Microbial resolution of racemic 2-endo-acetoxy-1,8-cineole by Glomerella cingulata

Article abstract of DOI:10.1016/S0957-4166(01)00555-9

Resolution of (±)-2-endo-acetoxy-1,8-cineole by Glomerella cingulata is described. Both (+)-2-endo-acetoxy-1,8-cineole and (-)-2-endo-hydroxy-1,8-cineole could be quantitatively obtained in enantiomerically pure form (yield 50%; e.e. 100%). In addition, t

Full text of DOI:10.1016/S0957-4166(01)00555-9

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 12 (2001) 3185–3187
Microbial resolution of racemic 2-endo-acetoxy-1,8-cineole by
Glomerella cingulata
Mitsuo Miyazawa* and Yuya Hashimoto
Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, Kowakae, Higashiosaka-shi,
Osaka 577-8502, Japan
Received 19 November 2001; accepted 6 December 2001
Abstract—Resolution of ( )-2-endo-acetoxy-1,8-cineole by Glomerella cingulata is described. Both (+)-2-endo-acetoxy-1,8-cineole
and (−)-2-endo-hydroxy-1,8-cineole could be quantitatively obtained in enantiomerically pure form (yield 50%; e.e. 100%). In
addition, the odor differences between the enantiomers are also described. In both compounds (acetoxy and hydroxy), the
(+)-enantiomers tended to have more bright, light and sweet odors than their (−)-antipodes. © 2002 Elsevier Science Ltd. All
rights reserved.
1. Introduction
obtained.5,6 Through these studies, we have found that
G. cingulata has the ability to esterify secondary terpene
alcohols enantioselectively.
It is well known that many terpenoids have odor differ-
ences between enantiomers, therefore, it is very impor-
tant to obtain enantiomerically pure compounds when
establishing the odor and thus, economical methods for
the resolution of terpenoid enantiomers are increasingly
required.
In contrast to our previous work, in the study reported
herein we have attempted to obtain enantiomerically
pure secondary terpene alcohol 1 by utilizing the ability
of G. cingulata to hydrolyze enantioselectively the cor-
responding acetate 2. The racemate ( )-2 was
hydrolyzed with G. cingulata to give compounds 1 and
2 in enantiomerically pure form. Moreover, the odor
differences between enantiomers 1 and 2 were evaluated
and it was found that in both compounds the (+)-enan-
tiomers tended to have more light and sweet odors than
the (−)-enantiomers.
It has been reported that ( )-2-endo-hydroxy-1,8-cine-
ole 1, one of the terpene alcohols, had the characteristic
terpenoid odor.1 However, the compound 1 evaluated
in the study was a racemic mixture and thus, the odors
of the enantiomerically pure compounds 1 are not yet
known. The odor differences between both enantiomers
of 2-endo-acetoxy-1,8-cineole 2 have been evaluated.2,3
In the reports, however, each enantiomer of 2 was
prepared via enantiomerically pure 1 (which was pre-
pared from enantiomerically pure a-terpineol). Thus,
methods for the resolution of ( )-1 and ( )-2 are
desired in order to obtain enantiomerically pure com-
pounds from the inexpensive racemates.
2. Results and discussion
The racemic mixture, (1RS,2RS,4SR)-2, dissolved in
DMSO, was added to the culture medium of G. cingu-
lata and hydrolyzed to give, after 18 h, the enantiomer-
ically pure alcohol (−)-(1R,2R,4S)-1 in 50% yield (e.e.
100%) (Scheme 1, Table 1). The recovered acetate 2 was
also obtained in enantiomerically pure form in 50%
yield (e.e. 100%), this was the (+)-(1S,2S,4R)-enan-
tiomer. Thus, the microbial resolution of compounds 1
and 2 was successfully achieved via enantioselective
hydrolysis by the use of G. cingulata in this study.
In order to obtain the enantiomerically pure alcohols,
we have previously utilized enantioselective esterifica-
tion with the plant-pathogenic fungus, Glomerella
cingulata4 as a biocatalyst. As a result, the enantiomer-
ically pure alcohols and their malonates were
Nishimura and Noma reported that ( )-1 had a slightly
medicinal odor.1 Kubota et al. reported that (+)-
* Corresponding author. Tel.: +81-6-6721-2332; fax: +81-6-6727-4301;
e-mail: miyazawa@apch.kindai.ac.jp
0957-4166/01/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(01)00555-9

