Enzymatic resolution of α-tetralols by CALB-catalyzed acetylation

Article abstract of DOI:10.1016/j.tetasy.2007.05.007

A series of homochiral α-tetralols, as well as their respective acetates, has been obtained by esterification of racemic tetralols, using Candida antarctica lipase (CALB-Novozym 435) as the biocatalyst. This enzyme is shown to be highly efficie

Full text of DOI:10.1016/j.tetasy.2007.05.007

Tetrahedron: Asymmetry 18 (2007) 1070–1076
Enzymatic resolution of a-tetralols by CALB-catalyzed acetylation
Helena M. C. Ferraz,a,* Graziela G. Bianco,a Carla C. Teixeira,a
a
b
´
Leandro H. Andrade and Andre L. M. Porto
aInstituto de Quı´mica, Universidade de Sa˜o Paulo, Av. Prof. Lineu Prestes, 748, CEP 05508-900 S. Paulo, SP, Brazil
bInstituto de Quı´mica de Sa˜o Carlos, Universidade de Sa˜o Paulo, CP 780, 13560-970 S. Carlos, SP, Brazil
Received 1 March 2007; accepted 3 May 2007
Available online 1 June 2007
Abstract—A series of homochiral a-tetralols, as well as their respective acetates, has been obtained by esterification of racemic tetralols,
using Candida antarctica lipase (CALB—Novozymꢀ 435) as the biocatalyst. This enzyme is shown to be highly efficient for the kinetic
resolution of the substrates studied, affording the (+)-tetralols and the (+)-acetates in excellent enantiomeric excess (up to >99%) and
very good yields (>40%).
ꢁ 2007 Elsevier Ltd. All rights reserved.
1. Introduction
a-tetralols, by using an enzymatic acetylation reaction. The
lipase B from Candida antarctica (CALB—Novozymꢀ
435), chosen as the biocatalyst, has proven to be very effi-
cient for a wide variety of enantioselective reactions, such
as transesterification,12–18 aminolysis,19 and hydrolysis.20
Enantiomerically pure a- and b-tetralols constitute versa-
tile homochiral building blocks in organic synthesis.1–4 In
our efforts concerning the asymmetric synthesis of natural
products, such as mutisianthol (I),5,6 and flossonol (II),7
(Fig. 1), we reasoned that some a-tetralol derivatives could
be useful intermediates or even model substrates for these
studies.
2. Results and discussion
2.1. Preparation of the racemic a-tetralols 1b–7b and
acetates 1c–7c
OH
HO
MeO
The racemic a-tetralols were prepared by the reduction of
the corresponding a-tetralones, using sodium borohydride
in methanol. Thus, the commercially available a-tetralones
1a–4a furnished a-tetralols 1b–4b in excellent yields
(Scheme 1).
O
(I)
(II)
Figure 1. Mutisianthol (I) and flossonol (II).
The kinetic enzymatic resolution of some b-tetralols, by
porcine pancreatic lipase-catalyzed acetylation, has been
reported by Martinez.8 The bioreduction of b-tetralones,
leading to enantiomerically pure b-tetralols, has been stud-
ied by several groups.9–11 On the other hand, few attention
has been addressed to biotransformations involving substi-
tuted a-tetralones or a-tetralols. Therefore, we decided to
investigate the resolution of a series of substituted racemic
O
OH
R3
R2
R3
R2
NaBH4, MeOH
2 h, 0 °C
R1
R1
1a: R1=R2=R3=H
( )-1b (97%)
( )-2b (93%)
( )-3b (91%)
( )-4b (98%)
2a: R1=OMe, R2=R3=H
3a: R1=R2=H, R3=OMe
4a: R1=R3=Me, R2=H
*
Corresponding author. Tel.: +11 3091 3851; fax: +11 3815 5578; e-mail:
hmferraz@iq.usp.br
Scheme 1.
0957-4166/$ - see front matter ꢁ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2007.05.007

H. M. C. Ferraz et al. / Tetrahedron: Asymmetry 18 (2007) 1070–1076
1071
a-Tetralone 5a, a precursor of a-tetralol ( )-5b, was
obtained in three steps from 2-methylanisole, through an
earlier described procedure (Scheme 2).6,21
their enantiomers by chiral gas chromatography, which
was shown to be efficient for all the acetates, except for
2c. A representative chromatogram of the resolution pro-
cess is shown in Figure 2.
O
OH
MeO
MeO
MeO
a, b, c
d
( )-5b
5a
Scheme 2. Reagents and conditions: (a) succinic anhydride, C6H5NO2, 0–
5 ꢂC, AlCl3, 24 h (80%); (b) Zn(Hg), H2O, HCl, toluene, 2 d (83%); (c)
TFA, TFAA, 10 min (97%); (d) NaBH4, MeOH, 2 h, 0 ꢂC (95%).
