Enzymatic resolution of cis- and trans-1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl acetate derivatives

Article abstract of DOI:10.1016/S0957-4166(02)00551-7

Extensive screenings using commercially available enzymes were performed in relation to the asymmetric hydrolysis reactions of the (±)-cis- (1, 3 and 5) and (±)-trans-1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl acetates (7, 9 and 11). The combinations of enzymes from plants and cis-equatorial compounds as well as the combinations of lipases from microorganisms and trans-axial-5-methoxycarbonyl acetate showed high enantiomeric ratio in asymmetric hydrolysis. However, the enantiomeric ratio of the combinations of lipases from microorganisms and trans-axial isomers except trans-axial-5-methoxycarbonyl derivative was less satisfactory. High E values (>200) were observed when β-amylase from wheat and lipase from Candida cylindracea were used for the (±)-cis-acetate 1 and the (±)-trans-isomer 7, respectively, to obtain the corresponding chiral products with high enantiomeric ratios (>99:1).

Full text of DOI:10.1016/S0957-4166(02)00551-7

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 13 (2002) 2123–2131
Enzymatic resolution of cis- and
trans-1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl acetate
derivatives
Nobuko Shimizu,a,* Hiroyuki Akitab and Takeshi Kawamataa
aInstitute for Advanced Medical Research, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku,
Tokyo 160-8582, Japan
bFaculty of Pharmaceutical Sciences, Toho University, 2-2-1, Miyama, Funabashi, Chiba 274-8510, Japan
Received 2 August 2002; accepted 4 September 2002
Abstract—Extensive screenings using commercially available enzymes were performed in relation to the asymmetric hydrolysis
reactions of the ( )-cis- (1, 3 and 5) and ( )-trans-1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl acetates (7, 9 and 11). The
combinations of enzymes from plants and cis-equatorial compounds as well as the combinations of lipases from microorganisms
and trans-axial-5-methoxycarbonyl acetate showed high enantiomeric ratio in asymmetric hydrolysis. However, the enantiomeric
ratio of the combinations of lipases from microorganisms and trans-axial isomers except trans-axial-5-methoxycarbonyl derivative
was less satisfactory. High E values (>200) were observed when b-amylase from wheat and lipase from Candida cylindracea were
used for the ( )-cis-acetate 1 and the ( )-trans-isomer 7, respectively, to obtain the corresponding chiral products with high
enantiomeric ratios (>99:1). © 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
were carried out to find suitable combinations of com-
mercial enzymes and cis- and trans-1,2,3,4,6,7,8,8a-
octahydro-8a-methyl-6-oxo-naphthyl acetate deriva-
tives (5-COOMe, 5-Me and 5-H) for efficient hydrolytic
kinetic resolution (Scheme 1).
Enzyme-catalyzed organic synthesis has been widely
used and is a most effective method for the synthesis of
enantiomerically pure compounds. In particular, enan-
tioselective hydrolysis with hydrolase-containing lipases
has proved broadly useful because it is efficient, can be
carried out on a large scale, and can also be applied to
a broad range of substrates. Additionally, hydrolytic
enzymes are environmentally friendly catalysts that are
commercially available at low cost, and furthermore,
they do not require expensive and unstable coenzyme
systems.
2. Results
In preliminary experiments, it was found that 1:1 mix-
tures of two racemates [( )-1 and ( )-2], [( )-3 and
( )-4], [( )-5 and ( )-6], [( )-7 and ( )-8], [( )-9 and
( )-10] and [( )-11 and ( )-12] were well separated by
high-performance liquid-chromatographic (HPLC)
analysis with two kinds of chiral columns (Chiralcel
OD-H and ChiralPAk As). The results were shown in
Table 1. Thus, chemical yields and enantiomeric puri-
ties of the reaction products could be determined by
using the above method. First, screening of the asym-
metric hydrolyses of ( )-cis- and ( )-trans octahydro-
naphthyl acetate derivatives using 27 kinds of
enzymes was carried out, and the enzymes with E
value4 of >10 were selected. Next, we performed a
quantitative analysis using 5 mg of substrate by the
selective enzymes (Tables 2 and 4) and we then carried
out preparative experiments using a substantial amount
(ca. 100 mg) of the substrate (Tables 3 and 5).
Optically active bicyclic compounds have valuable
pharmacological effects and are also useful building
blocks for synthesis of various pharmacologically
important natural products, such as sesquiterpenoids,
diterpenoids and steroids.1
We have reported the enantioselective reduction of
bicyclic ketones with microorganisms (yeast).2 We then
turned our attention to enzyme-catalyzed asymmetric
hydrolysis in view of the brief treatment and large scale
involved.3 Herein, we describe investigations which
* Corresponding author.
0957-4166/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(02)00551-7

2124
N. Shimizu et al. / Tetrahedron: Asymmetry 13 (2002) 2123–2131
Scheme 1.
