Synthesis of substituted 3-furanoates from MBH-acetates of acetylenic aldehydes via tandem isomerization-deacetylation-cycloisomerization: Access to Elliott's alcohol

Article abstract of DOI:10.1039/c3ob42396d

A new method for the synthesis of 5-substituted furan-3-carboxylates from Morita-Baylis-Hillman acetates of acetylenic aldehydes is reported. The process involves palladium-catalyzed isomerization followed by base-promoted deacetylation and cycloisomerization reactions. The utility of this chemistry is further demonstrated by the synthesis of Elliott's alcohol, a key intermediate of the pyrethroid resmethrins. This journal is The Royal Society of Chemistry 2014.

Full text of DOI:10.1039/c3ob42396d

Organic &
Biomolecular Chemistry
View Article Online
View Journal | View Issue
PAPER
Synthesis of substituted 3-furanoates from
MBH-acetates of acetylenic aldehydes via
tandem isomerization–deacetylation–
Cite this: Org. Biomol. Chem., 2014,
12, 1664
cycloisomerization: access to Elliott’s alcohol†‡
Chada Raji Reddy,* Gaddam Krishna and Motatipally Damoder Reddy
Received 1st December 2013,
Accepted 7th January 2014
A new method for the synthesis of 5-substituted furan-3-carboxylates from Morita–Baylis–Hillman acet-
ates of acetylenic aldehydes is reported. The process involves palladium-catalyzed isomerization followed
by base-promoted deacetylation and cycloisomerization reactions. The utility of this chemistry is further
demonstrated by the synthesis of Elliott’s alcohol, a key intermediate of the pyrethroid resmethrins.
DOI: 10.1039/c3ob42396d
www.rsc.org/obc
Introduction
Furans have received substantial interest as important targets
in organic synthesis because of their frequent use in various
fields such as pharmaceuticals, agrochemicals, functional
materials, cosmetics, etc.1 In particular, 5-substituted furan-3-
carboxylate has been recognized as one of the important
frameworks due to its occurrence in many bio-active natural
products.2 For example, flufuran (A),2a tournefolin C (B)2b and
angelone (C)2c pukalide class of molecules (D)2d are some of
the representative natural products possessing the furan-3-car-
boxylate skeleton embedded in their structures (Fig. 1).
Further, 5-substituted 3-furanoates were also found to be valu-
able intermediates for the synthesis of bio-active molecules3
including pesticides such as pyrethroid resmethrin,4 a syn-
thetic insecticide (E, Fig. 1). Although numerous methods
have been developed towards diversely functionalized furans,5
the procedures available for the synthesis of 5-substituted
furan-3-carboxylate derivatives are very limited.6,7 Usually the
title compounds are achieved through the functionalization at
the C5-position of furan-3-carboxylate.6 Alternative strategies
for their construction from acyclic precursors are (i) the reac-
tion of acrylates with aldehydes in the presence of the Pd-
(OAc)2/HPMoV/CeCl3/O2 system, (ii) Au/Ag-catalyzed annula-
tion of enynyl-aryl ethers, (iii) condensation of the ethylene
acetals of 5-substituted levulic esters with ethyl formate fol-
lowed by acid-mediated cyclization and a few other examples.7
Nonetheless, the development of novel approaches for the
Fig. 1 Structures of selected natural products having substituted
3-furanoate and resmethrin.
synthesis of 5-substituted 3-furanoates from readily accessible
starting materials remains highly desirable.
Morita–Baylis–Hillman (MBH) adducts and their derivatives
have been recognized as handy synthons in the preparation of
valuable synthetic products including carbocycles and hetero-
cycles via various transformations.8 These multifunctional
adducts were easily accessible through the Morita–Baylis–
Hillman reaction,9 one of the atom-economic carbon–carbon
bond forming reactions. Recently, we have explored the utility
of MBH-acetates of acetylenic aldehydes in the synthesis of
pyrroles, cyclopentenes and thiophenes.10 In continuation,
herein we describe a novel one-pot access to 5-substituted
3-furanoates from MBH-acetates of acetylenic aldehydes
via a tandem isomerization–deacetylation–cycloisomerization
reaction sequence. To the best of our knowledge, to date there
Division of Natural Products Chemistry, CSIR-Indian Institute of Chemical
Technology, Hyderabad – 500607, India. E-mail: rajireddy@iict.res.in
†Dedicated to Dr. S. Chandrasekhar, CSIR-IICT, on his 50th birthday.
‡Electronic supplementary information (ESI) available: Copies of 1H NMR and
13C NMR spectra of all the new compounds. See DOI: 10.1039/c3ob42396d
1664 | Org. Biomol. Chem., 2014, 12, 1664–1670
This journal is © The Royal Society of Chemistry 2014

View Article Online
Organic & Biomolecular Chemistry
Paper
has been no report on the one-pot synthesis of substituted effective to offer I in good yield (entries 3 to 5, Table 1). Having
furans starting from MBH adducts.11
allyl acetate I in hand, next we evaluated its conversion to (Z)-
2-en-4-yn-1-ol II through deacetylation using K2CO3 in metha-
nol at room temperature. To our delight, directly the formation
of 5-benzyl furan-3-carboxylate (2a) was observed in 97% yield
through deacetylation followed by intramolecular 5-exo-dig-oxa-
cycloisomerization and no traces of intermediate II were iso-
lated (entry 6, Table 1). This was confirmed by the isolation of
II from the reaction of I with K2CO3 at 0 °C for 5 min in 81%
yield (entry 7, Table 1) and after characterization of II, it was
subjected to the same base conditions at room temperature to
get 2a. It is important to mention that previously (Z)-2-en-4-yn-
1-ols were prepared and used in the synthesis of alkyl/aryl-sub-
stituted furans under various reaction conditions.13 In con-
trast, the present method offers a direct access to 5-substituted
3-furanoates for the first time, which is an added advance to
the Z-enynol chemistry. Having defined the reaction con-
ditions for the synthesis of allyl acetate I from MBH-acetate 1a
and its conversion to furan 2a, we were fascinated to develop a
one-pot reaction for the conversion of 1a to 2a.
Results and discussion
The optimization of reaction conditions was performed using
MBH acetate 1a, derived from the reaction of 3-phenylpropio-
laldehyde with methyl acrylate, as a model substrate (Table 1).
Based on our previous study,10d we first chose KOAc in aceto-
nitrile as the reaction conditions to get allylic acetate I through
allylic substitution and to our disappointment the formation
of I was not observed (entry 1, Table 1). This may be due to the
less nucleophilic nature of acetate (OAc), when compared to
thioacetate (SAc). Next, we decided to obtain the intermediate I
through isomerization of 1a, which was tested using different
reaction conditions. We were pleased to find that the allyl
acetate I was isolated in 98% yield from 1a after stirring at
room temperature in acetonitrile for 12 h in the presence of
10 mol% of Pd(Ph3P)4 (entry 2, Table 1).12 The other con-
ditions tested, such as NH4OAc in methanol, DABCO in tetra-
hydrofuran and TMSOTf in dichloromethane, were not
Consequently, MBH-acetate 1a was treated with 10 mol% of
Pd(Ph3P)4 in CH3CN for 12 h, followed by the addition of
K2CO3 in MeOH at room temperature, resulting in the clean
formation of disubstituted furan 2a in 94% yield (entry 8,
Table 1), which confirmed the success of optimal conditions
for one-pot reaction.