3186
M. Miyazawa, Y. Hashimoto / Tetrahedron: Asymmetry 12 (2001) 3185–3187
Scheme 1.
Table 1. Microbial resolution of compound 2 by G. cingulata
Time (h)
2
1
Yield (%)
E.e. (%)
Abs. configuration
Yield (%)
E.e. (%)
Abs. configuration
12
18
51.2
50.0
95.3
100
(+)-(1S,2S,4R)
(+)-(1S,2S,4R)
48.8
50.0
100
100
(−)-(1R,2R,4S)
(−)-(1R,2R,4S)
(1S,2S,4R)-2 and (−)-(1R,2R,4S)-2 showed weakly
woody odor and Alpinia galanga-like woody odor,
respectively, on GC-sniffing of the essential oil of A.
galanga.2,3 In the reports by Kubota et al., (+)-
(1S,2S,4R)-2 showed weaker odor than (−)-(1R,2R,4S)-
2, because (+)-(1S,2S,4R)-2 was less abundant than
(−)-(1R,2R,4S)-2 ((+)/(−)=18/82). To compare the
odor of these enantiomers, (−)-(1R,2R,4S)-2, (+)-
(1S,2S,4R)-2, (−)-(1R,2R,4S)-1 and (+)-(1S,2S,4R)-1
were prepared by hydrolysis and acetylation. The odor
evaluation in this study was performed by comparing
the same amount of enantiomers, and the odor descrip-
tion is shown in Table 2. (−)-(1R,2R,4S)-2 showed
camphorous, dry odor. (+)-(1S,2S,4R)-2 showed sharp,
fruity, sweet odor. (−)-(1R,2R,4S)-1 showed cam-
phorous odor. (+)-(1S,2S,4R)-1 had cineole-like, sweet
odor. This study is the first report of the odor differ-
ences between the enantiomers of 1. In both com-
pounds 1 and 2, (+)-(1S,2S,4R)-enantiomers tended to
have more bright, light and sweet odors than the (−)-
(1R,2R,4S)-enantiomers. Of these enantiomerically
pure compounds, (−)-1 and (−)-2, which had the char-
acteristic camphorous odor, are now available for
flavor and fragrance applications.
CHROMPACK WCOAT Fused silica Cp-Cyclodex-
trin-b-236-M-19 (50 m×0.25 mm i.d.). The column tem-
perature was programmed from 80 to 210°C at the rate
of 2°C/min. The injector and the detector temperatures
were 210°C. Helium at a flow rate of 1.52 mL/min was
used as a carrier gas.
4.2. Microbial resolution
A nutrient broth was prepared by dissolving saccharose
(15%), glucose (15%), polypeptone (5%), KCl (0.5%),
MgSO4·7H2O (0.5%), K2HPO4 (1%), FeSO4·7H2O
(0.01%) in distilled water (100 mL). The sterilized broth
was inoculated with G. cingulata. The culture medium
was incubated at 27°C on a reciprocatory shaker. After
72 h, the pH value of the culture medium was adjusted
at 7.0, and a solution of acetate 2 (50.0 mg) in DMSO,
was added to the medium. After 18 h, the reaction
mixture was extracted with diethyl ether and evapo-
rated. The residue was chromatographed on silica gel
(hexane/diethyl ether gradient system). Finally, (+)-2
(25.0 mg, 50%; colorless oil) and (−)-1 (20.0 mg, 50%;
colorless needle-like crystal) were obtained. Com-
pounds 1 and 2 were identified with spectral data
obtained in this study (shown below) and in the reports
by other workers.1,2 The absolute configurations of
compounds 1 and 2, which were obtained as a result of
the microbial resolution by G. cingulata, were deter-
mined by comparing the retention times on gas chro-
matography with authentic samples of (−)-(1R,2R,4S)-1
and (+)-(1S,2S,4R)-2.
3. Conclusions
The racemic acetate (1RS,2RS,4SR)-2 was hydrolyzed
enantioselectively using G. cingulata to give the enan-
tiopure compounds 1 and 2 in high yield. The odors of
each of the enantiomeric acetates 2 and alcohols 1 were
also evaluated.
Table 2. Odor description of enantiomers 1 and 2
4. Experimental
Compound
Odor description
4.1. Gas chromatography conditions
(−)-(1R,2R,4S)-2
(+)-(1S,2S,4R)-2
(−)-(1R,2R,4S)-1
(+)-(1S,2S,4R)-1
Camphorous, dry odor
Sharp, fruity, sweet odor
Camphorous odor
Gas chromatography was carried out using a Hewlett–
Packard 5890 Series II plus equipped with a flame
ionization detector on a capillary chiral column:
Cineole-like, sweet odor