Finally, the diastereomeric tetralols 6b/6b0 and 7b/7b0 were
obtained as 2:1 (trans:cis) and 2:3 (trans:cis) mixtures,
respectively, by reduction of the commercially available
tetralones 6a and 7a (Scheme 3).
O
OH
OH
NaBH4, MeOH,
0 °C, 2 h
+
96%
Figure 2. Chromatogram of the racemic acetates 7c/7c0—signals at 41.80
and 43.48 min: cis-enantiomer 7c0; signals at 42.19 and 44.23 min: trans-
enantiomer 7c.
( )-6a
( )-6b
( )-6b'
2:1 (trans:cis
)
O
OH
OH
2.2. Enzymatic resolution
NaBH4, MeOH,
0 °C, 2 h
+
The racemic a-tetralols were submitted to CALB-catalyzed
enzymatic acetylation employing vinyl acetate as the acyl
donor. This reagent has shown excellent performance in
this type of reaction.24,25 The reactions were performed in
hexane at 32 ꢂC, by the times indicated in Table 1. The
resulting acetates and the remaining tetralols were sepa-
rated by flash chromatography, and obtained in high yields
and excellent ee.
98%
( )-7a
( )-7b
( )-7b'
2:3 (trans:cis
)
Scheme 3.
The relative configurations of tetralols 6b/6b03,22 and
7b/7b022,23 were established by comparison to the literature
data.
Doubling the amount of CALB increased the ee to >99%
for tetralol (+)-4b and acetate (+)-4c. a-Tetralols 6b/6b0
were submitted to different experimental conditions (varia-
tion in time, temperature, and amount of CALB), but the
results were unsuccessful.
Tetralols 1b–7b were then acetylated using classical condi-
tions, to afford the corresponding racemic acetates 1c–7c
(Scheme 4). These products were analytically resolved into
The stereochemical preference of CALB was determined by
establishing the absolute configuration of the remaining
tetralols and of the obtained acetates. By comparison of
the specific rotation values to those in the literature, the
(S)-configuration was given to tetralols (+)-1b,27 (+)-2b,3
(+)-3b,28 and (+)-4b,3 while the acetates were assigned as
(R). Therefore, the acetylation takes place almost exclu-
sively in the (R)-tetralol, in according to Kazlauskas’ rule29
(Fig. 3a and b).
O
OH
O
R3
R2
R4
R3
R2
R4
Ac2O, Et3N,
DMAP, rt
R1 R5
R1 R5
( )-1b: R1=R2=R3=R4=R5=H
( )-1c (93%)
( )-2c (92%)
( )-3c (97%)
( )-4c (98%)
( )-5c (90%)
( )-6c/c’ (97%)
( )-7c/c’ (96%)
( )-2b: R1=OMe, R2=R3=R4=R5=H
( )-3b: R3=OMe, R1=R2=R4=R5=H
( )-4b: R1=R3=Me, R2=R4=R5=H
( )-5b: R1=R4=R5=H, R2=Me, R3=OMe
( )-6b/b’: R1=R2=R3=R5=H, R4=Me
( )-7b/b’: R1=R2=R3=R4=H, R5=Me
A possible explanation for the lack of reactivity of tetralols
6b/6b0, may be the influence of the methyl group at C-2, as
depicted in Figure 3c. Since the relative sizes of the two
substituents are similar, the enzyme becomes less able to
distinguish between them. In a previous study, Naemura
et al.30 reported that this same substrate is inert toward
the lipase YS (from Pseudomonas fluorescens). Moreover,
Scheme 4.

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H. M. C. Ferraz et al. / Tetrahedron: Asymmetry 18 (2007) 1070–1076
Table 1. CALB-catalyzed acetylation of ( )-tetralols 1b–7b
O
OH
OH
O
R3
R2
R4
R3
R2
R4
R3
R2
R4
CALB,
OAc
+
hexane, 32 °C
R1 R5
R1 R5
R1 R5
( )-1b-7b
(+)-1c-7c
(+)-1b-7b
Remaining substratea
eesb (%)
Isolated yield (%) [a]D
>99
>99
>99
99
Substrate Time (h)
Producta
Ed
b
c
c
eep (%)
Isolated yield (%) [a]D
1b
2b
2.3
3
(R)-1c
>99
>99
>99
99
>99
—
48
42
46
38
47
—
47
+109.7 (S)-1b
+101.8 (S)-2b
+88.5 (S)-3b
+98.1 (S)-4b
+106.6 (+)-5b
46
42
47
44
48
—
47
+33.9 >500
+23.3 >500
+41.9 >500
+38.9 >500
+36.9 >500
(R)-2c
(R)-3c
(R)-4c
(+)-5c
—
3b
4b
2.5
20
5b
6b+6b0
7b+7b0
4
98
Various times
20
—
—
—
—
—
—
—
>500
7c+7c0 Trans >99
Cis >99
7b+7b0 Trans >99
Cis >99
(2:3 trans:cis)
(2:3 trans:cis)
a The conversion rate [c = ees/(ees + eep)] was 50% in all reactions.