Table 1 Optimization of reaction conditions
To broaden the scope of this method, we carried out the
reaction with diverse MBH-acetates of acetylenic aldehydes
under optimized conditions (Table 2). Treatment of MBH-acet-
ates 1b and 1c, having 4-methylphenyl and 1-naphthyl groups
on alkyne, with 10 mol% of Pd(PPh3P)4 followed by K2CO3 in
MeOH provided the corresponding 5-substituted 3-furanoates
2b and 2c in 85% and 80% yields, respectively (entries 1 and 2,
Table 2 Synthesis of 5-substituted 3-furanoatesa
Deacetylation/
cyclization
Isomerization
Entry
(step 1; 1a to I)
(step 2; I to 2a or II)
Product
Yielda
—
Entry
MBH acetate (1)
Time (h)
Furan (2)b
Yieldc (%)
1
KOAc, CH3CN,
rt, 24 h
Pd(Ph3P)4,
CH3CN, rt, 12 h
NH4OAc, MeOH,
rt, 6 h
DABCO, THF,
rt, 12 h
TMSOTf, CH2Cl2,
0 °C-rt
—
—
—
—
—
I
2
I
98
1
2
3
4
5
6
7
8
R = 4-Me-C6H4, 1b
R = 1-Napthyl, 1c
R = 4-MeO-C6H4, 1d
R = 2-MeO-C6H4, 1e
R = 4-Cl-C6H4, 1f
R = 4-CN-C6H4, 1g
R = 4-COCH3-C6H4, 1h
R = 2-Thiophenyl, 1i
R = PhCHvCH, 1j
R = nC3H7, 1k
14
14
14
15
16
14
14
14
15
15
14
15
2b
2c
2d
2e
2f
2g
2h
2i
85
80
88
81
86
84
88
89
72
64
68
66
3
I
45
4
I
63
5
I
27
6b
7b
8c
—
K2CO3, MeOH,
rt, 4 h
K2CO3, MeOH,
0 °C, 5 min
K2CO3, MeOH,
rt, 4 h
2a
II
2a
97
9
2j
2k
2l
10
11
12
—
81
R = nC5H11, 1l
R = nC6H13, 1m
2m
Pd(Ph3P)4,
CH3CN, rt, 12 h
94
a Reaction conditions: MBH acetate 1 (0.38 mmol), Pd(Ph3P4)4 (10 mol%),
CH3CN (3 mL), 12 h, MeOH (3 mL), K2CO3 (1.16 mmol), rt. b All the
products were characterized by 1H, 13C NMR, IR and MS spectra.
c Isolated yields.
a Isolated yields. b Starting material for the reaction is I. c One-pot
reaction.
This journal is © The Royal Society of Chemistry 2014
Org. Biomol. Chem., 2014, 12, 1664–1670 | 1665

View Article Online
Paper
Organic & Biomolecular Chemistry
Table 2). The reaction was found to tolerate the electron-donat-
ing groups at various positions around the phenyl group
attached to the alkyne of MBH-acetates 1d and 1e in affording
the 3-furanoates 2d and 2e in 88% and 81% yields, respectively
(entries 3 and 4, Table 2). Similarly, MBH-acetates bearing aryl
substitution with electron-deficient groups such as 4-chloro
(1f), 4-cyano (1g), 4-acetyl (1h) were also successfully employed
in the tandem reaction to give the 5-substituted 3-furanoates
2f to 2h in good yield (entries 5 to 7, Table 2). The reaction of
MBH-acetate 1i containing 2-thiophenyl on alkyne also
afforded the furan-3-carboxylate 2i in 89% yield (entry 8,
Table 2). The developed strategy was found to be effective for
MBH acetates of acetylenic aldehydes having alkenyl group
(phenyl vinyl) 1j as well as alkyl chain such as n-propyl (1k),
n-pentyl (1l) and n-hexyl (1m) substitution, to give the respective
substituted 3-furanoates 2j to 2m, albeit in moderate yield
(entries 9–12, Table 2).
Additionally, MBH acetate 1n, obtained from the reaction
of 3-phenylpropiolaldehyde with t-butyl acrylate, was found to
be a good substrate in providing 5-benzyl t-butyl furan-3-car-
boxylate in 90% yield. Interestingly, MBH acetate 1o, derived
from methyl vinyl ketone, underwent tandem isomerization–
deacetylation–cycloisomerization reactions to give the corres-
ponding aceto-furanone 2o in 83% yield. Similarly, the present
protocol was also extended to MBH acetate 1p, prepared from
cyclohexenone, which successfully furnished the tri-substi-
tuted furanone 2p in 78% yield (Table 3).
Scheme 1 Synthesis of Elliott’s alcohol (3).
and have some drawbacks such as generation of chlorinated
by-products and use of expensive starting materials such as
isobutene diacetate.15 In 2008, Righi and co-workers have
reported an alternate four-step strategy to Elliott’s alcohol
starting from triethyl phosphonoacetate involving a tandem
olefination/Baylis–Hillman sequence.16 Herein, we presented a
novel approach for the synthesis of 3 using the currently
developed methodology in two steps from readily accessible
MBH-acetate 1a (Scheme 1), which was carried out in gram-
scale.
Conclusions
In summary, we have developed a novel approach for the con-
struction of 5-substituted furan-3-carboxylates from readily
accessible Morita–Baylis–Hillman acetates of acetylenic alde-
hydes through tandem Pd-catalyzed isomerization followed by
base-promoted deacetylative 5-exo-dig-cycloisomerization reac-
tions. The method was demonstrated by the synthesis of
various 3-furanoates and also extended to furanones. Further,
the developed methodology provided an alternative access to
Elliott’s alcohol, a key subunit of pyrethroid insecticide resme-
thrin. We believe that the present method may have potential
for the synthesis of a wide range of bioactive compounds
bearing such furan skeletons.
Encouraged by the above success, we turned our attention
to show the applicability of the obtained 3-furanoates having
ester as a handle for further elaboration towards the useful
derivatives. In this direction, methyl 5-benzylfuran-3-carboxy-
late 2a, achieved from MBH acetate 1a, was converted to
(5-benzylfuran-3-yl)methanol(3),Elliott’salcohol,14 byreduction
of the ester using DIBAL-H in dichloromethane (Scheme 1).
The resulting Elliott’s alcohol (3) is a key intermediate for the
manufacture of resmethrins, pyrethroid insecticides (Fig. 1).