Table 1. HPLC analysis of six pairs of racemates, (9)-1 and (9)-2, (9)-3 and (9)-4, (9)-5 and (9)-6, (9)-7 and (9)-8,
(9)-9 and (9)-10 and (9)-11 and (9)-12 using chiral columns
Entry
Substrate
Analytical conditions
Retention time
(min)
1
2
3
4
(9)-1
(9)-2
(9)-3
(9)-4
(9)-5
(9)-6
(9)-7
(9)-8
Column (Chiralcel OD-H), detector (UV 230 nm), flow rate (0.5 ml/min),
solvent (iso-propanol (16.8%)/EtOH (4%)/n-hexane)
46, 53,
77, 93
22, 26,
66, 70
29, 34,
62, 68
58, 65
Column (Chiralcel OD-H), detector (UV 230 nm), flow rate (0.5 ml/min),
solvent (0–24 min; iso-propanol (5%)/n-hexane, 25–95 min; iso-propanol (2.1%)/n-hexane)
Column (Chiralcel OD-H), detector (UV 230 nm), flow rate (0.5 ml/min),
solvent (0–35 min; iso-propanol (2.4%)/n-hexane, 35–70 min; iso-propanol (3.5%) n-hexane)
Column (Chiralcel OD-H), detector (UV 230 nm), flow rate (0.4 ml/min),
solvent (EtOH (2%)/n-hexane)
Column (ChiralPAK As), detector (UV 230 nm), flow rate (0.5 ml/min), solvent (EtOH
(2.4%)/n-hexane)
113, 122
5
6
(9)-9
Column (Chiralcel OD-H), detector (UV 230 nm), flow rate (0.5 ml/min),
solvent (iso-propanol (2.9%)/n-hexane)
column (Chiralcel OD-H), detector (UV 230 nm), flow rate (0.5 ml/min),
solvent (iso-propanol (4.1%)/n-hexane)/hexane)
18, 23,
42, 46
22, 28,
45, 53
(9)-10
(9)-11
(9)-12
2.1. Enantioselective hydrolysis of ( )-cis-
1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl
acetate derivatives 1, 3 and 5
octahydronaphthyl acetates 1,5 36 and 5.7 Nine enzymes
were found with E values of >10 in the hydrolysis of the
5-methoxycarbonyl derivative ( )-1, whilst ten were
found with E >10 for the 4-methyl derivative ( )-3, and
five enzymes had E >10 for substrate ( )-5. Next,
quantitative hydrolysis of cis-8a-methyl-octahydro-
The first enzyme screenings were performed for the
enantioselective hydrolysis of ( )-cis-8a-methyl-6-oxo-

Table 2. Quantitative enzymatic hydrolysis of cis-1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl acetates (9)-1, (9)-3 and (9)-5
Entry
Substrate (5 mg)
Enzyme (5–15 mg)
Time (h)
Alcohol
Yield (%)
Recovered acetate
Yield (%)
C*
E*
ee (%)
ee (%)
1
2
3
4
5
6
7
8
(9)-1
(9)-1
(9)-1
(9)-1
(9)-1
(9)-3
(9)-3
(9)-3
(9)-3
(9)-3
(9)-5
(9)-5
(9)-5
(9)-5
(9)-5
b-AmW
LWG
b-AmSP
LMJ
LRN
b-AmW
LWG
a-AmB
LAN
PHP
b-AmW
LWG
a-AmB
a-AmBS
LMJ
7
24
37
200
200
53
3
36
28
108
3
(1R,8aR)-2
(1R,8aR)-2
(1R,8aR)-2
(1R,8aR)-2
(1R,8aR)-2
(1R,8aR)-4
(1R,8aR)-4
(1R,8aR)-4
(1R,8aR)-4
(1R,8aR)-4
(1R,8aR)-6
(1R,8aR)-6
(1R,8aR)-6
(1R,8aR)-6
(1R,8aR)-6
93
86
98
87
95
98
98
88
79
\99
99
78
89
98
50
46
33
12
14
21
44
10
11
3
21
42
31
22
11
(1S,8aS)-1
(1S,8aS)-1
(1S,8aS)-1
(1S,8aS)-1
(1S,8aS)-1
(1S,8aS)-3
(1S,8aS)-3
(1S,8aS)-3
(1S,8aS)-3
(1S,8aS)-3
(1S,8aS)-5
(1S,8aS)-5
(1S,8aS)-5
(1S,8aS)-5
(1S,8aS)-5
98
74
57
23
18
28
77
9
48
48
66
55
60
78
56
88
47
88
71
38
56
98
70
51
46
37
21
16
22
44
9
127
29
176
18
47
/
130
\200
17
9
17
1
18
1
10
10
11
12
13
14
15
\200
\200
23
27
129
11
29
87
44
27
10
23
53
33
22
11
3
25
40
47
1
82
2
* See Ref. 4.
b-AmW: b-Amylase from wheat.
LWG: Lipase from wheat germ.
213
b-AmSP: b-Amylase type I-B from sweet potato.
LMJ: Lipase from Mucor javanicus.
2
LRN: Lipase from Rizopus niveus.
a-AmB: b-Amylase type VIII-A from barley.
LAN: Lipase from Aspergillus niger.
PHP: Pancreatin from hog pancreas.
a-AmBS: a-Amylase from Bacillus subtilis.

2126
N. Shimizu et al. / Tetrahedron: Asymmetry 13 (2002) 2123–2131
Table 3. Preparative hydrolysis of cis-1,2,3,4,5,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl acetates (9)-1, (9)-3 and (9)-5
Entry
Substrate
(mg)
Enzyme
Time (h)
Alcohol
Recovered acetate
C* E*
ee (%)
(1R,8aR)-2 98
(1R,8aR)-4 92
(1R,8aR)-6 94
Yield (%)
ee (%)
Yield (%)
1
2
3
(9)-1 (100) b-AmW
(9)-3 (100) LWG
(9)-5 (100) b-AmW
18
4
12
40
51
50
(1S,8aS)-1
(1S,8aS)-3
(1S,8aS)-5
\99
\99
97
46
44
41
50 \200
52
51
180
136
* See Ref. 4.
naphthyl acetates using the selective enzymes (E >10)
was performed. The results are shown in Table 2. The
enzyme b-AmW8 was found to be the most effective for
enantioselective hydrolysis of ( )-1 with respect to the
reaction time and E values (Table 2, entry 1). A prepar-
ative experiment on ( )-1 using b-AmW was performed
to give the (−)-2 (40% yield, 98% ee) and the recovered
acetate (+)-1 (46% yield, >99% ee) (Table 3, entry 1).
