Kinetic resolution of trans-2-acetoxycycloalkan-1-ols by lipase-catalysed enantiomerically selective acylation

Article abstract of DOI:10.1016/S0957-4166(03)00568-8

Kinetic resolution of a series of racemic trans-cycloalkane-1,2-diol monoacetates rac-2a-d was performed by enantiomerically selective transesterification with vinyl acetate catalysed by commercial and our own-prepared fungal lipases to yield diacetates (

Full text of DOI:10.1016/S0957-4166(03)00568-8

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 14 (2003) 2605–2612
Kinetic resolution of trans-2-acetoxycycloalkan-1-ols by
lipase-catalysed enantiomerically selective acylation
Vikto´ria Bo´dai,a,b Olive´r Orovecz,a Gyo¨rgy Szaka´cs,b Lajos Nova´ka and La´szlo´ Poppea,*
aInstitute for Organic Chemistry and Research Group for Alkaloid Chemistry of the Hungarian Academy of Sciences,
Budapest University of Technology and Economics, H-1111 Budapest, Gelle´rt te´r 4., Hungary
bDepartment of Agricultural Chemical Technology, Budapest University of Technology and Economics, Gelle´rt te´r 4,
H-1111 Budapest, Hungary
Received 23 May 2003; accepted 1 July 2003
Abstract—Kinetic resolution of a series of racemic trans-cycloalkane-1,2-diol monoacetates rac-2a–d was performed by enan-
tiomerically selective transesterification with vinyl acetate catalysed by commercial and our own-prepared fungal lipases to yield
diacetates (R,R)-3a–d and monoacetates (S,S)-2a–d in high enantiomeric purity. The monoacetates (R,R)-2a–d were also prepared
from the racemic diacetates rac-3a–d by lipase-catalysed hydrolysis.
© 2003 Elsevier Ltd. All rights reserved.
1. Introduction
Enantiopure trans-cycloalkane-1,2-diols 1a–d are useful
as building blocks in the synthesis of optically active
crown ethers1 and as chiral auxiliaries for various asym-
metric reactions.2,3 Recently, (S,S)-cyclohexane-1,2-diol
(S,S)-1b have been applied in mechanistic studies of
rearrangement reactions.4
Optically active derivatives of trans-cycloalkane-1,2-
diols 1a–d were previously prepared by enzyme-
catalysed acylation of the racemic diols rac-1a–d with
lipase from Pseudomonas sp. (SAM II)5 or with lipase
Figure 1. Enzymatic acylation of trans-cycloalkane-1,2-diols
from Pseudomonas cepacia (lipase PS, Amano)6 (Fig. 1).
rac-1a–d.
On the other hand, enzymatic hydrolyses of the corre-
and enantiomeric composition.7 Although the parame-
ters of the sequential kinetic resolution of racemic
trans-diacetoxycyclohexane rac-3a by hydrolysis with
PLE and lipase P were precisely optimized,12 hydrolysis
could not provide both diacetates and monoacetates in
high yield and enantiomeric purity. The ambiguous
configuration assignment of the five-membered
monoacetate [(+)-2a was assigned as (R,R)-9,10] indi-
cates the uncertainty of the configuration for monoac-
etates 2a–d obtained by enzymatic hydrolysis from
diacetates 3a–d.
sponding racemic diacetates rac-3a–d with SAM II5 or
with porcine liver esterase (PLE)7 have also been
described (Fig. 2). Highly enantiomerically selective
hydrolyses of rac-3a,8 rac-3a9,10 or rac-3a–c11 were
performed with lipase from Pseudomonas fluorescens
(lipase P, Amano).
PLE-catalysed hydrolysis of racemic diacetates rac-3a–d
was only moderately enantiomerically selective and
yielded monoacetates 2a–d in variable configuration
Irrespective of whether starting from racemic diols rac-
1a–d (Fig. 1) or diacetates rac-3a–d (Fig. 2), these
* Corresponding author. Tel.: +36-1 463 2229; fax: +36-1 463 3297;
e-mail: poppe@mail.bme.hu
0957-4166/$ - see front matter © 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0957-4166(03)00568-8

2606
V. Bo´dai et al. / Tetrahedron: Asymmetry 14 (2003) 2605–2612
Figure 3. Enzymatic acylation of trans-2-acetoxycycloalkan-
1-ols rac-2a–d.
Figure 2. Enzyme-mediated hydrolysis of trans-cycloalkane-
1,2-diol diacetates rac-3a–d.
monoacetates from symmetric 1,2-diols has recently
been published.14
enzymatic processes were sequential kinetic resolutions
in which three fractions of diols 1a–d, monoacetates
2a–d and diacetates 3a–d were produced in variable
yields and enantiomeric compositions. Even if the pro-
cesses are virtually irreversible—thus the back reactions
would not significantly influence the overall results—
their outcome is dependent on the relative measures of
four independent rate constants (k1S, k1R, k2S, and k2R
for acylation; or k-2S, k-2R, k-1S and k-1R, for hydrolysis).
Analysis of the data available for acylation reactions5,6
indicated that k2S is by far the slowest step, thus
(R,R)-3a–d was produced almost exclusively as a diac-
etate (Fig. 1). Systematic evaluation of the rate con-
stants for the hydrolysis of rac-3b12 indicated k-2S—the
formal back reaction rate of k2S—as the slowest step in
hydrolysis. As a result, accumulation of (S,S)-3b in the
unreacted diacetate fraction was observed (Fig. 2).
With the racemic trans-monoacetates rac-2a–d in hand,
the enantiomer selectivity of the enzyme-catalysed
acylations of racemic trans-2-acetoxycycloalkan-1-ols
rac-2a–d was screened with a wide selection of lipases
(Tables 1–4).