The literature procedures for the preparation of 3 are lengthy
Experimental
General
Reactions were monitored by thin-layer chromatography
carried out on silica plates using UV-light and anisaldehyde
or potassium permanganate or β-naphthol for visualization.
Column chromatography was performed on silica gel
(60–120 mesh) using hexanes and ethyl acetate as eluents.
Evaporation of solvents was conducted under reduced pressure
at temperatures less than 45 °C. FTIR spectra were recorded on
KBr thin film or neat. 1H NMR and 13C NMR spectra were
recorded in CDCl3 solvent on a 300 MHz and 500 MHz NMR
spectrometer. Chemical shifts δ and coupling constants J are
given in ppm (parts per million) and Hz (hertz) respectively.
Chemical shifts are reported relative to the residual solvent as
an internal standard for 1H and 13C (CDCl3: δ 7.26 ppm for
1H and 77.0 ppm for 13C). Mass spectra were obtained on a VG
70–70H or LC/MSD trapSL spectrometer operating at 70 eV
using the direct inlet system.
Table 3 Synthesis of substituted furans
Reaction conditions: MBH acetate 1 (0.38 mmol), Pd(Ph3P)4 (10 mol%),
CH3CN (3 mL), rt, 12 h, MeOH (3 mL), K2CO3 (1.16 mmol), rt.
1666 | Org. Biomol. Chem., 2014, 12, 1664–1670
This journal is © The Royal Society of Chemistry 2014

View Article Online
Organic & Biomolecular Chemistry
Paper
Morita–Baylis–Hillman acetates 1a–1p have been prepared General procedure for the preparation of substituted furans
using the literature procedure10,17 and known compounds (2a–2p)
data compared with the reported data. Characterization
Pd(Ph3P)4 (0.038 mmol) was added to a solution of MBH-
data for new compounds (1e, g, h, j, and 1l) are given
acetate 1 (0.38 mmol) in 3 mL of CH3CN and the reaction
below.
mixture was stirred at room temperature for 12 h, followed by
Methyl 3-acetoxy-5-(2-methoxyphenyl)-2-methylenepent-
addition of 3 mL of MeOH and K2CO3 (1.14 mmol) stirred for
4-ynoate (1e). 0.93 g, 78%; colourless liquid; 1H NMR
2 to 4 h at the same temperature. After the completion of the
(300 MHz, CDCl3): δ 7.42 (dd, J = 7.4, 1.6 Hz, 1H), 7.33–7.29
reaction (monitored by TLC), the mixture was evaporated in a
(m, 1H), 6.92–6.83 (m, 2H), 6.58 (s, 1H), 6.54 (s, 1H), 6.51 (s,
vacuum, and the crude residue was purified by column
1H), 3.85 (s, 3H), 3.79 (s, 3H), 2.10 (s, 3H); 13C NMR (75 MHz,
chromatography on silica gel (EtOAc–hexanes) to afford the
corresponding furanoates (2a–2p).
CDCl3): δ 169.0, 164.8, 160.3, 136.4, 133.5, 130.2, 130.1, 129.4,
120.1, 110.5, 87.4, 83.7, 62.1, 55.4, 51.9, 20.6; IR (KBr): νmax
Methyl 5-benzylfuran-3-carboxylate (2a). 77 mg, 94%; pale
2953, 2840, 2232, 1745, 1596, 1493, 1437, 1259, 1148, 1024,
yellow solid; M.P.: 92–94 °C; 1H NMR (300 MHz, CDCl3): δ 7.67
978, 812, 756 cm−1; MS (ESI): m/z 311 (M + Na)+; HRMS (ESI):
(d, J = 7.5 Hz, 2H), 7.32 (t, J = 7.5 Hz, 2H), 7.17 (t, J = 7.5 Hz,
m/z calcd for C16H16O5Na (M
+
Na)+: 311.0895, found:
1H), 7.00 (s, 1H), 5.63 (s, 1H), 5.31 (s, 2H), 3.82 (s, 3H);
13C NMR (75 MHz, CDCl3): δ 162.7, 159.6, 146.7, 135.7, 128.6,
128.3, 128.1, 126.3, 104.5, 51.9, 34.3; IR (KBr): νmax 2926, 1727,
1640, 1446, 1271, 1218, 966, 769 cm−1; MS (ESI): m/z 239
(M + Na)+; HRMS-ESI (m/z): calcd for C13H12O3Na (M + Na)+:
239.0679, found: 239.0682.
Methyl 5-(4-methylbenzyl)furan-3-carboxylate (2b). 67 mg,
85%; pale yellow liquid; 1H NMR (300 MHz, CDCl3): δ 7.40
(s, 1H), 7.35–7.21 (m, 4H), 6.31 (s, 1H), 4.50 (s, 2H), 3.39 (s,
3H), 2.42 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 162.7, 147.4,
135.8, 129.2, 129.1, 128.0, 126.4, 107.9, 104.6, 51.9, 29.6, 21.2;
IR (KBr): νmax 2925, 1709, 1633, 1367, 1260, 1089, 834,
748 cm−1; MS (ESI): m/z 229 (M − H)+; HRMS-ESI (m/z): calcd
for C14H13O3 (M − H)+: 229.0859, found: 229.0856.
311.0884.
Methyl 3-acetoxy-5-(4-cyanophenyl)-2-methylenepent-4-ynoate
(1g). 0.99 g, 86%; white solid; M.P.: 78–80 °C; 1H NMR
(300 MHz, CDCl3): δ 7.66 (d, J = 6.7 Hz, 2H), 7.60 (d, J = 6.7 Hz,
2H), 7.55 (s, 1H), 7.07 (s, 1H), 6.53 (s, 1H), 3.85 (s, 3H), 2.08 (s,
3H); 13C NMR (75 MHz, CDCl3): δ 170.4, 165.3, 137.5, 132.3,
132.0, 129.2, 126.4, 118.0, 112.6, 101.1, 87.7, 59.5, 52.4, 20.7;
IR (KBr): νmax 2953, 2228, 2194, 1716, 1614, 1442, 1252, 1122,
1030, 839, 760, 554 cm−1; MS (ESI): m/z 306 (M + Na)+; HRMS
(ESI): m/z calcd for C16H13O4NNa (M + Na)+: 306.0742, found:
306.0736.
Methyl 3-acetoxy-5-(4-acetylphenyl)-2-methylenepent-4-ynoate
(1h). 1.08 g, 93%; white solid; M.P.: 74–76 °C; 1H NMR
(300 MHz, CDCl3): δ 7.90 (d, J = 8.5 Hz, 2H), 7.54 (d, J = 8.5 Hz,
2H), 6.53 (s, 2H), 6.31 (s, 1H), 3.83 (s, 3H), 2.60 (s, 3H), 2.14
(s, 3H); 13C NMR (75 MHz, CDCl3): δ 196.9, 169.0, 164.4, 136.5,
131.9, 129.0, 127.9, 124.1, 86.7, 85.9, 61.7, 59.5, 52.0, 26.3,
20.6; IR (KBr): νmax 2954, 2193, 1749, 1715, 1681, 1600, 1441,
1369, 1260, 1223, 1149, 1022, 830, 590 cm−1; MS (ESI): m/z 323
(M + Na)+; HRMS (ESI): m/z calcd for C17H16O5Na (M + Na)+:
323.0895, found: 323.0889.
