Synthesis of chalcones and flavanones using Julia-Kocienski olefination

Article abstract of DOI:10.1016/j.tet.2010.09.089

A new application of Julia-Kocienski olefination for the synthesis of chalcones and flavanones has been described. 2-(Benzo[d]thiazol-2-ylsulfonyl)-1- phenylethanones have been developed as new reagents for direct Julia-Kocienski olefination with aldehydes in the presence of a base, afforded chalcones in good to excellent yields. Whereas, 2-(benzo[d]thiazol-2-ylsulfonyl)-1-(2- hydroxyphenyl)ethanone reacted with the aromatic aldehydes to furnish flavanones in good yields via one-pot intra-molecular cyclization.

Full text of DOI:10.1016/j.tet.2010.09.089

Tetrahedron 66 (2010) 9445e9449
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis of chalcones and flavanones using JuliaeKocienski olefination
*
Atul Kumar , Siddharth Sharma, Vishwa Deepak Tripathi, Suman Srivastava
Medicinal and Process Chemistry Division, Central Drug Research Institute, CSIR, Lucknow 226001, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 20 July 2010
Received in revised form 30 August 2010
Accepted 27 September 2010
Available online 1 October 2010
A new application of JuliaeKocienski olefination for the synthesis of chalcones and flavanones has been
described. 2-(Benzo[d]thiazol-2-ylsulfonyl)-1-phenylethanones have been developed as new reagents
for direct JuliaeKocienski olefination with aldehydes in the presence of a base, afforded chalcones in
good to excellent yields. Whereas, 2-(benzo[d]thiazol-2-ylsulfonyl)-1-(2-hydroxyphenyl)ethanone re-
acted with the aromatic aldehydes to furnish flavanones in good yields via one-pot intra-molecular
cyclization.
Keywords:
Chalcone
Ó 2010 Elsevier Ltd. All rights reserved.
Flavanones
JuliaeKocienski olefination
1. Introduction
Chalcones are generally synthesized by the ClaiseneSchmidt
reaction but very often reaction led to the complex mixture, which
The carbonecarbon double bonds formation is an important re-
action of organic chemistry. Thus, a variety of approaches for the
synthesis of olefins have been developed attempting to address their
regio and stereochemical demands from time to time.1 Wittig,2
Johnson,3 Peterson,4 WadswortheEmmons,5 and Julia6 olefination
reactions are the most familiar methods for the synthesis of olefins.
Among these methodologies Julia olefination has an important
place. The classical Julia7 olefination is based on a two-step reductive
is tedious to separate.30 Although there are several methods
available for the synthesis of chalcones but most of them have some
limitation.31 Recently, Buszek et al. have also reported synthesis of
chalcones from N-vinlypyridinium tetrafluoroborate salt as new
class of electrophilic coupling partner via Suzuki reaction.32 We
wish to report here a new application for JuliaeKocienski olefina-
tion via the condensation of new Julia coupling partners with al-
dehyde for the synthesis of conjugated enones (Fig. 1).
elimination process of b
-acyloxy aryl sulfones. The modified Julia8
reaction also known as JuliaeKocienski olefination, which involves
direct coupling of heteroarylsulfones with carbonyl compounds in
a single step protocol. Since its discovery, the versatility of Julia re-
action has been proved by its application in the synthesis of bi-
ologically active natural products9 and emerging as a powerful tool
for the synthesis of olefins. Recently JuliaeKocienski olefination has
been utilized for the synthesis of simple olefines,10,11 alkenyl ha-
lides,12 fluoroalkenoate,13 methylenation of ketones,14 vinyl ethers,15
2. Results and discussion
Initially our focus was on to the synthesis of efficient Julia cou-
pling partners. Recently Jùrgensen et al. synthesized
b-keto het-
erocyclic sulfone for the enantioselective conjugate addition to
enones via a Smiles rearrangement, which inspired us to evaluate
the efficacy of heterocyclic sulfone directly into the JuliaeKocienski
reaction for the synthesis of chalcones and flavanones.33 Therefore,
some commonly used starting material such as 2-mercaptobenzo-
thiazole, pyridine-2-thiol,1-phenyl-1H-tetrazole-5-thiol, and 3,5-bis
(trifluoromethyl)benzenethiol were converted in to the Julia re-
agents34 1aed via the reaction of phenacyl bromide, followed by the
oxidation with meta-chloroperbenzoic acid (m-CPBA) (Scheme 1).