The first and most extensive enzymatic acylation screen
was carried out with 73 commercial and our own-iso-
lated fungal enzymes for the racemic trans-2-acetoxycy-
clohexan-1-ol rac-2b (Table 2). As a result, numerous,
highly enantiomerically selective enzymes for this
acylation reaction were found. As expected from the
previously discussed results, lipases from the Pseu-
domonas strains (lipase PS, P. fluorescens lipase, lipase
AK) were quite selective, exhibiting E >500. Also,
several fungal lipases (Lipozyme IM, Lipozyme IM 20,
Lipozyme TL IM, and a number of our novel prepara-
tions from thermophilic fungi15) exhibited excellent
selectivities, with E >500 as well.
Previously, we have systematically compared the six
possible kinetic resolution strategies—acylations of the
1,2-diols, 1-acetates or 2-acetates and hydrolyses of the
1,2-diacetates, 1-acetates or 2-acetates—for acyclic 1,2-
diol derivatives.13 Among these reactions, the lipase-
catalysed acylation of 2-acetoxy-1-ols proved to be the
fastest and most selective.
Next, the 30 most effective enzymes in the screen on the
six-membered monoacetate rac-2b were tested with the
five- and seven-membered monoacetates rac-2a and
rac-2c (Tables 1 and 3, respectively). As expected, the
enzymes which performed best on the six-membered
monoacetate rac-2b were also quite selective towards
the five- and seven-membered analogues rac-2a and
rac-2c, thus enabling the preparation of the highly
enantiopure diacetates (R,R)-3a,c and monoacetates
(S,S)-2a,c.
Due to the kinetic analysis of the sequential kinetic
resolutions of cyclic 1,2-diols rac-1a–d by acylation or
by hydrolysis of their diacetates rac-3a–d—together
with the results for lipase-catalysed kinetic resolutions
of the acyclic 1,2-diols—implying acylation of the
racemic monoacetates rac-2a–d as the most selective
process, we thought it worthwhile investigating this
unprecedented simple kinetic resolution (Fig. 3).
The lipases from the Candida strains (lipase from C.
rugosa, C. cylindracae, lipase A from C. antarctica and
lipase AY) turned out to be only moderately (R)-selec-
tive in acylations of the six- and seven-membered
monoacetates rac-2b,c with formation of (R,R)-3b,c
(Tables 2 and 3). Interestingly, C. rugosa lipase and
lipase AY exhibited low but opposite enantiomer pref-
erence for the five-membered monoacetate rac-2a and
catalysed the formation of (S,S)-3a (Table 1).
Herein we report the results on simple kinetic resolu-
tion of racemic trans-2-acetoxycycloalkan-1-ols rac-2a–
d with a wide selection of lipases.
2. Results and discussion
Preparation of the racemic monoacetates rac-2a–d from
the easily available diols rac-1a–d was performed using
Ac2O/Na2CO3 as reagents.12 Another high yield method
using YbCl3 (10%)/Ac2O (10 equiv.) for preparation of
Finally, lipase-catalysed acylation of the eight-mem-
bered monoacetate rac-2d was studied with those
lipases which were most selective in acylations of rac-
2a–c (Table 4).

V. Bo´dai et al. / Tetrahedron: Asymmetry 14 (2003) 2605–2612
2607
Table 1. Lipase-catalysed acylation of racemic trans-2-acetoxycyclopentan-1-ol rac-2aa
Enzyme
Time (h)
c (%)
2a
3a
Config.
Ee (%)b
Config.
Ee (%)c
Lipase TUB 3b
Lipase PS
Lipozyme IM
Pseudomonas fluorescens lipase
Lipase A
PPL
Lipozyme IM 20
Lipase TUB 11b
Lipase AK
Novozyme 435
Lipase TUB 25b
Lipozyme TL IM
Lipase TUB 7b
Lipase M
24
168
168
168
72
168
168
168
24
50
50
43
49
47
26
40
31
51
54
47
49
26
10
92
26
28
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(SS)
(RR)
(RR)
>99
>99
76
>99
93
36
67
44
98
>99
80
89
37
9
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(R,R)
(S,S)
(S,S)
>99
>99
>99
>99
>99
>99
99
99
94
85
90
93
90
84
5
25
46
72
168
168
168
168
24
Candida antarctica lipase A
Candida rugosa lipase
Lipase AY
57
9
18
168
168
a Results with enzymes of c >10% within 168 h. For reaction details, see Section 3.
b The ee2a (estd. error: 0.6%) and c (estd. error: 1.3%) values were determined by GC on an HP Chiral column.
c The ee3a value was calculated from c and ee2a
.
Table 2. Lipase-catalysed acylation of racemic trans-2-acetoxycyclohexan-1-ol rac-2ba
Enzyme
Time (h)
c (%)
(S,S)-2b Ee (%)b
(R,R)-3b Ee (%)b
Ec
Lipase TUB 3b
Lipase PS
Lipozyme IM
Lipase TUB 30b
Lipase AK
Lipozyme IM 20
Pseudomonas fluorescens lip.