Thus, the combination of ( )-1 and b-AmW showed
high enantiomeric ratio (E >200).
number of enzymes with E values of >10 was eight in
the hydrolysis of the 5-methoxycarbonyl derivative ( )-
7, seven for the 5-methyl derivative ( )-9 and four for
the substrate ( )-11, respectively.
Next, quantitative hydrolysis of trans-8a-methylnaph-
thyl acetates using the selected enzymes (E >10) was
performed. The results are shown in Table 4. The
lipases LMJ, LCCOF and LCCMY were selected as
suitable catalysts for ( )-7 (Table 4, entries 2, 3 and 4).
The reaction rate using LCCOF was a little faster (39
h) than those of the others (43 h). A preparative
experiment on ( )-7 using lipase LCCOF was per-
formed to give the optically active alcohol (+)-8 (49%
yield, 99% ee) and the recovered acetate (−)-7 (46%
yield, 98% ee, Table 5, entry 1). The combination of
( )-7 and lipase LCOF showed high enantiomeric ratio
(E >200).
The lipase LWG was found to be the most effective for
the enantioselective hydrolysis of 5-methyl derivative
( )-3 with respect to the reaction time and E values
(Table 2, entry 7). A preparative experiment on ( )-3
using the LWG was performed to give (−)-4 (51% yield,
92% ee) and the recovered acetate (+)-3 (44% yield,
>99% ee) (Table 3, entry 2). Thus, the combination of
( )-3 and LWG showed high enantiomeric ratio (E=
180).
The lipases LCCOF and LCR were proved to be suit-
able catalysts for the hydrolytic kinetic resolution of
( )-9 (Table 4, entries 5 and 6). The reaction rate using
LCCOF (56 h) was faster than that using LCR (207 h).
A preparative experiment on ( )-9 using LCCOF was
performed to give the optically active alcohol (+)-10
(73% yield, 30% ee) and the recovered acetate (−)-9
(22% yield, >99% ee) (Table 5, entry 2). In this reaction,
the combination of the compound ( )-9 and lipase
LCCOF showed low enantiomeric ratio (E=8), though
the enantiomeric excess of the recovered acetate (−)-9
was high.
The enzyme b-AmW was found to be the most effective
for enantioselective hydrolysis of ( )-5 with respect to
the reaction time and E values (Table 2, entry 11). A
preparative experiment on ( )-5 using b-AmW was
performed to give the cis-alcohol (−)-6 (50% yield, 94%
ee) and the recovered acetate (+)-5 (41% yield, 97% ee)
(Table 3, entry 3). Thus, the combination of ( )-5 and
b-AmW showed high enantiomeric ratio (E=136).
The absolute configuration of the cis-alcohol (−)-2 was
found to be 1R,8aR, because the negative sign of the
rotation of alcohol 2 ([h]D −139 (CHCl3)) was opposite
to that of the authentic sample of (1S,8aS)-2 ([h]D +105
(CHCl3));2a,c accordingly, that of the recovered acetate
1 was assigned as 1S,8aS. The absolute configurations
of the cis-alcohols (−)-4 ([h]D −147 (CHCl3)) and (−)-6
([h]D −166 (CHCl3)) were established to be 1R,8aR on
comparison with the rotation of the authentic samples
(1S,8aS)-4 ([h]D +162 (CHCl3));1a and (1R,8aR)-6 ([h]2D5
−196 (c=1.4, CHCl3));1d respectively.
The lipase LCCMY was selected as a catalyst for ( )-11
(Table 4, entry 7). A preparative experiment on ( )-11
using lipase LCCMY was performed to give (+)-12
(48% yield, 93% ee) and the recovered acetate (−)-11
(42% yield, 83% ee) (Table 5, entry 3). In this reaction,
the enantiomeric excess of the optically active alcohol
(+)-12 was high, and the combination of the compound
12 and LCCMY showed moderate enantiomeric ratio
(E=72).
2.2. Enantioselsective hydrolysis of ( )-trans-
1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl
acetates 7, 9 and 11
The absolute configuration of the trans-alcohol (+)-8
was found to be 1R,8aS, because the positive sign of
the optical rotation of 8 ([h]D +84 (CHCl3)) was oppo-
site to that of the authentic sample (1S,8aR)-8 ([h]D
−77 (CHCl3));2a,c accordingly, the absolute configura-
tion of the recovered acetate 7 was 1S,8aR. The sign of
the optical rotation in diketone (+)-13 ([h]D +18
The first enzyme screenings were performed for the
enantioselective hydrolysis of ( )-trans-8a-methyl-6-
oxo-octahydronaphthyl acetates 7,9 910 and 11.10 The

Table 4. Quantitative enzymatic hydrolysis of trans-1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl acetates (9)-7, (9)-9 and (9)-11
/
Entry
Substrate (5 mg)
Enzyme (5–10 mg)
Time (h)
Alcohol
Yield (%)
Recovered acetate
Yield (%)
C*
E*
ee (%)
ee (%)
1
2
3
4
5
6
7
(9)-7
(9)-7
(9)-7
(9)-7
(9)-9
(9)-9
(9)-11
b-AmSP
LMJ
LCCOF
LCCMY
LCCOF
LCR
72
43
39
43
56
(1R,8aS)-8
(1R,8aS)-8
(1R,8aS)-8
(1R,8aS)-8
(1R,8aS)-10
(1R,8aS)-10
(1R,8aS)-12
90
90
92
86
73
82
18
14
30
21
40
39
19
80
(1S,8aR)-7
(1S,8aR)-7
(1S,8aR)-7
(1S,8aR)-7
(1S,8aR)-9
(1S,8aR)-9
(1S,8aR)-11
26
84
32
87
60
62
39
55
38
43
64
2
22
48
50
50
45
19
85
25
50
33
38
12
12
7
1
207
48
19
\99
(
LCCMY
* See Ref. 4.
