Enantiodivergence in the reduction of α-methyl and α-halomethyl enones by microorganisms

Article abstract of DOI:10.1016/j.tetasy.2013.07.007

Enones (Z)-3-methyl-(Z)-3-chloromethyl- and (Z)-3-bromomethyl-4-R-3-buten- 2-one (R = n-pentyl, phenyl, 2′- and 4′-chlorophenyl, 3′- and 4′-nitrophenyl, 4′-methoxyphenyl) were synthesized and subjected to reduction by the microorganisms Saccharomyces cerevisiae andGeotrichum candidum. Whereas the bioreduction of 3-methy-4-R-3-buten-2-ones afforded the corresponding (S)-4-R-3-methybutan-2-ones, the bioreduction of 3-chloromethyl- and 3-bromomethyl-4-R-3-buten-2-ones afforded the corresponding (R)-4-R-3-methybutan-2-ones.

Full text of DOI:10.1016/j.tetasy.2013.07.007

Tetrahedron: Asymmetry 24 (2013) 973–981
Contents lists available at SciVerse ScienceDirect
Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Enantiodivergence in the reduction of
enones by microorganisms
a-methyl and
a-halomethyl
⇑
Bruno R. S. de Paula, Dávila S. Zampieri, J. Augusto R. Rodrigues, Paulo J. S. Moran
Institute of Chemistry, University of Campinas, 13084-971 Campinas, SP, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 7 May 2013
Accepted 5 July 2013
Enones (Z)-3-methyl-(Z)-3-chloromethyl- and (Z)-3-bromomethyl-4-R-3-buten-2-one (R = n-pentyl,
phenyl, 20- and 40-chlorophenyl, 30- and 40-nitrophenyl, 40-methoxyphenyl) were synthesized and
subjected to reduction by the microorganisms Saccharomyces cerevisiae and Geotrichum candidum.
Whereas the bioreduction of 3-methy-4-R-3-buten-2-ones afforded the corresponding (S)-4-R-3-
methybutan-2-ones, the bioreduction of 3-chloromethyl- and 3-bromomethyl-4-R-3-buten-2-ones
afforded the corresponding (R)-4-R-3-methybutan-2-ones.
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
for a C–X bond at the b-position of a carbonyl can be used as a sub-
strate-based strategy to control the stereochemistry of the C@C
The bioreduction of activated C@C bonds is a powerful tool in
asymmetric organic synthesis and has been extensively studied
over recent years; both whole cell preparations and isolated enoate
reductases have been employed for this purpose.1 Among activated
olefins, those bearing a halogen at the a- or b-position with respect
to the electron withdrawing group show interesting behavior over
bond reduction.6,7 For example, the reduction of 2-chloromethyl-
and 2-methylcinnamaldehydes mediated by baker’s yeast has been
shown to afford the same alcohol, but with opposite stereochem-
istries.6 Thus, this strategy can overcome the drawback of needing
stereocomplementary biocatalysts when both enantiomers of a gi-
ven compound are needed. Herein we report the bioreductions of
the course of their bioreductions.
structurally related
a-methylenones and a-halomethylenones to
Generally,
a
-haloenones tend to afford the corresponding halo-
produce both stereoisomers of enantiomerically enriched
methylketones.
a-
hydrins after sequential C@C and C@O reductions.2–4 On the other
hand, bioreductions of b-haloenones show a distinct behavior due
to the acidity of the a-hydrogen in the b-haloketone intermediate,
which facilitates elimination of hydrogen halides.
2. Results and discussion
Elimination reactions in the bioreduction of b-haloketones have
been known for several years—for instance, it has been shown that
in the bioreduction of b-chloropropiophenone, it undergoes spon-
taneous elimination to afford a methyl vinyl ketone, whose C@C
bond is reduced to produce propiophenone.5 More recently, exam-
ples of b-elimination have been demonstrated in b-haloenals6,7 and
methyl trichloropropenoate and related esters.8 In these examples,
dehydrohalogenations occur spontaneously after the first C@C
Substrates 2a–g and 3a–g were prepared in two steps from
aldehydes and 3-buten-2-one, following procedures similar to
those described elsewhere for both the Morita–Baylis–Hillman
(MBH) reactions12,13 and reactions with concentrated HCl or
HBr.14 Substrates 4a–g were prepared from aldehydes and buta-
none in aldol condensations, following a procedure described else-
where15 (Scheme 1).
Substrate 2a was subjected to preliminary bioreduction exper-
iments to evaluate the capability of microorganisms producing
6a in high ee (Table 1). A range of products were observed over
the course of the reactions: along with the expected intermediate
5a and its bioreduction product 6a, the racemic MBH adduct 1a
and its isomer 716 were also observed in some cases (Table 1).
Experiments performed in the absence of microorganisms led to
the extensive formation of 1a and 7, suggesting that solvolysis of
2a competes with the bioreduction and prevails when the microor-
ganism is not capable of reducing 2a. It was observed that the MBH
adduct 1a was not further reduced by any of the microorganisms
screened.
bond reduction, producing an a,b-unsaturated carbonyl compound
that undergoes further C@C reduction. In contrast to spontaneous
dehydrohalogenations of b-haloketones, in cases where reductive
dehalogenation occurs in
a-haloketones, mechanisms other than
elimination have been proposed to account for the carbon–halogen
bond cleavage.9–11
For synthetic organic chemists, an interesting feature of these
reduction-elimination cascades is that the exchange of a C–H bond
⇑
Corresponding author. Tel.: +55 19 35213048; fax: +55 19 35213023.
E-mail address: moran@iqm.unicamp.br (P.J.S. Moran).
0957-4166/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetasy.2013.07.007

974
B. R. S. de Paula et al. / Tetrahedron: Asymmetry 24 (2013) 973–981
Table 2
O
Bioreduction of enones by S. cerevisiaea
OH
O
O
O
O
O
X
O
DABCO
O
HX
S. cerevisiae
S. cerevisiae
R
R
R
R
R
R
X = H
X = Cl, Br
X
1a-g
R
O
6
(S)-
(R)-6
2a-g
X = Cl
3a-g X = Br
H2SO4
HOAc
a
: b
c
d
: R = C6H5 : R = 2-Cl-C6H4; : R = 4-Cl-C6H4; : R = 3-NO2-C6H4;
: R = 4-NO2-C6H4; : R = 4-MeO-C6H4; : R = n-C5H11
e
f
g
Substrate
R
X
t (h)
Yield (%)b
ee (%)c
4a-g
2a
3a
4a
2b
3b
4b
2c
3c
4c
2d
3d
4d
2e
3e
4e
2f
Ph
Cl
Br
H
Cl
Br
H
Cl
Br
H
Cl
Br
H
Cl
Br
H
Cl
Br
H
Cl
Br
H
24
8
42
53
59
62
54
44
57
70
60
40
40
37
38
52
61
—
96 (R)
95 (R)
68 (S) [71]
>99 (R)
>99 (R)
96 (S)
92 (R)
94 (R)
80 (S)
83 (R)
78 (R)
93 (S) [>95]
82 (R)
80 (R)
63 (S)
a: R = C6H5; b: R = 2-Cl-C6H4; c: R = 4-Cl-C6H4; d: R = 3-NO2-C6H4;
e: R = 4-NO2-C6H4; f: R = 4-MeO-C6H4; g: R = n-C5H11
24
16
16
40
16
6
24
24
24
48
24
24
24
4
2-Cl-C6H4
4-Cl-C6H4
3-NO2-C6H4
4-NO2-C6H4
4-MeO-C6H4
n-C5H11
Scheme 1. Preparation of substrates 2a–g, 3a–g, and 4a–g.
It should be noted that, in general, the C@O bond reduction was
significantly slower than the C@C bond reduction, which means it
was possible to isolate ketone 6a free from the corresponding alco-
hol. Moreover, even though intermediate 5a did not accumulate in
the reaction medium, the production of (R)-6a from intermediate
5a is in agreement with the stereochemical outcome of a previ-
ously reported bioreduction of 5a by S. cerevisiae.18
We found that S. cerevisiae, Rhodotorula glutinis, and Geotrichum
candidum showed the best conversion to (R)-6a, although only S.
cerevisiae and G. candidum afforded (R)-6a in high ee. Thus,
commercial lyophilized S. cerevisiae and G. candidum were used
—
—
3f
4f
2g
3g
4g
4
—
24
12
12
8
63
16
25
38
53 (S) [61]
92 (R)
95 (R)
91 (S)
for subsequent reductions of
–bromomethylenones 3a–g, and
results are summarized in Tables 2 and 3.
In general, enones bearing an -halomethyl group produced
the corresponding -methylketones (R)-6a–g. On the other hand,
the reduction of -methylenones 4a–g gave the corresponding
-methylketones (S)-6a–g. Generally, S. cerevisiae gave products
a-chloromethylenones 2a–g,
a
a
-methylenones 4a–g. The
a
Yeast type II from S. cerevisiae, Sigma.
In cases where no yield is given, only the starting material and/or degradation
products were recovered.
b
a
c
19,20
a
a
ee Values between brackets refer to bioreductions reported in Ref.
.
a
of the activated double bond. This step is followed by a proton
in better yields and ee than G. Candidum, which did not reduce
abstraction by the
a-carbon, constituting an overall formal
several substrates.
trans-hydrogen addition to the double bond.25 According to a
recently published work,25,26 the stereochemistry of these
reactions can be attributed to a ‘flipped’ binding mode of enones
4a–g and 5a–g to the active site of OYEs, as envisaged in Figure 1.