Lipase TUB 6b
Lipozyme TL IM
PPL
48
48
48
48
48
48
48
48
24
48
48
48
72
48
48
48
48
48
48
48
48
50
49
42
44
49
37
27
7
34
10
8
48
46
7
24
17
38
10
10
7
>99.5
98.3
68.0
77.2
99.3
56.3
33.5
4.9
43.3
4.3
2.9
89.4
83.2
1.5
25.6
18.5
33.6
2.1
>99.8
>99.8
>99.8
>99.8
99.6
>99.8
>99.8
>99.8
>99.8
>99.8
>99.8
99.7
99.7
96.1
94.8
92.5
64.6
64.8
60.6
54.0
>250
>250
>250
>250
>250
>250
>250
>100
>100
>100
>100
>100
>100
54
50
31
6.8
5.0
4.3
3.5
2.9
Lipase M
Novozyme 435
Lipase TUB 31b
Lipase R
Lipase TUB 25b
Lipase TUB 7b
Candida antarctica lipase A
Candida cylindracae lipase
Lipase TUB 10a
Lipase AY
2.0
1.3
1.1
Candida rugosa lipase
8
46.7
a Results with enzymes of c >5% within 48 h. For reaction details, see Section 3.
b The ee values of (S,S)-2b (estd. error: 0.3%) and (R,R)-3b (estd. error: 0.2%) and c (estd. error: 1.2%) were determined by GC on an HP
Chiral column.
16
17
c Degree of enantiomer selectivity (E) was calculated from c and ee3b
,
and confirmed by independent calculation from ee2b and ee3b
.
(Due to
the sensitivity of experimental errors, E values calculated in the 500–5000 range are reported as >100, and E values calculated above 5000 are
given as >250.)
In accordance with the previously reported results,5,6
enzymatic acylation of trans-2-acetoxycyclooctan-1-ol
rac-2d proved to be significantly less selective and yielded
the optically active monoacetate (S,S)-2d and diacetate
(R,R)-3d in only moderate enantiomeric purity.
To demonstrate the synthetic applicability of these pro-
cesses and to obtain an unambiguous configuration/opti-
calrotation correlation—especially for the five-membered
monoacetate 2a—the lipase AK-catalysed acylations of
the racemic trans-2-acetoxy-cycloalkan-1-ols rac-2a–d

2608
V. Bo´dai et al. / Tetrahedron: Asymmetry 14 (2003) 2605–2612
Table 3. Lipase-catalysed acylation of racemic trans-2-ace-
toxycycloheptan-1-ol rac-2ca
Enzyme
Time (h)
c (%)
(S,S)-2c Ee (%)b
(R,R)-3c Ee (%)b
Ec
Novozyme 435
Lipase AK
Lipase TUB 3b
Lipase PS
48
48
50
49
50
48
44
43
39
34
19
13
13
11
42
10
>98
>98
>98
>98
63
57
46
31
7
3
4
2
9
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
70
>250
>250
>250
>250
>250
>100
>100
>100
>100
>100
168
168
168
168
168
168
168
168
168
168
48
Pseudomonas fluorescens lipase
Lipozyme TL IM
Lipozyme IM
Lipozyme IM 20
Lipase TUB 11b
Lipase M
Candida cylindracae lipase
Candida rugosa lipase
Candida antarctica lipase A
Lipase AY
6.4
53
38
33
3.5
2.8
2.0
168
1
a Results with enzymes of c >10% within 168 h. For reaction details, see Section 3.
b The ee values of (S,S)-2c (estd. error: 0.6%) and (R,R)-3c (estd. error: 0.5%) and c (estd. error: 1.4%) were determined by GC on HP Chiral
column.
16
17
c Degree of enantiomer selectivity (E) was calculated from c and ee3c
,
and confirmed by independent calculation from ee2c and ee3c
.
(Due to
the sensitivity of experimental errors, E values calculated in the 500–5000 range are reported as >100, and E values calculated above 5000 are
given as >250.)
Table 4. Lipase-catalysed acylation of racemic trans-2-ace-
toxycyclooctan-1-ol rac-2da
(S,S)-1a–d and the hydrolysis of diacetates 3a–d yielded
(R,R)-diols (R,R)-1a–d. It is noteworthy, that a dis-
crepancy was found between ours and the previously
reported9,10 specific rotations for 2a. The configuration of
(+)-2a ([h] in CHCl3) was assigned as (R,R)-,9,10 whereas
in our hand (S,S)-2a gave a positive rotation in acetoni-
trile. This might be related to the selection of the solvent
(we have measured inaccurate and unreproducible results
for monoacetates 2a in chloroform due to solubility issues
which were eliminated by using acetonitrile).
Enzyme
Time (h)
c (%)
(S,S)-2d Ee
(R,R)-3d Ee
(%)b
(%)c
Novozyme
435
24
97
99
4
Lipase PS
Lipase TUB
3b
168
24
80
72
95
94
26
42
Lipase AK
Lipozyme
TL IM
Lipozyme
IM
24
24
71
78
91
83
41
27
Topreparetheoppositeenantiomersofthemonoacetates,
lipase AK-catalysed hydrolysis from the racemic diac-
etates rac-3a–d was applied.
168
60
43
32
Results of a small scale preliminary hydrolysis screen of
rac-3binpurelyaqueoussystems(unbufferedwater,0.2M
phosphate buffers pH 7, pH 7.5 and pH 8) or in the same
systems but containing 50% (v/v) acetone showed, that
hydrolysis in unbuffered water was the fastest and most
selective. Therefore, the preparative scale hydrolyses were
also performed in unbuffered water (Table 6). The results
indicate that the enantiomer selectivity of the hydrolysis is
lower than that which can be achieved in the correspond-
ing acylation reaction: Thus the monoacetates (R,R)-2a–d
prepared by hydrolysis of the diacetates rac-3a–d were
obtained in lower enantiomeric excesses as their enan-
tiomers (S,S)-2a–d prepared by acylation. In addition,
tracesofthediols1a–dwerealsoobservedinthehydrolytic
reactions.
a A selection of the best performing enzymes on rac-2a–c was only
tested. For reaction details, see Section 3.
b The ee2d (estd. error: 1.2%) and c (estd. error: 1.6%) values were
determined by GC on Beta-DEX 225 column.
c The ee3d value was calculated from c and ee2d
.
were performed on a preparative scale (300–500 mg) as
well.