(E)-Methyl 3-acetoxy-2-methylene-7-phenylhept-6-en-4-ynoate
(1j). 1.10 g, 94%; brownish liquid; 1H NMR (300 MHz, CDCl3):
δ 7.41–7.25 (m, 5H), 7.01 (d, J = 16.4 Hz, 1H), 6.51 (s, 1H), 6.47
(s, 1H), 6.29 (s, 1H), 6.20 (dd, J = 16.4, 1.8 Hz, 1H), 3.81 (s, 3H),
2.12 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 169.2, 164.8, 142.8,
136.4, 135.6, 128.9, 128.8, 128.6, 126.2, 106.6, 86.2, 85.5, 62.1,
52.0, 20.7; IR (KBr): νmax 3027, 2950, 1735, 1633, 1442, 1364,
1223, 1144, 956, 763, 694 cm−1; MS (ESI): m/z 307 (M + Na)+;
HRMS (ESI): m/z calcd for C17H16O4Na (M + Na)+: 307.0946,
found: 307.0942.
Methyl 3-acetoxy-2-methylenedec-4-ynoate (1l). 0.93 g, 78%
yellow oil; 1H NMR (300 MHz, CDCl3): δ 6.45 (s, 1H), 6.28
(s, 1H), 6.25 (s, 1H), 3.79 (s, 3H), 2.24 (t, J = 7.5 Hz, 2H), 2.09
(s, 3H), 1.57–1.47 (m, 3H), 1.41–1.29 (m, 3H), 0.96–0.81 (t, J =
1.8 Hz, 3H); 13C NMR (75 MHz, CDCl3): δ 169.3, 165.0, 136.9,
128.8, 88.6, 74.7, 62.0, 52.0, 30.9, 27.9, 22.0, 22.0, 18.6, 13.8;
IR (KBr): νmax 2956, 2903, 2236, 1747, 1639, 1438, 1368, 1268,
1226, 1132, 1019, 771 cm−1; MS (ESI): m/z 275 (M + Na)+;
HRMS-ESI (m/z): calcd for C14H20O4Na (M + Na)+: 275.1253,
found: 275.1255.
Methyl 5-(naphthalen-1-ylmethyl)furan-3-carboxylate (2c). 66 mg,
1
77%; colourless liquid; H NMR (300 MHz, CDCl3): δ 8.72 (d,
J = 7.3 Hz, 1H), 8.13 (d, J = 8.1 Hz, 1H), 7.86–7.82 (m, 1H), 7.71
(d, J = 7.9 Hz, 1H), 7.55–7.44 (m, 3H), 7.15 (t, J = 2.0 Hz, 1H),
6.37 (s, 1H), 5.33 (s, 2H), 3.85 (s, 3H); 13C NMR (75 MHz,
CDCl3): δ 163.1, 144.8, 135.1, 133.8 133.1, 131.4, 131.2, 128.6,
127.7, 126.8, 126.1, 125.6, 125.4, 125.3, 123.6, 51.5, 33.4;
IR (KBr): νmax 2924, 2853, 1627, 1459, 1099, 793, 674 cm−1
;
MS (ESI): m/z 289 (M + Na)+; HRMS-ESI (m/z): calcd for
C17H14O3Na (M + Na)+: 289.0835, found: 289.0831.
Methyl 5-(4-methoxybenzyl)furan-3-carboxylate (2d). 75 mg,
1
88%; pale yellow solid; M.P.: 101–103 °C; H NMR (300 MHz,
CDCl3): δ 7.59 (d, J = 9.0 Hz, 2H), 6.98 (s, 1H), 6.86 (dd, J = 6.7,
9.0 Hz, 2H), 5.59 (s, 1H), 5.27 (s, 2H), 3.81 (s, 6H); 13C NMR
(75 MHz, CDCl3): δ 163.7, 158.4, 156.6, 146.6, 129.6, 129.3,
113.9, 113.6, 105.9, 55.2, 51.4, 33.4; IR (KBr): νmax 2925, 2852,
1724, 1607, 1512, 1441, 1250, 1032, 837, 706 cm−1; MS (ESI):
m/z 245 (M − H)+; HRMS-ESI (m/z): calcd for C14H13O4
(M − H)+: 245.0808, found: 245.0807.
Methyl 5-(2-methoxybenzyl)furan-3-carboxylate (2e). 67 mg,
1
79%; colourless liquid; H NMR (300 MHz, CDCl3): δ 8.11 (d,
J = 7.5, Hz, 1H), 7.31–7.28 (m, 1H), 7.03 (s, 1H), 6.95 (t, J = 7.4,
Hz, 1H), 6.85 (d, J = 8.1, Hz, 1H), 6.09 (s, 1H), 5.28 (s, 2H), 3.85
(s, 3H), 3.81 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 162.8, 159.6,
155.9, 136.2, 133.6, 128.8, 127.5, 124.5, 120.6, 110.2, 97.9, 55.5,
51.9, 29.7; IR (KBr): νmax 2924, 2924, 2854, 1724, 1681, 1607,
1548, 1437, 1250, 1032, 837, 761 cm−1; MS (ESI): m/z 269
This journal is © The Royal Society of Chemistry 2014
Org. Biomol. Chem., 2014, 12, 1664–1670 | 1667

View Article Online
Paper
Organic & Biomolecular Chemistry
(M + Na)+; HRMS-ESI (m/z): calcd for C14H14O4 (M + Na)+:
269.0790, found: 269.0784.
Methyl 5-hexylfuran-3-carboxylate (2l). 56 mg, 68%; pale
yellow liquid; H NMR (300 MHz, CDCl3): δ 7.87 (s, 1H), 6.32
1
Methyl 5-(4-chlorobenzyl)furan-3-carboxylate (2f). 73 mg, (s, 1H), 3.81 (s, 3H), 2.61 (t, J = 7.3 Hz, 2H), 1.68–1.54 (m, 2H),
1
86%; pale yellow solid; M.P.: 148–150 °C; H NMR (300 MHz, 1.41–1.21(m, 6H), 0.88 (t, J = 5.8 Hz, 3H); 13C NMR (75 MHz,
CDCl3): δ 7.56 (d, J = 8.6 Hz, 2H), 7.27 (d, J = 8.6 Hz, 2H), 6.97 CDCl3): δ 158.0, 146.0, 126.5, 119.4, 104.6, 51.4, 31.4, 28.6,
(s, 1H), 5.57 (s, 1H), 5.28 (s, 2H), 3.82 (s, 3H); 13C NMR 27.8, 27.6, 22.5, 14.0; IR (KBr): νmax 2927, 2857, 1738, 1727,
(75 MHz, CDCl3): δ 162.5, 159.9, 135.4, 134.7, 134.0, 131.6, 1549, 1306, 1202, 1140, 1028, 762, 597 cm−1; MS (ESI): m/z 233
129.2, 128.4, 103.2, 77.0, 52.0; IR (KBr): νmax 2926, 2854, 1708, (M + Na)+; HRMS-ESI (m/z): calcd for C12H18O3Na (M + Na)+:
1636, 1440, 1369, 1259, 1086, 833, 741 cm−1; MS (ESI): m/z 273 233.1148, found: 233.1157.