Heteroaryl-sulfonyl phenylethanones 1aed were used as coupling
reagents for the JuliaeKocienski olefination of aldehydes, resulting
in the formation of 1,3-diphenyl-2-propen-1-one 3a.
a,b
-unsaturated esters and amides, respectively.16,17 A careful survey
of the literature revealed that JuliaeKocienski olefination has not
been applied for the synthesis of
-unsaturated ketones.18 Chal-
a,b
cones belong to flavanoid family, have exhibited an impressive array
of biological activities, such as anti-malarial,19 anti-cancer,20 anti-
tuberculosis,21 anti-mitotic,22 cardiovascular,23 anti-leishmanial.24
Besides, this conjugated enones system is also a key precursor in
the synthesis of many biologically important heterocycles such as
benzothiazepine,26 pyrazolines,27 1,4-diketones,28 and flavones.29
In our attempt to find an efficient base for the JuliaeKocienski
olefination, benzaldehyde was taken as a model and reacted with
different coupling reagents 1aed. Several bases were used such as
DBU, LiHMDS, P4-t-Bu, t-BuOK, and DABCO to optimize the reaction
* Corresponding author. Tel.: þ91 522 2612411; fax: þ91 522 26233405/2623938;
e-mail address: dratulsax@gmail.com (A. Kumar).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.09.089

9446
A. Kumar et al. / Tetrahedron 66 (2010) 9445e9449
Table 1
Screening of base for the coupling of benzaldehyde and sulfones 1aeda
O
O
O2
S
PhCHO
base
Ph
Ph
Ph
Act
3a
Entry
Act-
Base
Time/h
Yieldc
Z/Ed (%)
1
2
3
4
1a
1b
1c
1d
1a
1b
1c
1d
1a
1b
1c
1d
1a
1a
LiHMDS
LiHMDS
LiHMDS
LiHMDS
P4-t-Bu
P4-t-Bu
P4-t-Bu
P4-t-Bu
DBU
DBU
DBU
DBU
t-BuOK
DABCO
14
18
18
d
36
23
Trace
d
2:98
d
d
d
5b
6b
7b
8b
9
16
19
19
d
37
26
12
d
5:95
d
d
d
16
16
24
24
d
81
79
37
<10
0
1:99
1:99
d
10
11
12
13
14
d
d
d
0
d
a
Reaction carried out in THF and sulfone (1.8 equiv), and base (1.5 equiv).
b
c
Reaction analyzed at 0 ꢁC.
Isolated yields.
d
Analyzed by 1H NMR.
Solvent effect on Julia-Kocienski olefination
100
80
60
40
20
0
Fig. 1. New application of JuliaeKocienski olefination.
THF
DCM
CHCl3
Solvents
CH3CN
MeOH
Fig. 2. Solvent effects on Julia olefination.
stabilized by carbonyl group at
a
-position as well as relatively high
stability at lower temperature of the sulfonyl anion limits its re-
activity. Thus it can be concluded that modified Julia reaction leads
to predominant formation of E-chalcones (Scheme 2).
Scheme 1. Synthesis of Julia coupling partners.
condition. Julia reagent (1a) was found to be most efficient Julia
coupling reagent from all the coupling reagents (1aed) used for the
synthesis of conjugated enones in the presence of DBU.
It is noteworthy that Julia activators 1a and 1b exhibited better
results in comparison to other coupling reagents (1c, 1d) with base
such as DBU, LiHMDS, and P4-t-Bu. Whereas, all the used bases such
as DBU, LiHMDS, and P4-t-Bu were found unsuitable for the re-
action with coupling reagent 1d. The efficacy of t-BuOK and DABCO
were not sufficient enough to push the reaction even with 1a. DBU
was found to be most efficient base among all the bases used. The
results of coupling reagents and base optimization are summarized
in Table 1.
Scheme 2. Effect of the temperature on JuliaeKocienski olefination.
The scope of the modified Julia olefination was examined for the
synthesis of series of E-enones via the two Julia activators (1a and
The solvent effect on the Julia coupling of benzaldehyde with
coupling partner 1a was studied and solvents such as DCM, CHCl3,
THF, CH3CN, and methanol were used to optimize the reaction.
Non-polar solvents were proved to be better in comparison of polar
solvents and the study revealed interesting correlation between
solvent polarity and yield (Fig. 2).
