Cobalt(II) chloride hexahydrate-diisopropylamine catalyzed mild and chemoselective reduction of carboxylic esters with sodium borohydride

Article abstract of DOI:10.1055/s-0028-1083353

The cobalt-catalyzed reduction of unsaturated α-cyano carboxylic esters using sodium borohydride (NaBH₄) leads to the corresponding saturated cyano alcohols in high yields. In particular, the new catalytic system cobalt(II) chloride-diisopropylamine in combination with NaBH₄ showed excellent activity in the chemoselective reduction of a variety of carboxylic esters to their corresponding alcohols in good to excellent yields under mild conditions. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-0028-1083353

660
PAPER
Cobalt(II) Chloride Hexahydrate–Diisopropylamine Catalyzed Mild and
Chemoselective Reduction of Carboxylic Esters with Sodium Borohydride
C
atalyze
d
Mild an
r
d
C
hemo
u
selective Re
n
duction of Carboxy
R
lic
E
sters . Jagdale, Abhimanyu S. Paraskar, Arumugam Sudalai*
Chemical Engineering and Process Development Division, National Chemical Laboratory, Pashan Road, Pune 411 008, India
Fax +91(20)25902676; E-mail: a.sudalai@ncl.res.in
Received 28 July 2008; revised 13 October 2008
try 2). However, when the reaction was carried out
Abstract: The cobalt-catalyzed reduction of unsaturated a-cyano
without CoCl2·6H2O in ethanol at 25 °C, only the reduc-
tion of the carbon–carbon double bond was observed to
carboxylic esters using sodium borohydride (NaBH4) leads to the
corresponding saturated cyano alcohols in high yields. In particular,
give ethyl 2-cyano-3-phenylpropanoate (Table 1, entry
the new catalytic system cobalt(II) chloride–diisopropylamine in
combination with NaBH4 showed excellent activity in the chemose- 1).
lective reduction of a variety of carboxylic esters to their corre-
sponding alcohols in good to excellent yields under mild conditions.
CO2Et
CoCl2•6H2O (1 mol%)
R
R
OH
Key words: reductions, amines, catalysis, esters, alcohols
CN
CN
NaBH4, EtOH, 6 h
1a–i
2a–i
Sodium borohydride (NaBH4) is a mild, inexpensive yet
powerful reducing agent capable of reducing a wide range
of functional groups, such as aldehydes, ketones, and im-
ines.1 Despite its low reactivity towards carboxylic esters,2
studies have indicated that the reactivity of NaBH4 and its
derivatives towards these compounds and carboxylic
Scheme 1 Cobalt(II) chloride hexahydrate catalyzed reduction of
a-cyano-a,b-unsaturated esters using sodium borohydride
Table 1 Cobalt(II) Chloride Hexahydrate Catalyzed Reduction of
a-Cyano-a,b-unsaturated Esters Using Sodium Borohydridea
Entry
R
Product
Yieldb (%)
acids can be enhanced by the addition of certain additives,
resulting in the use of reagents such as NaBH4–MX
(MX = LiCl, ZnCl2, AlCl3, LiBr, MgBr2, MgCl2, CaCl2),3
KBH4–MX (MX = ZnCl2, AlCl3, MgCl2),4 NaBH4–
trifluoroacetic acid,5 NaBH4–sulfuric acid,6 NaBH4–
iodine,7 and borane–dimethyl sulfide complex.8 However,
some of the major disadvantages of the reported proce-
dures on ester reduction include the lack of generality9 and
the use of harsh reaction conditions10 and higher equiva-
lents of NaBH4 and additives.11 The reduction of esters
with hydroxy, amino, and cyano12 substituents at the a-
position and that of carbon–carbon double bonds in a,b-
unsaturated esters using NaBH4 have also been reported.13
In this paper, we report a simple procedure in which co-
balt(II) chloride hexahydrate (CoCl2·6H2O) in combina-
tion with diisopropylamine catalyzes the chemoselective
reduction of carboxylic esters to saturated alcohols using
NaBH4 at ambient conditions.
