and (1R,2S)-2-amino-1,2-diphenylethanol were
purchased from Aldrich Chemical Company. The chiral oxaza-
borolidines 2–4 were prepared by treatment of the correspond-
ing amino alcohols with BH3–THF according to the known
procedure.22–24
Preparation of ꢀ-sulfonyloxyaryl ketone derivatives 8
According to the literature,20 compounds 8 were prepared by
refluxing aryl methyl ketones or their trimethylsilyl enol ethers
with {hydroxy[aryl(or methyl)sulfonyloxy]iodo}benzenes in
acetonitrile, 1,4-dioxane, toluene or diethylene glycol bis(methyl
ether) (diglyme).
Experimental
General
All operations with air-sensitive materials were carried out
under a nitrogen atmosphere with oven-dried glassware. Liquid
materials were transferred with a double-ended needle. The
reactions were monitored by TLC using silica gel plates and
the products were purified by flash column chromatography on
silica gel (Merck; 230–400 mesh). NMR spectra were recorded
2-(Methylsulfonyloxy)-1-phenylethanone 8a. 84% Yield; mp
78–80 ЊC (lit.,20b 76–77 ЊC); νmax (KBr/cmϪ1) 1709, 1358, 1180;
δH (400 MHz; CDCl3) 3.29 (3 H, s, CH3), 5.52 (2 H, s, CH2O),
7.50–7.54 (2 H, m), 7.66 (1 H, m) and 7.89–7.91 (2 H, m) (ArH);
δC (100 MHz; CDCl3) 39.66 (CH3SO2), 70.62 (CH2O), 128.19,
129.50, 133.84 and 134.89 (Ar-C), 191.51 (CO).
1
at 400 MHz for H and 100 MHz for 13C using Me4Si as the
internal standard in CDCl3 or CD3COCD3. J-values are
given in Hz. Optical rotations were measured with a high-
resolution digital polarimeter. [α]D-Values are given in units
1-Phenyl-2-(p-tolylsulfonyloxy)ethanone 8b. 87% Yield; mp
91–92 ЊC (lit.,20a 91–92 ЊC); νmax (KBr/cmϪ1) 1715, 1377, 1194;
δH (400 MHz; CDCl3) 2.45 (3 H, s, CH3), 5.28 (2 H, s, CH2O),
7.35 (2 H, d, J 8.19), 7.46–7.49 (2 H, m), 7.59–7.63 (1 H, m) and
7.83–7.87 (4 H, m) (ArH); δC (100 MHz; CDCl3) 21.70 (CH3),
69.95 (CH2O), 128.00, 128.16, 128.93, 129.92, 132.62, 133.76,
134.22 and 145.32 (Ar-C), 190.32 (CO).
of 10Ϫ1 deg cm2
g
Ϫ1. Mps were measured by the capillary
method and are uncorrected. Enantiomeric excesses (% ee) of
the product epoxides were determined with a GLC apparatus
equipped with a 25 m β-Dex 120 (Supelco) or G-TA
(Astec) chiral capillary column or with an HPLC apparatus
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J. Chem. Soc., Perkin Trans. 1, 2001, 1204–1211

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2-(p-Nitrophenylsulfonyloxy)-1-phenylethanone
8c.
80%
1712, 1527, 1378, 1348, 1191; δH (400 MHz; CDCl3) 2.46 (3 H, s,
Yield; mp 128–130 ЊC (lit.,20c 129–131 ЊC); νmax (KBr/cmϪ1
)
CH3), 5.25 (2 H, s, CH2O), 7.37 (2 H, d, J 8.17), 7.83 (2 H, d,
J 8.26), 8.01–8.05 (2 H, m) and 8.30–8.33 (2 H, m) (ArH);
δC (100 MHz; CDCl3) 21.73 (CH3), 69.99 (CH2O), 124.08,
128.16, 129.36, 130.06, 132.27, 138.23, 145.72 and 150.81
(Ar-C), 189.79 (CO).
1711, 1527, 1377, 1349, 1207; δH (400 MHz; CDCl3) 5.49 (2 H, s,
CH2O), 7.48–7.52 (2 H, m), 7.64 (1 H, m), 7.82–7.84 (2 H, m),
8.18–8.21 (2 H, m) and 8.39–8.42 (2 H, m) (ArH); δC (100 MHz;
CDCl3) 70.89 (CH2O), 124.36, 127.85, 129.12, 129.47, 133.29,
134.60, 141.94 and 150.86 (Ar-C), 189.72 (CO).
1-(4-Phenylphenyl)-2-(p-tolylsulfonyloxy)ethanone 8k. 85%
Yield; mp 137–138 ЊC (Found: C, 68.75; H, 4.92; S, 8.79.
C21H18O4S requires C, 68.83; H, 4.95; S, 8.75%); νmax (KBr/
cmϪ1) 1703, 1374, 1192; δH (400 MHz; CDCl3) 2.45 (2 H, s,
CH3), 5.29 (2 H, s, CH2O), 7.35 (2 H, d, J 8.18), 7.40–7.50 (3 H,
m), 7.61 (2 H, d, J 7.35), 7.69 (2 H, d, J 8.34), 7.87 (2 H, d,
J 8.21) and 7.92 (2 H, d, J 8.34) (ArH); δC (100 MHz; CDCl3)
21.71 (CH3), 69.98 (CH2O), 127.28, 127.50, 128.18, 128.56,
128.65, 129.05, 129.93, 132.43, 132.66, 139.46, 145.32 and
146.91 (Ar-C), 189.94 (CO).
1-(2-Chlorophenyl)-2-(p-tolylsulfonyloxy)ethanone 8d. 78%
Yield; mp 65–67 ЊC (Found: C, 55.43; H, 4.02; S, 9.79. C15H13-
ClO4S requires C, 55.47; H, 4.03; S, 9.87%); νmax (KBr/cmϪ1
)
1714, 1691, 1588, 1431, 1365, 1178, 1041; δH (400 MHz; CDCl3)
2.45 (3 H, s, CH3), 5.17 (2 H, s, CH2O), 7.33–7.37 (3 H, m),
7.40–7.48 (2 H, m) and 7.52 (1 H, dd, J 1.63 and 7.71), 7.81
(1 H, d, J 8.34) (ArH); δC (100 MHz; CDCl3) 21.70 (CH3), 71.75
(CH2O), 127.19, 128.13, 129.92, 130.26, 130.59, 131.64, 132.62,
133.15, 135.26 and 145.32 (Ar-C), 193.61 (CO).