Whereas the C@C bond reduction of 4a–g affords (S)-6a–g, the
An explanation for the observed stereochemical outcome of
these reactions takes into account the mechanism of action of
enzymes of the Old Yellow Enzyme (OYE) family. These enzymes,
present in S. cerevisiae,21–24 catalyze the transfer of a formal
hydride from a flavin mononucleotide (FMNH2) to the b-carbon
Table 1
Reaction mixture composition in the bioreduction of (Z)-3-chloromethyl-4-phenyl-3-buten-2-one 2a mediated by microorganisms
O
O
microorganisms
O
6a
(R)-
5a
OH
O
O
Cl
2a
H2O
+
OH
1a
7
Microorganism
t (h)
2a (%)
5a (%)
1a + 7 (%)
6a (ee) (%)
Saccharomyces cerevisiaea
Saccharomyces cerevisiaeb
Saccharomyces boulardii
Rhodotorula glutinis
Candida albicans
16
24
72
10
72
6
0
0
14
0
4
0
2
8
10
3
0
9
12
14
60
0
95
0
86 (96)
78 (94)
16 (85)
97 (59)
1 (n.d.)c
91 (87)
2 (n.d.)c
Geotrichum candidum
Curvularia lunata
72
6
0
92
a
b
c
Yeast type II from S. cerevisiae, Sigma.
S. cerevisiae CCT 3019 obtained from Fundação André Tosello.17
Not determined.

B. R. S. de Paula et al. / Tetrahedron: Asymmetry 24 (2013) 973–981
975
Table 3
the MBH adduct formed 1f was not further biotransformed by
either microorganism.
Bioreduction of enones by G. candidum
O
O
X
O
The bioreduction of 2a by S. cerevisiae was carried out with up
to 10 mmol (1.94 g) of substrate. The bioreduction product (R)-
6a, upon treatment with an alkaline solution of sodium hypobro-
mite27 was converted into the carboxylic acid (R)-8a (Scheme 2),
with a slight loss of enantiomeric purity. Acid (R)-8a has been used
as a chiral building block in the synthesis of zaragozic Acids A and
C C-1 side-chains.28
G. candidum
G. candidum
R
R
R
X = H
X = Cl, Br
6
(R)-
(S)-6
a
: b
c
d
: R = C6H5 : R = 2-Cl-C6H4; : R = 4-Cl-C6H4; : R = 3-NO2-C6H4;
: R = 4-NO2-C6H4; : R = 4-MeO-C6H4; : R = n-C5H11
e
f
g
Substrate
R
X
t (h)
Yield (%)a
ee (%)
3. Conclusion
2a
3a
4a
2b
3b
4b
2c
3c
4c
2d
3d
4d
2e
3e
4e
2f
Ph
Cl
Br
H
Cl
Br
H
Cl
Br
H
Cl
Br
H
Cl
Br
H
Cl
Br
H
Cl
Br
H
6
6
66
57
—
—
—
87 (R)
84 (R)
—
—
—
The yeast Saccharomyces cerevisiae was used to reduce enones
96
96
96
96
10
6
96
16
12
48
10
6
24
4
4
96
96
96
96
4a–g to produce
-chloromethylenones 2a–e and 2g and
3a–e and 3g were subjected to the same bioreduction conditions,
a reduction-elimination-reduction sequence afforded the -meth-
a
-methylketones (S)-6a–g in 63–96% ee. When
2-Cl-C6H4
4-Cl-C6H4
3-NO2-C6H4
4-NO2-C6H4
4-OMe-C6H4
n-C5H11
a
a-bromomethylenones
—
—
50
66
13
48
42
53
44
48
51
—
—
16
—
—
—
86 (R)
87 (R)
54 (S)
71 (R)
74 (R)
42 (S)
72 (R)
71 (R)
33 (S)
—
—
17 (S)
—
—
—
a
ylketone antipodes (R)-6a–e and (R)-6g in 78–99% ee. The p-anis-
aldehyde-derived enones 2f and 3f underwent rapid solvolysis,
possibly due to the electron-donating effect of the methoxy group;
the solvolysis product 1f was not further bioreduced. The fungus
Geotrichum candidum was also able to reduce some of the sub-
strates in the same manner as S. cerevisiae although enantiomeric
excesses were generally poorer.
3f
4f
2g
3g
4g
4. Experimental
4.1. General
a
In cases where no yield is given, only the starting material and/or degradation
Benzaldehyde, 2-chlorobenzaldehyde, 3-nitrobenzaldehyde,
4-nitrobenzaldehyde, hexanal, p-anysaldehyde, 3-buten-2-one,
DABCO, bromine, and AmberliteÒ XAD7HP were purchased from Al-
drich. Hydrobromic acid, 1,4-dioxane, and 4-chlorobenzaldehyde
were purchased from Merck. Glacial acetic acid, sodium hydroxide,
and hydrochloric acid were purchased from Synth. Benzaldehyde
and p-anysaldehyde were distilled before use; all other reagents
were used as received. Thin-layer chromatography (TLC) analyses
were performed with precoated aluminum sheets (silica gel 60
Merck), and column chromatography was carried out on silica
(200–400 mesh, Merck). Detection was performed by UV inspection
(254 nm) for all compounds except for 6g, which was detected
using a 2,4-DNP/H2SO4 stain. 1H NMR spectra were recorded at
250, 400, 500, or 600 MHz, and 13C NMR spectra were recorded at
62.5, 100, 125, or 150 MHz. Chemical shifts are reported in ppm rel-
ative to tetramethylsilane (d = 0) in CDCl3, and coupling constants
(J) are reported in Hz. GC/MS analyses were obtained on an Agilent
6890 Series GC System with a Hewlett-Packard 5973 Mass Selective
Detector (70 eV) using a HP-5MS fused silica capillary column
products were recovered.
O
O
O
H
Ar
R1 = CH2Ar
R2 = H
5
4
H
Me
O
R1
(R)-6
R1 = Me
R2 = Ar
R2
H
Me
H
"H
"
Ar
(from FMNH2)
(S)-6
Figure 1. ‘Flipped’ binding mode of enones 4a–g and 5a–g to the active site of OYEs
as an explanation for the enantiodivergence of the enone reductions.
(crosslinked 5% phenyl ethyl siloxane, 30 m ꢀ 0.25 m ID ꢀ 0.25
lm
film thickness) and helium as a carrier gas (1 mL minꢁ1). The split
ratio was 1:50. The injector temperature was kept 270 °C and
detector was kept at 280 °C. The column temperature was held at
60 °C for 3 min, increased to 280 °C at a rate of 25 °C minꢁ1, and
reduction of intermediate 5a–g produced from 2a–g and 3a–g af-
fords (R)-6a–g by the same ‘flipped’ binding mode.
A particular reactivity was observed for p-anisaldehyde-derived
enones 2f and 3f. Whereas 4f was reduced to the corresponding
(S)-a-methylketone, both 2f and 3f afforded the corresponding
then kept at 280 °C for 5 min. The 1 lL of a compound solution
(1 mg mLꢁ1) in ethyl acetate was injected and the retention times
(min) are reported for all compounds. Chiral GC/FID analyses were
obtained on an Agilent 6850 Series GC System, using a Hydrodex
MBH adduct 1f after only 4 h of reaction. This is an indication that
both 2f and 3f undergo rapid solvolysis, possibly due to the elec-
tron-donating effect of the methoxy group at the para-position;
O
O
NaBrO, NaOH
water/1, 4-dioxane
S. cerevisiae
2a
OH
(10 mmol)
61%
48%
(R)-6a
(R)-8a
95% ee
92% ee
Scheme 2. Preparation of (R)-8a.

976
B. R. S. de Paula et al. / Tetrahedron: Asymmetry 24 (2013) 973–981
chiral capillary column (30 m ꢀ 0.25 mm ID ꢀ 0.25
l
l
m film thick-
-cyclodextrin
(CDCl3, 62.5 MHz) d 26.5, 72.8, 126.5, 126.6, 127.7, 128.4, 141.6,
150.0, 200.3.
ness, Methods A and B) or a Chirasil-Dex CB
(30 m ꢀ 0.25 mm ID ꢀ 0.25
lm film thickness, Method C). Hydro-
gen was used as a carrier gas (1 mL minꢁ1), the injector tempera-
ture was 200 °C, and the detector temperature was 220 °C. Three
different methods were employed for the analysis of the bioreduc-
tion products. Method A: the column temperature was kept at 80 °C
for 3 min, increased to 180 °C at a rate of 3 °C minꢁ1, and then kept
at 180 °C for 20 min. Method B: the column temperature was kept
at 80 °C for 3 min, increased to 180 °C at a rate of 1 °C minꢁ1, and
then kept at 180 °C for 20 min. Method C: the column temperature
was kept at 80 °C for 3 min, increased to 130 °C at a rate of
1 °C minꢁ1, then to 180 °C at a rate of 10 °C minꢁ1 and kept at
4.4.2. 4-(20-Chlorophenyl)-4-hydroxy-3-methylidenebutan-2-
one 1b
Following the general procedure for the Morita–Baylis–Hillman
reaction, 1b was obtained in 58% yield as a colorless solid. Mp 39.9-
41.3 °C; Retention time on GC/MS: 10.644 min; EI-MS m/z (%): 210/
212 (12/4) [M+], 209/211 (62/22), 176 (12), 175 (100), 173 (43),
149 (14), 141 (31), 139 (52), 131 (12), 116 (12), 115 (32), 111
(21), 103 (14), 77 (58), 75 (23), 70 (16), 55 (17), 51 (19); 1H NMR
(CDCl3, 250 MHz) d 2.39 (s, 3H), 3.49 (d, 1H, J = 4.25 Hz), 5.67 (s,
1H), 5.99 (d, 1H, J = 4.25 Hz), 6.16 (s, 1H), 7.20–7.59 (m, 4H);13
C
180 °C for 1 min. In all cases, 1
lL of a compound solution
NMR (CDCl3, 100 MHz) d 26.3, 69.0, 127.0, 127.5, 128.2, 128.9,
(1 mg mLꢁ1) in ethyl acetate was injected; the retention times
(min) are reported for all compounds. IR spectra were recorded
on a FT-IR BOMEM MB-100 from Hartmann & Braun. Melting points
were recorded on a Metler Toledo MP50 Melting Point System.