In continuation of our work13a,b on the cobalt-catalyzed re-
duction of carbon–carbon double bonds and phenyl esters
using NaBH4, we became interested in subjecting (E)-eth-
yl 2-cyano-3-phenylacrylate (1a) to CoCl2-catalyzed re-
duction conditions. Surprisingly, we found that ethyl
acrylate 1a underwent reduction using NaBH4 at the car-
bon–carbon double bond as well as at the ester carbonyl
functionality to provide 2-(hydroxymethyl)-3-phenylpro-
panenitrile (2a) in 95% yield (Scheme 1 and Table 1, en-
c
1
2
Ph
–
80
95
90
97
92
85
80
96
99
70
Ph
2a
2b
2c
2d
2e
2f
3
4-ClC6H4
4-MeOC6H4
4-Tol
4
5
6
3-F3CC6H4
3-O2NC6H4
3,4-(MeO)2C6H3
3,4-(OCH2O)C6H3
n-C8H17
7
8
2g
2h
2i
9
10
a Reaction conditions: cyano ester (10 mmol), NaBH4 (40 mmol),
CoCl2·6H2O (1 mol%), EtOH (5 mL), 25 °C, 6 h.
b Isolated yield after chromatographic purification.
c Ethyl 2-cyano-3-phenylpropanoate was isolated when the reaction
was carried out in the absence of CoCl2·6H2O.
The results of the reduction of several a-cyano-a,b-unsat-
urated esters are presented in Table 1; those groups in the
ester substrates capable of being reduced, such as nitro
and cyano groups, were found to be unaffected under the
reduction conditions. The high yields obtained, coupled
with the use of ethanol as solvent over diglyme, makes
this procedure straightforward and highly economical. It
may be that the strong electron-withdrawing nature of the
cyano group as well as that of the ester functionality re-
sults in the b-positions of the a-cyano esters being more
SYNTHESIS 2009, No. 4, pp 0660–0664
x
x
.
x
x
.2
0
0
9
Advanced online publication: 02.02.2009
DOI: 10.1055/s-0028-1083353; Art ID: T12508SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Catalytic Mild and Chemoselective Reduction of Carboxylic Esters
661
electrophilic for carbon–carbon double bond reduction to
occur.
OH
cat. i-Pr2NH
85%
O
4a
5a
This catalytic procedure provides 3-aryl-2-(hydroxymeth-
yl)propanenitriles 2a–h and 3-n-octyl derivative 2i in high
yields; such compounds are potential intermediates in the
synthesis of aminooxazolines.11c–e We noticed that the re-
duction of a-cyano esters is more facile compared with
that of alkyl carboxylic esters with an a-cyano group. To
make the ester reduction procedure more general and
practical, we became interested in enhancing the reactivi-
ty of NaBH4 by the addition of additives.14,15 Thus, the ad-
dition of various amines (i.e., Et3N, DMAP, Me2NPh, or
i-Pr2NH) in catalytic amounts was shown to enhance the
rate of reduction of carboxylic esters at 50 °C, for example
the reduction of ethyl cinnamate (Scheme 2 and Table 2,
entries 1–6). After careful study, we found that the com-
bination of CoCl2·6H2O–i-Pr2NH in catalytic amounts is
an effective catalytic system in the reduction of a variety
of esters, including a,b-unsaturated, aliphatic, and
aromatic ones and lactones, giving the corresponding sat-
urated alcohols 4 in high yields.