To explore the effect of temperature on the selectivity, we car-
ried out reaction of BT-sulfone 1a and benzaldehyde at ꢀ78 ꢁC. No
significant effect was observed of low temperature and still the E
product was the major diastereomer. Reaction yield was also de-
creased significantly at ꢀ78 ꢁC. Formation of anion, which might be
1b) (Table 2). The reaction of a-phenacyl sulfones with O/N-acyl-
ated benzaldehyde, and indole-3-carboxaldehyde resulted to the
synthesis of functionalized chalcones in high yields. These chal-
cones are generally not accessible by conventional KOH/NaOH
mediated synthesis (Scheme 3).31
Recently, Alonso et al. explained the stereoselectivity of olefins
interestingly involves enolates. The stereoselectivity of chalcones
can be explained by Newman projection (Scheme 4). There are two
possible intermediate states (5a and 5b). The Newman projection
of the intermediate state 5a reveals that it is highly unstable due
to a steric repulsion between the two aryl groups thus, the

A. Kumar et al. / Tetrahedron 66 (2010) 9445e9449
Table 2 (continued)
9447
Table 2
DBU mediated synthesis of E-enones by the coupling of BT-sulfones and benzalde-
Entry
23
R1
Act-
Productc,d
Yieldb
hyde derivatives in THFa
O
O
1a
3l
78
64
O
O
S
Fe
O
R1
DBU
THF
OHC R1
Act
R2
H
24
1b
3l
R2
1a, 1b, 2a, 2b
R1
Act-
Productc,d
Yieldb
25
26
2a
2b
3m
3m
69
43
Entry
1
HN
1a
1b
3a
81
74
2
3a
27
28
2a
2b
3n
3n
76
64
3
4
1a
1b
3b
3b
84
69
MeO
MeO
29
30
2a
2b
3o
3o
79
69
5
1a
1b
3c
3c
86
75
Cl
O
6
31
2a
2b
3p
3p
81
80
MeO
7
8
1a
1b
3d
3d
77
59
32
a
Reaction conditions: BT-sulfone (1.8 equiv), benzaldehyde (1 equiv), DBU
(1.5 equiv), and time for the completion of reaction varies from 13 to 21 h.
F
b
Isolated yield.
c
All compounds characterized by mass, IR, 1H NMR, 13C NMR.
d
Z/E ratio for all the products was >1:99% and determined by 1H NMR/HPLC
9
1a
1b
3e
3e
63
71
analysis.
10
11
12
1a
1b
3f
3f
88
82
13
14
1a
1b
3g
3g
74
63
Cl
Scheme 3. Plausible mechanism for the synthesis of enones.
15
16
1a
1b
3h
3h
67
24
HN
17
18
1a
1b
3i
3i
66
nd
AcHN
AcO
19
20
1a
1b
3j
3j
74
nd
Scheme 4. Possible intermediates of the modified Julia olefination.
intermediate 5a is less favorable. On the other hand the reaction
proceeds via more stable intermediate 5b resulting to the forma-
tion of E-conjugated enones in >99% stereoselectivity.
The versatility of developed Julia activators was utilized for the
synthesis of flavanones via one-pot coupling reaction. 2-(Benzo[d]
21
22
1a
1b
3k
3k
73
46

9448
A. Kumar et al. / Tetrahedron 66 (2010) 9445e9449
thiazol-2-ylsulfonyl)-1-(2-hydroxyphenyl)ethanone (6) was reac-
ted with benzaldehyde in the presence of DBU to furnish flavanones
in moderate yield at refluxing condition, although corresponding
chalcone was also formed as a side product (Scheme 5, Table 3).
acetate. Ethyl acetate layer was dried, and evaporated under vac-
uum to give title compound as light yellow solid, Rf¼0.33 (EtOAc/
hexane 1:4, v/v), which was further recrystallized by methanol in
96% yield.
4.2.1.1. (Benzo[d]thiazol-2-ylsulfonyl)(phenyl)methanone
(1a)33. Physical state: solid, Rf¼0.33 (EtOAc/hexane 1:4, v/v).