The preparative scale experiments proved that the simple
kinetic resolution method from the racemic of the five-,
six- and seven-membered monoacetates rac-2a–c can be
applied for the preparation of highly enantiopure
monoacetates (S,S)-2a–c and diacetates (R,R)-3a–c
(Table 5, >97% ee for the product and remaining substrate
fractionsatcꢀ0.5). Unfortunately, acylationoftheeight-
membered monoacetate rac-2d gave the (S,S)-monoac-
etate (S,S)-2d only in lower enantiomeric excess (94% ee).
The usefulness of our methods in the preparation of both
enantiomeric forms of the monoacetates of trans-
cycloalkane-1,2-diols(S,S)-and(R,R)-2a–dinhighchem-
ical and enantiomeric purity was further confirmed by the
finding that in our hands the enantiomers of trans-2-ace-
toxycyclohexan-1-ol (S,S)- and (R,R)-2b were solids (mp
59.5–61°C and mp 57–59°C, respectively; lit.,9 oil; lit.,18
mp 28°C).
The configuration of the products was determined by an
established method;6 by conversion of the products of the
acylation reaction 2a–d and 3a–d into their parent diols
1a–d of known absolute configuration by hydrolysis.
Thus, monoacetates 2a–d were hydrolysed to (S,S)-diols

V. Bo´dai et al. / Tetrahedron: Asymmetry 14 (2003) 2605–2612
2609
Table 5. Preparative scale acylation of racemic trans-2-acetoxycyclo-alkan-1-ols rac-2a–d by lipase AKa
Substrate
Time (h)
(S,S)-2
Ee (%)
(R,R)-3
Yield (%)
Yield (%)
Ee (%)
rac-2a
rac-2b
rac-2c
rac-2d
12
10
18
24
33
36
36
43
>99
97
>99
94
43
37
40
44
>98
>99
>98
N.d.b
a For reaction details see Section 3.
b Not determined.
Table 6. Preparative scale hydrolysis of racemic trans-1,2-
diacetoxy-cycloalkanes rac-3a–d by lipase AKa
The results indicated, that an extraction with 20%
MeOH–water system is optimal for the separation of
the mixture of 2b and 3b with a selectivity factor
(K3b/K2b) of 149. This selectivity enables an efficient,
extractive separation of the products without
chromatography.
Substrate
Time (h)
(R,R)-2
Yield (%)
Ee (%)b
[h]2D2
rac-3a
rac-3b
rac-3c
rac-3d
30
24
24
30
28
21
37
25
96
99
>98
9
−28.2c
−43.8d
−21.9c
−0.9c
3. Experimental
3.1. Materials and methods
a For reaction details see Section 3.
b Determined by GC on HP Chiral or Beta-DEX 225.
c c 1.0 in acetonitrile.
3.1.1. Analytical methods. NMR spectra were recorded
on a Bruker DRX-500 spectrometer (500 MHz for H
1
d c 1.0 in chloroform.
and 125 MHz for 13C; CDCl3; TMS; ppm on l scale).
IR spectra were taken on a Specord 2000 spectrometer
in film and the wavenumbers reported in cm−1. GC
analyses were carried out on Agilent 4890D or HP 5890
instruments equipped with FID detector using H2 as
the carrier gas (injector: 250°C, detector: 250°C, head
pressure: 12 psi). For the separations HP Chiral (30
m×0.32 mm×0.25 mm film of 20% permethylated b-
cyclodextrin, HP Part No.: 190916-B213) with a 1:50
split ratio; or Beta-DEX 225 (30 m×0.25 mm×0.25 mm
film, Supelco Column No.: 16161-0413) with a 1:80
split ratio were used. Optical rotations were determined
on a Perkin Elmer 241 polarimeter. TLC was carried
out on Kieselgel 60 F254 (Merck) sheets. Spots were
visualized by treatment with 5% ethanolic phospho-
molybdic acid solution and heating of the dried plates.
Solvents used were freshly distilled.
Our final effort was to find an efficient extraction
system for the separation of the resulting monoacetate
2a–d and diacetate 3a–d fractions, which might be
useful for the elaboration of chromatography-free
purification processes or even for the development of
continuously operating tube reactor-extractor systems.
To solve this task, a systematic search was made to find
the most selective hexane—a water/methanol two-phase
extraction system using a hexane solution of equimolar
mixture of the six-membered mono- and diacetates 2b
and 3b (Table 7).
Table 7. Extractive separation of 2-acetoxycyclohexan-1-ol
2b and 1,2-diacetoxycyclohexane 3ba
c
MeOH (%)
3b (%)
2b (%)
K3b/K2b
3.1.2. Reagents and solvents. trans-Cyclopentane-1,2-
diol rac-1a, trans-cyclohexane-1,2-diol rac-1b and vinyl
acetate were products of Aldrich. trans-Cycloheptane-
1,2-dol rac-1c19 and trans-cyclooctane-1,2-diol rac-1d20
were prepared by literature procedures.