213
LCCOF: Lipase from Candida cylindracea.
LCCMY: Lipase from Candida cylindracea.
LCR: Lipase from Candida rugosa.
2

2128
N. Shimizu et al. / Tetrahedron: Asymmetry 13 (2002) 2123–2131
Table 5. Preparative hydrolysis of trans-1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl acetates (9)-7, (9)-9 and (9)-
11
Entry
Substrate
(mg)
Enzyme
Time (h)
Alcohol
Recovered acetate
C* E*
ee (%)
(1R,8aS)-8 99
(1R,8aS)-10 30
(1R,8aS)-12 93
Yield (%)
ee (%)
Yield (%)
1
2
3
(9)-7 (100) LCCOF
(9)-9 (60) LCCOF
(9)-11 (78) LCCMY
65
42
54
49
73
48
(1S,8aR)-7
(1S,8aR)-9 \99
(1S,8aR)-11 83
98
46
22
42
50 \200
77
47
8
72
* See Ref. 4.
(MeOH), corresponding to 30% ee) obtained by Jones’
oxidation of the hydrolysed product (+)-10 was the
same as that of the authentic sample (8aS)-13 ([h]D +79
(MeOH), corresponding to >99% ee).11 The absolute
configuration of the trans-alcohol (+)-10 was thus
established as 1R,8aS. Accordingly, that of the recov-
ered acetates 9 was 1S,8aR. The absolute configuration
of the recovered acetate (−)-11 ([h]D −81 (CHCl3)) was
the same as that of an authentic sample of (1S,8aR)-11
([h]D −93 (CHCl3));12 accordingly, the trans-alcohol 12
was assigned to have 1R,8aS configuration.
ing methyl and methoxycarbonyl groups and the M
substituent is only a methylene group. The great differ-
ence in the size of the substituents can well explain the
very high enantioselectivity observed in practice. The
stereochemical preference of enzymes observed during
the above-described kinetic resolution is in line with
Kazlauskas’ rule, namely, derivative 2 possessing 1R-
configuration was preferentially formed. So far as the
size of the 5-substituent is concerned, the E value for
the cis-isomers increased in proportion to the size of
the substituent, in the order ( )-5, ( )-3 and ( )-1.
The poorer enantioselectivity in the hydrolysis of ( )-
trans-8a-methyl-6-oxo-octahydronaphthyl acetates
9
3. Discussion
and 11 could not be explained using the same empirical
rule, because both M and L substituents for ( )-3 and
( )-9 as well as ( )-5 and ( )-11 are the same. A
predictive active site model for lipase YS from Pseu-
domonas sp. toward the racemic secondary alcohol hav-
ing pseudo-axial configuration is proposed.14 At
present, it is not known why the enzymatic hydrolysis
of substrates possessing axial substituents was difficult.
We will investigate further in relation to the stereostruc-
ture and enantioselectivity for substrates having an
axial substituent at the C-1-position. The hydrolysis of
compounds with the equatorial stereocenter at the C-1-
position proceeded faster than that of compounds hav-
ing an axial substituent at C-1. The high E value of
5-methoxycarbonyl isomer ( )-7 with an axial sub-
stituent at C-1 was high (>200) as well as that of the
cis-isomer ( )-1 with a 5-methoxycarbonyl group. The
5-methoxycarbonyl group in the octahydronaphthyl
High enantioselectivities (E 136ꢀ>200) were observed
when both cis-isomers ( )-1, ( )-3 and ( )-5, with
equatorial substituents at the C-1 position, and the
5-methoxycarbonyl isomer ( )-7, with an axial sub-
stituent at C-1, were subjected to asymmetric hydrolysis
using enzymes from plants and using lipase from
microorganisms, respectively. Moderate enantioselectiv-
ities (E 8ꢀ72) were observed when trans-isomers ( )-9
and ( )-11 with axial substituents at the C-1 position
were hydrolyzed using lipase from Candida sp. From
the reactivities of the six substrates towards the enzy-
matic hydrolysis process, it is important to point out
that the reaction of the (1R)-enantiomer proceeded
faster than that of the (1S)-enantiomer in all cases.
These results are in accordance with Kazlauskas’ rule13
for resolution of secondary alcohols. Namely, a lipase
distinguishes the two enantiomers on the basis of the
size of the substituents, large (L) and medium (M), at
the alcohol bearing the stereocenter [L-CH(OH)-M].
The more reactive enantiomer involves the (R) absolute
configuration when the Cahn–Ingold–Prelog priority of
the L group is higher than that of the M group and H
is behind the plane (Fig. 1). In the case of ( )-cis-5-
methoxycarbonyl-8a-methyl-6-oxo-octahydronaphthyl
acetate 1, the L substituent is the cyclohexenone bear-
acetate might have
a stabilizing effect over the
stereostructure of the substrate fitting into the active
site as suggested by Lemke.15
4. Conclusion
We were able to show that ( )-cis- 1, 3 and 5 and
( )-trans-octahydronaphthyl acetates 7, 9 and 11 can be
resolved using the enzymes selected by screening, giving
the corresponding enantiomers in good yield and high
enantiomeric excess. cis- and trans-Octahydronaphthyl
acetate ( )-1 and ( )-7, bearing a 5-carbomethoxy
group were successfully resolved with very high enan-
tioselectivities (E >200) by using amylase b-AmW from
wheat and lipase LCCOF from Candida cylindracea,
respectively.