1-(3-Chlorophenyl)-2-(p-tolylsulfonyloxy)ethanone 8e. 76%
Yield; mp 54–56 ЊC (Found: C, 55.42; H, 4.01; S, 9.83. C15H13-
1-(2-Naphthyl)-2-(p-tolylsulfonyloxy)ethanone 8l. 83% Yield;
mp 118–119 ЊC (Found: C, 67.15; H, 4.81; S, 9.45. C19H16O4S
requires C, 67.04; H, 4.74; S, 9.42%); νmax (KBr/cmϪ1) 1698,
1343, 1186, 1046; δH (400 MHz; CDCl3) 2.44 (3 H, s, CH3), 5.40
(2 H, s, CH2O), 7.34 (2 H, d, J 8.16), 7.56–7.66 (2 H, m), 7.87–
7.90 (5 H, m), 7.95 (1 H, d, J 8.03) and 8.35 (1 H, s) (ArH);
δC (100 MHz; CDCl3) 21.70 (CH3), 70.02 (CH2O), 87.12,
123.28, 127.19, 127.89, 128.19, 128.92, 129.15, 129.64, 129.92,
130.00, 131.11, 132.29, 132.69, 135.97 and 145.31 (Ar-C),
190.28 (CO).
ClO4S requires C, 55.47; H, 4.03; S, 9.87%); νmax (KBr/cmϪ1
)
1718, 1362, 1191, 987, 771; δH (400 MHz; CDCl3) 2.46 (3 H, s,
CH3), 5.22 (2 H, s, CH2O), 7.35 (2 H, d, J 8.19), 7.42 (1 H, m),
7.57–7.59 (1 H, m), 7.71–7.73 (1 H, m), 7.79 (1 H, m) and 7.83–
7.85 (2 H, m) (ArH); δC (100 MHz; CDCl3) 21.72 (CH3), 69.85
(CH2O), 126.15, 128.17, 129.98, 130.26, 132.48, 134.12, 135.25,
135.34 and 145.49 (Ar-C), 189.50 (CO).
1-(4-Chlorophenyl)-2-(p-tolylsulfonyloxy)ethanone 8f. 84%
Yield; mp 123–124 ЊC (Found: C, 55.48; H, 4.06; S, 9.72.
C15H13ClO4S requires C, 55.47; H, 4.03; S, 9.87%); νmax (KBr/
cmϪ1) 1702, 1593, 1375, 1190, 1058; δH (400 MHz; CDCl3) 2.45
(3 H, s, CH3), 5.21 (2 H, s, CH2O), 7.35 (2 H, d, J 8.19), 7.43–
7.47 (2 H, m), 7.78–7.81 (2 H, m) and 7.84 (2 H, d, J 8.28)
(ArH); δC (100 MHz; CDCl3) 21.71 (CH3), 69.82 (CH2O),
128.16, 129.30, 129.51, 129.96, 132.10, 132.51, 140.79 and
145.44 (Ar-C), 189.48 (CO).
1-(Methylsulfonyloxy)nonan-2-one 8m. 46% Yield; mp 49–
51 ЊC (Found: C, 50.92; H, 8.51; S, 13.47. C10H20O4S requires C,
50.82; H, 8.53; S, 13.57%); νmax (KBr/cmϪ1) 1730, 1301, 1167;
δH (400 MHz; CDCl3) 0.88 (3 H, t, J 7.06, CH3CH2), 1.28–1.32
(8 H, m, 4 × CH2), 1.58–1.64 (2 H, m, CH2CH2CO), 2.46 (2 H,
t, J 7.35, CH2CO), 3.20 (3 H, s, CH3SO2), 4.79 (2 H, s, CH2O);
δC (100 MHz; CDCl3) 14.05 (CH3), 22.57, 23.13, 28.97, 29.01
and 31.59 (CH2), 38.61 (CH2CO), 38.84 (CH3SO2), 71.64
(CH2O), 203.07 (CO).
1-(3,4-Dichlorophenyl)-2-(p-tolylsulfonyloxy)ethanone
8g.
80% Yield; mp 130–132 ЊC (Found: C, 50.17; H, 3.27; S,
8.89. C15H12Cl2O4S requires C, 50.15; H, 3.37; S, 8.93%);
νmax (KBr/cmϪ1) 1709, 1399, 1348, 1189; δH (400 MHz; CDCl3)
2.46 (3 H, s, CH3), 5.18 (2 H, s, CH2O), 7.36 (2 H, d, J 8.17),
7.56 (1 H, d, J 8.42), 7.68 (1 H, dd, J 2.06 and 8.33), 7.83 (2 H,
d, J 8.35) and 7.90 (1 H, d, J 2.01) (ArH); δC (100 MHz; CDCl3)
21.73 (CH3), 69.77 (CH2O), 127.12, 128.15, 130.00, 130.08,
131.05, 132.70, 133.26, 133.78, 138.92 and 145.60 (Ar-C),
188.85 (CO).
1-Cyclohexyl-2-(p-tolylsulfonyloxy)ethanone 8n. 68% Yield;
mp 53–55 ЊC (Found: C, 60.86; H, 6.92; S, 10.92. C15H20O4S
requires C, 60.79; H, 6.80; S, 10.82%); νmax (KBr/cmϪ1) 1721,
1367, 1184; δH (400 MHz; CDCl3) 1.20–1.32 (6 H, m, 3 × CH2),
1.75–1.78 (5 H, m, 2 × CH2 ϩ CH), 2.46 (3 H, s, CH3), 4.60
(2 H, s, CH2O), 7.36 (2 H, d, J 8.20) and 7.82 (2 H, d, J 8.26)
(ArH); δC (100 MHz; CDCl3) 21.70 (CH3), 25.38, 25.61 and
27.86 (CH2), 46.80 (CH), 70.55 (CH2O), 128.09, 128.92, 129.96,
132.53 and 145.36 (Ar-C), 205.30 (CO).
1-(4-Fluorophenyl)-2-(p-tolylsulfonyloxy)ethanone 8h. 82%
Yield; mp 108–110 ЊC (Found: C, 58.28; H, 4.23; S, 10.25.