Optical rotation measurements were recorded on a Perkin Elmer
341 polarimeter with a sodium lamp. GC/EI-HRMS analysis of 2g
was performed on a GCT Premier (Waters) GC–MS/TOF using a
129.4, 132.6, 138.5, 138.5, 200.7.
4.4.3. 4-(40-Chlorophenyl)-4-hydroxy-3-methylidenebutan-2-
one 1c
Following the general procedure for the Morita–Baylis–Hillman
reaction, 1c was obtained in 63% yield as a colorless oil. Retention
time on GC/MS: 10.939 min; EI-MS m/z (%): 210/212 (14/4) [M+],
209/211 (88/29), 195 (26), 176 (11), 175 (100), 157 (13), 149
(18), 141 (43), 140 (16), 139 (63), 129 (11), 116 (10), 115 (39),
114 (10), 113 (29), 111 (34), 103 (11), 99 (10), 78 (10), 77 (78),
75 (30), 74 (12), 70 (21), 55 (22), 51 (20); 1H NMR (CDCl3,
250 MHz) d 2.34 (s, 3H), 3.09 (d, 1H, J = 5.00 Hz), 5.58 (d, 1H,
J = 5.00 Hz), 5.97 (s, 1H), 6.20 (s, 1H), 7.25–7.31 (m, 4H);13C NMR
(CDCl3, 150 MHz) d 26.4, 72.2, 126.9, 127.9, 128.5, 133.4, 140.1,
149.7, 200.3.
HP5-MS column (30 m ꢀ 0.25 mm ID ꢀ 0.25
lm film thickness).
The injector temperature was kept at 260 °C and the detector was
kept at 280 °C. The column temperature was held at 100 °C for
1 min and then increased to 280 °C at a rate of 10 °C minꢁ1. One
lL
of a compound solution (1 mg mLꢁ1) in ethyl acetate was injected.
ESI-HRMS analysis of 3g was performed on a Waters Xevo Q-Tof.
4.2. Microorganisms
Saccharomyces cerevisiae CCT 3019, Saccharomyces boulardii CCT
3007, Rhodotorula glutinis CCT 2182, Geotrichum candidum CCT
1205, Candida albicans CCT 0776, and Curvularia lunata CCT 5628
were purchased from André Tosello Research Foundation.17 Yeast
type II from Saccharomyces cerevisiae was purchased from Sigma
(Lot BCBG5157V).
4.4.4. 4-Hydroxy-3-methylidene-4-(30-nitrophenyl)butan-2-one
1d
Following the general procedure for the Morita–Baylis–Hillman
reaction, 1d was obtained in 68% yield as a colorless solid. Mp
81.2–81.7 °C (lit.29 77–78 °C); Retention time on GC/MS:
12.173 min; EI-MS m/z (%): 221 (6) [M+], 220 (44), 206 (25), 205
(15), 204 (100), 203 (34), 202 (25), 177 (16), 175 (15), 174 (43),
162 (18), 161 (14), 160 (19), 159 (10), 152 (12), 151 (15), 150
(85), 134 (12), 132 (21), 131 (43), 130 (11), 129 (10), 128 (19),
116 (20), 115 (41), 114 (13), 106 (13), 105 (37), 104 (49), 103
(27), 102 (19), 78 (24), 77 (67), 76 (60), 75 (24), 74 (17), 70 (31),
63 (18), 55 (35), 53 (10), 52 (10), 51 (36); 1H NMR (CDCl3,
500 MHz) d 2.36 (s, 3H), 3.40 (d, 1H, J = 5.50 Hz), 5.68 (d, 1H,
J = 5.50 Hz), 6.09 (s, 1H), 6.29 (s, 1H), 7.51 (t, 1H, J = 8.00 Hz),
4.3. Growth conditions
Microorganisms were grown in a medium containing 10 g Lꢁ1
of sucrose, 5 g Lꢁ1 of malt extract, 5 g Lꢁ1 of yeast extract and
3 g Lꢁ1 of peptone for 24 h, in an orbital shaker at 30 °C and
180 rpm. Cells were harvested by centrifuging at 3500 rpm for
10 min in the case of S. cerevisiae, S. boulardii, R. glutinis, and C. albi-
cans; G. candidum and C. lunata cells were harvested by filtration.
7.73 (d, 1H, J = 8.00 Hz), 8.12 (d, 1H, J = 8.00 Hz), 8.22 (s, 1H);13
C
NMR (CDCl3, 125 MHz) d 26.4, 72.1, 121.4, 122.6, 127.8, 129.3,
4.4. General procedure for the Morita–Baylis–Hillman reaction
between 3-buten-2-one and aldehydes
132.7, 144.0, 148.3, 149.0, 200.1.
4.4.5. 4-Hydroxy-3-methylidene-4-(40-nitrophenyl)butan-2-one
1e
3-Buten-2-one (1.82 g, 26 mmol) and aldehyde (20 mmol) were
added to a 25 mL round-bottom flask. Next, DABCO (448 mg,
4 mmol) was added, and the mixture was stirred for 48 h. Then,
10% HCl (10 mL) was added to the flask, and the mixture was ex-
tracted with ethyl acetate (50 mL). The mixture was washed with
10% HCl, 10% NaHCO3, brine, and then dried over Na2SO4. The sol-
vent was removed under reduced pressure, and the residue was
purified by column chromatography.
Following the general procedure for the Morita–Baylis–Hillman
reaction, 1e was obtained in 72% yield as a colorless solid. Mp
71.1–74.5 °C (lit.29 76–77 °C); Retention time on GC/MS:
12.335 min; EI-MS m/z (%): 220 (16), 206 (16), 205 (13), 204
(100), 202 (11), 177 (11), 175 (13), 174 (76), 150 (35), 132 (11),
131 (14), 116 (14), 115 (19), 105 (15), 104 (27), 103 (15), 78
(14), 77 (33), 76 (25), 75 (12), 63 (10), 55 (21), 51 (18); 1H NMR
(CDCl3, 600 MHz) d 2.35 (s, 3H), 3.51 (d, 1H, J = 5.40 Hz), 5.69 (d,
1H, J = 5.40 Hz), 6.07 (s, 1H), 6.28 (s, 1H), 7.55 (d, 1H, J = 9.00 Hz),
8.17 (d, 1H, J = 9.00 Hz); 13C NMR (CDCl3, 150 MHz) d 26.3, 72.0,
123.6, 127.3, 127.7, 147.3, 149.1, 149.1, 200.1.
4.4.1. 4-Hydroxy-3-methylidene-4-phenylbutan-2-one 1a
Following the general procedure for the Morita–Baylis–Hillman
reaction, 1a was obtained in 51% yield as a colorless oil. Retention
time on GC/MS: 9.825 min; EI-MS m/z (%): 176 (23) [M+], 175
(100), 161 (14), 158 (24), 131 (13), 116 (15), 115 (53), 105 (42),
79 (29), 78 (10), 77 (54), 55 (13), 51 (18); 1H NMR (CDCl3,
250 MHz) d 2.32 (s, 3H), 3.18 (d, 1H, J = 5.00 Hz), 5.61 (d, 1H,
J = 5.00 Hz), 5.97 (s, 1H), 6.18 (s, 1H), 7.27–7.35 (m, 5H);13C NMR
4.4.6. 4-Hydroxy-4-(40-methoxyphenyl)-3-methylidenebutan-2-
one 1f
Following the general procedure for the Morita–Baylis–Hillman
reaction, 1f was obtained in 18% yield as a colorless solid. Mp 45.3–

B. R. S. de Paula et al. / Tetrahedron: Asymmetry 24 (2013) 973–981
977
46.0 °C; Retention time on GC/MS: 11.227 min; EI-MS m/z (%): 206
(22) [M+], 205 (100), 191 (13), 188 (13), 175 (63), 146 (12), 145
(54), 137 (38), 135 (52), 131 (10), 115 (12), 109 (27), 108 (37),
103 (11), 102 (10), 94 (27), 92 (12), 91 (10), 78 (11), 77 (39), 65
(14), 55 (12); 1H NMR (CDCl3, 250 MHz) d 2.31 (s, 3H), 3.13 (d,
1H, J = 4.75 Hz), 3.78 (s, 3H), 5.56 (d, 1H, J = 4.75 Hz), 5.99 (s, 1H),
61.5–62.5 °C; Retention time on GC/MS: 11.674 min; EI-MS m/z
(%): 237/239 (70/68), 193 (23), 158 (30), 151 (11), 150 (14), 149
(23), 116 (12), 115 (100), 114 (21), 113 (17), 89 (15), 88 (11), 87
(10), 75 (13), 63 (19), 62 (10); 1H NMR (CDCl3, 250 MHz) d 2.53
C NMR (CDCl3,
62.5 MHz) d 24.6, 26.1, 127.2, 129.7, 129.9, 130.8, 132.8, 134.4,
(s, 3H), 4.23 (s, 2H), 7.33–7.79 (m, 5H);13
6.16 (s, 1H), 6.85 (d, 2H, J = 8.75 Hz), 7.25 (d, 2H, J = 8.75 Hz);13
C
138.8, 139.3, 197.0.