cat. CoCl2
O
OEt
NaBH4
EtOH
OEt
no amine
95%
3a
Scheme 2 Cobalt-catalyzed reduction of ethyl cinnamate with sodi-
um borohydride
The simultaneous reduction of the carbon–carbon double
bond along with the carboxylic ester functionality was
also observed in the case of (E)-ethyl 3-arylacrylates
(Table 2, entries 7–9). In addition, diethyl 2-benzylidene-
malonate smoothly underwent reduction to provide 2-
benzylpropane-1,3-diol (4e) in 94% yield (entry 10). Aro-
matic esters were reduced to the corresponding benzyl al-
cohols (entries 11 and 12). More interestingly, aliphatic
esters and lactones were reduced to the corresponding al-
cohols in good yields under mild conditions (entries 13
Table 2 Cobalt(II) Chloride Hexahydrate–Diisopropylamine Catalyzed Chemoselective Reduction of Esters Using Sodium Borohydride: The
Role of Diisopropylaminea
Entry
Ester
Additive
no catalyst
no amine
i-Pr2NH
DMAP
Product
Yieldb (%)
CO2Et
OH
CO2Et
1
2
3
4
5
6
5a
5a
4a
4a
4a
4a
5
Ph
Ph
95
85
12
30
21
Ph
Et3N
Me2NPh
CO2Et
OH
7
8
i-Pr2NH
i-Pr2NH
i-Pr2NH
i-Pr2NH
4b
4c
4d
4e
87
82
87
94
Cl
Cl
MeO
MeO
CO2Et
OH
MeO
MeO
CO2Et
OH
OH
9
NO2
NO2
CO2Et
CO2Et
10
OH
11
12
13
PhCO2Et
4-BrC6H4CO2Et
i-Pr2NH
i-Pr2NH
i-Pr2NH
4f
PhCH2OH
4-BrC6H4CH2OH
87
82
79
4g
4h
4-O2NC6H4CH2CO2Et
4-O2NC6H4CH2CH2OH
O
14
i-Pr2NH
4i
81
OH
HO
O
a Reaction conditions: carboxylic ester (2 mmol), NaBH4 (4 mmol), CoCl2·6H2O (10 mol%), i-Pr2NH (20 mol%), EtOH (12 mL), 50 °C, 24 h.
b Isolated yield after chromatographic purification.
Synthesis 2009, No. 4, 660–664 © Thieme Stuttgart · New York

662
A. R. Jagdale et al.
PAPER
Anal. Calcd for C10H10ClNO: C, 61.39; H, 5.15; N, 7.16. Found: C,
61.42; H, 5.11; N, 7.21.
and 14, respectively). The results of the CoCl2·6H2O–
i-Pr2NH/NaBH4 reduction clearly showed that esters can
be reduced under mild conditions even when they contain
various reducible groups, such as nitro and halo groups;
such reactions are quite difficult with other strong reduc-
ing agents, e.g. lithium aluminum hydride. Mechanistical-
ly, the role of diisopropylamine is probably to enhance the
nucleophilicity of the borohydride reagent by way of co-
ordination.15a
2-(Hydroxymethyl)-3-(4-methoxyphenyl)propanenitrile (2c)
Yield: 97% (1.22 g); gray solid; mp 122–124 °C (CHCl3).
IR (CHCl3): 667, 756, 837, 1033, 1068, 1111, 1180, 1249, 1301,
1442, 1463, 1514, 1612, 1660, 2244, 2837, 2935, 3014, 3448 cm–1.
1H NMR (200 MHz, CDCl3): d = 2.70–3.10 (m, 4 H), 3.70–3.90 (m,
5 H), 6.8 (d, J = 8.0 Hz, 2 H), 7.01 (d, J = 7.12 Hz, 2 H).
13C NMR (200 MHz, CDCl3): d = 32.8, 38.0, 55.2, 61.1, 114.3,
114.4, 119.9, 130.2, 130.6, 131.4, 163.4.
In conclusion, we have demonstrated a simple catalytic
combination comprising CoCl2·6H2O–i-Pr2NH with sto-
ichiometric NaBH4 that reduces both the carbon–carbon
double bond and ester carbonyl functionality in unsaturat-
ed carboxylic esters containing other reducible groups,
such as halo, cyano, and nitro groups. Mild reaction con-
ditions, easy-to-handle reagents, and good chemoselectiv-
ity are distinct features of this methodology; this
procedure is a promising alternative to those involving ex-
pensive and difficult-to-handle lithium aluminum hy-
dride.