In aqueous phasea
In hexane phaseb
0
10
20
30
40
50
60
70
80
90
8.1
8.5
7.6
6.3
6.1
3.5
2.9
1.8
1.8
2.6
88.0
92.8
92.5
88.6
80.6
68.4
50.9
35.7
24.3
21.0
83
138
149
115
64
59
34
30
17
3.1.3. Biocatalysts. Lipase A, lipase AK, lipase AY,
lipase M, lipase PS and lipase R were obtained from
Amano Europe. Lipozyme IM, Lipozyme IM 20,
Lipozyme TL IM, Novozyme 435 and Candida antarc-
tica lipase A were products of Novozymes, Denmark.
Lipases from Candida rugosa and Pseudomonas fluores-
cens were purchased from Fluka. PPL and lipase from
Candida cylindracae were obtained from Sigma. A
selection of extracellular hydrolases from various ther-
mophilic fungi (lipases TUB 1-52a,b) were isolated as
10
a Hexane solution (1 ml) of 2b (0.1 mmol) and 3b (0.1 mmol) was
extracted with a water–MeOH mixture (1 ml).
b Amounts of 2b and 3b (%) are relative to those which were present
in the original hexane solution, and were determined by GC on HP
Chiral column using undecene as internal standard.
acetone
dried
supernatants
of
shake
flask
c Ratio of distribution coefficients K for 3b and 2b.
fermentations.15

2610
V. Bo´dai et al. / Tetrahedron: Asymmetry 14 (2003) 2605–2612
3.2. Racemic trans-2-acetoxycycloalkan-1-ols, rac-2a–d
3.3.1. trans-1,2-Diacetoxycyclopentane, rac-3a. Yield:
1
1.16 g, 72%; IR: 2976, 1748, 1372, 1252, 1088, 1040; H
To a suspension of racemic diol rac-1a–d (17.2 mmol)
and Na2CO3 (5.48 g, 52 mmol) in EtOAc (60 ml), Ac2O
(0.052 mol) was added at room temperature over a
period of 15 min. After stirring for 14 h, the mixture
was poured into 40 ml of ice-water, and the aqueous
phase extracted with EtOAc (2×40 ml). The combined
organic extracts were dried over MgSO4 and concen-
trated. Separation of the residue by chromatography
(silica gel, 33–100% gradient of EtOAc in hexane) gave
the monoacetate rac-2a–d as a colourless oil.
NMR: 1.34–1.41 (2H, m), 1.48–1.54 (2H, m), 1.79 (6H,
s, 2 CO-CH3), 1.8–1.89 (2H, m), 4.82 (2H, br s, C(1)H
and C(2)H); 13C NMR: 20.49, 21.08, 29.90, 78.28,
169.10; Anal. calcd for C9H14O4: C, 58.05; H, 7.58.
Found: C, 57.96; H, 7.62%.
3.3.2. trans-1,2-Diacetoxycyclohexane, rac-3b. Yield:
1
1.39 g, 80%; IR: 2944, 2896, 1740, 1368, 1232, 1044; H
NMR: 1.26–1.42 (4H, m), 1.65–1.73 (2H, m), 2.01
(6H,s, 2 CO-CH3), 2.03 (2H, m), 4.78 (2H, mc, C(1)H
and C(2)H); 13C NMR: 21.21, 23.49, 30.17, 73.63,
170.09; Anal. calcd for C10H16O4: C, 59.98; H, 8.05.
Found: C, 60.01; H, 8.01%.
3.2.1. trans-2-Acetoxycyclopentan-1-ol, rac-2a. Yield:
1.36 g, 55%; IR: 3448, 2968, 1736, 1376, 1244, 1140,
1092; 1H NMR: 1.45–1.7 (4H, m), 1.8–1.9 (1H, m), 1.99
(3H, s, CO-CH3), 2.0–2.1 (1H, m), 3.29 (1H, m, OH),
4.00 (1H, br s, C(1)H), 4.40 (1H, m, C(2)H); 13C NMR:
21.09, 21.36, 29.77, 32.22, 77.30, 83.04, 171.45; Anal.
calcd for C7H12O3: C, 58.32, H, 8.39. Found: C, 58.49,
H, 8.32%.
3.3.3. trans-1,2-Diacetoxycycloheptane, rac-3c. Yield:
1.47 g, 79%; IR: 2936, 2838, 1740, 1372, 1240, 1032,
1
992; H NMR: 1.44–1.65 (4H, m), 1.58–1.66 (4H, m),
1.72–1.79 (2H, m), 1.97 (6H, s, 2 CO-CH3), 4.92 (2H,
mc, C(1)H and C(2)H); 13C NMR: 21.20, 22.82, 28.31,
30.37, 76.76, 169.84; Anal. calcd for C11H18O4: C,
61.66; H, 8.47. Found: C, 61.59; H, 8.43%.
3.2.2. trans-2-Acetoxycyclohexan-1-ol, rac-2b. Yield:
1.66 g, 61%; IR: 3432, 2936, 2896, 1732, 1384, 1232,
1
1080, 1040; H NMR: 1.2–1.36 (4H, m), 1.62–1.71 (2H,
m), 1.95–2.05 (2H, m), 2.06 (3H, s, CO-CH3), 2.53 (1H,
m, OH), 3.52 (1H, mc, C(1)H), 4.56 (1H, mc, C(2)H);
13C NMR: 21.40, 23.84, 23.94, 30.03, 33.11, 72.57,
78.09, 171.04; Anal. calcd for C8H14O3: C, 60.74; H,
8.92. Found: C, 60.56; H, 8.88%.
3.3.4. trans-1,2-Diacetoxycyclooctane, rac-3d. Yield:
1.39 g, 70%; IR: 2936, 2838, 1736, 1368, 1248, 1032,
1020, 980; 1H NMR: 1.43–1.51 (2H, m), 1.62–1.86
(10H, m), 1.97 (6H, s, 2 CO-CH3), 4.84 (2H, m, C(1)H
and C(2)H); 13C NMR: 21.46, 22.53, 27.23, 30.13,
73.90, 168.88; Anal. calcd for C12H20O4: C, 63.14; H,
8.83. Found: 63.21; H, 8.78%.
3.2.3. trans-2-Acetoxycycloheptan-1-ol, rac-2c. Yield:
1.36 g, 46%; IR: 3448, 2936, 2888, 1736, 1452, 1376,
1248, 1028; 1H NMR: 1.35–1.50 (4H, m), 1.52–1.69
(4H, m), 1.71–1.82 (2H, m), 2.03 (3H, s, CO-CH3), 2.88
(1H, s, OH), 3.67 (1H, m, C(1)H), 4.64 (1H, m, C(2)H);
13C NMR: 21.38, 22.73, 22.86, 28.00, 30.19, 32.69,
75.47, 81.56, 171.12; Anal. calcd for C9H16O3: C, 62.77;
H, 9.36. Found: C, 62.91; H, 9.29%.
3.4. Analytical scale enzymatic acylation of the racemic
trans-2-acetoxycycloalkan-1-ols, rac-2a–d
Enzyme (20 mg, for rac-2a: see Table 2; for rac-2b: see
Table 1; for rac-2c: see Table 3; for rac-2d: see Table 4)
was added to a solution of racemic trans-2-acetoxycy-
cloalkan-1-ol rac-2a–d (20 mg) in hexane (1.5 ml) and
vinyl acetate (0.5 ml) and the resulting suspension
shaken in a sealed glass vial at 1000 rpm, at room
temperature for the time indicated in Tables 1–4. The
reaction was then analysed by GC. The conversion and
enantiomeric composition of the resulting monoacetates
(S,S)-2a–d and diacetates (R,R)-3a–d are listed in
Tables 1–4.
3.2.4. trans-2-Acetoxycyclooctan-1-ol, rac-2d. Yield:
0.99 g, 31%; IR: 3416, 2936, 2888, 1732, 1368, 1248,
1052, 1040; 1H NMR: 1.35–1.50 (2H, m), 1.61–1.83
(10H, m), 1.98 (3H, s), 2.13 (1H, s, OH), 3.78 (1H, m,
C(1)H), 4.84 (1H, m C(2)H); 13C NMR: 21.58, 22.03,
22.94, 27.39, 30.09, 30.48, 33.52, 71.31, 74.39, 170.21;
Anal. calcd for C10H18O3: C, 64.49; H, 9.74. Found: C,
64.56; H, 9.82%.
3.4.1. GC analysis for acylation reactions from trans-2-
acetoxy-cyclopentan-1-ol rac-2a. Rt (HP Chiral; 100–
116°C, 2°C/min)/min: 5.76 (S,S)-2a, 6.27 (R,R)-2a, 6.98
(S,S)- and (R,R)-3a.
3.3. Racemic trans-1,2-diacetoxycycloalkanes, rac-3a–d
To a solution of rac-1a–d (8.7 mmol) in dry Et3N (2.53
g, 25 mmol), Ac2O (1.77 g, 17.4 mmol) was added over
a period of 15 min and the mixture stirred at room
temperature for 24 h. The resulting mixture was then
poured into cold water (20 ml), and the aqueous phase
extracted with hexane (3×20 ml). The combined organic
extracts were washed with 5% HCl (10 ml), saturated
NaHCO3 (10 ml) and brine (10 ml). The solution was
dried over MgSO4 and concentrated. Separation of the
residue by chromatography (silica gel, 33–100% gradi-
ent of EtOAc in hexane) gave the diacetate rac-3a–d as
a colourless oil.
3.4.2. GC analysis for acylation reactions from trans-2-
acetoxy-cyclohexan-1-ol rac-2b. Rt (HP Chiral; 100–
115°C, 1°C/min)/min: 10.57 (S,S)-2b, 10.98 (R,R)-2b,
12.21 (S,S)-3b, 12.59 (R,R)-3b.
3.4.3. GC analysis for acylation reactions from trans-2-
acetoxy-cycloheptan-1-ol rac-2c. Rt (HP Chiral; 100–
136°C, 2°C/min)/min: 13.22 (S,S)-2c, 13.38 (R,R)-2c,
15.11 (S,S)-3c, 15.29 (R,R)-3c.

V. Bo´dai et al. / Tetrahedron: Asymmetry 14 (2003) 2605–2612
2611
3.4.4. GC analysis for acylation reactions from trans-2-
3.6. Preparative scale enzymatic hydrolysis of racemic
acetoxycyclooctan-1-ol rac-2d. Rt (Beta-DEX 225; 100–
170°C, 2°C/min)/min: 28.62 (S,S)-2d, 28.79 (R,R)-2d,
33.21 (S,S)- and (R,R)-3d.
trans-1,2-diacetoxycycloalkanes, rac-3a–d
Lipase AK (150 mg for rac-3a and rac-3b; 75 mg for
rac-3c and rac-3d) was added to racemic trans-2-diace-
toxycycloalkane (rac-3a: 300 mg, 1.61 mmol; rac-3b:
500 mg, 2.50 mmol; rac-3c: 120 mg, 0.56 mmol; rac-3d:
150 mg, 0.66 mmol) in water (3 ml for rac-3a and
rac-3d; 5 ml for rac-3b; 1.5 ml for rac-3c) and the
resulting mixture shaken at 1000 rpm at room tempera-
ture (30 h for rac-3a and rac-3d; 24 h for rac-3b and
rac-3c). The mixture was extracted with EtOAc (2×10
ml) and the combined extracts washed with brine (10
ml), dried over Na2SO4, and concentrated in vacuum.