b Determined by chiral GC.
c See Section 4 for values of temperature and concentration.
d The enantiomeric ratio (E) was calculated using Sih’s method.26
a
b
c
H OH
H OH
Large
R3
H OH
Large
Large
Medium
(R)
(R)
L
M
R2
R1
1b-4b
M: Medium group
L: Large group
6b/6b'
Figure 3. (a) Enantiomer more reactive; (b) reactive substrates; (c)
unreactive substrate.
Kasai et al.31 reported that the hydrolysis of the corre-
sponding acetate 6c gave the desired alcohol in poor ee
(22%) and 42% of conversion, by using the mold Rhizopus
nigricans.
The stereoselectivity of CALB was studied by Uppenberg
et al.32 through crystallographic and molecular modeling.
This study provided a structural explanation for the high
stereoselectivity of CALB toward many secondary alco-
hols, and the authors concluded that the (R)-enantiomer
of this type of substrate fits better into the active site pocket
of the enzyme than the (S)-enantiomer. Our results are in
agreement with these observations, since the enzyme pro-
motes the preferential acetylation of the (R)-enantiomer
of all the tetralols studied.
Figure 4. Chromatogram of acetates 7c/7c0 (2:3 trans:cis) (a) produced in
the enzymatic acetylation and (b) obtained from the remaining tetralols
7b/7b0. For better comprehension, see Figure 2, which shows the
chromatogram of racemic acetates ( )-(7c+7c0).
good separation by chiral gas chromatography. The chro-
matogram of the acetates produced in the enzymatic acet-
ylation is shown in Figure 4b. It was possible to observe
that only one enantiomer of each pair cis and each pair
trans was formed.
The absolute configuration of acetate (+)-5c was not deter-
mined, but we strongly believe that it is (R), by analogy
with the others. Acetates 7c and 7c0 (trans:cis mixture)
could not be separated either by flash chromatography or
by high performance liquid chromatography (HPLC). Fig-
ure 4a shows the chromatogram of acetates 7c/7c0 obtained
from the remaining tetralols 7b/7b0, which did not undergo
The remaining tetralols (+)-1b, (+)-3b, (+)-4b, and (+)-5b
were acetylated, in order to measure the ½aꢀD values of the
acetates obtained and thus verify their absolute configura-
tions (Table 2). The specific rotation values are in

H. M. C. Ferraz et al. / Tetrahedron: Asymmetry 18 (2007) 1070–1076
1073
Table 2. Acetylation of (+)-tetralols 1b and 3b–5b
OH
OAc
R3
R2
R3
R2
Ac2O, Et3N
DMAP, rt
1 h
R1
R1
b
b
Entry
Substrate
R1 = R2 = R3 = H
R1 = R2 = H, R3 = OMe
R1 = R3 = Me, R2 = H
eea (%)
[a]D
Product
eea (%)
[a]D
1
2
3
4
(+)-(S)-1b
(+)-(S)-3b
(+)-(S)-4b
(+)-5b
>99
>99
99
+33.9
+41.9
+38.9
+36.9
(ꢁ)-(S)-1c
(ꢁ)-(S)-3c
(ꢁ)-(S)-4c
(ꢁ)-5c
>99
>99
99
ꢁ89.1
ꢁ85.5
ꢁ90.4
ꢁ96.9
R1 = H, R2 = Me, R3 = OMe
98
98
a Determined by chiral GC.
b See Section 4 for values of temperature and concentration.
agreement with the expected ones, since all the obtained
(S)-acetates are levorotatory, while those produced by
enzymatic resolution are dextrorotatory. In the same fash-
ion, acetate (+)-2c was hydrolyzed to tetralol (ꢁ)-2b
(Scheme 5), since the analytical resolution of acetate ( )-
2c was not achieved.
1H and 13C NMR spectra were measured in CDCl3 with
Me4Si as the internal standards and recorded on Bruker
and Varian spectrometers. IR spectra were measured on
a Perkin–Elmer 1750-FT, absorbances are reported in
cmꢁ1. Gas chromatography analyses were performed in a
HP-6890 series II. Conversions and enantiomeric excesses
of the enzyme-catalyzed reactions were determined using
a HP-6890 series II gas chromatograph equipped with a
chiral capillary column AG100-2000 (packed b-cyclodex-
trin (30 m · 0.32 mm · 0.25 lm)—Agilent-HP). The carrier
gas was hydrogen. GC–MS analyses were performed using
Finnigan-MAT INCOS 50B and GC Varian 2400. Elemen-
tal analyses were performed using Perkin–Elmer 2400
apparatus. High-resolution mass spectra were performed
on a Bruker Daltonics Microtof Eletrospray instrument.