Anal. Calcd for C11H13NO2: C, 69.09; H, 6.85; N, 7.32. Found: C,
69.10; H, 6.80; N, 7.28.
2-(Hydroxymethyl)-3-(4-tolyl)propanenitrile (2d)
Yield: 92% (1.46 g); colorless solid; mp 100–101 °C (CHCl3).
IR (CHCl3): 667, 757, 1070, 1214, 1381, 1446, 1516, 1625, 1903,
2245, 2887, 2927, 3018, 3444 cm–1.
1H NMR (200 MHz, CDCl3): d = 2.35 (s, 3 H), 2.91 (s, 3 H), 3.35
(s, 2 H), 3.71 (m, 1 H), 7.14 (m, 4 H).
13C NMR (200 MHz, CDCl3): d = 20.7, 33.7, 36.5, 61.2, 120.5,
128.6, 129.1, 133.3, 136.3.
The IR spectra were collected on a Shimadzu FTIR-8400 spectrom-
eter. The NMR spectroscopy was performed on Bruker AV-200 and
AV-400 NMR spectrometers with TMS as an internal standard.
Quantitative analyses were determined using a Carlo Erba CHNS-
O apparatus. Melting points are uncorrected. Solvents were purified
and dried by standard procedures before use; petroleum ether of
boiling range 60–80 °C was used.
Anal. Calcd for C11H13NO: C, 75.40; H, 7.48; N, 7.99. Found: C,
75.32; H, 7.35; N, 8.00.
2-(Hydroxymethyl)-3-[3-(trifluoromethyl)phenyl]propane-
nitrile (2e)
Yield: 85% (1.48 g); colorless solid; mp 105–108 °C (CHCl3).
1H NMR (200 MHz, CDCl3): d = 3.00 (s, 3 H), 3.54 (br s, 1 H), 3.76
(m, 2 H), 7.44–7.53 (m, 4 H).
13C NMR (200 MHz, CDCl3): d = 33.9, 36.4, 61.2, 120.2, 121.1,
124.0, 125.5, 129.2, 131.1, 132.4, 137.4.
2-(Hydroxymethyl)-3-phenylpropanenitrile (2a); Typical Pro-
cedure
To cyano ester 1a (2.01 g, 10 mmol) in a 10-mL round-bottomed
flask was added a solution of CoCl2·6H2O (0.024 g, 0.11 mmol) in
EtOH (10 mL) under a nitrogen atmosphere. Then, NaBH4 (1.51 g,
40 mmol) was added, and the mixture was stirred at 25 °C for 6 h.
After completion of the reaction (monitored by TLC), the mixture
was transferred to a separating funnel containing EtOAc–H2O (1:1,
100 mL), diluted with ice water (25 mL), and extracted with EtOAc
(3 × 300 mL). The organic layer was washed with brine soln (2 ×
400 mL), dried (anhyd Na2SO4), and concentrated under reduced
pressure. The product was purified by column chromatography
(EtOAc–petroleum ether, 3:1) to afford 2-(hydroxymethyl)-3-phe-
nylpropanenitrile (2a) as a colorless solid. Yield: 1.53 g (95%); mp
75–78 °C [following recrystallization from CHCl3 (91% yield)].
Anal. Calcd for C11H10F3NO: C, 57.64; H, 4.40; N, 6.11. Found: C,
57.50; H, 4.45; N, 6.10.
2-(Hydroxymethyl)-3-(3-nitrophenyl)propanenitrile (2f)
Yield: 80% (1.43 g); yellowish solid; mp 182–184 °C (EtOH–
CHCl3).
1H NMR (200 MHz, CDCl3): d = 3.10 (s, 3 H), 3.84 (m, 3 H), 7.56
(d, J = 8.72 Hz, 2 H), 8.14 (d, J = 6.19 Hz, 2 H).
13C NMR (200 MHz, CDCl3): d = 33.8, 36.2, 61.3, 119.7, 122.4,
123.9, 129.8, 135.4, 138.5, 148.3.