Found: C, 56.73, H, 3.76, N, 4.53. C15H11NO3S2 requires C, 56.76; H,
O
O
O
O
S
CHO
N
3.49; N, 4.41%; IR (KBr) 2942, 1722, 1698, 1363 cmꢀ1 1H NMR
;
DBU
THF
OH
S
O
(300 MHz, CDCl3) 5.1 (2H, s, CH2CO), 7.37e7.58 (5H, m), 7.85e7.95
(3H, m), 8.09 (1H, d, J 7.41 Hz); 13C NMR (75 MHz, CDCl3) 61.68,
123.64, 125.22, 128.25, 128.56, 129.17, 129.38, 134.82, 135.71, 136.83,
152.32, 188.75; MS (ES): m/z (%)¼318.1(100) [Mþ1]þ.
R1
R1
7a-7d
6
Scheme 5. One-pot synthesis of flavanone.
4.2.1.2. 2-(Benzo[d]thiazol-2-ylsulfonyl)-1-(4-methoxyphenyl)
ethanone (2a)33. Physical state: solid, Rf¼0.15 (EtOAc/hexane 1:4,
v/v). Found: C, 55.26; H, 3.62; N, 3.92. C16H13NO4S2 requires C,
Table 3
One-pot synthesis of flavanones based on JuliaeKocienski olefinationa
55.32; H, 3.77; N, 4.03%; IR (KBr) 2941, 1719, 1534, 1326 cmꢀ1 1H
;
Entryc
R1
Product
Time (h)
Yieldb (%)
NMR (300 MHz, CDCl3) 3.91 (3H, s, OCH3), 5.26 (2H, s, CH2CO), 7.11
(2H, d, J 8.73 Hz), 7.31e7.42 (2H, m), 7.78 (2H, d, J 7.91 Hz), 8.03 (1H,
d, J 7.77 Hz), 8.09 (2H, d, J 8.73 Hz); 13C NMR (75 MHz, CDCl3) 55.48,
61.67, 121.39, 124.16, 128.22, 128.56, 129.02, 129.38, 134.77, 135.71,
136.81, 153.78, 184.73; MS (ES): m/z (%)¼348 (100) [Mþ1]þ.
1
2
3
4
H
7a
7b
7c
7d
13
11
18
16
62
68
40
65
OCH3
OH
Br
a
Reaction conditions: BT-sulfone (1.8 equiv), benzaldehyde (1 equiv), DBU
(1.5 equiv), and time for the completion of reaction varies from 11e18 h at refluxing
condition.
b
4.2.1.3. 1-Phenyl-2-(1-phenyl-1H-tetrazole-5-sulfonyl)-ethanone
(1b). Physical state: yellow solid, Rf¼0.25 (EtOAc/hexane 3:7, v/v).
Found: C, 54.86; H, 3.62; N, 16.86. C15H12N4O3S requires C, 54.87; H,
3.68; N, 17.06%; IR (KBr) 3104, 3041, 2975, 1721, 1363, 879 cmꢀ1; 1H
NMR (300 MHz, CDCl3) 5.25 (2H, s), 7.43e7.47 (2H, m), 7.51e7.65
(6H, m), 7.81e7.82 (2H, m); 13C NMR (75 MHz, CDCl3) 62.48, 125.92,
128.94, 129.47, 129.85, 130.48, 131.81, 134.11, 135.34, 153.82, 187.26;
MS (ES): m/z (%)¼329 (100) [Mþ1]þ.
Isolated yield.
c
All compounds characterized by 1H NMR.
In continuation to our antidiabetic drug discovery program,35
some of newly developed Julia reagents were exhibiting promis-
ing anti-hyperglycemic activity and detail studies are in progress.
3. Conclusion
4.2.1.4. 1-(4-Methoxyphenyl)-2-(1-phenyl-1H-tetrazol-5-ylsul-
fonyl)ethanone (2b). Physical state: yellow solid, Rf¼0.17 (EtOAc/
hexane 3:7, v/v). Found: C, 53.62; H, 3.94; N, 15.63. C16H14N4O4S
requires C 53.59; H, 3.92; N, 16.87%; IR (KBr) 3098, 3041, 2972, 1711,
In summary, for the first time, we have demonstrated an ap-
plication of JuliaeKocienski olefination reaction leading to the
synthesis of chalcones and flavanones in high yields. We have also
successfully developed new Julia coupling reagents for direct
JuliaeKocienski olefination.
1365 cmꢀ1 1H NMR (300 MHz, CDCl3) 3.84 (3H, s), 5.25 (2H s),
;
7.21e7.25 (2H, m), 7.50e7.65(6H, m), 7.87e7.89(2H, m); 13C NMR
(75 MHz, CDCl3) 55.47, 62.43, 123.41, 128.26, 129.44, 129.38, 130.41,
131.54, 133.76, 138.54, 156.67, 186.83; MS (ES): m/z (%)¼359 (100)
[Mþ1]þ.