The residue was separated by vacuum-chromatography
(silica gel, hexane–acetone 10:1 v/v) to yield the
monoacetate (RR)-2a–d and diacetate (SS)-3a–d.
3.5. Preparative scale enzymatic acylation of racemic
trans-2-acetoxycycloalkan-1-ols, rac-2a–d
Lipase AK (150 mg for rac-2a, rac-2b and rac-2c; 100
mg for rac-2d) was added to a solution of racemic
trans-2-acetoxycycloalkan-1-ol (rac-2a: 300 mg, 2.08
mmol; rac-2b: 500 mg, 3.16 mmol; rac-2c: 300 mg, 1.74
mmol; rac-2d: 400 mg, 2.15 mmol) in vinyl acetate (3
ml for rac-2a, rac-2c and rac-2d; 5 ml for rac-2b) and
the resulting suspension shaken at 1000 rpm at room
temperature (12 h for rac-2a, 10 h for rac-2b; 18 h for
rac-2c; 52 h for rac-2d). The enzyme was filtered off
and the filtrate concentrated in vacuum. The residue
was separated by vacuum-chromatography (silica gel,
hexane–acetone 10:1 v/v) to yield the monoacetate
(S,S)-2a–d and diacetate (R,R)-3a–d.
3.6.1. (R,R)-2-Acetoxycyclopentan-1-ol (R,R)-2a. Yield:
65 mg, 28% as colourless oil; [h]2D2=−28.2 (c 1.0 in
1
acetonitrile); IR, H and 13C NMR data were indistin-
guishable from the spectra of rac-2a.
3.5.1. (S,S)-2-Acetoxycyclopentan-1-ol (S,S)-2a. Yield:
99 mg, 33% as colourless oil; [h]2D2=+29.2 (c 1.0 in
acetonitrile) (lit.,10 [h]D20=+22.3 (c 1.12 in CHCl3) and
lit.,9 [h]D25=+29.3 (c 1.1 in CHCl3) were reported for
(RR)-2a); IR, 1H and 13C NMR data were indistin-
guishable from the spectra of rac-2a.
3.6.2. (S,S)-1,2-Diacetoxycyclopentane (S,S)-3a. Yield:
154 mg, 51% as colourless oil; [h]2D2=+23.2 (c 1.0 in
1
acetonitrile); IR, H and 13C NMR data were indistin-
guishable from the spectra of rac-3a.
3.5.2. (R,R)-1,2-Diacetoxycyclopentane (R,R)-3a. Yield:
168 mg, 43% as colourless oil; [h]2D2=−29.7 (c 1.0 in
3.6.3. (R,R)-2-Acetoxycyclohexan-1-ol (R,R)-2b. Yield:
106 mg, 21% as white crystals; mp 57–59 (lit.,9, oil;
lit.,18, mp 28°C); [h]D22=−43.8 (c 1.0 in CHCl3) (lit.9
[h]D22=−37.5 (c 1.1 in CHCl3), lit.,9 [h]2D8=−30.2 (c 1.60
1
acetonitrile); IR, H and 13C NMR data were indistin-
guishable from the spectra of rac-3a.
1
in CHCl3)); IR, H and 13C NMR data were indistin-
3.5.3. (S,S)-2-Acetoxycyclohexan-1-ol (S,S)-2b. Yield:
180 mg, 36% as white crystals; mp 59.5–61°C; [h]2D2=
+44.3 (c 1.0 in CHCl3); IR, 1H and 13C NMR data were
indistinguishable from the spectra of rac-2b.
guishable from the spectra of rac-2b.
3.6.4. (S,S)-1,2-Diacetoxycyclohexane (S,S)-3b. Yield:
94 mg, 24% as colourless oil; [h]2D2=+9.5 (c 1.0 in
CHCl3) (lit.,21 [h]D20=+12.0 (c 0.96 in CHCl3), lit.,12
3.5.4. (R,R)-1,2-Diacetoxycyclohexane (R,R)-3b. Yield:
231 mg, 37% as colourless oil; [h]2D2=−13.7 (c 1.0 in
CHCl3) (lit.,21 [h]2D2 −10.7 (c 0.58 in CHCl3), lit.,22 [h]2D7
1
[h]2D0=+16.1 (c 0.42 in MeOH)); IR, H and 13C NMR
data were indistinguishable from the spectra of rac-3b.
1
−12.5 (c 1.60 in CHCl3)); IR, H and 13C NMR data
were indistinguishable from the spectra of rac-3b.
3.6.5. (R,R)-2-Acetoxycycloheptan-1-ol (R,R)-2c. Yield:
36 mg, 37% as colourless oil; [h]2D2=−21.9 (c 1.0 in
1
acetonitrile); IR, H and 13C NMR data were indistin-
3.5.5. (S,S)-2-Acetoxycycloheptan-1-ol (S,S)-2c. Yield:
106 mg, 36% as colourless oil; [h]2D2=+22.9 (c 1.0 in
guishable from the spectra of rac-2c.
1
acetonitrile); IR, H and 13C NMR data were indistin-
guishable from the spectra of rac-2c.
3.6.6. (S,S)-1,2-Diacetoxycycloheptane (S,S)-3c. Yield:
52 mg, 43% as colourless oil; [h]2D2=+3.0 (c 1.0 in
3.5.6. (R,R)-1,2-Diacetoxycycloheptane (R,R)-3c. Yield:
156 mg, 40% as colourless oil; [h]2D2=−13.1 (c 1.0 in
1
acetonitrile); IR, H and 13C NMR data were indistin-
guishable from the spectra of rac-3c.