Optical rotation values were measured in a JASCO DIP-
378 polarimeter and the reported data refer to the Na-line
value using a 1 dm cuvette. CALB was a gift from Novo
OAc
(R
OH
(R)
K2CO3, MeOH
30 min, rt
)
91%
OMe
OMe
(−)-2b
(+)-2c
[α]D27 +101.8°
[α]D27 -15.2°
ee >99%
ee >99%
Scheme 5.
´
Nordisk (Parana-Brazil).
3. Conclusion
4.2. General procedure for reduction of the tetralones
It was possible to prepare a series of optically active a-tet-
ralols, as well as their respective acetates, in excellent enan-
tiomeric excess and high conversion rate. CALB was
shown to be highly efficient for the resolution of the race-
mic a-tetralols studied, allowing their enantiomeric resolu-
tion in very good yields. These results certainly contribute
to corroborate the enantioselectivity of the enzyme CALB
toward secondary alcohols. a-Tetralols 7b/7b0 should be
employed in model studies directed toward the asymmetric
synthesis of mutisianthol. Moreover, the homochiral a-tet-
ralol (+)-5b seems to be a useful intermediate for the syn-
thesis of flossonol, as indicated by some preliminary
experiments performed in our laboratory.
4.2.1. Preparation of 1,2,3,4-tetrahydronaphthalen-1-ol 1b.3
To a solution of 1,2,3,4-tetrahydronaphthalen-1-one 1a
(0.45 g, 3.1 mmol) in anhydrous MeOH (9 mL) at 0 ꢂC un-
der N2, NaBH4 (0.34 g, 8.9 mmol) was added portionwise.
The mixture was allowed to reach room temperature and
then stirred for 2 h. The reaction mixture was quenched
with water and extracted with AcOEt. The organic layer
was washed with brine, dried over MgSO4, and concen-
trated under reduced pressure. The residue was purified
by silica flash chromatography (hexanes–AcOEt, 7:3 as elu-
ent), to give 1b as a viscous oil (97%; 0.44 g, 3.0 mmol).
4.2.2. 1,2,3,4-Tetrahydro-5-methoxynaphthalen-1-ol 2b.3
Using the general procedure described for 1b, 1,2,3,4-tetra-
hydro-5-methoxynaphthalen-1-one 2a (0.53 g, 3.0 mmol)
was converted into 2b (93%; 0.50 g, 2.8 mmol); white solid
mp: 102.0–103.0 ꢂC.
4. Experimental
4.1. General
All solvents and chemicals used were previously purified
according to the usual methods. Column chromatography
was performed using silica gel Acros 200–400 Mesh. TLC
analyses were performed with silica gel plates Merck, using
UV-254 nm and p-anisaldehyde solutions for visualization.
4.2.3. 1,2,3,4-Tetrahydro-7-methoxynaphthalen-1-ol 3b.28
Using the general procedure described for 1b, 1,2,3,4-tetra-
hydro-7-methoxynaphthalen-1-one 3a (1.9 g, 11 mmol) was
converted into 3b (91%; 1.8 g, 10 mmol); white solid mp:
38.0–39.0 ꢂC.

1074
H. M. C. Ferraz et al. / Tetrahedron: Asymmetry 18 (2007) 1070–1076
4.2.4. 1,2,3,4-Tetrahydro-5,7-dimethylnaphthalen-1-ol 4b.3
Using the general procedure described for 1b, 1,2,3,4-tetra-
hydro-5,7-dimethylnaphthalen-1-one 4a (0.71 g, 4.1 mmol)
was converted into 4b (98%; 0.70 g, 4.0 mmol); white solid
mp: 79.0–80.0 ꢂC.
131.1, 132.4, 156.1, 171.0; IR (film) mmax: 3425, 2960,
2840, 1719, 1619, 1510 cmꢁ1; LRMS (EI) m/z (%): 234
(M+Å, 6), 191 (4), 174 (100), 159 (56), 91 (22).
4.3.6. 1,2,3,4-Tetrahydro-2-methylnaphthalen-1-yl acetate
6c/6c0.22 In the same manner as described in the general
procedure, 6b/6b0 (0.047 g, 0.29 mmol) was converted into
6c/6c0 (97%; 0.057 g, 0.28 mmol) as a viscous colorless oil.
4.2.5. 1,2,3,4-Tetrahydro-6-methyl-7-methoxynaphthalen-1-
ol 5b.33 Using the general procedure described for 1b,
1,2,3,4-tetrahydro-6-methyl-7-methoxynaphthalen-1-one 5a
(0.38 g, 2.0 mmol) was converted into 5b (95%; 0.36 g,
1.9 mmol); white solid mp: 67.5–68.5 ꢂC.