4. Experimental
4.1. Materials and general
4.2.1.5. 1-Phenyl-2-(pyridin-2-ylsulfonyl)ethanone (1c). Physical
state: light yellow solid, Rf¼0.22 (EtOAc/hexane 1.5:4, v/v). Found:
C, 59.73; H, 3.96; N, 5.13. C13H11NO3S requires C, 59.76; H, 4.24; N,
All the reactions were carried out at room temperature, that is,
28e32 ꢁC. Unless otherwise specified, all the reagents were pur-
chased from SigmaeAldrich Chemical Co., Lancaster and were used
directly without further any purification. NMR spectra were
obtained using the Brucker DRX 200 and 300 MHz spectrometers.
5.36%; IR (KBr) 1722, 1698, 1542, 1354, 789 cmꢀ1
;
1H NMR
(300 MHz, CDCl3) 5.32 (2H, s, CH2CO), 7.49e7.74 (5H, m), 7.92e8.37
(5H, m); 13C NMR (75 MHz, CDCl3) 64.37, 122.65, 127.24, 128.45,
128.89, 133.56, 136.72, 136.83, 154.37, 158.63, 188.75; MS (ES): m/z
(%)¼362 (100) [Mþ1]þ.
Chemical shifts (d) are given in parts per million relative to TMS,
coupling constants (J) in hertz. IR spectra were taken on VARIAN FT-
IR spectrometer as KBr pellets (when solid). Elemental analysis was
preformed using a Perkin Elmer Autosystem XL Analyzer. Melting
points were measured using a COMPLAB melting-point apparatus.
Reactions were monitored by thin-layer chromatography (TLC)
carried out on 0.25 mm silica gel plates visualized with UV light.
4.2.1.6. 2-(3,5-Bis(trifluoromethyl)phenylsulfonyl)-1-phenyl-
ethanone (1d). Physical state: white solid, Rf¼0.30 (EtOAc/hexane
3:7, v/v). Found: C, 48.38, H, 2.45. C16H10F6O3S requires C, 48.49; H,
2.54%; IR (KBr) 2984, 2936, 1667, 1354, 1287, 821 cmꢀ1 1H NMR
;
(300 MHz, CDCl3) 5.28 (2H, s, CH2CO), 7.49 (2H, d, J 8.55 Hz), 7.82
(1H, m), 7.91(2H, d, J 8.55 Hz), 8.18 (1H, s), 8.41 (2H, s); 13C NMR
(75 MHz, CDCl3) 63.33, 122.65 (q, J 274.5 Hz, 2CF3), 127.4, 128.25,
129.76, 129.38, 133.0 (q, JCeF¼35.2 Hz, 2CCF3), 133.56, 136.72,
136.83, 140.3, 187.05; MS (ES): m/z (%)¼397 (100) [Mþ1]þ.
4.2. General procedure
4.2.1. 2-(Benzo[d]thiazol-2-ylsulfonyl)-1-phenylethanone (1a)33. Benzo
[d]thiazol-2-yl benzothioate (1 mmol) in 15 mL DCM was taken in
100 mL round bottom flask and m-CPBA (2.5 equiv) in DCM (25 mL)
was taken into dropping funnel and added drop wise into solution
of benzo[d]thiazol-2-yl benzothioate in THF. Reaction mixture was
diluted with sodium bicarbonate solution and extracted by ethyl
4.2.2. Synthesis of 1,3-diphenyl-2-propen-1-one (3a) by JuliaeKocienski
olefination reaction. (Benzo[d]thiazol-2-ylsulfonyl)(phenyl)meth-
anone 1 mmol (1.8 equiv) was taken in 50 mL round bottom flask in
10 mL THF, then DBU (1.5 equiv) was added and reaction mixture

A. Kumar et al. / Tetrahedron 66 (2010) 9445e9449
9449
10. Bellingham, R.; Jarowicki, K.; Kocienski, P. J.; Martin, V. Synthesis 1996, 285.
was stirred about half an hour. Benzaldehyde (1 mmol) was added
to the reaction mixture and further stirred the solution for about
16 h. THF was evaporated under reduced pressure and extracted by
ethyl acetate. Ethyl acetate layer was dried, and evaporated under
vacuum to give light yellow solid, Rf¼0.54 (EtOAc/hexane 15:85,
v/v), which was further recrystallized by ethanol. Organic layer was
washed with water, brine (20 mL) solution, and evaporated under
vacuum to give desired crude product, which, further purified by
column chromatography. Yield (81%).