C15H13FO4S requires C, 58.43; H, 4.25; S, 10.40%); νmax (KBr/
cmϪ1) 1701, 1596, 1377, 1233, 1139; δH (400 MHz; CDCl3) 2.45
(3 H, s, CH3), 5.21 (2 H, s, CH2O), 7.06–7.18 (2 H, m), 7.35
(2 H, d, J 8.13) and 7.84–7.92 (4 H, m) (ArH); δC (100 MHz;
CDCl3) 21.71 (CH3), 69.81 (CH2O), 116.31, 128.16, 129.95,
130.25, 130.94, 132.55, 145.42, 165.00 and 167.55 (Ar-C),
189.00 (CO).
1-(2-Pyridyl)-2-(p-tolylsulfonyloxy)ethanone 8o. 72% Yield;
mp 64–66 ЊC (lit.,20e 65–68 ЊC) (Found: C, 57.68; H, 4.43; N,
4.79; S, 10.96. C14H13NO4S requires C, 57.72; H, 4.50; N, 4.81;
S, 11.01%); νmax (KBr/cmϪ1) 1722, 1365, 1190; δH (400 MHz;
CDCl3) 2.45 (3 H, s, CH3), 5.63 (2 H, s, CH2O), 7.36 (2 H,
d, J 8.20), 7.50–7.53 (1 H, m), 7.84–7.91 (3 H, m), 8.02 (1 H,
d, J 7.95) and 8.61 (1 H, d, J 4.44) (ArH); δC (100 MHz;
CDCl3) 21.69 (CH3), 70.93 (CH2O), 121.99, 128.15, 128.20,
129.86, 133.09, 137.21, 145.01, 149.11 and 151.13 (Ar-C),
191.11 (CO).
1-(p-Tolyl)-2-(p-tolylsulfonyloxy)ethanone 8i. 87% Yield; mp
92–94 ЊC (lit.,26 82–83 ЊC); νmax (KBr/cmϪ1) 1701, 1609, 1348,
1171, 1055; δH (400 MHz; CDCl3) 2.41 (3 H, s, CH3), 2.45 (3 H,
s, Me), 5.24 (2 H, s, CH2O), 7.25–7.28 (2 H, m), 7.35 (2 H,
d, J 8.22), 7.74 (2 H, d, J 8.20) and 7.86 (2 H, d, J 8.26)
(ArH); δC (100 MHz; CDCl3) 21.67 (CH3), 21.76 (CH3), 69.86
(CH2O), 128.07, 128.13, 129.57, 129.87, 131.25, 132.64, 145.23
and 145.28 (Ar-C), 189.81 (CO).
1-(2-Thienyl)-2-(p-tolylsulfonyloxy)ethanone 8p. 78% Yield;
mp 93–95 ЊC (lit.,20e 94–96 ЊC) (Found: C, 52.78; H, 4.07; S,
21.81. C13H12O4S2 requires C, 52.68; H, 4.08; S, 21.64%);
νmax (KBr/cmϪ1) 1683, 1416, 1384, 1187, 1043; δH (400 MHz;
CDCl3) 2.45 (3 H, s, CH3), 5.09 (2 H, s, CH2O), 7.16 (1 H, d,
J 4.21), 7.35 (2 H, d, J 8.10), 7.73 (1 H, d, J 4.76), 7.80 (1 H,
d, J 3.73) and 7.85 (2 H, d, J 8.21) (Ar-H and thienyl-H);
δC (100 MHz; CDCl3) 21.71 (CH3), 69.90 (CH2O), 128.20,
128.49, 129.97, 132.39, 133.16, 135.16, 140.03 and 145.46 (Ar-C
and thienyl-C), 183.66 (CO).
1-(4-Nitrophenyl)-2-(p-tolylsulfonyloxy)ethanone 8j. 86%
Yield; mp 134–136 ЊC (lit.,26 130–131 ЊC); νmax (KBr/cmϪ1
)
J. Chem. Soc., Perkin Trans. 1, 2001, 1204–1211
1207

View Article Online
General procedure for oxazaborolidine-catalyzed asymmetric
borane reduction of ꢀ-sulfonyloxy ketones 8
(S)-(؉)-1-(4-Chlorophenyl)-2-(p-tolylsulfonyloxy)ethanol 9f.
99% Yield; Rf 0.63; mp 89–90 ЊC (Found: C, 53.38; H, 4.67;
S, 9.69. C15H15ClO4S requires C, 53.13; H, 4.63; S, 9.81%);
[α]D22 ϩ45.5 (c 1.00, CHCl3); νmax (neat/cmϪ1) 3537, 1348, 1178;
δH (400 MHz; CDCl3) 2.45 (3 H, s, CH3), 2.59 (1 H, br s, OH),
4.02 (1 H, dd, J 8.20 and 10.47, OCHaHb), 4.12 (1 H, dd, J 3.45
and 10.47, OCHaHb), 4.97 (1 H, m, CHOH), 7.24–7.35 (6 H, m)
and 7.74–7.76 (2 H, m) (ArH); δC (100 MHz; CDCl3) 22.08
(CH3), 71.69 (CH2O), 74.36 (CHOH), 127.95, 128.32, 129.22,
130.36, 132.86, 134.73, 137.11 and 145.62 (Ar-C).
To a solution of 1 (0.2 M; 1.0 cm3, 0.2 mmol) in THF was
added a solution of N-ethyl-N-isopropylaniline–borane com-
plex 5 (2.0 M; 1.0 cm3, 2.0 mmol) in THF. To this was added
slowly 2 cm3 of a THF solution of 8 (2 mmol) over a period of
1 h using a syringe pump at 25 ЊC. After the addition, the reac-
tion mixture was stirred for 10 min, quenched cautiously with
methanol (0.5 cm3), and stirred for an additional 30 min. The
solvent was evaporated off under reduced pressure. The crude
products 9 obtained were further purified by flash column
chromatography on silica gel (230–400 mesh), using hexane–
ethyl acetate (1 : 1) as eluent, unless otherwise indicated.
(S)-(؉)-1-(3,4-Dichlorophenyl)-2-(p-tolylsulfonyloxy)ethanol
9g. 99% Yield; Rf 0.57; mp 87–88 ЊC (Found: C, 49.83; H, 4.00;
S, 8.93. C15H14Cl2O4S requires C, 49.87; H, 3.91; S, 8.88%);
[α]D22 ϩ39.6 (c 1.04, CHCl3); νmax (neat/cmϪ1) 3502, 1356, 1190;
δH (400 MHz; CDCl3) 2.46 (3 H, s, CH3), 2.66 (1 H, br s, OH),
4.02 (1 H, dd, J 7.92 and 10.53, OCHaHb), 4.12 (1 H, dd, J 3.59
and 10.53, OCHaHb), 4.94 (1 H, m, CHOH), 7.14 (1 H, d, J 1.93
and 8.35), 7.33 (2 H, d, J 8.17), 7.38–7.40 (2 H, m) and 7.73
(2 H, d, J 8.35) (ArH); δC (100 MHz; CDCl3) 21.71 (CH3), 70.79
(CH2O), 73.62 (CHOH), 125.53, 127.91, 128.21, 128.30, 129.99,
130.59, 132.33, 132.52, 132.89, 138.57 and 145.36 (Ar-C).
