The Baylis-Hillman adducts as valuable source for one-pot multi-step synthesis: A facile synthesis of substituted piperidin-2-ones

Article abstract of DOI:10.1002/hlca.200900352

A facile, convenient, and one-pot multi-step synthesis of substituted piperidin-2-ones from the Baylis - Hillman alcohols derived from various aldehydes and acrylonitrile, involving Johnson - Claisen rearrangement, reduction of an α,β-unsaturated nitrile

Full text of DOI:10.1002/hlca.200900352

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Helvetica Chimica Acta – Vol. 93 (2010)
The Baylis – Hillman Adducts as Valuable Source for One-Pot Multi-Step
Synthesis: A Facile Synthesis of Substituted Piperidin-2-ones
by Deevi Basavaiah*, Raju Jannapu Reddy, and Dandamudi V. Lenin
School of Chemistry, University of Hyderabad, Hyderabad-500046, India
(fax: þ 91-40-23012460; e-mail: dbsc@uohyd.ernet.in)
A facile, convenient, and one-pot multi-step synthesis of substituted piperidin-2-ones from the
Baylis – Hillman alcohols derived from various aldehydes and acrylonitrile, involving Johnson – Claisen
rearrangement, reduction of an a,b-unsaturated nitrile moiety into the saturated amine-skeleton,
followed by cyclization, in an operationally simple procedure, is described.
Introduction. – In continuation of our interest in the synthesis of heterocyclic
molecules [1], we herein report a simple, facile, and one-pot multi-step synthesis of
piperidin-2-one derivatives, that is, 5-substituted and 3,5-disubstituted piperidin-2-ones
from Baylis – Hillman adducts. The piperidin-2-one moiety occupies a special place in
nitrogen heterocyclic chemistry because of the presence of this moiety in a variety of
biologically important compounds and therefore, the development of simple proce-
dures for the synthesis of such frameworks is an attractive endeavor in heterocyclic
chemistry [2]1).
Results and Discussion. – Applications of the Baylis – Hillman adducts in various
organic transformation methodologies have been well documented in the literature
[1][4][5]. We have, some time ago, developed a stereo-defined synthesis of
functionalized trisubstituted alkenes, i.e., ethyl (4Z)-4-cyanoalk-4-enoates via the
Johnson – Claisen (Claisen orthoester) rearrangement2) of the Baylis – Hillman alco-
hols, which represent CN-substituted allylic alcohols, with triethyl orthoacetate
(Scheme 1) [7a]3).
Scheme 1. Johnson – Claisen Rearrangement of 3-Hydroxy-2-methylidenealkanenitriles [6]
1
)
)
)
For a leading review on synthesis of piperidones and piperidines, see [3].
For leading references on the Johnson – Claisen rearrangement, see [6].
For other Johnson – Claisen rearrangement of Baylis – Hillman adducts, see [7b][7c].
2
3
ꢀ 2010 Verlag Helvetica Chimica Acta AG, Zꢁrich