NMR (CDCl3, 62.5 MHz) d 26.5, 55.2, 72.2, 113.8, 126.1, 127.9,
133.8, 150.3, 159.1, 200.3.
4.5.5. 3-Chloromethyl-4-(40-chlorophenyl)-3-buten-2-one 2c
Following the general procedure for the reaction of 1c with con-
centrated HCl, 2c was obtained in 82% yield as a colorless solid. Mp
86.6–87.3 °C (lit.31 87–89 °C); Retention time on GC/MS:
11.631 min; EI-MS m/z (%): 228/230 (23/17) [M+], 227/229 (14/
13), 195 (19), 194 (10), 193 (57), 192 (13), 177 (12), 157 (10),
151 (26), 150 (26), 149 (63), 139 (11), 116 (12), 115 (100), 114
(23), 113 (16), 89 (14), 87 (10), 75 (17), 74 (10), 63 (19); 1H NMR
(CDCl3, 250 MHz) d 2.50 (s, 3H), 4.41 (s, 2H), 7.43–7.56 (m, 4H),
7.63 (s, 1H);13C NMR (CDCl3, 62.5 MHz) d 25.9, 37.3, 129.3, 131.0,
132.6, 136.1, 137.5, 142.1, 197.1.
4.4.7. 4-Hydroxy-3-methylidenenonan-2-one 1g
Following the general procedure for the Morita–Baylis–Hillman
reaction, 1g was obtained in 52% yield as a colorless oil. Retention
time on GC/MS: 8.753 min; EI-MS m/z (%): 109 (33), 99 (100), 95
(12), 85 (11), 81 (10), 70 (10), 67 (15), 55 (24); 1H NMR (CDCl3,
250 MHz) d 0.85–0.89 (m, 3H), 1.29–1.61 (m, 9H), 2.36 (s, 3H),
4.42 (t, 1H, J = 1.25 Hz), 6.00 (s, 1H), 6.10 (s, 1H);13C NMR (CDCl3,
62.5 MHz) d 14.0, 22.6, 25.6, 26.5, 31.7, 36.3, 71.5, 125.5, 150.5,
200.8.
4.5. General procedure for the reaction of Morita–Baylis–Hillman
adducts 1a–f with concentrated HCl or HBr
4.5.6. 3-Bromomethyl-4-(40-chlorophenyl)-3-buten-2-one 3c
Following the general procedure for the reaction of 1c with con-
centrated HBr, 3c was obtained in 87% yield as a colorless solid. Mp
97.8–98.4 °C (lit.32 99–100 °C); Retention time on GC/MS:
12.060 min; EI-MS m/z (%): 195 (24), 194 (11), 193 (79), 192
(11), 151 (12), 150 (25), 149 (25), 139 (11), 116 (13), 115 (100),
114 (22), 113 (15), 89 (15), 75 (14), 63 (19); 1H NMR (CDCl3,
250 MHz) d 2.50 (s, 3H), 4.32 (s, 2H), 7.43–7.58 (m, 5H);13C NMR
(CDCl3, 62.5 MHz) d 24.8, 26.0, 129.3, 131.0, 132.7, 136.0, 137.8,
141.3, 197.0.
In a 10 mL round-bottom flask, 36% HCl or 48% HBr (4 mL) was
added to the Morita–Baylis–Hillman adduct (2 mmol) with vigorous
stirring. The mixture was stirred for 1 minute (in some cases, a solid
mass formed in the first few seconds, and the reaction mixture had
to be shaken manually), and then poured into water (50 mL), using
ethyl acetate to dissolve the solid mass when necessary. The aque-
ous phase was extracted with ethyl acetate (3 ꢀ 50 mL), the organic
layer was washed with 10% NaHCO3, brine, and then dried over
MgSO4. The solvent was removed under reduced pressure, and the
residue was purified by column chromatography.
4.5.7. 3-Chloromethyl-4-(30-nitrophenyl)-3-buten-2-one 2d
Following the general procedure for the reaction of 1d with con-
centrated HCl, 2d was obtained in 84% yield as a colorless solid.
133.3–133.8 °C (lit.33 130–132 °C); Retention time on GC/MS:
12.762 min; EI-MS m/z (%): 239 (13) [M+], 224 (26), 204 (15),
188 (19), 180 (11), 179 (13), 161 (25), 151 (11), 150 (13), 149
(28), 143 (18), 116 (14), 115 (100), 114 (25), 113 (11), 89 (22),
65 (10), 63 (23); 1H NMR (CDCl3, 500 MHz) d 2.55 (s, 3H), 4.40 (s,
2H), 7.70 (t, 1H, J = 8.00 Hz), 7.72 (s, 1H), 7.95 (d, 1H, J = 8.00 Hz),
8.29 (d, 1H, J = 8.00 Hz), 8.43 (s, 1H);13C NMR (CDCl3, 125 MHz) d
26.0, 36.8, 124.3, 124.4, 130.2, 135.0, 135.8, 139.3, 140.3, 148.6,
196.7.
4.5.1. 3-Chloromethyl-4-phenyl-3-buten-2-one 2a
Following the general procedure for the reaction of 1a with con-
centrated HCl, 2a was obtained in 73% yield as a colorless solid. Mp
46.1–46.7 °C; Retention time on GC/MS: 10.631 min; EI-MS m/z
(%): 194/196 (29/10) [M+], 193/195 (40/16), 159 (10), 158 (17),
143 (10), 116 (28), 115 (100), 89 (11), 63 (10); 1H NMR (CDCl3,
250 MHz) d 2.50 (s, 3H), 4.45 (s, 2H), 7.39–7.61 (m, 5H), 7.69 (s,
1H);13C NMR (CDCl3, 62.5 MHz) d 25.9, 37.6, 129.0, 129.7, 129.9,
134.2, 137.1, 143.6, 197.4.
4.5.2. 3-Bromomethyl-4-phenyl-3-buten-2-one 3a
4.5.8. 3-Bromomethyl-4-(30-nitrophenyl)-3-buten-2-one 3d
Following the general procedure for the reaction of 1d with con-
centrated HBr, 3d was obtained in 92% yield as a colorless solid.
127.0–127.9 °C; Retention time on GC/MS: 13.233 min; EI-MS m/
z (%): 207 (18), 205 (10), 204 (100), 162 (14), 161 (14), 158 (51),
116 (14), 115 (82), 114 (21), 89 (26), 88 (11), 82 (11), 79 (10), 77
(11), 75 (11), 63 (21); 1H NMR (CDCl3, 250 MHz) d 2.55 (s, 3H),
4.29 (s, 2H), 7.65 (s, 1H), 7.70 (t, 1H, J = 8.25 Hz), 7.97 (d, 1H,
J = 8.25 Hz), 8.28 (d, 1H, J = 8.25 Hz), 8.44 (s, 1H);13C NMR (CDCl3,
62.5 MHz) d 23.8, 26.1, 124.1, 124.3, 130.2, 134.8, 135.9, 139.3,
139.7, 148.6, 196.6.
Following the general procedure for the reaction of 1a with con-
centrated HBr, 3a was obtained in 82% yield as a colorless solid. Mp
45.9–46.5 °C (lit.30 52.5–53.0 °C); Retention time on GC/MS:
11.093 min; EI-MS m/z (%): 159 (67), 158 (22), 116 (37), 115 (100),
89 (14), 63 (13); 1H NMR (CDCl3, 250 MHz) d 2.51 (s, 3H), 4.36 (s,
2H), 7.39–7.64 (m, 5H), 7.64 (s, 1H);13C NMR (CDCl3, 150 MHz) d
25.2, 26.0, 129.0, 129.7, 129.8, 134.3, 137.4, 142.9, 197.3
4.5.3. 3-Chloromethyl-4-(20-chlorophenyl)-3-buten-2-one 2b
Following the general procedure for the reaction of 1b with con-
centrated HCl, 2b was obtained in 80% yield as a colorless solid. Mp
51.5–52.0 °C; Retention time on GC/MS: 11.258 min; EI-MS m/z
(%): 193/195 (100/34), 149 (25), 115 (41); 1H NMR (CDCl3,
250 MHz) d 2.53 (s, 3H), 4.33 (s, 2H), 7.36–7.74 (m, 4H), 7.82 (s,
1H); 13C NMR (CDCl3, 100 MHz) d 26.1, 37.4, 127.2, 129.9, 130.2,
130.9, 132.7, 134.3, 138.4, 140.1, 197.2.
4.5.9. 3-Chloromethyl-4-(40-nitrophenyl)-3-buten-2-one 2e
Following the general procedure for the reaction of 1e with con-
centrated HCl, 2e was obtained in 82% yield as a colorless solid.