(M + Na)+; HRMS-ESI (m/z): calcd for C13H11O3ClNa (M + Na)+:
273.0294, found: 273.0296.
Methyl 5-heptylfuran-3-carboxylate (2m). 55 mg, 66%; pale
yellow oil; H NMR (300 MHz, CDCl3): δ 7.88 (s, 1H), 6.33 (s,
1
Methyl 5-(4-cyanobenzyl)furan-3-carboxylate (2g). 71 mg, 1H), 3.82 (s, 3H), 2.62 (t, J = 7.3 Hz, 2H), 1.66–1.58 (m, 2H),
84%; pale yellow solid; M.P.: 85–87 °C; 1H NMR (300 MHz, 1.32–1.27 (m, 8H), 0.88 (t, J = 5.8 Hz, 3H); 13C NMR (75 MHz,
CDCl3): δ 7.91 (s, 1H), 7.61 (d, J = 7.9 Hz, 2H), 7.33 (d, J = CDCl3): δ 158.0, 146.0, 126.5, 119.4, 104.6, 51.4, 31.4, 29.6,
7.9 Hz, 2H), 6.41 (s, 1H), 4.03 (s, 2H), 3.82 (s, 3H); 13C NMR 28.6, 27.8, 27.6, 22.5, 14.0; IR (KBr): νmax 2930, 2861, 1734,
(75 MHz, CDCl3): δ 170.4, 137.5, 132.3, 132.0, 131.8, 129.2, 1731, 1551, 1310, 1202, 1140, 1028, 762, 597 cm−1; MS (ESI):
126.4, 123.8, 118.0, 112.6, 59.5, 52.4; IR (KBr): νmax 3029, 2924, m/z 247 (M + Na)+; HRMS-ESI (m/z): calcd for C13H20O3Na
2252, 1755, 1634, 1452, 1250, 1116, 1021, 758, 701 cm−1
;
(M + Na)+: 247.1304, found: 247.1315.
tert-Butyl 5-benzylfuran-3-carboxylate (2n). 77 mg, 90%; col-
ourless liquid; 1H NMR (300 MHz, CDCl3): δ 7.62 (d, J = 7.5 Hz,
MS (ESI): m/z 264 (M + Na)+; HRMS-ESI (m/z): calcd for
C14H11NO3 (M + Na)+: 264.0637, found: 264.0631.
Methyl 5-(4-acetylbenzyl)furan-3-carboxylate (2h). 75 mg, 2H), 7.40–7.25 (m, 2H), 7.22–7.11 (m, 1H), 6.89 (s, 1H), 5.58
1
88%; white solid; M.P.: 88–90 °C; H NMR (300 MHz, CDCl3): (s, 1H), 5.24 (s, 2H), 1.53 (s, 9H); 13C NMR (75 MHz, CDCl3):
δ 7.94–7.89 (m, 3H), 7.32 (d, J = 8.3 Hz, 2H), 6.39 (s, 1H), 4.02 δ 162.1, 144.5, 139.5, 135.2, 130.2, 128.7, 128.6, 126.7, 125.7,
(s, 2H), 3.81 (s, 3H), 2.60 (s, 3H); 13C NMR (75 MHz, CDCl3): 80.8, 36.2, 28.2; IR (KBr): νmax 2977, 2928, 1715, 1650, 1368,
δ 197.6, 163.4, 154.8, 146.8, 142.4, 135.7, 128.8, 128.6, 119.7, 1271, 1142, 838, 762 cm−1; MS (ESI): m/z 281 (M + Na)+;
106.6, 51.4, 34.1, 26.5; IR (KBr): νmax 2924, 2854, 1722, 1633, HRMS-ESI (m/z): calcd for C16H18O3Na (M + Na)+: 281.1148,
1460, 1375, 1247, 767 cm−1; MS (ESI): m/z 281 (M + Na)+; found: 281.1147.
HRMS-ESI (m/z): calcd for C15H14O4 (M + Na)+: 281.0790,
found: 281.0784.
1-(5-Benzylfuran-3-yl)ethanone (2o). 68 mg, 83%; colourless
liquid; 1H NMR (300 MHz, CDCl3): δ 7.52–7.45 (m, 2H),
Methyl 5-(thiophen-2-ylmethyl)furan-3-carboxylate (2i). 80 mg, 7.41–7.33 (m, 4H), 6.91 (s, 1H), 4.45 (s, 2H), 2.40 (s, 3H);
1
89%; white solid; M.P.: 94–96 °C; H NMR (500 MHz, CDCl3): 13C NMR (75 MHz, CDCl3): δ 192.1, 145.3, 142.2, 139.2, 131.4,
δ 7.24 (d, J = 4.9 Hz, 1H), 7.13 (d, J = 2.9 Hz, 1H), 7.02–6.98 (m, 128.5, 128.4, 126.6, 120.3, 36.1, 27.1; IR (KBr): νmax 2923, 2854,
2H), 5.98 (s, 1H), 5.31 (s, 2H), 3.82 (s, 3H); 13C NMR (75 MHz, 2192, 1669, 1601, 1445, 1228, 1106, 757, 690 696 cm−1; MS
CDCl3): δ 157.8, 146.1, 138.5, 134.3, 127.1, 125.9, 125.0, 123.6, (ESI): m/z 223 (M
98.5, 51.9, 29.7; IR (KBr): νmax 3108, 2950, 2846, 1715, 1544, C13H12O2Na (M + Na)+: 223.0735, found: 223.0731.
1462, 1260, 1234, 770 cm−1; MS (ESI): m/z 245 (M + Na)+;
2-Benzyl-6,7-dihydrobenzofuran-4(5H)-one (2p). 65 mg, 78%;
HRMS-ESI (m/z): calcd for C11H10O3SNa (M + Na)+: 245.0243, pale yellow liquid; 1H NMR (300 MHz, CDCl3): δ 7.51–7.48
found: 245.0239. (m, 2H), 7.39–7.34 (m, 3H), 6.79 (s, 1H), 3.35 (s, 2H), 2.68–2.61
+
Na)+; HRMS-ESI (m/z): calcd for
Methyl 5-cinnamylfuran-3-carboxylate (2j). 60 mg, 72%; (m, 1H), 2.35–2.28 (m, 1H), 2.25–2.18 (m, 2H), 1.85–1.77
colourless liquid; 1H NMR (300 MHz, CDCl3): δ 7.92 (s, 1H), (m, 2H); 13C NMR (75 MHz, CDCl3): δ 200.1, 150.5, 144.7,
7.42–7.25 (m, 5H), 6.50 (d, J = 16.0 Hz, 1H), 6.43 (s, 1H), 131.7, 129.3, 128.5, 122.3, 119.3, 101.9, 56.2, 39.7, 29.4, 17.7;
6.24–6.29 (m, 1H), 3.81 (s, 3H), 3.54 (d, J = 6.6 Hz, 2H); IR (KBr): νmax 2923, 2854, 2189, 1676, 1429, 1233, 1070, 751,
13C NMR (75 MHz, CDCl3): δ 163.7, 155.3, 146.6, 146.5, 136.8, 696 cm−1; MS (ESI): m/z 249 (M + Na)+; HRMS-ESI (m/z): calcd
132.6, 128.5, 127.4, 126.1, 124.3, 105.7, 51.4, 31.4; IR (KBr): for C15H14O2Na (M + Na)+: 249.0886, found: 249.0888.