11. Smith, N. D.; Kocienski, P. J.; Street, S. D. Synthesis 1996, 652.
12. (a) Lebrun, M.; Marquand, P. L.; Berthelette, C. J. Org. Chem. 2006, 71, 2009; (b)
Baudin, J. B.; Hareau, G.; Julia, S. A.; Lorne, R.; Ruel, O. Bull. Soc. Chim. Fr. 1993,
130, 856; (c) Ghosh, A. K.; Zajc, B. Org. Lett. 2006, 8, 1553.
13. (a) Chevrie, D.; Lequeux, T.; Demoute, J. P.; Pazenok, S. Tetrahedron Lett. 2003,
44, 8127; (b) Zajc, B.; Kake, S. Org. Lett. 2006, 8, 4457; (c) He, M,; Gosh, A. K.;
Zajc, B. Synlett 2008, 999; (d) Pfund, E.; Lebargy, C.; Rouden, J.; Lequeux, T.
J. Org. Chem. 2007, 72, 7871.
ꢀ
14. (a) Alonso, D. A.; Fuensanta, M.; Najera, C.; Varea, M. J. Org. Chem. 2005, 70,
€
6404; (b) Aõssa, C. J. Org. Chem. 2006, 71, 360.
15. Surprenant, S.; Chan, W. Y.; Berthelette, C. Org. Lett. 2003, 5, 4851.
16. (a) Manjunath, B. N.; Sane, N. P.; Aidhen, I. S. Eur. J. Org. Chem. 2006, 2851; (b)
Mirk, D.; Grassot, J. M.; Zhu, J. Synlett 2006, 1255; (c) Alonso, D. A.; Fuensanta,
Acknowledgements
ꢀ
ꢀ
M.; Gomez-Bengoa, E.; Najera, C. Eur. J. Org. Chem. 2008, 2915; (d) Blakemore, P.
R.; Ho, D. K. H.; Nep, W. M. Org. Biomol. Chem. 2005, 3, 1365.
ꢀ
ꢀ
17. Alonso, D. A.; Fuensanta, M.; Gomez-Bengoa, E.; Najera, C. Adv. Synth. Catal.
2008, 1823.
S.S, V.D.T, and S.S are thankful to CSIR New Delhi for financial
support in the form of SRF. The authors also acknowledge SAIF-
CDRI for providing analytical and spectral data. CDRI communica-
tion Number is 7640.
€
18. Aõssa, C. Eur. J. Org. Chem. 2009, 12, 1831.
19. Esteruelas, M. A.; Oro, L. A. Chem. Rev. 1998, 98, 577.
20. Zassinovich, G.; Mestroni, G.; Gladiali, S. Chem. Rev. 1992, 92, 1051.
21. Suwa, T.; Sugiyama, E.; Shibata, I.; Baba, A. Synlett 2000, 556.
22. Yang, J. W.; Fonseca, M. T. H.; List, B. Angew. Chem., Int. Ed. 2005, 44, 108.
23. Ramachary, D. B.; Kishor, M.; Ramakumar, K. Tetrahedron Lett. 2006, 47, 651.
24. Adolfsson, H. Angew. Chem., Int. Ed. 2005, 44, 3340.
Supplementary data
26. Wymore, T.; Nicholas, H. B.; Hempel, J. Chem.-Biol. Interact. 2001, 201, 130.
27. Cunningham, M. A.; Ho, L. L.; Nguyen, D. T.; Gillilan, R. E.; Bash, P. A. Bio-
chemistry 1997, 36, 4800.
Supplementary data associated with this article can be found in
the online version, at doi:10.1016/j.tet.2010.09.089.