126.6–129.6 °C (decomp.; lit.31 134–136 °C); Retention time on
GC/MS: 12.880 min; EI-MS m/z (%): 239/241 (3/1) [M+], 224 (37),
223 (10), 222 (73), 203 (10), 192 (24), 188 (11), 162 (12), 161
(28), 158 (14), 157 (15), 150 (13), 143 (33), 116 (13), 115 (100),
114 (16), 103 (10), 89 (19), 63 (19); 1H NMR (CDCl3, 250 MHz) d
2.54 (s, 3H), 4.38 (s, 2H), 7.71 (s, 1H), 7.75 (d, 2H, J = 8.75 Hz),
4.5.4. 3-Bromomethyl-4-(20-chlorophenyl)-3-buten-2-one 3b
Following the general procedure for the reaction of 1b with con-
centrated HBr, 3b was obtained in 79% yield as a colorless solid.

978
B. R. S. de Paula et al. / Tetrahedron: Asymmetry 24 (2013) 973–981
8.33 (d, 2H, J = 8.75 Hz);13C NMR (CDCl3, 62.5 MHz) d 26.1, 36.8,
124.1, 130.3, 139.7, 140.2, 140.5, 148.1, 196.7.
4.6. General procedure for the aldol condensation between
butanone and aldehydes
4.5.10. 3-Bromomethyl-4-(40-nitrophenyl)-3-buten-2-one 3e
Following the general procedure for the reaction of 1e with con-
centrated HBr, 3e was obtained in 65% yield as a colorless solid. Mp
132.4–133.6 °C (decomp.; lit.32 137 °C); Retention time on GC/MS:
13.359 min; EI-MS m/z 283/285 (2/2) [M+], 207 (14), 204 (23), 162
(43), 161 (16), 159 (13), 158 (100), 145 (11), 143 (13), 116 (15), 115
(67), 114 (14), 89 (21), 77 (13), 63 (20), 51 (12); 1H NMR (CDCl3,
250 MHz) d 2.55 (s, 3H), 4.28 (s, 2H), 7.65 (s, 1H), 7.77 (d, 2H,
J = 8.75 Hz), 8.34 (d, 2H, J = 8.75 Hz); 13C NMR (CDCl3, 62.5 MHz)
d 23.9, 26.1, 124.1, 130.2, 139.3, 140.1, 140.7, 148.0, 196.6.
Glacial acetic acid (10 mL), aldehyde (10 mmol), and butanone
(20 mmol for the preparation of 4a–f, and 100 mmol for 4g) were
added to a 50 mL round bottom flask. Under stirring, sulfuric acid
(2 mL) was added dropwise after which the reaction was stirred
at room temperature for 16 hours. Next, the reaction mixture
was neutralized with 10% NaOH and extracted with diethyl ether
(3 ꢀ 50 mL). The organic layer was washed with brine and dried
over MgSO4. The solvent was removed under reduced pressure,
and the residue was purified by column chromatography.
4.6.1. 3-Methyl-4-phenyl-3-buten-2-one 4a
4.5.11. 3-Chloromethyl-4-(40-methoxyphenyl)-3-buten-2-one 2f
Following the general procedure for the reaction of 1f with
concentrated HCl, 2f was obtained in 69% yield as a colorless solid.
Mp 77.6–78.7 °C (lit.14 65–67 °C); Retention time on GC/MS:
12.088 min; EI-MS m/z 224/226 (11/4) [M+], 189 (25), 188 (60),
173 (13), 147 (16), 146 (41), 145 (100), 131 (21), 130 (16), 115
(21), 103 (18), 102 (40), 77 (14); 1H NMR (CDCl3, 250 MHz) d
2.48 (s, 3H), 3.86 (s, 3H), 4.49 (s, 2H), 6.99 (d, 2H, J = 8.75 Hz),
7.59 (d, 2H, J = 8.75 Hz), 7.64 (s, 1H);13C NMR (CDCl3, 62.5 MHz)
d 25.8, 38.0, 55.4, 114.5, 126.6, 132.0, 135.0, 143.8, 161.1, 197.3.
Following the general procedure for the aldol condensation, 4a
was obtained in 39% yield as a pale yellow solid. Mp 34.9–36.7 °C
(lit.34 35–37 °C); Retention time on GC/MS: 9.454 min; EI-MS m/z
(%): 160 (70) [M+], 159 (100), 145 (37), 118 (10), 117 (90), 116
(26), 115 (99), 91 (32); 1H NMR (CDCl3, 250 MHz) d 2.06 (s, 3H),
2.46 (s, 3H), 7.30–7.42 (m, 5H), 7.52 (s, 1H);13C NMR (CDCl3,
125 MHz) d 12.9, 25.9, 128.5, 128.6, 129.7, 135.9, 137.8, 139.7, 200.3.
4.6.2. 4-(20-Chlorophenyl)-3-methyl-3-buten-2-one 4b
Following the general procedure for the aldol condensation, 4b
was obtained in 47% yield as a pale yellow oil. Retention time on
GC/MS: 10.184 min; EI-MS m/z (%): 160 (12), 159 (100), 116 (24),
115 (36); 1H NMR (CDCl3, 250 MHz) d 1.93 (s, 3H), 2.49 (s, 3H),
7.26–7.46 (m, 5H), 7.62 (s, 1H); 13C NMR (CDCl3, 125 MHz) d 12.9,
25.9, 126.5, 129.6, 129.7, 130.5, 134.0, 134.4, 136.6, 139.2, 200.1.
4.5.12. 3-Bromomethyl-4-(40-methoxyphenyl)-3-buten-2-one 3f
Following the general procedure for the reaction of 1f with con-
centrated HBr, 3f was obtained in 82% yield as a colorless solid.
Mp 80.9–82.0 °C (lit.14 85–86 °C); Retention time on GC/MS:
12.502 min; EI-MS m/z 189 (53), 188 (62), 173 (15), 147 (19), 146
(45), 145 (100), 131 (23), 130 (15), 115 (21), 103 (21), 102 (39), 82
(12), 80 (14), 77 (16), 63 (10), 51 (10); 1H NMR (CDCl3, 250 MHz) d
2.48 (s, 3H), 3.87 (s, 3H), 4.40 (s, 2H), 7.01 (d, 2H, J = 8.75 Hz), 7.59
(s, 1H), 7.61 (d, 2H, J = 8.75 Hz);13C NMR (CDCl3, 62.5 MHz) d 25.9,
55.4, 114.6, 126.7, 132.1, 135.2, 143.1, 161.1, 197.2.
4.6.3. 4-(40-Chlorophenyl)-3-methyl-3-buten-2-one 4c
Following the general procedure for the aldol condensation, 4c
was obtained in 58% yield as a colorless solid. Mp 49.4–50.0 °C
(lit.35 50–51 °C); retention time on GC/MS: 10.591 min; EI-MS m/z
(%): 194/196 (30/11) [M+], 193 (28), 181 (14), 179 (40), 176 (10),
159 (52), 151 (27), 141 (20), 139 (13), 116 (71), 115 (100), 89 (14),
75 (12), 63 (14); 1H NMR (CDCl3, 250 MHz) d 2.03 (s, 3H), 2.45 (s,
3H), 7.26–7.41 (m, 5H), 7.45 (s, 1H);13C NMR (CDCl3, 100 MHz) d
13.0, 25.9, 128.7, 131.0, 134.3, 134.5, 138.2, 138.2, 200.0.
4.5.13. 3-Chloromethyl-3-nonen-2-one 2g
Following the general procedure for the reaction of 1g with con-
centrated HCl, 2g was obtained in 68% yield as a colorless oil that
decomposes rapidly on standing at room temperature. Retention
time on GC/MS: 9.483 min; EI-MS m/z 173 (11), 153 (30), 123
(12), 119 (14), 110 (20), 109 (100), 103 (19), 97 (11), 96 (10), 95
(42), 82 (12), 81 (29), 79 (14), 77 (10), 69 (16), 67 (44), 65 (10),
55 (24), 54 (18), 53 (23); IR (film) 3478, 3411, 2958, 2930, 2860,
1715, 1675, 1639, 1620, 1435, 1380, 1353, 1292, 1265, 1175,
1074, 1023, 967, 882, 728; 1H NMR (CDCl3, 250 MHz) d 0.89–1.64
(m, 9H), 2.35 (s, 3H), 2.39 (q, 2H, J = 7.50 Hz), 4.31 (s, 2H), 6.85
(t, 1H, J = 7.50 Hz); 13C NMR (CDCl3, 62.5 MHz) d 13.9, 22.4, 25.5,
28.2, 29.2, 31.6, 35.5, 138.3, 149.1, 196.9; EI-HRMS (M+) calcd:
188.0968; found: 188.0975.
4.6.4. 3-Methyl-4-(30-nitrophenyl)-3-buten-2-one 4d
Following the general procedure for the aldol condensation, 4d
was obtained in 59% yield as a colorless solid. Mp 74.9–75.4 °C;
Retention time on GC/MS: 11.744 min; EI-MS m/z (%): 205 (17)
[M+], 204 (11), 190 (44), 188 (31), 145 (11), 116 (68), 115 (100), 89
(11), 63 (10); 1H NMR (CDCl3, 250 MHz) d 2.07 (s, 3H), 2.49 (s, 3H),
7.53 (s, 1H), 7.618.27 (m, 4H); 13C NMR (CDCl3, 125 MHz) d 13.1,
26.0, 123.1, 124.2, 129.6, 135.3, 136.4, 137.6, 140.1, 148.3, 199.6.