4.3.7. 1,2,3,4-Tetrahydro-4-methylnaphthalen-1-yl acetate
7c/7c0.22 In the same manner as described in the general
procedure, 7b/7b0 (0.083 g, 0.51 mmol) was converted into
7c/7c0 (96%; 0.10 g, 0.49 mmol) as a colorless oil.
4.2.6. 1,2,3,4-Tetrahydro-2-methylnaphthalen-1-ol 6b/6b0.22
Using the general procedure described for 1b, 1,2,3,4-tetra-
hydro-2-methylnaphthalen-1-one 6a (0.82 g, 5.1 mmol) was
converted into a trans:cis (2:1) mixture of 6b/6b0 (96%;
0.79 g, 4.9 mmol) as a viscous oil.
4.4. Control of the enzymatic resolution of the ( )-a-tetralols
Tetralols and the corresponding acetates were compared
with the racemic mixtures previously analyzed. GC condi-
tions: injector: 250 ꢂC, detector: 350 ꢂC, oven: 120–180 ꢂC
(120 min), rate: 0.5 ꢂC/min, flow: 1.4 mL/min; pressure of
H2(g): 10 psi, constant pressure, split ratio 1:50. tR = reten-
tion time (min).
4.2.7. 1,2,3,4-Tetrahydro-4-methylnaphthalen-1-ol 7b/7b0.22
Using the general procedure described for 1b, 1,2,3,4-tetra-
hydro-4-methylnaphthalen-1-one 7a (0.82 g, 5.1 mmol) was
converted into a trans:cis (2:3) mixture of 7b/7b0 (98%;
0.81 g, 5.0 mmol) as a viscous oil.
4.4.1. General procedure for the enzymatic resolution of the
( )-a-tetralols. To a magnetically stirred solution of the
tetralol in hexane (32 mL/mmol), CALB (1.2 g/g tetralol)
was added, followed by vinyl acetate (4 equiv). This mix-
ture was stirred at 32 ꢂC, for the time indicated in Table
1. The enzyme was filtered off and washed with AcOEt.
The solvent was removed under reduced pressure and the
residue was subjected to flash chromatography (hexanes–
AcOEt, 7:3 as eluent).
4.3. General procedure for acetylation of the tetralols
4.3.1. Preparation of 1,2,3,4-tetrahydronaphthalen-1-yl ace-
tate 1c. To a solution of 1,2,3,4-tetrahydronaphthalen-1-
ol 1b (0.41 g, 2.8 mmol) in Et3N (5 mL), Ac2O (0.85 mL,
8.5 mmol) was added, followed by DMAP (cat.) at room
temperature. After stirring for 1 h, the reaction mixture
was diluted with MeOH and concentrated under reduced
pressure. The residue was quenched with water, extracted
with AcOEt, washed with brine, dried over MgSO4, and
concentrated under reduced pressure. The crude product
was chromatographed on silica flash (hexanes–AcOEt,
8:2 as eluent), to give 1c (93%; 0.49 g, 2.6 mmol) as a color-
less oil.
4.4.2. (S)-1,2,3,4-Tetrahydronaphthalen-1-ol 1b, (S)- and
(R)-1,2,3,4-tetrahydronaphthalen-1-yl acetate 1c. Reac-
tion time: 2 h 20 min; ( )-1b (0.16 g, 1.1 mmol) was
converted into (+)-(S)-1b (46%; 0.075 g, 0.51 mmol) and
(+)-(R)-1c (48%; 0.10 g, 0.53 mmol).
27
4.3.2. 1,2,3,4-Tetrahydro-5-methoxynaphthalen-1-yl acetate
2c.34 In the same manner as described in the general pro-
cedure, 2b (0.091 g, 0.51 mmol) was converted into 2c
(92%; 0.10 g, 0.47 mmol); white solid mp: 36.0–37.0 ꢂC.
(+)-(S)-1b ½aꢀD ¼ þ33:9 (c 1.13, CHCl3), ee >99%; {lit.27
27
(S)-1b ½aꢀD ¼ þ32:2 (c 2.51, CHCl3), ee = 99%}.
27
(+)-(R)-1c ½aꢀD ¼ þ109:7 (c 1.21, CHCl3), ee >99%; tR =
24
35.53 min (100%); {lit.30 (R)-1c ½aꢀD ¼ þ106:1 (c
4.3.3. 1,2,3,4-Tetrahydro-7-methoxynaphthalen-1-yl acetate
3c.28 In the same manner as described in the general
procedure, 3b (0.18 g, 1.0 mmol) was converted into 3c
(97%; 0.21 g, 0.97 mmol); white solid mp: 67.5–68.5 ꢂC.