Anal. Calcd for C10H10N2O3: C, 58.25; H, 4.89; N, 13.59. Found: C,
58.22; H, 4.85; N, 13.60.
IR (CHCl3): 700, 750, 1070, 1218, 1454, 1496, 1602, 1641, 1718,
1955, 2245, 2887, 2935, 3028, 3064, 3421 cm–1.
1H NMR (200 MHz, CDCl3): d = 2.94 (s, 3 H), 3.71 (m, 3 H), 7.26
3-(3,4-Dimethoxyphenyl)-2-(hydroxymethyl)propanenitrile
(2g)
Yield: 96% (1.61 g); brown solid; mp 170–171 °C (CHCl3).
(m, 5 H).
13C NMR (200 MHz, CDCl3): d = 34.1, 36.6, 61.1, 120.5, 127.0,
128.5, 128.8, 136.4.
IR (CHCl3): 765, 812, 858, 1026, 1072, 1141, 1157, 1238, 1263,
1336, 1421, 1465, 1515, 1591, 1724, 2243, 2837, 2937, 3494 cm–1.
1H NMR (200 MHz, CDCl3): d = 3.11 (s, 3 H), 3.48 (br s, 1 H), 3.71
(m, 2 H), 3.81 (s, 6 H), 6.58–6.72 (m, 3 H).
Anal. Calcd for C10H11NO: C, 74.51; H, 6.88; N, 8.69. Found: C,
74.45; H, 6.85; N, 8.70.
13C NMR (200 MHz, CDCl3): d = 33.7, 36.3, 56.3, 61.1, 114.7,
115.7, 132.2, 132.6, 138.2, 144.5, 147.1.
3-(4-Chlorophenyl)-2-(hydroxymethyl)propanenitrile (2b)
Yield: 90% (1.18 g); colorless solid; mp 118–120 °C (CHCl3).
IR (CHCl3): 669, 757, 1215, 1492, 2400, 3020, 3433 cm–1.
1H NMR (200 MHz, CDCl3): d = 2.98 (s, 3 H), 3.78 (m, 3 H), 7.47
(d, J = 8.72 Hz, 2 H), 7.75 (d, J = 7.12 Hz, 2 H).
13C NMR (200 MHz, CDCl3): d = 34.2, 36.7, 61.2, 120.2, 122.3,
128.2, 128.5, 134.1, 136.0, 140.2.
Anal. Calcd for C12H15NO3: C, 65.14; H, 6.83; N, 6.33. Found: C,
65.11; H, 6.80; N, 6.35.
3-Benzo[1,3]dioxol-5-yl-2-(hydroxymethyl)propanenitrile (2h)
Yield: 99% (1.66 g); colorless solid; mp 190–192 °C (CHCl3).
Synthesis 2009, No. 4, 660–664 © Thieme Stuttgart · New York

PAPER
Catalytic Mild and Chemoselective Reduction of Carboxylic Esters
663
IR (CHCl3): 771, 813, 864, 927, 1039, 1091, 1193, 1247, 1365,
1444, 1510, 1608, 1728, 1843, 2245, 2781, 2893, 3452 cm–1.
1H NMR (200 MHz, CDCl3): d = 2.97 (s, 3 H), 3.44 (br s, 1 H), 3.62
(m, 2 H), 5.87 (s, 2 H), 6.53–6.62 (m, 3 H).
13C NMR (200 MHz, CDCl3): d = 34.1, 35.3, 61.1, 91.1, 115.3,
115.9, 132.3, 132.8, 138.4, 145.1, 146.8.
1H NMR (200 MHz, CDCl3): d = 1.76 (br s, 1 H), 1.78–1.92 (m, 2
H), 2.67 (t, J = 7.3 Hz, 2 H), 3.61 (t, J = 7.3 Hz, 2 H), 7.12 (d, J =
8.5 Hz, 2 H), 7.24 (d, J = 8.5 Hz, 2 H).
13C NMR (50 MHz, CDCl3): d = 31.1, 33.7, 61.3, 128.1, 129.5,
131.2, 140.0.