(S)-(؉)-2-(Methylsulfonyloxy)-1-phenylethanol 9a. 99%
Yield; Rf 0.51; oil (Found: C, 49.98; H, 5.61; S, 14.62. C9H12O4S
requires C, 49.99; H, 5.59; S, 14.83%); [α]D22 ϩ53.8 (c 1.12,
CHCl3); νmax (neat/cmϪ1) 3495, 3110, 1352, 1172, 979; δH (400
MHz; CDCl3) 2.92 (3 H, s, CH3), 4.17–4.26 (2 H, m, CH2O),
4.94 (1 H, m, CHOH), 7.25–7.36 (5 H, m) (ArH); δC (100 MHz;
CDCl3) 37.33 (CH3SO2), 71.72 (CH2O), 74.04 (CHOH),
126.24, 128.48, 128.65 and 138.62 (Ar-C).
(S)-(؉)-1-(4-Fluorophenyl)-2-(p-tolylsulfonyloxy)ethanol 9h.
99% Yield; Rf 0.58; mp 65–67 ЊC (Found: C, 58.09; H, 4.79; S,
10.46. C15H15FO4S requires C, 58.05; H, 4.87; S, 10.33%);
[α]D22 ϩ47.0 (c 1.05, CHCl3); νmax (neat/cmϪ1) 3529, 1344, 1185;
δH (400 MHz; CDCl3) 2.45 (3 H, s, CH3), 2.60 (1 H, d, J 3.19,
OH), 4.02 (1 H, dd, J 8.39 and 10.44, OCHaHb), 4.12 (1 H, dd,
J 3.44 and 10.47, OCHaHb), 4.97 (1 H, m, CHOH), 7.00–7.05
(2 H, m), 7.26–7.32 (2 H, m), 7.34 (2 H, d, J 8.18) and 7.75–7.78
(2 H, m) (ArH); δC (100 MHz; CDCl3) 21.67 (CH3), 71.33
(CH2O), 74.12 (CHOH), 115.49, 115.71, 127.94, 128.01, 129.97,
132.59, 134.04, 134.07 and 145.19 (Ar-C).
(S)-(؉)-1-Phenyl-2-(p-tolylsulfonyloxy)ethanol
9b.
99%
Yield; Rf 0.74; mp 71–72 ЊC (lit.,3 65–66 ЊC; lit.,2 73 ЊC) (Found:
C, 61.63; H, 5.63; S, 10.95. C15H16O4S requires C, 61.62; H,
5.52; S, 10.97%); [α]D22 ϩ50.4 (c 2.41, CHCl3) {lit.,21 [α]D21 ϩ51.1
(c 1.00, CHCl3); lit.,22 [α]D23 ϩ55.0 (c 2.4, CHCl3)}; νmax (neat/
cmϪ1) 3539, 1376, 1177, 961, 867, 757, 704; δH (400 MHz;
CDCl3) 2.45 (3 H, s, CH3), 4.04 (1 H, dd, J 8.57 and 10.45,
OCHaHb), 4.14 (1 H, dd, J 3.20 and 10.39, OCHaHb), 4.98 (1 H,
ddd, J 8.58, 3.20 and 3.24, CHOH), 7.26–7.36 (7 H, m) and
7.76–7.78 (2 H, m) (ArH); δC (100 MHz; CDCl3) 21.68 (CH3),
71.97 (CH2O), 74.34 (CHOH), 126.19, 127.97, 128.56, 128.69,
129.96, 132.63, 138.17 and 145.10 (Ar-C).
(S)-(؉)-1-(4-Tolyl)-2-(p-tolylsulfonyloxy)ethanol 9i. 99%
Yield; Rf 0.60; mp 84–85 ЊC (Found: C, 62.76; H, 5.99; S, 10.31.
C16H18O4S requires C, 62.72; H, 5.92; S, 10.47%); [α]D22 ϩ56.7
(c 1.01, CHCl3); νmax (neat/cmϪ1) 3502, 1350, 1185; δH (400
MHz; CDCl3) 2.33 (3 H, s, CH3), 2.46 (3 H, s, CH3), 2.47 (1 H,
br s, OH), 4.03 (1 H, dd, J 8.63 and 10.37, OCHaHb), 4.13 (1 H,
dd, J 3.28 and 10.29, OCHaHb), 4.95 (1 H, m, CHOH), 7.13–
7.34 (6 H, m) and 7.76–7.78 (2 H, m) (ArH); δC (100 MHz;
CDCl3) 21.14 and 21.66 (CH3), 71.78 (CH2O), 74.37 (CHOH),
126.09, 127.95, 129.32, 129.91, 132.65, 135.17, 138.38 and
145.03 (Ar-C).
(S)-(؉)-2-(p-Nitrophenylsulfonyloxy)-1-phenylethanol
9c.
99% Yield; Rf 0.64; mp 106–107 ЊC (Found: C, 52.04; H, 4.24;
N, 4.41; S, 9.80. C14H13NO6S requires C, 52.01; H, 4.05; N, 4.33;
S, 9.92%); [α]D22 ϩ40.0 (c 1.00, acetone); νmax (neat/cmϪ1) 3561,
3520, 1547, 1382, 1182; δH (400 MHz, acetone-d6) 4.37–4.47
(2 H, m, CH2O), 5.14 (1 H, m, CHOH), 7.44–7.54 (5 H, m),
8.30 (2 H, d, J 2.0) and 8.63 (2 H, d, J 2.0) (ArH); δC (100 MHz,
acetone-d6) 72.06 (CH2O), 76.83 (CHOH), 125.84, 127.58,
129.09, 129.51, 130.70, 141.43 and 142.83 (Ar-C).
(S)-(؉)-1-(2-Chlorophenyl)-2-(p-tolylsulfonyloxy)ethanol 9d.