0.15, CHCl3), ee = 93%}. (+)-(S)-1b was converted into
(ꢁ)-(S)-1c by chemical acetylation, as described in the
27
general procedure. (ꢁ)-(S)-1c ½aꢀD ¼ ꢁ89:1 (c 1.85,
CHCl3), ee >99%; tR = 36.14 min (100%).
4.3.4. 1,2,3,4-Tetrahydro-5,7-dimethylnaphthalen-yl acetate
4c.35 In the same manner as described in the general pro-
cedure, 4b (0.18 g, 1.0 mmol) was converted into 4c (98%;
0.21 g, 0.98 mmol); white solid mp: 40.0–41.0 ꢂC.
4.4.3. (S)- and (R)-1,2,3,4-Tetrahydro-5-methoxynaphthal-
en-1-ol 2b and (R)-1,2,3,4-tetrahydro-5-methoxynaphthal-
en-1-yl acetate 2c. Reaction time: 3 h; ( )-2b (0.18 g,
1.0 mmol) was converted into (+)-(S)-2b (42%; 0.075 g,
0.42 mmol) and (+)-(R)-2c (42%; 0.092 g, 0.42 mmol).
4.3.5. 1,2,3,4-Tetrahydro-6-methyl-7-methoxynaphthalen-1-
yl acetate 5c. In the same manner as described in the gen-
eral procedure, 5b (0.92 g, 4.8 mmol) was converted into 5c
(90%; 1.0 g, 4.3 mmol) as a colorless oil. 1H NMR
(300 MHz) d: 1.73–2.04 (m, 4H), 2.08 (s, 3H), 2.18 (s,
3H), 2.58–2.80 (m, 2H), 3.79 (s, 3H), 5.95–5.97 (m, 1H),
6.72 (s, 1H), 6.89 (s, 1H); 13C NMR (125 MHz) d: 16.0,
18.9, 21.6, 28.1, 29.2, 55.4, 70.2, 110.5, 127.3, 129.6,
27
(+)-(S)-2b ½aꢀD ¼ þ23:3 (c 1.04, CHCl3), ee >99%;
20
tR = 75.10 min (99.84%); {lit.3 (R)-2b ½aꢀD ¼ ꢁ15:3 (c
0.99, CHCl3), ee = 100%}; white solid mp: 97.0–98.0 ꢂC;
1H NMR (500 MHz) d: 1.71 (br s, 1H), 1.77–2.07 (m,
4H), 2.54–2.60 (m, 1H), 2.76–2.81 (m, 1H), 3.85 (s, 3H),
4.79–4.80 (m, 1H), 6.79 (dd, J 8 Hz and J 0.8 Hz, 1H),
7.09 (d, J 5.0 Hz, 1H), 7.22 (t, J 8 Hz, 1H); 13C NMR

H. M. C. Ferraz et al. / Tetrahedron: Asymmetry 18 (2007) 1070–1076
1075
1
(75 MHz) d: 18.1, 22.9, 31.7, 55.4, 68.1, 108.7, 120.5, 126.1,
126.5, 140.1, 157.1; IR (film) mmax: 3333, 2936, 2836, 1583,
1467, 1314 cmꢁ1; LRMS (EI) m/z (%) 178 (M+Å, 75), 160
(100), 147 (40), 121 (41), 91 (79). HRMS [ESI(+)]: m/z
calcd for [C11H14O2Na]+ 201.0891, found 201.0883.
solid mp: 85.0–86.0 ꢂC; H NMR (300 MHz) d: 1.76–2.05
(m, 5H), 2.19 (s, 3H), 2.29 (s, 3H), 2.44–2.70 (m, 2H),
4.71–4.74 (m, 1H), 6.92 (s, 1H), 7.11 (s, 1H); 13C NMR
(75 MHz) d: 18.5, 19.4, 20.9, 26.2, 31.8, 68.5, 126.9,
130.1, 132.4, 135.2, 136.4, 138.7; IR (film) mmax: 3304,
2922, 2860, 1480, 1072 cmꢁ1; LRMS (EI) m/z (%): 176
(M+Å, 76), 158 (93), 143 (100), 133 (52). HRMS [ESI(+)]:
m/z calcd for [C12H16ONa]+ 199.1099, found 199.1094.
27
(ꢁ)-(R)-2b ½aꢀD ¼ ꢁ15:2 (c 0.65, CHCl3), ee >99%; tR =
74.29 min (100%).