Anal. Calcd for C9H11ClO: C, 63.35; H, 6.50. Found: C, 63.32; H,
6.52.
Anal. Calcd for C11H11NO3: C, 64.38; H, 5.40; N, 6.83. Found: C,
64.43; H, 5.36; N, 6.70.
3-(3,4-Dimethoxyphenyl)propan-1-ol (4c)
Yield: 82% (320 mg); gum.
IR (CHCl3): 745, 857, 968, 1029, 1060, 1460, 1495, 3498 cm–1.
2-(Hydroxymethyl)undecanenitrile (2i)
Yield: 70% (1.21 g); colorless solid; mp 50–53 °C (CHCl3).
IR (KBr): 667, 757, 1047, 1215, 1377, 1465, 1670, 1730, 2200,
2854, 2925, 3018, 3386 cm–1.
1H NMR (200 MHz, CDCl3): d = 0.88 (t, J = 6.66 Hz, 3 H), 1.27–
1.57 (m, 16 H), 1.90 (br s, 1 H), 3.88 (m, 2 H), 4.49 (m, 1 H).
13C NMR (200 MHz, CDCl3): d = 14.1, 17.8, 54.0, 59.2, 99.3, 126.3,
127.3, 128.4, 144.9, 148.4, 152.2, 165.4.
1H NMR (200 MHz, CDCl3): d = 1.64 (br s, 1 H), 1.61–1.95 (m, 2
H), 2.67 (t, J = 8.1 Hz, 2 H), 3.68 (t, J = 8.1 Hz, 2 H), 3.86 (s, 3 H),
3.87 (s, 3 H), 6.72–6.86 (m, 3 H).
13C NMR (50 MHz, CDCl3): d = 31.5, 34.2, 55.7, 55.8, 62.1, 111.2,
111.6, 120.1, 134.3, 147.0, 147.7.
Anal. Calcd for C11H16O3: C, 67.32; H, 8.22. Found: C, 67.28; H,
8.21.
Anal. Calcd for C12H23NO: C, 73.04; H, 11.75; N, 7.10. Found: C,
73.98; H, 11.95; N, 7.60.
3-(2-Nitrophenyl)propan-1-ol (4d)
Yield: 87% (326 mg); gum.
IR (CHCl3): 857, 968, 1029, 1060, 1245, 1440, 1507, 3430 cm–1.
Cobalt(II) Chloride Hexahydrate–Diisopropylamine Catalyzed
Reduction of Esters to Alcohols 4; General Procedure
To a solution of the appropriate carboxylic ester (2 mmol) and
CoCl2·6H2O (4.72 mg, 0.2 mmol) in distilled EtOH (8 mL) was add-
ed 1 M i-Pr2NH (20 mol%) in distilled EtOH (4 mL). To the stirred
mixture was then added NaBH4 (156 mg, 4 mmol) portionwise. The
mixture was stirred at 50 °C for 24 h. After completion of the reac-
tion (monitored by TLC), the mixture was diluted with H2O (50 mL)
and EtOAc (50 mL). The organic layer was separated, washed with
brine soln (2 × 20 mL), dried (anhyd Na2SO4), and concentrated un-
der reduced pressure to give the crude product. Flash column chro-
matography (silica gel, 230–400 mesh, petroleum ether–EtOAc,
3:2) afforded the saturated alcohol 4 in pure form.
1H NMR (200 MHz, CDCl3): d = 1.67 (br s, 1 H), 1.87–2.01 (m, 2
H), 1.99 (t, J = 7.6 Hz, 2 H), 3.72 (t, J = 6.2 Hz, 2 H), 7.31–7.60 (m,
3 H), 7.92 (dd, J = 1.2, 8.1 Hz, 1 H).
13C NMR (50 MHz, CDCl3): d = 29.1, 33.2, 61.6, 124.4, 126.8,
131.8, 132.8, 136.7, 149.1.
Anal. Calcd for C9H11NO3: C, 59.66; H, 6.12; N, 7.73. Found: C,
59.63; H, 6.10; N, 7.75.