99% Yield; Rf 0.63; oil (Found: C, 53.34; H, 4.66; S, 9.66.
C15H15ClO4S requires C, 53.13; H, 4.63; S, 9.81%); [α]D22 ϩ43.8
(c 1.08, CHCl3); νmax (neat/cmϪ1) 3471, 1355, 1176, 971;
δH (400 MHz; CDCl3) 2.44 (3 H, s, CH3), 2.78 (1 H, br s, OH),
3.98 (1 H, dd, J 8.33 and 10.55, OCHaHb), 4.27 (1 H, dd, J 2.65
and 10.58, OCHaHb), 5.36 (1 H, m), 7.22–7.35 (5 H, m), 7.56–
7.59 (1 H, m) and 7.77–7.79 (2 H, m) (ArH); δC (100 MHz;
CDCl3) 21.65 (CH3), 68.82 (CH2O), 72.74 (CHOH), 127.24,
127.81, 127.98, 129.41, 129.47, 129.92, 131.79, 132.52, 135.61
and 145.09 (Ar-C).
(S)-(؉)-1-(4-Nitrophenyl)-2-(p-tolylsulfonyloxy)ethanol 9j.
99% Yield; Rf 0.42; mp 168–169 ЊC (Found: C, 53.32; H, 4.54;
N, 4.19; S, 9.49. C15H15NO6S requires C, 53.40; H, 4.48; N, 4.15;
S, 9.51%); [α]D22 ϩ30.3 (c 1.02, acetone); νmax (neat/cmϪ1) 3507,
1516, 1346, 1172; δH (400 MHz, acetone-d6) 2.31 (3 H, s, CH3),
4.02–4.11 (2 H, m, CH2O), 4.99 (1 H, m, CHOH), 7.27 (d, 2 H,
J 8.16), 7.49–7.52 (2 H, m), 7.54–7.57 (2 H, m) and 8.01–8.05
(2 H, m) (ArH); δC (100 MHz, acetone-d6) 71.41 (CH2O), 75.01
(CHOH), 124.46, 128.79, 129.07, 131.16, 134.25, 146.30 and
149.31 (Ar-C).
(S)-(؉)-1-(4-Phenylphenyl)-2-(p-tolylsulfonyloxy)ethanol 9k.
99% Yield; Rf 0.61; mp 101–102 ЊC (Found: C, 68.34; H, 5.62; S,
8.57. C21H20O4S requires C, 68.46; H, 5.47; S, 8.70%); [α]D22 ϩ50.0
(c 1.01, CHCl3); νmax (neat/cmϪ1) 3530, 1330, 1187; δH (400 MHz;
CDCl3) 2.43 (3 H, s, CH3), 2.61 (1 H, d, J 3.24, OH), 4.09
(1 H, dd, J 8.41 and 10.39, OCHaHb), 4.19 (1 H, dd, J 3.34
and 10.39, OCHaHb), 5.03 (1 H, m, CHOH), 7.31–7.39 (5 H,
m), 7.42–7.46 (2 H, m), 7.55–7.57 (4 H, m) and 7.77–7.79
(2 H, m) (ArH); δC (100 MHz; CDCl3) 21.66 (CH3), 71.74
(CH2O), 74.27 (CHOH), 126.65, 127.08, 127.38, 127.53, 127.97,
128.83, 129.95, 132.63, 137.19, 140.48, 141.49 and 145.10
(Ar-C).
(S)-(؉)-1-(3-Chlorophenyl)-2-(p-tolylsulfonyloxy)ethanol 9e.
99% Yield; Rf 0.65; oil (Found: C, 53.34; H, 4.59; S, 9.67.
C15H15ClO4S requires C, 53.13; H, 4.63; S, 9.81%); [α]D22 ϩ39.6
(c 1.32, CHCl3); νmax (neat/cmϪ1) 3518, 1356, 1176, 974;
δH (400 MHz; CDCl3) 2.45 (3 H, s, CH3), 2.86 (1 H, d, J 3.1,
OH), 4.02 (1 H, dd, J 8.22 and 10.42, OCHaHb), 4.12 (1 H, dd,
J 3.43 and 10.42, OCHaHb), 4.95 (1 H, m, CHOH), 7.17–7.34
(6 H, m) and 7.74 (2 H) (ArH); δC (100 MHz; CDCl3) 21.68
(CH3), 71.26 (CH2O), 73.03 (CHOH), 124.41, 125.88, 126.36,
127.92, 128.15, 128.58, 129.92, 129.99, 132.39, 134.60, 140.40
and 145.24 (Ar-C).
1208
J. Chem. Soc., Perkin Trans. 1, 2001, 1204–1211

View Article Online
(S)-(؉)-1-(2-Naphthyl)-2-(p-tolylsulfonyloxy)ethanol 9l. 99%
Yield; Rf 0.62; mp 113–115 ЊC (Found: C, 66.69; H, 5.41; S,
9.27. C19H18O4S requires C, 66.65; H, 5.30; S, 9.37%); [α]D22 ϩ57.2
(c 1.00, CHCl3); νmax (neat/cmϪ1) 3553, 1350, 1173; δH (400 MHz;
CDCl3) 2.41 (3 H, s, CH3), 2.68 (1 H, br s, OH), 4.14 (1 H, dd,
J 8.30 and 10.35, OCHaHb), 4.24 (1 H, dd, J 3.38 and 10.38,
OCHaHb), 5.15 (1 H, m, CHOH), 7.25–7.27 (2 H, m), 7.38 (1 H,
m), 7.47–7.51 (2 H, m), 7.72–7.74 (2 H, m) and 7.79–7.84 (4 H,
m) (ArH); δC (100 MHz; CDCl3) 21.63 (CH3), 72.04 (CH2O),
74.23 (CHOH), 123.69, 125.41, 126.33, 126.40, 126.63, 127.89,
127.98, 128.48, 129.87, 132.51, 133.11, 133.26, 135.61 and
145.04 (Ar-C).
reduced pressure, and the residue was further purified by flash
column chromatography on silica gel (230–400 mesh), using
ethyl acetate–hexane (1 : 2) as eluent, unless otherwise indicated.