Figure 1.

N. Shimizu et al. / Tetrahedron: Asymmetry 13 (2002) 2123–2131
2129
5. Experimental
5.5. Enantioselective hydrolysis of ( )-cis-
1,2,3,4,6,7,8,8a-octahydro-5-methoxycarbonyl-8a-
methyl-6-oxo-naphthyl acetate, 1
5.1. General
A mixture of ( )-1 (100 mg) and b-amylase (100 mg) in
phosphate buffer (200 ml, pH 7.25) was shaken at 33°C
for 18 h. The reaction mixture was extracted with ethyl
acetate and the organic solution was dried over anhy-
drous MgSO4. Evaporation of the organic solvent gave
a crude product, which was subjected to preparative
TLC [silica gel, 20×20 cm; developing solvent, hexane–
ethyl acetate (1:1)] to afford (1R,8aR)-2 (34 mg, 40%
yield, tR=77 min (99%), tR=93 min (1%), 98% ee) and
(1S,8aS)-1 (46 mg, 46% yield, tR=46 min (>99%),
tR=53 min (<0%), >99% ee). (1R,8aR)-2: colorless
prism, mp 151–152°C. [h]3D2 −139 (c=1.19, CHCl3). IR
Melting points were measured with a Kofler micro
melting point apparatus and are uncorrected. H NMR
1
spectra were measured on a JEOL JNM-GSX (500 Hz)
spectrometer were taken as 5–10% (w/v) solutions in
CDCl3 with Me4Si as an internal reference. Infrared
(IR) spectra (KBr) were measured on a JASCO FT/IR
410 spectrophotometer. Mass spectra were obtained on
a JEOL JMS-700H fast atom bombardment and JEOL
JMS D-300 and JEOL JMS-AX505HA mass spectrom-
eter. Optical rotations were measured with a JASCO
DIP-360 polarimeter in a CHCl3 solution. The HPLC
system was composed of a Shimadzu LC 10AD flow
system, a Soma S-310A UV detector and Shimadzu
chromatopac CR-4A data analysis system.
1
(KBr) cm−1: 3460, 1719, 1672, 1618. H NMR (CDCl3)
l: 1.24 (s, 3H), 3.50 (dd, 1H, J=4, 8 Hz), 3.81 (s, 3H).
HRMS m/z: 238.1191 (calcd for C13H18O4: 238.1205).
EIMS m/z: 238 (M+), 206, 178, 163, 150. (1S,8aS)-1:
colorless prism, mp 119–123°C. [h]3D2 +103 (c=0.99,
1
CHCl3). IR (KBr) cm−1: 1719, 1671, 1620. H NMR
5.2. HPLC analysis of pairs of racemates, ( )-1 and
( )-2, ( )-3 and ( )-4, ( )-5 and ( )-6, ( )-7 and ( )-8,
( )-9 and ( )-10 and ( )-11 and ( )-12
(CDCl3) l: 1.32 (s, 3H), 2.09 (s, 3H), 3.82 (s, 3H), 4.72
(dd, 1H, J=4, 8 Hz). HRMS m/z: 280.1307 (calcd for
C15H20O5: 280.1303). EIMS m/z: 280 (M+), 238, 206,
188, 178, 150.
Two 1:1 mixtures of six racemates give well separated
peaks as shown in Table 1.
5.6. Enantioselective hydrolysis of ( )-cis-
1,2,3,4,6,7,8,8a-octahydro-5,8a-dimethyl-6-oxo-naphthyl
acetate, 3
5.3. Screening for enantioselective hydrolysis of ( )-cis-
and trans-1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-
naphthyl acetates 1, 3, 5, 7, 9 and 11
A mixture of ( )-3 (101 mg) and lipase (101 mg) in
phosphate buffer (40 ml, pH 7.25) was shaken at 33°C
for 6.5 h. The reaction mixture was extracted with ethyl
acetate and the organic solution was dried over anhy-
drous MgSO4. Evaporation of the organic solvent
afforded a crude product, which was subjected to
preparative TLC [silica gel, 20×20 cm; developing sol-
vent, hexane–ethyl acetate (1:1)] to afford (1R,8aR)-4
(42 mg, 51% yield, tR=66 min (96%), tR=70 min (4%),
92% ee) and (1S,8aS)-3 (44 mg, 44% yield, tR=22 min
(>99%), tR=26 min (<0%), >99% ee). (1R,8aR)-4: col-
orless oil. [h]D28 −147 (c=1.0, CHCl3). IR (KBr) cm−1:
A mixture of substrate and enzyme in phosphate buffer
(2 ml, pH 7.25) was shaken at 33°C for a suitable time
under TLC monitoring. The reaction mixture was
extracted with ethyl acetate and the organic solution
was dried over anhydrous MgSO4. Evaporation of the
organic solvent gave a crude product. The reaction
mixture was subjected to a silica gel short column (ca.
3 g) using n-hexane–ethyl acetate (1:1, 10 ml) as the
eluent to afford the products, which were analyzed by
HPLC under the analytical condition, as shown in
Table 1.