27
22
(+)-(R)-2c ½aꢀD ¼ þ101:8 (c 1.30, CHCl3), ee >99%; white
(+)-(R)-4c: ½aꢀD ¼ þ98:1 (c 1.22, CHCl3), ee = 99%;
1
solid mp: 36.0–37.0 ꢂC; H NMR (500 MHz) d: 1.79–2.0
tR = 66.51 min (99.50%); white solid mp: 45.5–46.5 ꢂC;
1H NMR (500 MHz) d: 1.79–1.99 (m, 4H), 2.07 (s, 3H),
2.20 (s, 3H), 2.27 (s, 3H), 2.47–2.53 (m, 1H), 2.68–2.73
(m, 1H), 5.95–5.97 (m, 1H), 6.95 (br s, 2H); 13C NMR
(125 MHz) d: 18.5, 19.4, 20.8, 21.6, 26.0, 28.6, 70.5,
127.7, 130.7, 133.3, 134.2, 135.2, 136.5, 170.8; IR (film)
(m, 4H), 2.08 (s, 3H), 2.50–2.56 (m, 1H), 2.80–2.85 (m,
1H), 3.82 (s, 3H), 5.98–5.99 (m, 1H), 6.78 (dd, J 8.0 Hz
and J 0.7 Hz, 1H), 6.90 (d, J 8 Hz, 1H), 7.17 (t, J 8 Hz,
1H); 13C NMR (125 MHz) d: 18.0, 21.5, 22.7, 28.6, 55.4,
70.0, 109.2, 121.4, 126.4, 127.1, 135.7, 157.1, 170.8; IR
(film) mmax: 3441, 2932, 2867, 1728, 1588, 1472 cmꢁ1
;
m
max: 2950, 2861, 1731, 1480, 1237 cmꢁ1; LRMS (EI) m/z
LRMS (EI) m/z (%): 220 (M+Å, 2), 160 (100), 145 (24),
129 (22), 91 (18). Anal. Calcd for C13H16O3: C, 70.89; H,
7.32. Found: C, 70.77; H, 7.35.
(%): 218 (M+Å, 1), 176 (15), 158 (100), 143 (89). Anal. Calcd
for C14H18O2: C, 77.03; H, 8.31. Found: C, 76.83; H, 8.53.
22
(ꢁ)-(S)-4c: ½aꢀD ¼ ꢁ90:4 (c 1.35, CHCl3), ee = 99%; tR =
4.4.4. (S)-1,2,3,4-Tetrahydro-7-methoxynaphthalen-1-ol 3b,
(S)- and (R)-1,2,3,4-tetrahydro-7-methoxynaphthalen-1-yl
acetate 3c. Reaction time: 2 h 30 min. ( )-3b (0.19 g,
1.1 mmol) was converted into (+)-(S)-3b (47%; 0.093 g,
0.52 mmol) and (+)-(R)-3c (46%; 0.11 g, 0.51 mmol).
67.54 min (99.40%).
4.4.6. (S)-1,2,3,4-Tetrahydro-6-methyl-7-methoxynaphthal-
en-1-ol 5b, (S)- and (R)-1,2,3,4-tetrahydro-6-methyl-7-
methoxynaphthalen-1-yl acetate 5c. Reaction time: 4 h.
( )-5b (0.16 g, 0.83 mmol) was converted into (+)-5b
(48%; 0.77 g, 0.40 mmol) and (+)-5c (47%; 0.91 g,
0.39 mmol).
24
(+)-(S)-3b: ½aꢀD ¼ þ41:9 (c 1.05, CHCl3), ee >99%; {lit.28
25
(S)-3b: ½aꢀD ¼ þ45:8 (c 3.63, CHCl3), ee = 100%}; mp:
1
45.0–46.0 ꢂC; H NMR (300 MHz) d: 1.65–1.97 (m, 4H),
2.29 (s, 1H), 2.56–2.76 (m, 2H), 3.75 (s, 3H), 4.65–4.68
(m, 1H), 6.95–6.99 (m, 2H), 6.74 (dd, J 8 Hz and J 3 Hz,
1H), 2.29 (br s, 1H); 13C NMR (75 MHz) d: 19.1, 28.3,
32.3, 55.1, 68.2, 112.6, 114.1, 129.0, 129.7, 139.8, 157.8;
IR (film) mmax: 3434, 3367, 2847, 1611, 1502 cmꢁ1; LRMS
(EI) m/z (%): 178 (M+Å, 85), 160 (100), 121 (73), 91 (36).
Anal. Calcd for C11H14O2: C, 74.13; H, 7.92. Found: C,
74.08; H, 8.19.
27
(+)-5b: ½aꢀD ¼ þ36:9 (c 0.99, CHCl3), ee = 98%; white
1
solid mp: 82.0–83.0 ꢂC; H NMR (500 MHz) d: 1.70–2.00
(m, 5H), 2.17 (s, 3H), 2.57–2.72 (m, 2H), 3.81 (s, 3H),
4.70–4.72 (m, 1H), 6.85 (s, 1H), 6.88 (s, 1H); 13C NMR
(125 MHz) d: 15.9, 19.2, 28.3, 32.6, 55.4, 68.4, 109.6,
126.3, 128.5, 131.0, 137.0, 156.2; IR (film) mmax: 3391,
3011, 2935, 2861, 2836, 1589, 1253, 1028 cmꢁ1; LRMS
(EI) m/z (%) 192 (M+, 100), 177 (76), 159 (50), 149 (38);
Anal. Calcd for C12H16O2: C, 74.97; H, 8.39. Found: C,
74.64; H, 8.55.