(S)-(؊)-Phenyloxirane 10. 96% Yield; Rf 0.82; oil (Found: C,
79.91; H, 6.65. C8H8O requires C, 79.97; H, 6.71%); [α]D22 Ϫ44.5
(c 1.15, PhH); {lit.,14 [α]D23 Ϫ44.9 (c 1.02, PhH), S}; HPLC anal-
ysis using a Chiralcel OD column showed it to be 99% ee
[iPrOH–hexane 0.2 : 99.8, flow rate 0.2 cm3 minϪ1, tR(S) 56.79
min and tR(R) 60.99 min]; νmax (neat/cmϪ1) 1496, 1476, 1452,
1390; δH (400 MHz; CDCl3) 2.81 (1 H, dd, J 2.62 and 5.46,
CHaCHbO), 3.15 (1 H, dd, J 4.13 and 5.45, CHaCHbO), 3.87
(1 H, dd, J 2.65 and 3.92, CHO), 7.26–7.36 (5 H, m, Ar-H) ;
δC (100 MHz; CDCl3) 51.22 (CH2O), 52.36 (CHOH), 125.47,
128.18, 128.39 and 137.57 (Ar-C).
(S)-(؉)-1-(Methylsulfonyloxy)nonan-2-ol 9m. 99% Yield; Rf
0.42; mp 39–41 ЊC (Found: C, 50.43; H, 9.51; S, 13.42.
C10H22O4S requires C, 50.39; H, 9.30; S, 13.45%); [α]D22 ϩ3.5
(c 1.20, CHCl3); νmax (KBr/cmϪ1) 3426, 1346, 1173; δH (400
MHz; CDCl3) 0.88 (3 H, t, J 7.02, CH3), 1.28–1.30 (9 H, m) and
1.48–1.52 (3 H, m) (6 × CH2), 2.10–2.11 (1 H, m, OH), 3.07
(3 H, s, CH3SO2), 3.91–3.94 (1 H, m, CHOH), 4.10 (1 H, dd,
J 7.51 and 10.54, OCHaHb), 4.26 (1 H, dd, J 2.80 and 10.55,
OCHaHb); δC (100 MHz; CDCl3) 13.47, 23.01, 25.67, 29.52,
29.80, 32.12, 33.13 and 37.93 (CH3 and CH2), 70.12 (CH2O),
74.07 (CHOH).
(S)-(؉)-(2-Chlorophenyl)oxirane 11. 94% Yield; Rf 0.76; oil
(Found: C, 62.18; H, 4.61. C8H7ClO requires C, 62.15; H,
4.56%); [α]D22 ϩ43.7 (c 1.42, CHCl3); {lit.,27 [α]D25 ϩ32.2 (c 1.19,
CHCl3), >99% ee, S}; GLC analysis using a β-Dex 120 chiral
column (Supelco) showed it to be 80% ee [100 ЊC (isothermal),
tR(R) 54.00 min and tR(S) 55.68 min]; νmax (neat/cmϪ1) 1498,
1441, 1381, 1250; δH (400 MHz; CDCl3) 2.67 (1 H, dd, J 2.64
and 5.72, CHaCHbO), 3.20 (1 H, dd, J 4.09 and 5.68, CHa-
CHbO), 4.22 (1 H, dd, J 2.59 and 4.03, CHO), 7.21–7.26 (3 H,
m) and 7.35–7.38 (1 H, m) (ArH); δC (100 MHz; CDCl3) 50.05
(CH2O), 50.73 (CHOH), 125.68, 127.07, 128.93, 129.15, 133.28
and 135.60 (Ar-C).
(S)-(؉)-1-Cyclohexyl-2-(p-tolylsulfonyloxy)ethanol 9n. 99%
Yield; Rf 0.55 (Et2O–CHCl3 1 : 2); oil (Found: C, 60.34; H, 7.65;
S, 10.47. C15H22O4S requires C, 60.38; H, 7.43; S, 10.75%);
[α]D22 ϩ12.1 (c 1.02, CHCl3); νmax (neat) 3535, 1598, 1450, 1358,
1175; δH (400 MHz; CDCl3) 0.96–1.22 (6 H, m, 3 × CH2), 1.53–
1.61 (5 H, m, 2 × CH2 ϩ CH), 2.00 (1 H, d, J 4.95, OH), 2.45
(3 H, s, CH3), 3.55–3.60 (1 H, m, CHOH), 3.97 (1 H, dd, J 7.31
and 10.11, OCHaHb), 4.12 (1 H, dd, J 2.90 and 10.11,
OCHaHb), 7.36 (2 H, d, J 8.21) and 7.80 (2 H, d, J 8.23)
(ArH); δC (100 MHz; CDCl3) 15.28, 21.67, 25.82, 25.95, 26.19,
28.09, 28.86, 40.22 and 65.86 (CH2 and CH), 72.70 (CH2O),
73.56 (CHOH), 127.97, 129.95, 132.73 and 145.03 (Ar-C).
(S)-(؉)-(3-Chlorophenyl)oxirane 12. 95% Yield; Rf 0.72; oil
(Found: C, 62.16; H, 4.59. C8H7ClO requires C, 62.15; H,
4.56%); [α]D22 ϩ11.15 (c 1.56, CHCl3) {lit.,28 [α]D20 ϩ11.1 (c 1.23,
CHCl3), >99% ee, R}. GLC analysis using a G-TA column
(Astec) showed it to be 99.3% ee [120 ЊC (isothermal); tR (R)
9.34 min and tR(S) 6.97 min]; νmax (neat/cmϪ1) 1481, 1434;
δH (400 MHz; CDCl3) 2.76 (1 H, dd, J 2.52 and 5.45, CHa-
CHbO), 3.15 (1 H, dd, J 4.08 and 5.45, CHaCHbO), 3.84 (1 H,
dd, J 2.57 and 3.96, CHO), 7.16–7.29 (4 H, m, Ar-H); δC (100
MHz; CDCl3) 51.24 (CH2O), 51.70 (CHOH), 123.72, 125.50,
129.78, 134.59 and 139.82 (Ar-C).
(S)-(؉)-1-(2-Pyridyl)-2-(p-tolylsulfonyloxy)ethanol 9o. 99%
Yield; mp 66–68 ЊC (Found: C, 57.37; H, 5.35; N, 4.77; S, 10.92.