1
3398, 1640, 1602. H NMR (CDCl3) l: 1.18 (s, 3H),
1.78 (d, 3H, J=1 Hz), 3.42 (dd, 1H, J=5, 11 Hz). FAB
HRMS m/z: 195.1390 (calcd for (M++H) C12H19O2:
195.1385). FAB MS m/z: 195 (M+). (1S,8aS)-3: color-
less oil. [h]2D81+95 (c=1.0, CHCl3). IR (KBr) cm−1: 1735,
1668, 1615. H NMR (CDCl3) l: 1.25 (s, 3H), 1.79 (d,
3H, J=1 Hz), 2.08 (s, 3H), 4.65 (dd, 1H, J=4, 12 Hz).
HRMS m/z: 236.1409 (calcd for C14H20O3: 236.1412).
EI-MS m/z: 236 (M+), 194, 138, 123.
5.4. General procedure for the quantitative analysis of
enantioselective hydrolysis of ( )-cis- and trans-
1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl
acetates 1, 3, 5, 7, 9 and 11
A mixture of substrate (5 mg) and enzyme (5–15 mg) in
phosphate buffer (2–4 ml, pH 7.25) was shaken at 33°C
for a suitable time under TLC monitoring. The reaction
mixture was extracted with ethyl acetate and the
organic solution was dried over anhydrous MgSO4.
Evaporation of the organic solvent gave a crude
product, which was subjected to a silica gel (ca. 5 g)
short column using n-hexane–ethyl acetate (1:1, 30 ml)
as the eluent to afford the reaction product. Thus
obtained reaction product was separately analyzed by
HPLC and the results are shown in Tables 2 and 4.
5.7. Enantioselective hydrolysis of ( )-cis-
1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl
acetate, 5
A mixture of ( )-5 (100 mg) and b-amylase (100 mg) in
phosphate buffer (40 ml, pH 7.25) was shaken at 33°C
for 12 h. The reaction mixture was extracted with ethyl
acetate and the organic solution was dried over anhy-
drous MgSO4. Evaporation of the organic solvent
afforded a crude product, which was subjected to

2130
N. Shimizu et al. / Tetrahedron: Asymmetry 13 (2002) 2123–2131
preparative TLC [silica gel, 20×20 cm; developing sol-
vent, hexane–ethyl acetate (1:1)] to afford (1R,8aR)-6
(42 mg, 50% yield, tR=62 min (97%), tR=68 min (3%),
94% ee) and (1S,8aS)-5 (41 mg, 41% yield, tR=29 min
(98.5%), tR=34 min (1.5%), 97% ee). (1R,8aR)-6: color-
less oil. [h]2D8 −166 (c=0.8, CHCl3). IR (KBr) cm−1:
colorless prism, mp 68–70°C. [h]3D0 −79 (c=1.4, CHCl3).
IR (KBr) cm−1: 1727, 1665, 1656, 1610. 1H NMR
(CDCl3) l: 1.29 (s, 3H), 1.80 (d, 3H, J=1.5 Hz), 2.05
(s, 3H), 4.80 (dd, 1H, J=2, 3 Hz). Anal. calcd for
C14H20O3: C, 71.16; H, 8.53. Found: C, 71.21; H,
8.57%.
1
3430, 1682 (sh), 1658, 1618. H NMR (CDCl3) l: 1.21
(d, 3H, J=0.5 Hz), 3.44 (dd, 1H, J=5, 11 Hz), 5.80 (s,
3H). FAB HRMS m/z: 181.1229 (calcd for (M++H)
C11H17O2: 181.1228). FAB MS m/z: 181 (M+).
(1S,8aS)-5: colorless prism, mp 56–58°C. [h]2D8 +102
5.10. Enantioselective hydrolysis of ( )-trans-
1,2,3,4,6,7,8,8a-octahydro-8a-methyl-6-oxo-naphthyl
acetate, 11
1
(c=1.0, CHCl3). IR (KBr) cm−1: 1730, 1682, 1618. H
A mixture of ( )-11 (60 mg) and lipase (100 mg) in
phosphate buffer (80 ml, pH 7.25) was shaken at 33°C
for 54 h. The reaction mixture was extracted with ethyl
acetate and the organic solution was dried over anhy-
drous MgSO4. Evaporation of the organic solvent
afforded a crude product, which was subjected to
preparative TLC [silica gel, 20×20 cm; developing sol-
vent, hexane–ethyl acetate (1:1)] to afford (1R,8aS)-12
(23 mg, 48% yield, tR=53 min (96.5%), tR=45 min
(3.5%), 93% ee) and (1S,8aR)-11 (25 mg, 42% yield,
tR=28 min (91.5%), tR=22 min (8.5%), 83% ee).
(1R,8aS)-12: colorless prism, mp 84–86°C. [h]2D7 +93
(c=1.6, CHCl3). IR (KBr) cm−1: 3434, 1659 (sh), 1645,
NMR (CDCl3) l: 1.28 (s, 3H), 2.08 (d, 3H, J=0.4 Hz),
4.65 (dd, 1H, J=4, 12 Hz), 5.81 (d, 1H, J=2 Hz).
HRMS m/z: 222.1247 (calcd for C13H18O3: 222.1256).
EIMS m/z: 222 (M+), 180, 124, 109.