28. Murakami, Y.; Kikuchi, J. I.; Hisaeda, Y.; Hayashida, O. Chem. Rev. 1996, 96, 721.
29. Martin, N. J. A.; List, B. J. Am. Chem. Soc. 2006, 128, 13368.
References and notes
30. Bohm, B. A. Introduction to Flavonoids; Harwood Academic: Amsterdam, 1998.
31. (a) Micheli, F.; Degiorgis, F.; Feriani, A.; Paio, A.; Pozzan, A.; Zarantonello, P.;
Seneci, P. J. Comb. Chem. 2001, 3, 224; (b) Powers, D. G.; Casebier, D. S.; Fokas, D.;
Ryan, W. J.; Troth, J. R.; Coffen, D. L. Tetrahedron 1998, 54, 4085; (c) Bu, X.; Zhao,
L.; Li, Y. Synthesis 1997, 1246; (d) Sinisterra, J. V.; Raso, A. G.; Cabello, J. A.;
Marinas, J. M. Synthesis 1984, 502; (e) Alcantara, A. R.; Marinas, J. M.; Sinisterra,
J. V. Tetrahedron Lett. 1987, 28, 1515; (f) Climent, M. J.; Corma, A.; Iborra, S.; Velty,
A. J. Catal. 2004, 221, 474; (g) Daskiewicz, J. B.; Comte, G.; Barron, D.; Pietro, A.
D.; Thomasson, F. Tetrahedron Lett. 1999, 40, 7095.
1. (a) Carruthers, W. Some Modern Methods of Organic Synthesis, 3rd ed.; Cam-
bridge University: Cambridge, 1986; (b) Mundy, B. P.; Ellerd, M. G. Name Re-
actions and Reagents in Organic Synthesis; Wiley: New York, NY, 1988.
2. (a) Wittig, G.; Geissler, G. Ann. Chem. 1953, 580, 44; (b) Maryanoff, B. E.; Reitz,
A. B. Chem. Rev. 1989, 89, 863.
3. Johnson, C. R.; Shanklin, J. R.; Kirchhoff, R. A. J. Am. Chem. Soc. 1973, 95, 1468.
4. (a) Peterson, D. J. J. Org. Chem. 1968, 33, 780; (b) Van Staden, L. F.; Gravestock,
D.; Ager, D. J. Chem. Soc. Rev. 2002, 31, 195.
32. Buszek, K. R.; Brown, N. Org. Lett. 2007, 9, 707.
33. Nielsen, M.; Jacobsen, C. B.; Paixaeo, M. W.; Holub, N.; Jùrgensen, K. A. J. Am.
5. (a) Wadsworth, W. S., Jr.; Emmons, W. D. J. Am. Chem. Soc. 1961, 83, 1733; (b)
Boutagy, J.; Thomas, R. Chem. Rev. 1974, 74, 87.
6. Julia, M.; Paris, J. M. Tetrahedron Lett. 1973, 14, 4833.
Chem. Soc. 2009, 131, 10581.
34. Paixao, M. W.; Holub, N.; Vila, C.; Nielsen, M.; Jùrgensen, K. A. Angew. Chem., Int.
Ed. 2009, 48, 1.
7. (a) Dumeunier, R.; Marko, I. E. In Modern Carbonyl Olefination; Takeda, T., Ed.;
Wiley-VCH: Weinheim, Germany, 2004; p 104; (b) Kociensky, P. J. In Compre-
hensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, UK,
1991; Vol. 6; (c) Kocienski, P. J.; Lythgoe, B.; Waterhouse, I. J. Chem. Soc., Perkin
Trans. 1 1980, 1045.
8. (a) Blakemore, P. R. J. Chem. Soc., Perkin Trans. 1 2002, 2563; (b) Baudin, J. B.;
Hareau, G.; Julia, S. A.; Ruel, O. Tetrahedron Lett. 1991, 32, 1175.
9. Prilezhaeva, E. N. Russ. Chem. Rev. 2000, 69, 367.
35. (a) Kumar, A.; Maurya, R. A.; Sharma, S.; Ahmad, P.; Singh, A. B.; Tamrakar, A. K.;
Srivastava, A. K. Bioorg. Med. Chem. 2009, 17, 5285; (b) Kumar, A.; Ahmad, P.;
Maurya, R. A.; Singh, A. B.; Tamrakar, A. K.; Srivastava, A. K. Eur. J. Med. Chem.
2009, 44, 109; (c) Kumar, A.; Maurya, R. A.; Sharma, S.; Ahmad, P.; Singh, A. B.;
Bhatia, G.; Srivastava, A. K. Bioorg. Med. Chem. Lett. 2009, 19, 6447; (d) Kumar,
A.; Sharma, S.; Tripathi, V. D.; Maurya, R. A.; Srivastava, S. P.; Bhatia, G.; Tam-
rakar, A. K.; Srivastava, A. K. Bioorg. Med. Chem. 2010, 18, 4138.