2-Benzylpropane-1,3-diol (4e)
Yield: 94% (342 mg); gum.
IR (CHCl3): 745, 857, 968, 1029, 1060, 1454, 1498, 3400 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.99–2.27 (m, 1 H, and br s, 2 H),
2.62 (d, J = 7.6 Hz, 2 H), 3.63–3.85 (m, 4 H), 7.17–7.36 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 34.1, 43.7, 64.9, 126.0, 128.9,
139.8.
The reaction of ethyl cinnamate without the use of i-Pr2NH resulted
in the formation of the saturated ester 5a.
3-Phenylpropan-1-ol (4a)
Yield: 85% (300 mg); colorless liquid.
IR (CHCl3): 698, 744, 968, 1029, 1060, 1454, 1495, 3325 cm–1.
Anal. Calcd for C10H14O2: C, 72.26; H, 8.49. Found: C, 72.23; H,
8.44.
1H NMR (200 MHz, CDCl3): d = 1.44 (br s, 1 H), 1.84–1.95 (m, 2
H), 2.70 (t, J = 8.0 Hz, 2 H), 3.65 (t, J = 6.3 Hz, 2 H), 7.13–7.31 (m,
5 H).
13C NMR (50 MHz, CDCl3): d = 31.1, 33.7, 63.3, 126.7, 127.1,
128.1, 140.4.
Phenylmethanol (4f)
Yield: 87% (322 mg); gum.
IR (CHCl3): 857, 968, 1495, 3498 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.99 (br s, 1 H), 4.66 (s, 2 H),
7.25–7.37 (m, 5 H).
Anal. Calcd for C9H12O: C, 79.37; H, 8.88. Found: C, 79.32; H,
8.82.
13C NMR (50 MHz, CDCl3): d = 64.3, 126.7, 127.1, 128.1, 140.6.
Ethyl 3-Phenylpropanoate (5a)
Yield: 95% (354 mg); colorless liquid.
IR (CHCl3): 698, 744, 968, 1029, 1060, 1454, 1495, 1747 cm–1.
Anal. Calcd for C7H8O: C, 77.75; H, 7.46. Found: C, 77.72; H, 7.45.
(4-Bromophenyl)methanol (4g)
Yield: 82% (332 mg); gum.
IR (CHCl3): 968, 1029, 1060, 1501, 3390 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.25 (t, J = 7.3 Hz, 3 H), 2.65–2.72
(m, 2 H), 2.81–2.91 (m, 2 H), 4.15 (q, J = 7.3 Hz, 2 H), 7.15–7.33
(m, 5 H).
1H NMR (200 MHz, CDCl3): d = 1.88 (br s, 1 H), 4.64 (s, 2 H), 7.23
(d, J = 8.5 Hz, 2 H), 7.48 (d, J = 8.5 Hz, 2 H).
13C NMR (50 MHz, CDCl3): d = 13.9, 30.6, 35.3, 59.8, 125.9, 127.9,
128.1, 140.3, 172.6.
13C NMR (50 MHz, CDCl3): d = 63.9, 121.1, 128.4, 131.3, 139.5.
Anal. Calcd for C11H14O2: C, 74.13; H, 7.92. Found: C, 74.11; H,
7.95.
Anal. Calcd for C7H7BrO: C, 44.95; H, 3.77. Found: C, 44.92; H,
3.73.
3-(4-Chlorophenyl)propan-1-ol (4b)
Yield: 87% (358 mg); gum.
IR (CHCl3): 754, 968, 1029, 1060, 1454, 1495, 3325 cm–1.
2-(4-Nitrophenyl)ethanol (4h)
Yield: 79% (319 mg); gum.
Synthesis 2009, No. 4, 660–664 © Thieme Stuttgart · New York

664
A. R. Jagdale et al.
PAPER
(7) Kanth, J. V. B.; Periasamy, M. J. Org. Chem. 1991, 56,
IR (CHCl3): 857, 1063, 1245, 1498, 3450 cm–1.