5.8. Enantioselective hydrolysis of ( )-trans-
1,2,3,4,6,7,8,8a-octahydro-5-methoxycarbonyl-8a-
methyl-6-oxo-naphthyl acetate, 7
A mixture of ( )-7 (100 mg) and lipase (100 mg) in
phosphate buffer (40 ml, pH 7.25) was shaken at 33°C
for 65 h. The reaction mixture was extracted with ethyl
acetate and the organic solution was dried over anhy-
drous MgSO4. Evaporation of the organic solvent
afforded a crude product, which was subjected to
preparative TLC [silica gel, 20×20 cm; developing sol-
vent, hexane–ethyl acetate (1:1)] to afford (1R,8aS)-8
(44 mg, 49% yield, tR=122 min (99%), tR=113 min
(1%), 98% ee) and (1S,8aR)-7 (46 mg, 46% yield, tR=
58 min (99%), tR=65 min (1%), 98% ee). (1R,8aS)-8:
colorless prism, mp 146–149°C. [h]3D0 +84 (c=1.1,
CHCl3). IR (KBr) cm−1: 3522, 1732, 1662, 1618. 1H
NMR (CDCl3) l: 1.20 (s, 3H), 3.60 (s, 1H), 3.74 (s,
3H). Anal. calcd for C13H18O4: C, 65.53; H, 7.62.
Found: C, 65.27; H, 7.65%. (1S,8aR)-7: colorless oil.
[h]D30 −100 (c=0.98, CHCl3). IR (KBr) cm−1: 1730,
1
1608. H NMR (CDCl3) l: 1.25 (d, 3H, J=0.5 Hz),
3.66 (bs, 1H), 5.87 (d, 1H, J=1.5 Hz). Anal. calcd for
C11H16O2: C, 73.30; H, 8.95. Found: C, 73.11; H,
8.99%. (1S,8aR)-11: colorless prism, mp 47–50°C. [h]D27
−81 (c=1.1, CHCl3). IR (KBr) cm−1: 1731, 1666, 1617.
1H NMR (CDCl3) l: 1.32 (s, 3H), 2.06 (s, 3H), 4.85 (bs,
3H), 5.89 (d, 1H, J=1.5 Hz). Anal. calcd for C13H18O3:
C, 70.24; H, 8.16. Found: C, 70.07; H, 8.20%.
5.11. Jones’ oxidation of (1R,8aS)-10
Jones’ reagent (two drops) was added to a stirred
solution of the hydrolysed product (1R,8aS)-10 (18 mg)
in acetone (2 ml) and the mixture was cooled in an
ice-salt bath for 30 min. After the addition of isopropyl
alcohol and sodium hydrogen carbonate, the reaction
mixture was filtered. The filtrate was evaporated to give
a crude product, which was subjected to preparative
TLC [silica gel, 20×20 cm; developing solvent, hexane–
ethyl acetate (1:1)] to afford the (8aS)-diketone 13 [16
mg, 88% yield from (1R,8aS)-10]. (8aS)-diketone [h]D30
+18 (c=0.8, MeOH). 1H NMR (CDCl3) l: 1.18 (s, 3H),
1.78 (d, 1H, J=1 Hz). The NMR data of (8aS)-13 were
identical with those the reported (8aS)-13.11
1
1665, 1628. H NMR (CDCl3) l: 1.36 (s, 3H), 2.08 (s,
3H), 3.82 (s, 3H), 4.87 (dd, 1H, J=3, 3 Hz). HRMS
m/z: 280.1329 (calcd for C15H20O5: 280.1311). EIMS
m/z: 280 (M+), 238, 206, 150.
5.9. Enantioselective hydrolysis of ( )-trans-
1,2,3,4,6,7,8,8a-octahydro-5,8a-dimethyl-6-oxo-naphthyl
acetate, 9
A mixture of ( )-9 (78 mg) and lipase (78 mg) in
phosphate buffer (80 ml, pH 7.25) was shaken at 33°C
for 42 h. The reaction mixture was extracted with ethyl
acetate and the organic solution was dried over anhy-
drous MgSO4. Evaporation of the organic solvent
afforded a crude product, which was subjected to
preparative TLC [silica gel, 20×20 cm; developing sol-
vent, hexane–ethyl acetate (1:1)] to afford (1R,8aS)-10
(47 mg, 73% yield, tR=42 min (65%), tR=46 min
(35%), 30% ee) and (1S,8aR)-9 (17 mg, 22% yield,
tR=23 min (>99%), tR=18 min (<0%), >99% ee).
(1R,8aS)-10: colorless prism, mp 108–109°C. [h]3D0 +39
References
1. (a) Duthcer, J. S.; Macmillan, J. G.; Heathcock, C. H. J.
Org. Chem. 1976, 41, 2663–2669; (b) Welch, S. C.; Rao,
A. S. C. P. J. Org. Chem. 1978, 43, 1957–1961; (c) Magee,
T. V.; Bornmann, W. G.; Isaacs, R. C. A.; Danishefsky,
S. J. J. Org. Chem. 1992, 57, 3274–3276; (d) Grieco, P.
A.; Collins, J. L.; Moher, E. D.; Fleck, T. J.; Gross, R. S.
J. Am. Chem. Soc. 1993, 115, 6078–6093; (e) Yeo, S.-K.;
Hata, N.; Seki, M.; Kanematsu, K. Tetrahedron 1995, 51,
3499–3506; (f) Danishefsky, S. J.; Masters, J. J.; Young,
W. B.; Link, J. T.; Snyder, L. B.; Magee, T. V.; Jung, D.
K.; Isaacs, R. C. A.; Bornmann, W. G.; Alaimo, C. A.;
1
(c=1.9, CHCl3). IR (KBr) cm−1: 3419, 1641, 1605. H
NMR (CDCl3) l: 1.23 (d, 3H, J=1.5 Hz), 1.79 (d, 3H,
J=1.5 Hz), 3.60 (bs, 1H). Anal. calcd for C12H18O2: C,
74.19; H, 9.34. Found C, 74.11; H, 9.39%. (1S,8aR)-9:

N. Shimizu et al. / Tetrahedron: Asymmetry 13 (2002) 2123–2131
2131
Coburn, C. A.; Di Grandi, M. J. J. Am. Chem. Soc. 1996,
118, 2843–2859; (g) Cheung, W. S.; Wong, H. N. C.