4.6.5. 3-Methyl-4-(40-nitrophenyl)-3-buten-2-one 4e
Following the general procedure for the aldol condensation, 4e
was obtained in 47% yield as a colorless solid. Mp 93.1–93.6 °C;
Retention time on GC/MS: 11.899 min; EI-MS m/z (%): 205 (8)
[M+], 190 (32), 189 (12), 188 (79), 159 (10), 158 (31), 145 (10),
144 (10), 117 (10), 116 (100), 115 (96), 89 (12), 63 (11); 1H NMR
(CDCl3, 250 MHz) d 2.06 (s, 3H), 2.49 (s, 3H), 7.52 (s, 1H), 7.56 (d,
2H, J = 8.75 Hz), 8.27 (d, 2H, J = 8.75 Hz); 13C NMR (CDCl3,
125 MHz) d 13.2, 26.0, 123.7, 130.3, 136.5, 140.7, 142.5, 147.3,
199.6.
4.5.14. 3-Bromomethyl-3-nonen-2-one 3g
Following the general procedure for the reaction of 1g with con-
centrated HBr, 3g was obtained in 80% yield as a colorless oil that
decomposes rapidly on standing at room temperature. Retention
time on GC/MS: 9.967 min; EI-MS m/z (%): 153 (100), 152 (12),
135 (18), 123 (11), 111 (14), 110 (16), 109 (99), 107 (13), 97
(24), 96 (15), 95 (96), 93 (18), 85 (17), 82 (14), 81 (40), 79 (24),
77 (14), 69 (28), 68 (10), 67 (61), 65 (13), 57 (16), 55 (32), 54
(27), 53 (35), 51 (10); IR (film) 3471, 3409, 2956, 2929, 1705,
1672, 1638, 1620, 1465, 1430, 1378, 1352, 1255, 1217, 1154,
977; 1H NMR (CDCl3, 250 MHz) d 0.89–1.59 (m, 9H), 2.35 (s, 3H),
4.6.6. 4-(40-Methoxyphenyl)-3-methyl-3-buten-2-one 4f
Following the general procedure for the aldol condensation, 4f
was obtained in 46% yield as a colorless oil. Retention time on
GC/MS: 11.064 min; EI-MS m/z (%): 190 (99) [M+], 189 (65), 176
(13), 175 (100), 159 (50), 147 (58), 146 (20), 136 (11), 135 (19),
132 (25), 131 (29), 128 (10), 121 (12), 117 (16), 116 (17), 115
2.36 (q, 2H, J = 7.25 Hz), 4.20 (s, 2H), 6.82 (t, 1H, J = 7.25 Hz);13
C
NMR (CDCl3, 62.5 MHz) d 14.9, 22.4, 22.6, 25.5, 28.0, 29.3, 31.6,
138.4, 148.8, 196.6; ESI+-HRMS ((M+H)+) calcd: 233.0541/
235.0521; found: 233.0540/235.0512.

B. R. S. de Paula et al. / Tetrahedron: Asymmetry 24 (2013) 973–981
979
(53), 107 (12), 104 (16), 103 (33), 102 (11), 91 (47), 89 (12), 78 (21),
77 (34), 63 (15), 51 (15); 1H NMR (CDCl3, 250 MHz) d 2.07 (s, 3H),
2.44 (s, 3H), 3.84 (s, 3H), 6.94 (d, 2H, J = 8.75 Hz), 7.41 (d, 2H,
J = 8.75 Hz), 7.47 (s, 1H);13C NMR (CDCl3, 125 MHz) d 12.9, 25.8,
55.3, 114.0, 128.5, 131.6, 135.9, 139.6, 159.9, 200.2.
When the reaction was performed with 10 mmol of 2a, the
reaction mixture was extracted with 100 g of AmberliteÒ XAD7HP
for 2 h, and then the resin was extracted with 3 ꢀ 200 mL of ethyl
acetate. The solvent was removed under reduced pressure and the
residue was purified by column chromatography to afford (R)-6a in
48% yield and 95% ee.
4.6.7. 3-Methyl-3-nonen-2-one 4g
Following the general procedure for the aldol condensation, 4g
was obtained in 36% yield as a colorless oil. Retention time on GC/
MS: 8.094 min; EI-MS m/z (%): 154 (16) [M+], 139 (49), 111 (99),
110 (11), 109 (10), 97 (10), 85 (34), 83 (22), 82 (11), 72 (23), 70
(10), 69 (98), 67 (15), 55 (100), 53 (14); 1H NMR (CDCl3,
250 MHz) d 0.88–0.94 (m, 3H), 1.25–1.51 (m, 6H), 1.77 (s, 3H),
2.24 (q, 2H, J = 7.25 Hz), 2.30 (s, 3H), 6.63 (t, 1H, J = 7.25 Hz); 13C
NMR (CDCl3, 100 MHz) d 11.1, 14.0, 22.5, 25.4, 28.4, 29.1, 31.6,
137.6, 144.0, 200.0.
4.9.1. (R)- and (S)-3-Methyl-4-phenylbutan-2-one (R)- and (S)-
6a
The reduction of 2a, following the general procedure for the bio-
reduction of enones by Saccharomyces cerevisiae, afforded (R)-6a as
a colorless oil. ½a D25
ꢂ
¼ ꢁ20:6 (c 1.00, CHCl3); lit.15
½
a 2D3
ꢂ
¼ þ40:7 (c
0.9, CHCl3) for the (S)-isomer; Retention time on GC/MS:
8.610 min; Retention time on GC/FID (Method A): 21.90 min ((R)-
isomer), 22.27 min ((S)-isomer); EI-MS m/z (%): 162 (27) [M+],
147 (22), 119 (13), 117 (10), 91 (100); 1H NMR (CDCl3, 250 MHz)
d 1.09 (d, 3H, J = 7.50 Hz), 2.08 (s, 3H), 2.56 (dd, 1H, J = 7.50,
13.5 Hz), 2.77 (sx, 1H, J = 7.50 Hz), 3.00 (dd, 1H, J = 7.50, 13.5 Hz),
7.13–7.31 (m, 5H);13C NMR (CDCl3, 125 MHz) d 16.2, 28.9, 38.9,
48.8, 126.3, 128.4, 128.9, 139.7, 212.1. Compound (R)-6a was also
obtained from the reduction of 3a by S. cerevisiae and from the
reduction of 2a and3a by G. candidum. Its enantiomer, (S)-6a,
was obtained from the reduction of 4a by S. cerevisiae.
4.7. Preparation of 3-methylidene-4-phenylbutan-2-one 5a
An authentic sample of 5a was prepared following a literature
procedure.15 4-Phenylbutan-2-one (2.96 g, 20 mmol), 37% aqueous
formaldehyde (2 mL), and morpholine (86 lL) were added to gla-
cial acetic acid (10 mL) in a 25 mL round-bottom flask. The mixture
was refluxed for 24 h, and then cooled to room temperature and
neutralized with 10% aqueous NaOH. The product was extracted
with EtOAc (3 ꢀ 20 mL), and the organic layer was dried over Na2-
SO4. The solvent was removed under reduced pressure, and the
residue was purified by column chromatography to afford 5a in
7% yield as a colorless oil. Retention time on GC/MS: 8.822 min;
EI-MS m/z (%): 160 (41) [M+], 159 (48), 145 (41), 117 (69), 116
(71), 115 (100), 91 (47), 89 (11), 65 (16), 63 (11), 51 (12); 1H
NMR (CDCl3, 250 MHz) d 2.34 (s, 3H), 3.59 (s, 2H), 5.64 (s, 1H),
6.08 (s, 1H), 7.15–7.29 (m, 5H);13C NMR (CDCl3, 62.5 MHz) d
26.0, 36.7, 126.2, 126.4, 128.5, 129.2, 139.2, 148.7, 199.1.
4.9.2. (R)- and (S)-4-(20-Chlorophenyl)-3-methyl-butan-2-one (R)-
and (S)-6b
The reduction of 2b, following the general procedure for the
bioreduction of enones by Saccharomyces cerevisiae, afforded (R)-
6b as
a
colorless oil.
½
a 2D5
ꢂ
¼ ꢁ22:5 (c 0.94, CHCl3); lit.15
½
a 2D1
ꢂ
¼ þ44:9 (c 1.1, CHCl3) for the (S)-isomer; Retention time on
GC/MS: 9.637 min; Retention time on GC/FID (Method A):
26.49 min ((R)-isomer), 26.78 min ((S)-isomer); EI-MS m/z (%):
196 [M+], 181 (14), 161 (70), 127 (35), 125 (100), 117 (12), 115
(24), 91 (10), 89 (13); 1H NMR (CDCl3, 400 MHz) d 1.10 (d, 3H,
J = 7.20 Hz), 2.12 (s, 3H), 2.66 (dd, 1H, J = 7.20, 13.6 Hz), 2.97 (sx,
1H, J = 7.20 Hz), 3.13 (dd, 1H, J = 7.20, 13.6 Hz), 7.15–7.38 (m,
4H); 13C NMR (CDCl3, 150 MHz) d 16.1, 28;9, 36.5, 46.5, 126.7,
127.9, 129.6, 131.6, 134.1, 137.4, 211.8. Compound (R)-6b was also
obtained from the reduction of 3b by S. cerevisiae. Its enantiomer,
(S)-6b, was obtained from the reduction of 4b by S. cerevisiae.