C14H15NO4S requires C, 57.32; H, 5.15; N, 4.77; S, 10.93%); [α]D22
ϩ4.5 (c 1.01, CHCl3); νmax (KBr/cmϪ1) 3132, 1597, 1374, 1187;
δH (400 MHz; CDCl3) 2.44 (3 H, s, CH3), 4.22–4.27 (2 H, m,
CH2), 4.94 (1 H, m, CHOH), 7.23–7.37 (4 H, m), 7.68–7.75
(3 H, m) and 8.51 (1 H, d, J 4.72) (Ar-H ϩ pyridyl-H); δC (100
MHz; CDCl3) 21.66 (CH3), 70.55 (CH2O), 73.18 (CHOH),
121.31, 123.24, 127.98, 129.86, 132.66, 136.96, 144.92, 148.53
and 156.87 (Ar-C ϩ pyridyl-C).
(S)-(؉)-(4-Chlorophenyl)oxirane 13. 96% Yield; Rf 0.76; oil
(Found: C, 62.12; H, 4.51. C8H7ClO requires C, 62.15; H,
4.56%); [α]D22 ϩ25.5 (c 1.00, CHCl3); {lit.,12b [α]D20 Ϫ24.0 (c 1.08,
CHCl3), >97% ee, R}; HPLC analysis using a Chiralpak OT
column showed it to be 99% ee [iPrOH–hexane 1 : 99, flow rate
0.2 cm3 minϪ1, tR(S) 30.90 min and tR(R) 33.47 min]; νmax (neat/
cmϪ1) 1496, 1089; δH (400 MHz; CDCl3) 2.76 (1 H, dd, J 2.51
and 5.47, CHaCHbO), 3.15 (1 H, dd, J 4.24 and 5.13, CHa-
CHbO), 3.84 (1 H, dd, J 2.87 and 3.62, CHO), 7.20–7.26 (2 H,
m) and 7.31–7.34 (2 H, m) (ArH); δC (100 MHz; CDCl3) 51.28
(CH2O), 51.81 (CHOH), 126.85, 128.73, 133.95 and 136.19
(Ar-C).
(R)-(؉)-1-(2-Thienyl)-2-(p-tolylsulfonyloxy)ethanol 9p. 99%
Yield; Rf 0.55 (Et2O–CHCl3 1 : 2); mp 75–76 ЊC (Found: C,
52.38; H, 4.71; S, 21.51. C13H14O4S2 requires C, 52.33; H, 4.73;
S, 21.49%); [α]D22 ϩ34.2 (c 1.05, CHCl3); νmax (KBr/cmϪ1) 3541,
1357, 1188; δH (400 MHz; CDCl3) 2.46 (3 H, s, CH3), 2.64 (1 H,
d, J 3.81, OH), 4.12–4.24 (2 H, m, CH2O), 5.21–5.25 (1 H, m,
CHOH), 6.96–6.98 (2 H, m), 7.27–7.29 (1 H, m), 7.35 (2 H, d,
J 8.20) and 7.79 (2 H, d, J 8.24) (Ar-H and thienyl-H); δC (100
MHz; CDCl3) 21.69 (CH3), 68.31 (CH2O), 73.67 (CHOH),
125.00, 125.67, 126.96, 128.01, 129.99, 132.65, 141.39 and
145.21 (Ar-C and thienyl-C).
(S)-(؉)-(3,4-Dichlorophenyl)oxirane 14. 94% Yield; Rf 0.75
(ethyl acetate–hexane 1 : 1); oil (Found: C, 50.79; H, 3.21.
C8H6Cl2O requires C, 50.83; H, 3.20%); [α]D22 ϩ15.3 (c 1.18,
CHCl3); {lit.,6f [α]D Ϫ11 (c 1.00, CHCl3), 96% ee, R}; HPLC
analysis using a Chiralpak OT column showed it to be 94% ee
[iPrOH–hexane 1 : 99, flow rate 0.2 cm3 minϪ1, tR(S) 32.84 min
and tR(R) 34.91 min]; νmax (neat/cmϪ1) 1469, 1410, 1370, 1132,
1029; δH (400 MHz; CDCl3) 2.73 (1 H, dd, J 2.49 and 5.47,
CHaCHbO), 3.15 (1 H, dd, J 4.08 and 5.43, CHaCHbO), 3.82
(1 H, dd, J 2.55 and 3.90, CHO), 7.12 (1 H, dd, J 1.99 and 8.31),
7.37 (1 H, d, J 1.97) and 7.42 (1 H, d, J 8.22) (ArH); δC (100
MHz; CDCl3) 51.23 (CH2O), 51.27 (CHOH), 124.84, 127.42,
130.55, 132.13, 132.86 and 138.08 (Ar-C).
General procedure for preparation of optically active terminal
oxiranes 10–22 from 1,2-diol monosulfonates 9
A solution of the crude product 9 (2 mmol), obtained from the
above experiments, in diethyl ether (15 cm3) was directly treated
with 2 M NaOH (5 cm3) for 3 h at room temperature. The ether
layer was separated and the aqueous layer was extracted with
diethyl ether (3 × 15 cm3). The combined ether layer was dried
over anhydrous MgSO4. The solvent was evaporated off under
(S)-(؉)-(4-Fluorophenyl)oxirane 15. 96% Yield; Rf 0.77 (ethyl
acetate–hexane 1 : 1); oil (Found: C, 69.71; H, 5.27. C8H7FO
J. Chem. Soc., Perkin Trans. 1, 2001, 1204–1211
1209

View Article Online
requires C, 69.56; H, 5.11%); [α]D22 ϩ19.2 (c 1.20, CHCl3); {lit.,12b
[α]D Ϫ17 (c 1.03, CHCl3), 97% ee, R}; GLC analysis using a β-
Dex 120 chiral column (Supelco) showed it to be 98% ee [110 ЊC
(isothermal), tR(R) 18.21 min and tR(S) 18.93 min]; νmax (neat/
cmϪ1) 1607, 1514, 1223; δH (400 MHz; CDCl3) 2.77 (1 H, dd,
J 2.55 and 5.41, CHaCHbO), 3.14 (1 H, dd, J 4.08 and 5.35,
CHaCHbO), 3.85 (1 H, dd, J 2.69 and 3.83, CHO), 7.02–7.06
(2 H, m), 7.23–7.27 (2 H, m) (ArH); δC (100 MHz; CDCl3) 51.18
(CH2O), 51.58 (CHOH), 115.39, 115.61, 127.14, 127.22, 133.33,
161.48 (Ar-C).
(S)-(؉)-Cyclohexyloxirane 21. 96% Yield; Rf 0.31 (Et2O–
CHCl3 1 : 2); oil (Found: C, 76.09; H, 11.26. C8H14O requires
C, 76.14; H, 11.18%); [α]D22 ϩ2.1 (c 0.88, CHCl3); GLC analysis
using a G-TA chiral column (Astec) showed it to be 96% ee
[65 ЊC (isothermal), tR(R) 12.13 min and tR(S) 13.12 min].