M. Miyazawa, Y. Hashimoto / Tetrahedron: Asymmetry 12 (2001) 3185–3187
3187
4.2.1.
(−)-2-endo-Hydroxy-1,8-cineole
1.
(−)-
H-3), 1.28 (3H, s, H-9), 1.22 (3H, s, H-10), 1.04 (3H, s,
H-7); 13C NMR (CDCl3) lC 170.5 (s, C-11), 73.7 (s,
C-8), 72.8 (d, C-2), 70.8 (s, C-1), 33.8 (d, C-4), 32.7 (t,
C-3), 28.8 (q, C-10), 28.5 (q, C-9), 25.9 (t, C-6), 24.1 (q,
C-7), 21.9 (t, C-5), 21.2 (q, C-12).
(1R,2R,4S)-1,3,3-Trimethyl-2-oxabicyclo[2.2.2]octan-6-
ol; a colorless needle-like crystal; [h]2D5 −19.6 (c 1.08 in
CHCl3); HRMS m/z 170.1305 ([M+], calcd for
C10H18O2, 170.1307); EI-MS m/z (rel. intensity) 170
[M+] (10), 155 (tr), 137 (1), 126 (44), 111 (34), 109 (12),
108 (65), 93 (34), 83 (40), 71 (63), 69 (37), 58 (19), 55
(21), 43 (100); IR wmax (KBr) cm−1 3445, 2966, 1457,
1
Acknowledgements
1364, 1063, 1034, 978; H NMR (CDCl3) lH 3.73 (1H,
ddd, J=10.0, 4.0, 2.0, H-2exo), 2.52 (1H, dddd, J=15.0,
10.0, 4.0, 3.0, H-3exo), 2.01–1.85 (2H, m, H-5, H-6),
1.58–1.48 (3H, m, H-4, H-5, H-6), 1.32 (1H, ddd,
J=15.0, 4.0, 3.0, H-3endo), 1.28 (3H, s, H-9), 1.20 (3H,
s, H-10), 1.10 (3H, s, H-7); 13C NMR (CDCl3) lC 73.4
(s, C-8), 72.5 (s, C-1), 71.1 (d, C-2), 34.6 (t, C-3), 34.2
(d, C-4), 29.0 (q, C-10), 28.6 (q, C-9), 24.9 (t, C-6), 24.0
(q, C-7), 22.1 (t, C-5).
We thank Dr. M. Ishihara of Shiono Koryo Co., Ltd.
for evaluating the odor characteristics.
References
1. Nishimura, H.; Noma, Y. ACS Symp. Ser. 1996, 637,
173–187.
4.2.2. (+)-2-endo-Acetoxy-1,8-cineole 2. Acetate, (+)-
(1S,2S,4R)-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-
ol; a colorless oil; [h]2D5 +74.2 (c 0.96 in CHCl3); HRMS
m/z 212.1414 ([M+], calcd for C12H20O3, 212.1413);
EI-MS m/z (rel. intensity) 212 [M+] (9), 197 (tr), 170
(tr), 155 (2), 137 (2), 126 (17), 111 (15), 109 (17), 108
(36), 93 (19), 82 (17), 71 (24), 55 (10), 43 (100); IR wmax
(KBr) cm−1 2973, 1742, 1457, 1376, 1241, 1027; 1H
NMR (CDCl3) lH 4.69 (1H, ddd, J=10.0, 4.0, 2.0,
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