4.8. General procedure for the bioreduction of enones by Geot-
richum candidum
Geotrichum candidum cells (10 g of wet cells) were added to dis-
tilled water at room temperature (50 mL) in a 125 mL Erlenmeyer
flask. The substrate (0.5 mmol) was adsorbed in filter paper
(approximately 2 cm2 per mg of substrate) and added in pieces
to the suspension. The reaction was stirred in an orbital shaker
at 30 °C and 180 rpm and monitored by GC/MS. After the appropri-
ate amount of time, the reaction mixture was extracted with ethyl
acetate (3 ꢀ 100 mL), the organic phase was washed with brine,
dried over sodium sulfate, and the solvent was removed under re-
duced pressure. The product was purified by column chromatogra-
phy. The ee was obtained by chiral GC/FID analysis and the results
are provided in Table 3.
4.9.3. (R)- and (S)-4-(40-Chlorophenyl)-3-methyl-butan-2-one
(R)- and (S)-6c
The reduction of 2c, following the general procedure for the bio-
reduction of enones by Saccharomyces cerevisiae, afforded (R)-6c as
a colorless oil. ½a D25
ꢂ
¼ ꢁ25:0 (c 1.60, CHCl3); lit.15
½
a 2D3
ꢂ
¼ þ27:7 (c
0.94, CHCl3) for the (S)-isomer; Retention time on GC/MS:
9.905 min; Retention time on GC/FID (Method A): 30.35 min ((R)-
isomer), 30.66 min ((S)-isomer); EI-MS m/z (%): 196/198 (24/8)
[M+], 181 (22), 153 (10), 127 (34), 125 (100), 89 (12); 1H NMR
(CDCl3, 400 MHz) d 1.09 (d, 3H, J = 7.20 Hz), 2.08 (s, 3H), 2.53
(dd, 1H, J = 7.20, 13.6 Hz), 2.78 (sx, 1H, J = 7.20 Hz), 2.97 (dd, 1H,
J = 7.20, 13.6 Hz), 7.07–7.27 (m, 4H); 13C NMR (CDCl3, 100 MHz) d
16.3, 28.9, 38.1, 48.7, 128.5, 130.3, 132.1, 138.2, 211.7. Compound
(R)-6c was also obtained from the reduction of 3c by S. cerevisiae
and from the reduction of 2c and 3c by G. candidum. Its enantio-
mer, (S)-6c, was obtained from the reduction of 4c by S. cerevisiae
and by G. candidum.
4.9. General procedure for the bioreduction of enones by Saccha-
romyces cerevisiae
Yeast from Saccharomyces cerevisiae, type II (5.0 g of lyophilized
cells), was added to distilled water at 40–42 °C (50 mL) in a 125 mL
Erlenmeyer flask. The substrate (0.5 mmol) was adsorbed in filter
paper (approximately 2 cm2 per mg of substrate) and added in
small pieces to the cell suspension. The reaction was stirred in an
orbital shaker at 30 °C and 180 rpm and monitored by GC/MS. After
the appropriate amount of time, the reaction mixture was ex-
tracted with ethyl acetate (3 ꢀ 100 mL), the organic phase was
washed with brine, dried over sodium sulfate, and the solvent
was removed under reduced pressure. The product was purified
by column chromatography. The ee value was obtained by chiral
GC/FID analysis and the results are provided in Table 2.
4.9.4. (R)- and (S)-3-Methyl-4-(30-nitrophenyl)butan-2-one (R)-
and (S)-6d
The reduction of 2d, following the general procedure for the
bioreduction of enones by Saccharomyces cerevisiae, afforded (R)-
6d as
a
colorless oil.
½
a 2D5
ꢂ
¼ ꢁ4:9 (c 1.50, CHCl3); lit.15
½
a 2D3
ꢂ
¼ þ3:9 (c 1.1, CHCl3) for (S)-isomer; Retention time on GC/
MS: 11.228 min; Retention time on GC/FID (Method B):

980
B. R. S. de Paula et al. / Tetrahedron: Asymmetry 24 (2013) 973–981
91.58 min ((R)-isomer), 92.08 min ((S)-isomer); EI-MS m/z (%): 192
(8), 148 (38), 147 (100), 136 (48), 120 (33), 118 (15), 117 (42), 115
(32), 91 (22), 90 (32), 89 (23), 77 (14), 63 (12); 1H NMR (CDCl3,
250 MHz) d 1.15 (d, 3H, J = 7.00 Hz), 2.12 (s, 3H), 2.66 (dd, 1H,
J = 7.20, 13.6 Hz), 2.97 (sx, 1H, J = 7.20 Hz), 3.13 (dd, 1H, J = 7.20,
13.6 Hz), 7.15–7.38 (m, 4H); 13C NMR (CDCl3, 62.5 MHz) d 16.5,
28.8, 38.0, 48.4, 121.5, 123.7, 129.3, 135.4, 141.9, 148.4, 210.8.
Compound (R)-6d was also obtained from the reduction of 3d by
S. cerevisiae and from the reduction of 2d and 3d by G. candidum.
Its enantiomer, (S)-6d, was obtained from the reduction of 4d by
S. cerevisiae and by G. candidum.
hydroxide (52 mmol) in water (20 mL) in an ice/salt bath. After
all the bromine was consumed, the bright yellow solution was di-
luted with 1,4-dioxane (5 mL), and added dropwise to a cooled
(cold water bath) solution of (R)-6a (95% ee, 648 mg, 4 mmol) in
dioxane (50 mL) and water (10 mL). The mixture was stirred for
2 h. Next, most of the dioxane/water mixture was evaporated un-
der reduced pressure, the residue was diluted in water (40 mL),
and extracted with CH2Cl2 (3 ꢀ 20 mL). The aqueous phase was
acidified, and then extracted with CH2Cl2 (3 ꢀ 20 mL). The organic
phase from the second extraction was dried over Na2SO4 and evap-
orated under reduced pressure to afford (R)-8a in 61% yield, and
92% ee as a colorless oil. ½a D25
ꢂ
¼ ꢁ20:8 (c 0.87, CHCl3); lit.37
½
a 2D5
500 MHz)
ꢂ
¼ ꢁ22:7 (c 1.02, CHCl3) for the (R)-isomer. 1H NMR (CDCl3,
4.9.5. (R)- and (S)-3-Methyl-4-(40-nitrophenyl)butan-2-one (R)-
and (S)-6e
d 1.18 (d, 3H, J = 7.00 Hz), 2.67 (dd, 1H, J = 8.00,
13.5 Hz), 2.77 (sx, 1H, J = 7.00 Hz), 3.08 (dd, 1H, J = 6.50, 13.5 Hz),
7.17–7.31 (m, 5H);13C NMR (CDCl3, 125 MHz) d 16.5, 39.3, 41.2,
126.4, 128.4, 129.0, 139.0, 182.5.
The reduction of 2e, following the general procedure for the bio-
reduction of enones by Saccharomyces cerevisiae, afforded (R)-6e as
colorless crystals of mp 52.5–55.6 °C (lit.36 64 °C); ½a D25
¼ ꢁ10:7 (c
ꢂ
1.45, CHCl3); lit.15
½
a 2D3
ꢂ
¼ þ10:9 (c 1.1, CHCl3) for the (S)-isomer;
4.11. Methyl 2-methyl-3-phenylpropanoate (methyl ester of 8a)
Retention time on GC/MS: 11.433 min; Retention time on GC/FID
(Method A): 45.88 min ((R)-isomer), 46.27 min ((S)-isomer); EI-
MS m/z (%): 207 (53) [M+], 192 (40), 166 (10), 165 (100), 148
(29), 136 (32), 120 (24), 118 (22), 117 (26), 116 (13), 115 (33),
106 (13), 91 (22), 90 (25), 89 (26), 78 (18), 77 (14), 63 (11); 1H
NMR (CDCl3, 250 MHz) d 1.15 (d, 3H, J = 7.00 Hz), 2.13 (s, 3H),
2.68 (dd, 1H, J = 7.00, 13.5 Hz), 2.88 (sx, 1H, J = 7.00 Hz), 3.13 (dd,
1H, J = 7.00, 13.5 Hz), 7.33 (d, 2H, J = 8.50 Hz), 8.14 (d, 2H,
J = 8.50 Hz); 13C NMR (CDCl3, 125 MHz) d 16.6, 28.8, 38.3, 48.4,
123.7, 129.9, 146.6, 147.8, 210.8. Compound (R)-6e was also ob-
tained from the reduction of 3e by S. cerevisiae and from the reduc-
tion of 2e and 3e by G. candidum. Its enantiomer, (S)-6e, was
obtained from the reduction of 4e by S. cerevisiae and by G.
candidum.
A solution of diazomethane in diethyl ether was added to a
sample of acid 8a in diethyl ether. The organic solvent was evapo-
rated to afford methyl ester of 8a as a colorless oil. Retention time
on GC/MS: 8.317 min; EI-MS m/z (%): 178 (16) [M+], 119 (15), 118
(47), 117 (14), 91 (100), 65 (10); Retention time on GC/FID (Meth-
od C): 28.41 min ((R)-isomer), 28.76 min ((S)-isomer); 1H NMR
(CDCl3, 500 MHz) d 1.15 (d, 3H, J = 6.50 Hz), 2.66 (dd, 1H, J = 7.50,
13.5 Hz), 2.74 (sx, 1H, J = 6.50 Hz), 3.03 (dd, 1H, J = 6.50, 13.5 Hz),
3.63 (s, 3H), 7.14–7.29 (m, 5H);13C NMR (CDCl3, 125 MHz) d 16.8,
39.7, 41.4, 51.6, 126.3, 128.4, 129.0, 139.4, 176.6.