1
acetonitrile); IR, H and 13C NMR data were indistin-
guishable from the spectra of rac-3c.
3.6.7. (R,R)-2-Acetoxycyclooctan-1-ol (R,R)-2d. Yield:
97 mg, 80% as colourless oil; [h]2D2=−0.9 (c 1.0 in
3.5.7. (S,S)-2-Acetoxycyclooctan-1-ol (S,S)-2d. Yield:
171 mg, 43% as colourless oil; [h]2D2=+9.1 (c 1.0 in
1
acetonitrile); IR, H and 13C NMR data were indistin-
1
acetonitrile); IR, H and 13C NMR data were indistin-
guishable from the spectra of rac-2d.
guishable from the spectra of rac-2d.
3.5.8. (R,R)-1,2-Diacetoxycyclooctane (R,R)-3d. Yield:
215 mg, 44% as colourless oil; [h]2D2=0 (c 1.0 in acetoni-
3.6.8. (S,S)-1,2-Diacetoxycyclooctane (S,S)-3d. Yield:
11 mg, 7% as colourless oil; [h]2D2=0 (c 1.0 in acetoni-
1
1
trile); IR, H and 13C NMR data were indistinguishable
trile); IR, H and 13C NMR data were indistinguishable
from the spectra of rac-3d.
from the spectra of rac-3d.

2612
V. Bo´dai et al. / Tetrahedron: Asymmetry 14 (2003) 2605–2612
6. Kaga, H.; Yamaguchi, Y.; Narumi, A.; Yokota, K.;
4. Conclusion
Kakuchi, T. Enantiomer 1998, 3, 203–205.
7. Crout, D. H. G.; Gaudet, V. S. B.; Laumen, K.;
Schneider, M. P. J. Chem. Soc., Chem. Commun. 1986,
808–810.
In conclusion, for simple kinetic resolutions of the
monoacetates of trans-cycloalkane-1,2-diols rac-2a–d, a
number of highly enantiomeric selective enzymes were
found. These enzymes enabled the preparation of
highly enantiopure diacetates (R,R)-3a–c and monoac-
etates (S,S)-2a–c in good yields. Our screen also
showed that most enzymes are significantly less selective
towards the monoacetate of trans-cyclooctane-1,2-diol
rac-2d.
8. Xie, Z.-F.; Suemune, H.; Sakai, K. J. Chem. Soc., Chem.
Commun. 1987, 838–839.
9. Fang, C.; Ogawa, T.; Suemune, H.; Sakai, K. Tetra-
hedron: Asymmetry 1991, 2, 389–398.
10. Xie, X.-F.; Suemune, H.; Nakamura, I.; Sakai, K. Chem.
Pharm. Bull. 1987, 35, 4454–4459.
11. Xie, Z.-F.; Nakamura, I.; Suemune, H.; Sakai, K. J.
Chem. Soc., Chem. Commun. 1988, 966–967.
12. Caron, G.; Kazlauskas, R. J. J. Org. Chem. 1991, 56,
7251–7256.
Acknowledgements
13. Egri, G.; Baitz-Ga´cs, E.; Poppe, L. Tetrahedron: Asym-
metry 1996, 7, 1437–1448.
14. Clarke, P. A.; Holton, R. A.; Kayaleh, N. E. Tetrahedron
The authors thank the Hungarian OTKA (T-033112)
and the National R&D Project, Ministry of Education
(NKFP3-35-2002) for financial support. Thanks are due
to Unilever Hungary Rt. for donating a HP 5890 gas
chromatograph.
Lett. 2000, 41, 2687–2690.
15. Bo´dai, V.; Peredi, R.; Ba´lint, J.; Egri, G.; Nova´k, L.;
Szaka´cs, G.; Poppe, L. Adv. Synth. Catal. 2003, 345,
811–818.
16. Chen, C. S.; Fujimoto, Y.; Girdaukas, G.; Sih, C. J. J.
Am. Chem. Soc. 1982, 104, 7294–7299.
17. Rakels, J. L. L.; Straathof, A. J. J.; Heijnen, J. J. Enzyme
References
Microb. Technol. 1993, 15, 1051–1056.
1. Hayward, R. C.; Overton, C. H.; Witham, G. H. J.
Chem. Soc., Perkin Trans. 1 1976, 2413–2415.
2. Sakai, K.; Suemune, H. Tetrahedron: Asymmetry 1993, 4,
2109–2118.
3. Kato, K.; Suemune, H.; Sakai, K. Tetrahedron Lett.
1993, 34, 4979–4980.
18. Sevin, C. Bull. Soc. Chim. Fr. 1974, 918–921.
19. Oven, L. N.; Saharia, G. S. J. Chem. Soc. 1953, 2582–
2588.
20. Cope, A. C.; Fenton, S. W.; Spencer, C. F. J. Am. Chem.
Soc. 1952, 74, 5884–5888.
21. Laine, D.; Fujita, M.; Ley, S. V. J. Chem. Soc., Perkin
Trans. 1 1999, 1639–1646.
22. Naemura, K.; Fukuda, R.; Murata, M.; Konishi, M.;
Hirose, K.; Tobe, Y. Tetrahedron: Asymmetry 1995, 6,
2385–2394.
4. Orovecz, O.; Kova´cs, P.; Kolonits, P.; Pa´rka´nyi, L.;
´
Szabo´, E.; Nova´k, L. Synthesis 2002, 2711–2716.
5. Seemayer, R.; Schneider, M. P. J. Chem. Soc., Chem.
Commun. 1991, 49–50.