Tetrahedron 1999, 55, 11001–11016.
with NaBH4 in MeOH followed by separation using
column chromatography and acetylation with Ac2O/
pyridine.
2. (a) Inayama, S.; Shimizu, N.; Ohkura, T.; Akita, H.;
Oishi, T.; Iitaka, Y. Chem. Pharm. Bull. 1986, 34, 2660–
2663; (b) Inayama, S.; Shimizu, N.; Ohkura, T.; Akita,
H.; Oishi, T.; Iitaka, Y. Chem. Pharm. Bull. 1987, 35,
429–432; (c) Inayama, S.; Shimizu, N.; Ohkura, T.;
Akita, H.; Oishi, T.; Iitaka, Y. Chem. Pharm. Bull. 1989,
37, 712–717; (d) Shimizu, N.; Ohkura, T.; Akita, H.;
Oishi, T.; Iitaka, Y.; Inayama, S. Chem. Pharm. Bull.
1989, 37, 1023–1027; (e) Shimizu, N.; Ohkura, T.; Akita,
H.; Oishi, T.; Iitaka, Y.; Inayama, S. Chem. Pharm. Bull.
1989, 37, 2561–2563; (f) Shimizu, N.; Ohkura, T.; Akita,
H.; Oishi, T.; Iitaka, Y.; Inayama, S. Chem. Pharm. Bull.
1991, 39, 2973–2979; (g) Saito, N.; Kawaguchi, H.; Oht-
suka, Y.; Shimizu, N.; Inayama, S. Chem. Pharm. Bull.
1991, 39, 3085–3087; (h) Shimizu, N.; Akita, H.; Oishi,
T.; Inayama, S. Chem. Pharm. Bull. 1994, 42, 1160–1162.
3. Shimizu, N.; Akita, H.; Kawamata, T. Chem. Pharm.
Bull. 1996, 44, 665–669.
8. Details of the enantioselective hydrolysis of cis-acetates
by b-amylase will be reported in the near future.
9. The conversion of ( )-3,4,8,8a-tetrahydro-8a-methyl-5-
metoxycarbonyl-1,6(2H,7H)-naphthalenedione to the
trans-acetate ( )-7 was successfully achieved by the
sequential reduction with L-selectride in THF at −78°C,
oxidation with MnO2 in CH2Cl2 followed by separation
using column chromatography and acetylation with
Ac2O/pyridine.
10. Shimizu, T.; Hiranuma, S.; Nakata, T. Tetrahedron Lett.
1996, 37, 6145–6148.
11. (a) Eder, U.; Sauer, G.; Wiechert, R. Angew. Chem., Int.
Ed. Engl. 1971, 10, 496–497; (b) Hiroi, K.; Yamada, S.
Chem. Pharm. Bull. 1975, 23, 1103–1109; (c) Uma, P.;
Swaminathan, S.; Rajagopalan, K. Tetrahedron Lett.
1984, 25, 5825–5828.
12. Fuhshuku, K.; Funa, N.; Akeboshi, T.; Ohta, H.;
Hosomi, H.; Ohba, S.; Sugai, T. J. Org. Chem. 2000, 65,
129–135.
4. Chen, C. S.; Fujimoto, Y.; Girdaukas, G.; Shi, C. J. J.
Am. Chem. Soc. 1982, 104, 7294–7299.
13. (a) Kazlauskas, R. J.; Weissfloch, A. N. E.; Rappaport,
A. T.; Cuccia, L. A. J. Org. Chem. 1991, 56, 2656–2665;
(b) Cygler, M.; Grochulski, P.; Kazlauskas, R. J.; Schrag,
J. D.; Bouthillier, F.; Rubin, B.; Serreqi, A. N.; Gupta,
A. K. J. Am. Chem. Soc. 1994, 116, 3180–3186.
14. (a) Naemura, K.; Fukuda, R.; Konishi, M.; Hirose, K.;
Tobe, Y. J. Chem. Soc., Perkin Trans. 1 1994, 1253–1256;
(b) Naemura, K.; Fukuda, R.; Murata, M.; Konishi, M.;
Hirose, K.; Tobe, Y. Tetrahedron: Asymmetry 1995, 6,
2385–2394; (c) Naemura, K.; Murata, M.; Tanaka, R.;
Yano, M.; Hirose, K.; Tobe, Y. Tetrahedron: Asymmetry
1996, 7, 3285–3294.
5. The conversion of ( )-3,4,8,8a-tetrahydro-8a-methyl-5-
methoxycarbonyl-1,6(2H,7H)-naphthalenedione2a,c to the
trans-acetate ( )-1 was successfully achieved by the
sequential reaction of reduction with NaBH4 in MeOH
followed by separation using column chromatography
and acetylation with Ac2O/pyridine.
6. The conversion of ( )-3,4,8,8a-tetrahydro-5,8a-dimethyl-
1,6(2H,7H)-naphthalenedione1a to the trans-acetate ( )-3
was successfully achieved by the sequential of reduction
with NaBH4 in MeOH and acetylation with Ac2O/
pyridine.
7. The conversion of ( )-3,4,8,8a-tetrahydro-8a-methyl-
1,6(2H,7H)-naphthalenedione to the trans-acetate ( )-5
was successfully achieved by the sequential of reduction
15. Lemke, K.; Lemke, M.; Theil, F. J. Org. Chem. 1997, 62,
6268–6273.