5964.
1H NMR (200 MHz, CDCl3): d = 1.70 (br s, 1 H), 2.96 (t, J = 6.3
Hz, 2 H), 3.91 (m, 2 H), 7.40 (d, J = 8.7 Hz, 2 H), 8.15 (d, J = 8.7
Hz, 2 H).
13C NMR (50 MHz, CDCl3): d = 67.2, 121.2, 128.6, 146.1, 147.1.
(8) Lane, C. F.; Myatt, H. L.; Daniels, J.; Hopps, H. B. J. Org.
Chem. 1974, 39, 3052.
(9) For a review, see: Periasamy, M.; Thirumalaikumar, M.
J. Organomet. Chem. 2000, 609, 137.
(10) (a) da Costa, J. C. S.; Pais, K. C.; Fernandes, E. L.;
de Oliveira, P. S. M.; Mendonça, J. S.; de Souza, M. V. N.;
Peralta, M. A.; Vasconcelos, T. R. A. ARKIVOC 2006, (i),
128. (b) Boechat, N.; da Costa, J. C. S.; Mendonça, J. S.;
de Oliveira, P. S. M.; de Souza, M. V. N. Tetrahedron Lett.
2004, 45, 6021. (c) Zhu, H. J.; Pittman, C. U. Synth.
Commun. 2003, 33, 1733. (d) Santaniello, E.; Ferraboschi,
P.; Sozzani, P. J. Org. Chem. 1981, 46, 4584. (e) See also
ref. 3a. (f) Guida, W. C.; Entreken, E. E.; Guida, A. R. J.
Org. Chem. 1984, 49, 3024.
(11) (a) Das, D.; Roy, S.; Das, P. K. Org. Lett. 2004, 6, 4133.
(b) Kokotos, G.; Noula, C. J. Org. Chem. 1996, 61, 6994.
(c) Meschino, J. A.; Bond, C. H. J. Org. Chem. 1963, 28,
3129. (d) Poos, G. I.; Carson, J. R.; Rosenau, J. D.;
Roszkowski, A. P.; Kelley, N. M.; McGowin, J. J. Med.
Chem. 1963, 6, 266. (e) Fodor, G.; Koczka, K. J. Chem. Soc.
1952, 850.
(12) (a) Li, L.-C.; Jiang, J.-X.; Ren, J.; Ren, Y. i.; Pittman, C. U.
Jr.; Zhu, H.-J. Eur. J. Org. Chem. 2006, 1981. (b) Patra, A.;
Batra, S.; Bhaduri, A. P. Synlett 2003, 1611. (c) Corrêa,
I. R. Jr.; Moran, J. S. Tetrahedron 1999, 55, 14221.
(d) Dalla, V.; Catteaua, J. P.; Pale, P. Tetrahedron Lett.
1999, 40, 5193. (e) Lanier, M.; Pastor, R. Tetrahedron Lett.
1995, 36, 2491.
Anal. Calcd for C8H9NO3: C, 57.48; H, 5.43; N, 8.38. Found: C,
57.44; H, 5.40; N, 8.35.
Butane-1,4-diol (4i)
Yield: 85% (312 mg); gum.
IR (CHCl3): 837, 938, 1291, 3098, cm–1.
1H NMR (200 MHz, CDCl3): d = 1.42–1.48 (m, 4 H), 1.94 (br s, 2
H), 3.51–3.58 (m, 4 H).
13C NMR (50 MHz, CDCl3): d = 28.1, 64.3.
Anal. Calcd for C4H10O2: C, 53.31; H, 11.18. Found: C, 53.61; H,
11.33.
Acknowledgment
A.R.J. and A.S.P. thank CSIR (Council of Scientific and Industrial
Research), New Delhi, for the award of research fellowships. The
authors are also thankful to Dr. B. D. Kulkarni, Head, CEPD (Che-
mical Engineering and Process Development), for his constant sup-
port and encouragement.
References
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Synthesis 2009, No. 4, 660–664 © Thieme Stuttgart · New York