νmax 2925, 1723, 1633, 1444, 1206, 1144, 763, 698 cm−1; MS
(ESI): m/z 265 (M
Na)+; HRMS-ESI (m/z): calcd for Pd(Ph3P)4 (22 mg, 0.019 mmol) was added to a solution of
C15H14O3Na (M + Na)+: 265.0841, found: 265.0842.
MBH-acetate 1a (50 mg, 0.19 mmol) in 4 mL of CH3CN and
(E)-Methyl 2-(acetoxymethyl)-5-phenylpent-2-en-4-ynoate (I).
+
Methyl 5-butylfuran-3-carboxylate (2k). 52 mg, 64%; pale the reaction mixture was stirred at room temperature for 12 h,
1
yellow liquid; H NMR (300 MHz, CDCl3): δ 7.87 (s, 1H), 6.33 then the reaction mixture was filtered through a pad of celite
(s, 1H), 3.82 (s, 3H), 2.62 (t, J = 7.5 Hz, 2H), 1.67–1.52 (m, 2H), and the filtrate was evaporated in vacuo. The residue was puri-
1.42–1.24 (m, 2H), 0.92 (t, J = 6.7 Hz, 3H); 13C NMR (75 MHz, fied by column chromatography on silica gel (EtOAc–hexanes)
CDCl3):
δ 158.2, 146.9, 146.0, 126.5, 104.6, 51.4, 29.7, to afford the product I as a pale yellow solid. 49 mg, 98%;
27.4, 22.0, 13.7; IR (KBr): νmax 2959, 2927, 1731, 1634, 1439, M.P.: 82–84 °C; 1H NMR (300 MHz, CDCl3): δ 7.05 (dd, J =
1253, 1087, 760 cm−1; MS (ESI): m/z 205 (M + Na)+; HRMS-ESI 1.5 Hz, 2H), 7.41–7.34 (m, 3H), 7.09 (s, 1H), 5.08 (s, 2H), 3.82
(m/z): calcd for C10H14O3Na (M + Na)+: 205.0841, found: (s, 3H), 2.08 (s, 3H); 13C NMR (75 MHz, CDCl3): δ 170.5, 165.7,
205.0835.
135.8, 131.9, 129.5, 128.4, 125.1, 121.8, 104.1, 84.4, 59.7, 52.2,
1668 | Org. Biomol. Chem., 2014, 12, 1664–1670
This journal is © The Royal Society of Chemistry 2014

View Article Online
Organic & Biomolecular Chemistry
Paper
20.7; IR (KBr): νmax 2951, 2924, 1716, 1605, 1439, 1367, 1259,
1147, 1017, 761 cm−1; MS (ESI): m/z 281 (M + Na)+; HRMS-ESI
(m/z): calcd for C15H14O4Na (M + Na)+: 281.0790, found:
281.0784.
p. 657; (d) J. K. Landquist, in Comprehensive Heterocyclic
Chemistry, ed. A. R. Katrizky, Pergamon Press, New York,
1984, vol. 1, p. 144; (e) B. A. Keay, Chem. Soc. Rev., 1999, 28,
209; (f) M. M. Faul and B. E. Huff, Chem. Rev., 2000, 100,
2407; (g) D. S. Mortensen, A. L. Rodriguez, K. E. Carlson,
J. Sun, B. S. Katzenellenbogen and J. A. Katzenellenbogen,
J. Med. Chem., 2001, 44, 3838.
(E)-Methyl 2-(hydroxymethyl)-5-phenylpent-2-en-4-ynoate
(II). K2CO3 (31 mg, 0.18 mmol) was added to a solution of
compound I (49 mg, 0.18 mmol) dissolved in 4 mL of MeOH
and stirred for 5 min at 0 °C. The mixture was evaporated
in vacuo and the crude was purified by column chromato-
graphy on silica gel (EtOAc–hexanes) to afford the title
compound II as a yellow solid. 40 mg, 97%; M.P.: 94–96 °C;
1H NMR (300 MHz, CDCl3): δ 7.05–7.03 (m, 2H), 7.37–7.31 (m,
3H), 6.88 (s, 1H), 4.57 (s, 2H), 3.84 (s, 3H); 13C NMR (75 MHz,
CDCl3): δ 166.8, 139.8, 131.8, 129.4, 128.4, 121.7, 103.3, 84.4,
59.7, 52.2, 29.6; IR (KBr): νmax 3451, 2951, 1742, 1716, 1605,
1439, 1367, 1259, 1147, 1017, 761 cm−1; MS (ESI): m/z 239
(M + Na)+; HRMS-ESI (m/z): calcd for C13H12O3Na (M + Na)+:
239.0679, found: 239.0682
2 For representative references, see: (a) A. Evidente,
G. Cristinzio, B. Punzo, A. Andolfi, A. Testa and D. Melck,
Chem. Biodiversity, 2009, 6, 328; (b) Y.–L. Lin, Y.–L. Tsai,
Y.-H. Kuo, Y.-H. Liu and M.–S. Shiao, J. Nat. Prod., 1999, 62,
1500; (c) D. A. Mulholland, A. Langlois, M. Randrianarivelojosia,
E. Derat and J. M. Nuzillard, Phytochem. Anal., 2006, 17, 87;
(d) A. S. Kate, I. Aubry, m. L. Tremblay and R. G. Kerr,
J. Nat. Prod., 2008, 71, 1977; (e) K. Pudhom, T. Vilaivan,
N. Ngamrojanavanich, S. Dechangvipart, D. Sommit,
A. Petsom and S. Roengsumran, J. Nat. Prod., 2007, 70,
659; (f) D. A. Barancelli, A. C. Mantovani, C. Jesse,
C. W. Nogueira and G. Zeni, J. Nat. Prod., 2009, 72, 857.
3 For selected references, see: (a) D. W. Sullins, T. A. Bobik,
R. S. Wolfe and K. L. Rinehart, J. Am. Chem. Soc., 1993, 115,
6646; (b) R. C. Anand and V. Singh, J. Nat. Prod., 1993, 56,
2207; (c) P. Franchetti, L. Cappellacci, M. Grifantini,
A. Barzi, G. Nocentini, H. Yang, A. O’Connor,
H. N. Jayaram, C. Carrell and B. M. Goldstein, J. Med.
Chem., 1995, 38, 3829; (d) D. H. Williams and
D. J. Faulkner, Tetrahedron, 1996, 52, 4245; (e) P. Franchetti,
S. Marchetti, L. Cappellacci, H. N. Jayaram, J. A. Yalowitz,
B. M. Goldstein, J.–L. Barascut, D. Dukhan, J.–L. Imbach
and M. Grifantini, J. Med. Chem., 2000, 43, 1264;
(f) J. A. Ragan, J. A. Murry, M. J. Castaldi, A. K. Conrad,
B. P. Jones, B. Li, T. W. Makowski, R. McDermott,
B. J. Sitter, T. D. White and G. Y. Young, Org. Process Res.
Dev., 2001, 5, 498; (g) A. Toró and P. Deslongchamps,
J. Org. Chem., 2003, 68, 6847.
(5-Benzylfuran-3-yl)methanol (Elliott’s alcohol, 3). To
a
stirred solution of furanoate 2a (2 g, 9.26 mmol) in CH2Cl2
(60 mL) was added DIBALH (25% w/v in toluene, 15.8 mL,
27.78 mmol) at −78 °C, and the mixture was stirred at the
same temperature for 1 h. The mixture was warmed to 0 °C,
quenched with aqueous saturated sodium potassium tartarate
(30 mL), and the mixture was stirred for 3 h. The aqueous
phase was extracted with ethyl acetate (2 × 20 mL). The com-
bined organic layer was washed with brine (40 mL), dried over
Na2SO4, and evaporated the organic solvent under reduced
pressure. The crude residue was purified by flash column
chromatography (silica gel, hexanes–EtOAc = 90 : 10) to give 3
1
(1.65 g, 95%) as a pale yellow oil; H NMR (300 MHz, CDCl3):
δ 7.58 (d, J = 7.5 Hz, 1H), 7.30–7.21 (m, 3H), 7.18–7.05 (m, 2H),
5.13 (s, 1H), 5.12 (s, 2H), 4.40 (s, 2H); 13C NMR (75 MHz,
CDCl3): δ 155.6, 138.7, 137.7, 131.3, 128.6, 128.4, 126.5, 106.4,
56.7, 34.5; IR (KBr): νmax 3387, 2924, 1755, 1629, 1493, 1451,
1384, 1017, 701, 562 cm−1; MS (ESI): m/z 211 (M + Na)+;
HRMS-ESI (m/z): calcd for C12H12O2Na (M + Na)+: 211.0735,
found 211.0735.
4 (a) M. G. Ford and D. R. Pert, Pestic. Sci., 1974, 5, 635;
(b) T. B. Gaines and R. E. Linder, Fundam. Appl. Toxicol.,
1986, 7, 299; (c) United Nations FADINAP (2002) Agro-
chemical Reports 2: 29.
5 For selected references, see: From alkyne-diols: (a) A. Blanc,
K. Tenbrink, J.-M. Weibel and P. Pale, J. Org. Chem., 2009,
74, 5342; (b) A. Aponick, C.-Y. Li, J. Malinge and
E. F. Marques, Org. Lett., 2009, 11, 4624; (c) M. Egi,
K. Azechi and S. Akai, Org. Lett., 2009, 11, 5002;
(d) B. Gabriele, L. Veltri, P. Plastina, R. Mancuso,
M. V. Vetere and V. Maltese, J. Org. Chem., 2013, 78, 4919;
From other alkyne-based strategies: (e) P. A. Allegretti
and E. M. Ferreira, Org. Lett., 2011, 13, 5924;
(f) A. S. K. Hashmi, T. Haffner, M. Rudolph and
F. Rominger, Eur. J. Org. Chem., 2011, 667; (g) S. Kramer
and T. Skrydstrup, Angew. Chem., Int. Ed., 2012, 51, 4681;
(h) C. He, S. Guo, J. Ke, J. Hao, H. Xu, H. Chen and A. Lei,
J. Am. Chem. Soc., 2012, 134, 5766; (i) J. S. Clark, A. Boyer,
A. Aimon, P. E. Garcia, D. M. Lindsay, A. D. F. Symington
and Y. Danoy, Angew. Chem., Int. Ed., 2012, 51, 12128;
( j) J. Gonzalez, J. Gonzalez, C. Perez-Calleja, L. A. Lopez
Acknowledgements
GK and MDR thank the Council of Scientific and Industrial
Research, New Delhi for the award of fellowships. CRR is
thankful to the Department of Science and Technology,
New Delhi for funding the project (SR/S1/OC-66/2011).
Notes and references
1 For representative references, see: (a) F. M. Dean, Naturally
Occurring Oxygen Ring Compounds, Butterworths, London,
1963, vol. 1; (b) M. G. Missakian, B. J. Burresons and
P. J. Scheuer, Tetrahedron, 1975, 31, 2513; (c) D. M. X. Donnelly
and M. J. Meegan, in Comprehensive Heterocyclic Chemistry,
ed. A. R. Katrizky, Pergamon Press, New York, 1984, vol. 4,
This journal is © The Royal Society of Chemistry 2014
Org. Biomol. Chem., 2014, 12, 1664–1670 | 1669

View Article Online
Paper
Organic & Biomolecular Chemistry
and R. Vicente, Angew. Chem., Int. Ed., 2013, 52, 1;
(k) H. Cao, H. Zhan, J. Cen, J. Lin, Y. Lin, Q. Zhu, M. Fu
Org. Biomol. Chem., 2012, 10, 9052; (d) C R Reddy,
R. R. Valleti and M. D. Reddy, J. Org. Chem., 2013, 78, 6495.
and H. Jiang, Org. Lett., 2013, 15, 1080; (l) H. Zhan, X. Lin, 11 Synthesis of fully substituted furan was accomplished
Y. Qiu, Z. Du, P. Li, Y. Li and H. Cao, Eur. J. Org. Chem.,
2013, 2284; Miscellaneous methods: (m) J. Fournier,
S. Arseniyadis and J. Cossy, Angew. Chem., Int. Ed., 2012, 51,
from an MBH-adduct in four steps. See: K. Y. Lee,
S. Gowrisankar, Y. J. Lee and J. N. Kim, Tetrahedron, 2006,
62, 8798.
7562; (n) A. N. Butkevich, L. Meerpoel, I. Stansfield, 12 J. Park, R. Heo, J.-Y. Kim, B. W. Yoo and C. M. Yoon, Bull.
P. Angibaud, A. Corbu and J. Cossy, Org. Lett., 2013, 15, Korean Chem. Soc., 2009, 30, 1195.
3840; (o) M. Zheng, L. Huang, W. Wu and H. Jiang, Org. 13 (a) W. G. Galesloot, L. Brandsma and J. F. Arens, Recl. Trav.