Absolute configuration of product 21 was determined by com-
parison with the optical rotation value of the same compound
obtained from (S)-(ϩ)-cyclohexylethane-1,2-diol;31 νmax (neat)
2927, 1449; δH (400 MHz; CDCl3) 1.08–1.30 (6 H, m, 3 × CH2),
1.66–1.76 (4 H, m, 2 × CH2), 1.86–1.89 (1 H, m, CH),
2.52 (1 H, t, J 4.24, CHaCHbO), 2.69–2.72 (2 H, m, CHa-
CHbO ϩ CHO); δC (100 MHz; CDCl3) 25.94, 26.10, 26.72,
29.22, 30.12 and 40.78 (cyclohexyl-C), 46.42 (CH2O), 57.07
(CHOH).
(S)-(؊)-(4-Tolyl)oxirane 16. 95% Yield; Rf 0.76; oil (Found:
C, 80.58; H, 7.63. C9H10O requires C, 80.56; H, 7.51%); [α]D22
Ϫ25.9 (c 1.02, PhH); {lit.,29 [α]D20 ϩ25.5 (c 1.3, PhH), 98% ee, R};
HPLC analysis using a Chiralcel OD column showed it to be
97% ee [iPrOH–hexane 0.2 : 99.8, flow rate 0.5 cm3 minϪ1, tR(S)
18.63 min and tR(R) 20.57 min]; νmax (neat/cmϪ1) 1518, 1383;
δH (400 MHz; CDCl3) 2.35 (3 H, s, CH3), 2.80 (1 H, dd, J 2.55
and 5.47, CHaCHbO), 3.13 (1 H, dd, J 4.08 and 5.41, CHa-
CHbO), 3.93 (1 H, dd, J 2.67 and 3.94, CHO), 7.14–7.19 (4 H,
m, Ar-H); δC (100 MHz; CDCl3) 21.58, 51.52 (CH2O), 52.74
(CHOH), 125.86, 129.59, 134.89 and 138.39 (Ar-C).
(S)-(؉)-(2-Pyridyl)oxirane 22. 92% Yield; Rf 0.63 (ethyl
acetate–hexane 1 : 4); oil (Found: C, 69.45; H, 5.79; N, 11.58.
C7H7NO requires C, 69.41; H, 5.81; N, 11.56%); [α]D22 ϩ2.9
(c 0.41, CHCl3) {lit.,32 [α]D19 ϩ14.0 (c 0.56, CHCl3), >99% ee, S};
GLC analysis using a G-TA chiral column (Astec) showed it to
be 21% ee [95 ЊC (isothermal), tR(R) 12.66 min and tR(S) 13.41
min]; νmax (neat) 3014, 1594, 1476, 1438; δH (400 MHz; CDCl3)
2.94 (1 H, dd, J 2.46 and 5.82, CHaCHbO), 3.18 (1 H, dd,
J 3.22 and 5.69, CHaCHbO), 4.02 (1 H, dd, J 2.58 and 3.98,
CHO), 7.25 (2 H, m), 7.68 (1 H, m) and 8.57 (1 H, d, J 4.55)
(pyridyl-H); δC (100 MHz; CDCl3) 50.76 (CH2O), 53.22
(CHOH), 120.06, 123.48, 137.18, 149.80 and 157.59 (pyridyl-
C).
(S)-(؉)-(4-Nitrophenyl)oxirane 17. 96% Yield; Rf 0.53; mp
84–85 ЊC (lit.,6h mp 84 ЊC) (Found: C, 58.21; H, 4.28; N, 8.51.
C8H7NO3 requires C, 58.18; H, 4.27; N, 8.48%); [α]D22 ϩ37.8
(c 1.34, CHCl3); {lit.,6h [α]D25 ϩ36.0 (c 1.25, CHCl3), 95% ee, S};
HPLC analysis using a Chiralpak OT column showed it to be
97% ee [iPrOH–hexane 1 : 40, flow rate 0.2 cm3 minϪ1, tR(S)
52.40 min and tR(R) 56.47 min]; νmax (KBr/cmϪ1) 1606, 1522,
1345; δH (400 MHz; CDCl3) 2.78 (1 H, dd, J 2.46 and 5.51,
CHaCHbO), 3.24 (1 H, dd, J 4.16 and 5.45, CHaCHbO), 3.97
(1 H, dd, J 2.54 and 3.91, CHO), 7.45–7.47 (2 H, m) and 8.21–
8.24 (2 H, m) (ArH); δC (100 MHz; CDCl3) 51.66 (CH2O), 51.89
(CHOH), 126.04, 126.42, 145.44 and 148.60 (Ar-C).
Acknowledgement
We are grateful to the Korea Research Foundation (KRF-99-
041-D00230) for financial support.
References
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69 ЊC (lit.,6f mp 61–63 ЊC) (Found: C, 84.64; H, 5.96. C12H10O
requires C, 84.68; H, 5.92%); [α]D22 ϩ11.4 (c 1.11, CHCl3), 100%
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1508, 1334; δH (400 MHz; CDCl3) 2.91 (1 H, dd, J 2.54 and
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4.04 (1 H, dd, J 2.66 and 3.92, CHO), 7.33 (1 H, m), 7.47–7.50
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(S)-(؊)-Heptyloxirane 20. 99% Yield; Rf 0.83; oil (Found: C,
75.90; H, 12.67. C9H18O requires C, 76.00; H, 12.76%); [α]D22
Ϫ3.7 (c 1.14, CHCl3), 40% ee {lit.,30 [α]D Ϫ8.9 (c 1.14, CHCl3),
97% ee, S}; νmax (neat/cmϪ1) 2924, 1480; δH (400 MHz; CDCl3)
0.83–0.93 (4 H, m), 1.18–1.41 (8 H, m) and 1.42–1.57 (3 H, m)
(n-heptyl-H), 2.46 (1 H, dd, J 2.73 and 5.02, CHaCHbO), 2.74
(1 H, t, J 4.68, CHaCHbO), 2.90 (1 H, m, CHO); δC (100 MHz;
CDCl3) 14.09 (CH3), 22.65, 25.99, 29.23, 29.42, 31.78 and 32.52
(CH2), 47.14 (CH2O), 52.42 (CHOH).
1210
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