Acknowledgements
4.9.6. (S)-4-(40-Methoxyphenyl)-3-methyl-butan-2-one (S)-6f
The reduction of 4f, following the general procedure for the bio-
reduction of enones by Saccharomyces cerevisiae, afforded (S)-6f as
This work was supported by FAPESP and CNPq.
References
a colorless oil. ½a D25
ꢂ
¼ þ12:1 (c 1.59, CHCl3); lit.15
½
a 2D3
ꢂ
¼ þ42:1 (c
1. Hall, M.; Bommarius, A. S. Chem. Rev. 2011, 111, 4088–4110.
2. Aleu, J.; Fronza, G.; Fuganti, C.; Perozzo, V.; Serra, S. Tetrahedron: Asymmetry
1998, 9, 1589–1596.
3. Filho, E. P. S.; Rodrigues, J. A. R.; Moran, P. J. S. J.Mol. Catal. B Enzym. 2001, 15,
23–28.
4. Zampieri, D. S.; de Paula, B. R. S.; Zampieri, L. A.; Vale, J. A.; Rodrigues, J. A. R.;
Moran, P. J. S J. Mol. Catal. B Enzym. 2013, 85–86, 61–64.
5. Fronza, G.; Fuganti, C.; Grasselli, P.; Mele, A J. Org. Chem. 1991, 56, 6019–6023.
6. Brenna, E.; Fronza, G.; Fuganti, C.; Gatti, F. G.; Manfredi, A.; Parmeggiani, F.;
Ronchi, P J. Mol. Catal. B Enzym. 2012, 84, 94–101.
7. Fronza, G.; Fuganti, C.; Serra, S. Eur. J. Org. Chem. 2009, 35, 6160–6171.
8. Tasnádi, G.; Winkler, C. K.; Clay, D.; Hall, M.; Faber, K. Catal. Sci. Technol. 2012, 2,
1548–1552.
1.1, CHCl3) for the (S)-isomer; Retention time on GC/MS:
10.203 min; Retention time on GC/FID (Method A): 32.02 min
((R)-isomer), 32.22 min ((S)-isomer); EI-MS m/z (%): 192 (11)
[M+], 121 (100); 1H NMR (CDCl3, 400 MHz)
d 1.07 (d, 3H,
J = 6.80 Hz), 2.08 (s, 3H), 2.51 (dd, 1H, J = 6.80, 13.6 Hz), 2.79 (sx,
1H, J = 6.80 Hz), 2.93 (dd, 1H, J = 6.80, 13.6 Hz), 3.78 (s, 3H) 6.80–
7.09 (m, 4H); 13C NMR (CDCl3, 100 MHz) d 16.2, 28.9, 38.1, 49.0,
55.2, 113.8, 129.9, 131.7, 158.1, 212.4. Compound (S)-6f was also
obtained, in low ee, from the reduction of 4f by G. candidum.
9. Tanner, D. D.; Stein, A. R J. Org. Chem. 1988, 53, 1642–1646.
10. Zampieri, D. S.; Zampieri, L. A.; de Paula, B. R. S.; Rodrigues, J. A. R.; Moran, P. J. S
J. Mol. Catal. B Enzym. 2011, 72, 289–293.
11. Jörg, G.; Bertau, M. ChemBioChem 2004, 4, 87–92.
12. Amri, B.; Villieras, J. Tetrahedron Lett. 1986, 27, 4307–4308.
13. Coelho, F.; Almeida, W. P.; Veronese, D.; Mateus, C. R.; Lopes, E. C. S.; Rossi, R.
C.; Silveira, G. P. C.; Pavam, C. H. Tetrahedron 2002, 58, 7437–7447.
14. Basavaiah, D.; Hyma, R. S.; Padmaja, K.; Krishnamacharyulu, M. Tetrahedron
1999, 55, 6971–6976.
15. Lu, S. M.; Bolm, C. Angew. Chem. 2008, 120, 9052–9055. Angew. Chem., Int. Ed.
2008, 47, 8920–8923.
16. Lee, K.-Y.; Gorwisankar, S.; Kim, J.-N. Bull. Korean Chem. Soc. 2004, 25, 413–414.
17. Fundação André Tosello Pesquisa e Tecnologia, Rua Latino Coelho 1301, 13087-
010 Campinas, SP, Brazil, http://www.fat.org.br/.
4.9.7. (R)- and (S)-3-Methylnonan-2-one (R)- and (S)-6g
The reduction of 4g, following the general procedure for the
bioreduction of enones by Saccharomyces cerevisiae, afforded (S)-
6g as a colorless oil. ½a D25
ꢂ
¼ þ6:0 (c 1.01, CHCl3); lit.18
½
a 2D0
ꢂ
¼
ꢁ17:1 (c 3.2, CHCl3) for the (R)-isomer. Retention time on GC/
MS: 7.522 min; Retention time on GC/FID (Method A): 14.11 min
((R)-isomer), 14.34 min ((S)-isomer); EI-MS m/z (%): 156 (2) [M+],
85 (10), 72 (100), 71 (16), 57 (25), 55 (10); 1H NMR (CDCl3,
250 MHz) d 0.85–0.90 (m, 3H), 1.08 (d, 3H, J = 7.00 Hz), 1.09–1.30
(m, 11H), 2.13 (s, 3H), 2.36–2.57 (m, 1H);13
C NMR (CDCl3,
62.5 MHz) d 14.1, 16.2, 22.6, 27.2, 28.0, 29.4, 31.7, 33.0, 47.3,
212.9. Its enantiomer, (R)-6g was obtained from the reduction of
2g and 3g by S. cerevisiae.
18. Filho, E. P. S.; Rodrigues, J. A. R.; Moran, P. J. S. Tetrahedron: Asymmetry 2001, 12,
847–852.
19. Kawai, Y.; Saitou, K.; Hida, K.; Ohno, A Tetrahedron: Asymmetry 1995, 6, 2143–
2144.
20. Kawai, Y.; Saitou, K.; Hida, K.; Dao, D. H.; Ohno, A. Bull. Chem. Soc. Jpn. 1996, 69,
2633–2638.
21. Stott, K.; Saito, K.; Thiele, D. J.; Massey, V J. Biol. Chem. 1993, 268, 6097–6106.
22. Niino, Y. S.; Chakraborty, S.; Brown, B. J.; Massey, V J. Biol. Chem. 1995, 270,
1983–1995.
4.10. Preparation of (R)-2-methyl-3-phenylpropanoic acid (R)-8a
A solution of sodium hypobromite was prepared by dropwise
addition of bromine (681 lL, 13.2 mmol) to a solution of sodium
23. Toogood, H.; Gardiner, J. M.; Scrutton, N. S. ChemCatChem 2010, 2, 892–914.

B. R. S. de Paula et al. / Tetrahedron: Asymmetry 24 (2013) 973–981
981
24. Hall, M.; Stueckler, C.; Ehammer, H.; Pointner, E.; Oberdorfer, G.; Gruber, K.;
30. Shimizu, H.; Hiroshi, H.; Suzuki, A. Synth. Commun. 1990, 20, 549–555.
31. Shi, M.; Jiang, J.-K.; Cui, S.-C. Molecules 2001, 6, 852–868.
32. Iwamura, T.; Fujita, M.; Kawakita, T.; Kinoshita, S.; Watanabe, S.-I.; Kataota, T.
Tetrahedron 2001, 57, 8455–8462.
33. Shi, M.; Jiang, J.-K. Tetrahedron 2000, 56, 4793–4797.
34. Chen, T.; Jiang, J.-J.; Xu, Q.; Shi, M. Org. Lett. 2007, 9, 865–868.
35. Huang, Y. Synth. Commun. 1989, 19, 501–509.
Hauer, B.; Stuermer, R.; Kroutil, W.; Macheroux, P.; Faber, K. Adv. Synth. Catal.
2008, 350, 411–418.
25. Brenna, E.; Cosi, S. L.; Ferrandi, E. E.; Gatti, F. G.; Monti, D.; Parmeggiani, F.;
Sacchetti, A. Org. Biomol. Chem. 2013, 11, 2988–2996.
26. Brenna, E.; Gatti, F. G.; Monti, F.; Parmeggiani, F.; Sacchetti, A. ChemCatChem
2012, 4, 653–659.
27. Dai, W.; Katzenellenbogen, J. A J. Org. Chem. 1993, 58, 1900–1908.
28. Bach, J.; Galobardes, M.; Garcia, J.; Romea, P.; Tey, C.; Urpí, F.; Vilarrasa, J.
Tetrahedron Lett. 1998, 39, 6765–6768.
29. Guo, P.-F.; Wei, Q.-Y.; Jiang, H.; Xie, P.-F. Res. Chem. Intermed. 2012, 38, 639–
644.
36. Masllorens, J.; Bouquillon, S.; Roglans, A.; Hénin, F.; Muzart, J. J. Organomet.
Chem. 2005, 690, 3822–3826.
37. Fox, M. E.; Jackson, M.; Lennon, I. C.; Klosin, J.; Abboud, K. A J. Org. Chem. 2008,
73, 775–784.