Lett., 2013, 15, 1838.
Chim. Pays-Bas, 1969, 88, 671; (b) D. Vegh, P. Zalupsky and
J. Kovac, Synth. Commun., 1990, 20, 1113; (c) J. A. Marshall
and W. J. DuBay, J. Org. Chem., 1993, 58, 3435;
(d) J. A. Marshall and W. J. DuBay, J. Org. Chem., 1994, 59,
1703; (e) B. Seiller, C. Bruneau and P. H. Dixneuf, J. Chem.
Soc., Chem. Commun., 1994, 493; (f) B. Seiller, C. Bruneau
and P. H. Dixneuf, Tetrahedron, 1995, 51, 13089;
(g) B. Gabriele and G. Salerno, Chem. Commun., 1997, 1083;
(h) B. Gabriele, G. Salerno and E. Lauria, J. Org. Chem.,
1999, 64, 7687; (i) F.-L. Qing and W.-Z. Gao, Tetrahedron
Lett., 2000, 41, 7727; ( j) A. S. K. Hashmi, L. Schwarz,
J.-H. Choi and T. M. Frost, Angew. Chem., Int. Ed., 2000, 39,
2285; (k) Y. Liu, F. Song, Z. Song, M. Liu and B. Yan, Org.
Lett., 2005, 7, 5409; (l) A. E. Diaz-alvarez, P. Crochet,
M. Zablocka, C. Duhayon, V. Cadierno, J. Gimeno and
J. P. Majoral, Adv. Synth. Catal., 2006, 348, 1671;
(m) P. Pierluigi, G. Bartolo and S. Giuseppe, Synthesis,
2007, 3083; (n) X. Du, H. Chen and Y. Liu, Chem.–Eur. J.,
2008, 14, 9495; (o) X. Du, F. Song, Y. Lu, H. Chen and
Y. Liu, Tetrahedron, 2009, 65, 1839; (p) J. Francos and
V. Cadierno, Green Chem., 2010, 12, 1552; (q) X. Zhang,
Z. Lu, C. Fu and S. Ma, J. Org. Chem., 2010, 75, 2589;
(r) C. C. Schneider, H. Caldeira, B. M. Gay, D. F. Back and
G. Zeni, Org. Lett., 2010, 12, 936; (s) A. S. K. Hashmi,
T. Haffner, M. Rudolph and F. Rominger, Chem.–Eur. J.,
2011, 17, 8195.
6 For selected references, see: (a) S. Divald, M. C. Chun and
M. M. Joullie, J. Org. Chem., 1976, 41, 2835; (b) B. Glover,
K. A. Harvey, B. Liu, M. J. Sharp and M. F. Tymoschenko,
Org. Lett., 2003, 5, 301; (c) F. Brucoli, A. Natoli,
P. Marimuthu, M. T. Borrello, P. Stapleton, S. Gibbons and
A. Schätzlein, Bioorg. Med. Chem., 2012, 20, 2019;
(d) B. Ball, A. Boyd, G. Churchill, M. Cuthbert, M. Drew,
M. Fielding, G. Ford, L. Frodsham, M. Golden, K. Leslie,
S. Lyons, B. McKeever-Abbas, A. Stark and P. Tomlin, Org.
Process Res. Dev., 2012, 16, 741.
7 (a) M. Elliott’s, N. F. Janes and B. C. Pearson, J. Chem.
Soc. C, 1971, 2551; (b) C.-K. Jung, J.-C. Wang and
M. J. Krische, J. Am. Chem. Soc., 2004, 126, 4118;
(c) H. Yoshiyuki, I. Tomoe and A. Toyohiko, Synthesis, 2004,
1359; (d) T. Ken-Ichi, H. Yuji, O. Yasushi, S. Satoshi and
I. Yasutaka, J. Org. Chem., 2007, 72, 8820; (e) E. Li, W. Yao,
X. Xie, C. Wang, Y. Shao and Y. Li, Org. Biomol. Chem.,
2012, 10, 2960; (f) X. Cui, X. Xu, L. Wojtas, M. M. Kim and
X. P. Zhang, J. Am. Chem. Soc., 2012, 134, 19981; (g) X. Huang,
B. Peng, M. Luparia, L. F. R. Gomes, L. F. Veiros and
N. Maulide, Angew. Chem., Int. Ed., 2012, 51, 8886.
8 For reviews, see: (a) D. Basavaiah, A. J. Rao and
T. Satyanarayana, Chem. Rev., 2003, 103, 811; (b) K. Y. Lee,
S. Gowrisankar and J. N. Kim, Bull Korean Chem. Soc., 2005,
1481; (c) Y. L. Shi and M. Shi, Eur. J. Org. Chem., 2007,
2905; (d) V. Singh and S. Batra, Tetrahedron, 2008, 64, 4511; 14 (a) M. Elliott, A. W. Farnham, N. F. Janes, P. H. Needham
(e) V. Declerck, J. Martinez and F. Lamaty, Chem. Rev., 2009,
109, 1; (f) D. Basavaiah and E. D. V. Lenin, Eur. J. Org.
and B. C. Pearson, Nature, 1967, 213, 493; (b) M. Elliott,
Chem. Ind., 1969, 776.
Chem., 2010, 5650; (g) D. Basavaiah, B. S. Reddy and 15 (a) K. Naumann, Synthetic Pyrethroid Insectides: Chemistry
S. S. Badsara, Chem. Rev., 2010, 110, 5447.
and Patents, in Chemistry of Plant Protection, ed. W. S. Bowers,
W. Ebing, D. Martin and R. Wegler, Springer-Verlag, Berlin,
1990, vol. 5, p. 112; (b) E. Michael and J. N. Frank, US Pat,
3 466 304, 1969; (c) T. Hans and B. Rainer, EP Pat, 0 187 345,
1986; T. Hans and B. Rainer, US Pat, 4 954 633, 1990.
9 (a) K. Morita, Z. Suzuki and H. Hirose, Bull. Chem. Soc.
Jpn., 1968, 41, 2815; (b) A. B. Baylis and M. E. D. Hillman,
German Patent, 2155113, 1972.A. B. Baylis and
M. E. D. Hillman, Chem. Abstr., 1972, 77, 34174.
10 (a) C. R. Reddy, M. D. Reddy, B. Srikanth and K. R. Prasad, 16 G. Rosini, V. Borzatta, C. Paoluccia and P. Righi, Green
Org. Biomol. Chem., 2011, 9, 6027; (b) C. R. Reddy, Chem., 2008, 10, 1146.
M. D. Reddy and B. Srikanth, Org. Biomol. Chem., 2012, 10, 17 S. P. Park, S. H. Ahn and K. J. Lee, Tetrahedron, 2010, 66,
4280; (c) C. R. Reddy, P. Kumaraswamy and M. D. Reddy, 3490.
1670 | Org. Biomol. Chem., 2014, 12, 1664–1670
This journal is © The Royal Society of Chemistry 2014