24
(+)-(R)-3c: ½aꢀD ¼ þ88:5 (c 1.14, CHCl3), ee >99%; tR =
73.92 min (100%); white solid mp: 92.0–93.0 ꢂC; 1H
NMR (500 MHz) d: 1.77–1.98 (m, 4H), 2.09 (s, 3H),
2.65–2.81 (m, 2H), 2.76–2.81 (m, 1H), 3.77 (s, 3H), 5.95–
5.96 (m, 1H), 6.80–6.82 (m, 2H), 7.04 (d, J 9 Hz, 1H);
13C NMR (125 MHz) d: 19.0, 21.5, 28.2, 29.1, 55.4, 70.2,
113.7, 114.8, 130.0, 130.0, 135.5, 157.8, 170.8; IR (film)
27
(+)-5c: ½aꢀD ¼ þ106:6 (c 1.22, CHCl3), ee >99%; tR =
80.09 min (100%); white solid mp: 52.5–53.5 ꢂC; for spec-
tral data, see Section 4.3.5; Anal. Calcd for C14H18O3: C,
71.77; H, 7.74. Found: C, 71.85; H, 7.58.
m
max: 3432, 3025, 2939, 2839, 1731, 1503 cmꢁ1; LRMS
27
(ꢁ)-5c: ½aꢀD ¼ ꢁ96:9 (c 1.15, CHCl3), ee = 98%; tR =
(EI) m/z (%): 220 (M+Å, 4), 160 (100), 145 (23), 129 (19),
115 (16), 91 (15). Anal. Calcd for C13H16O3: C, 70.89; H,
7.32. Found: C, 70.59; H, 7.56.
81.65 min (98.90%).
4.4.7. 1,2,3,4-Tetrahydro-4-methylnaphthalen-1-ol 7b/7b0
and 1,2,3,4-tetrahydro-4-methylnaphthalen-1-yl acetate 7c/
7c0. Reaction time: 20 h. ( )-7b/7b0 (trans:cis, 2:3)
(0.32 g, 2.0 mmol) was converted into a mixture 2:3 trans:-
cis of 7b/7b0 (47%; 0.15 g, 0.93 mmol) and a mixture 2:3
trans:cis of 7c/7c0 (47%; 0.19 g, 0.94 mmol).
24
(ꢁ)-(S)-3c: ½aꢀD ¼ ꢁ85:5 (c 1.27, CHCl3), ee >99%; tR =
74.49 min (100%).
4.4.5. (S)-1,2,3,4-Tetrahydro-5,7-dimethylnaphthalen-1-ol
4b, (S)- and (R)-1,2,3,4-tetrahydro-5,7-dimethyl naphthal-
en-1-yl acetate 4c. Reaction time: 20 h. ( )-4b (0.089 g,
0.50 mmol) was converted into (+)-(S)-4b (44%; 0.039 g,
0.22 mmol) and (+)-(R)-4c (38%; 0.041 g, 0.19 mmol).
tR = 41.80 min—7c0 cis (100%); tR = 42.20 min—7c trans
(100%).
27
(+)-(S)-4b: ½aꢀD ¼ þ38:9 (c 1.20, CHCl3), ee = 99%; {lit.3
tR = 44.36 min—7c0 cis (100%); tR = 45.09 min—7c trans
(100%).
22
(R)-4b ½aꢀD ¼ ꢁ31:6 (c 1.05, CHCl3), ee = 95%}; white

1076
H. M. C. Ferraz et al. / Tetrahedron: Asymmetry 18 (2007) 1070–1076
16. Zhang, Y.; Li, J.-f.; Yuan, C.-y. Tetrahedron 2003, 59, 473–
479.
Acknowledgments
´
17. Cordova, A.; Janda, K. D. J. Org. Chem. 2001, 66, 1906–
We are grateful to Novo Nordisk for a gift of CALB. We
are also indebted to FAPESP, CAPES, and CNPq, for
their continuous financial support, and to Professor Dr.
Luiz S. Longo Jr., for fruitful discussions.
1909.
18. Chojnacka, A.; Obara, R.; Wawrzenczyk, C. Tetrahedron:
Asymmetry 2007, 18, 101–107.
19. Gotor-Fernandez, V.; Fernandez-Torres, P.; Gotor, V. Tet-
rahedron: Asymmetry 2006, 17, 2558–2564.
20. Ghanem, A.; Schurig, V. Tetrahedron: Asymmetry 2003, 14,
57–62.
´
´
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