Helvetica Chimica Acta – Vol. 93 (2010)
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It occurred to us that (4Z)-4-cyanoalk-4-enoates would be excellent starting
materials for the synthesis of piperidin-2-one derivatives by complete reduction of the
ene-nitrile functionality into an amino group, which would be in the proximity of the
ester group for a possible cyclization to a six-membered heterocyclic framework with a
provision for having a different substitution profile at the 3- and 5-positions. It also
occurred to us that the entire operation can be performed in one-pot, starting from the
Baylis – Hillman adducts involving a Johnson – Claisen rearrangement and reduction,
followed by cyclization, to provide the piperidin-2-one framework (Scheme 2).
Scheme 2. Retro-Synthetic Aspect for the Synthesis of the Piperidin-2-one Framework
Accordingly, we have first selected 2-[hydroxy(phenyl)methyl]prop-2-enenitrile
(1a), a Baylis – Hillman alcohol (B – H alcohol) derived from benzaldehyde and
acrylonitrile (¼ prop-2-enenitrile), as a substrate for this multi-step probing. The best
result was obtained when 1a (1 mmol) was treated with triethyl orthoacetate (1 ml) at
1458 in the presence of a catalytic amount of propanoic acid (3 drops) for 2 h, followed
(after removing the excess of orthoester under reduced pressure) by treatment with
CoCl2 · 6 H2O (2 mmol)/NaBH4 (10 mmol)4) in MeOH at 08 for 30 min and then for 6 h
at room temperature, thus providing 5-benzylpiperidin-2-one (2) as a colorless solid in
60% yield, after workup and purification by column chromatography (Scheme 3 and
Table 1, Entry 1). This was indeed an encouraging result in the sense that three steps
were performed in one-pot to produce the desired 2 in an acceptable yield.
Scheme 3. One-Pot Three-Step Synthesis of 5-Substituted Piperidin-2-ones
To understand the general character of this reaction, we have, according to
Scheme 3, successfully transformed representative B – H alcohols 1b – 1f, obtained from
various aromatic aldehydes and acrylonitrile, into the corresponding 5-arylmethylpi-
4
)
For literature reports on reduction of CN group using CoCl2 · 6 H2O/NaBH4, see [8].

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Table 1. One-Pot Three-Step Synthesis of Substituted piperidin-2-onesa)
Entry
B – H alcohol
R
R1
Productb)
Yieldc) [%]
1
2
3d)
4
1a
1b
1c
1d
1e
1f
1g
1h
1a
C6H5
H
H
H
H
H
H
H
H
Me
2
3
4
5
6
7
8
9
10
60
58
64
56
53
55
59
65
61
2-MeC6H4
4-MeC6H4
4-(iPr)C6H4
2-ClC6H4
4-ClC6H4
C6H5CH2CH2
Heptyl
5
6
7d)
8
9e)
C6H5
a) All reactions were carried out on a 1 mmol scale of B – H alcohols 1a – 1h, which were prepared
according to a literature procedure [9]. b) Compounds 2 – 10 were obtained as colorless solids and were
c
fully characterized (see Exper. Part). ) Yields are of the pure products, based on B – H alcohols. d) The
structures of these molecules were also established by X-ray diffraction analysis (Figs. 1 and 2, Table 2).
e) Isolated as a 1 : 1 mixture of diastereoisomers.
peridin-2-ones 3 – 7 in 53 – 64% yield of isolated products (Table 1, Entries 2 – 6). With
the same procedure, we also have successfully transformed B – H alcohols 1g and 1h,
obtained from the corresponding aliphatic aldehydes (hydrocinnamaldehyde and
octanal) and acrylonitrile, into 5-alkylpiperidin-2-ones 8 and 9 in 59 and 65% yield,
respectively (Table 1, Entries 7 and 8). Piperidin-2-ones 4 and 8 delivered suitable
single crystals for an X-ray crystal-structure analysis, which further confirmed the
structures of these compounds (Figs. 1 and 2, Table 2).
Fig. 1. ORTEP Diagram of compound 4 (H-atoms are omitted for clarity)
Fig. 2. ORTEP Diagram of compound 8 (H-atoms are omitted for clarity)

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Table 2. Crystallographic Data for Compounds 4 and 8a)
4
8
Crystallized from
Empirical formula
MeOH
C13H17NO
203.28
colorless, plate
0.42 ꢁ 0.21 ꢁ 0.07
298
MeOH
C14H19NO
217.30
colorless, block
0.46 ꢁ 0.38 ꢁ 0.23
298
Formula weight [g molꢀ1
Crystal color, habit
]
Crystal dimensions [mm]
Temperature [K]
Crystal system
Space group
Monoclinic
P21/c
Triclinic
P1
¯
Z
4
2
Reflections for cell determination
2316
2438
2q Range for cell determination [8]
Unit cell parameters a [ꢂ]
1.43 – 26.27
14.335(5)
5.812(2)
14.026(5)
90.00
96.357(6)
90.00
1161.4(7)
440
1.49 – 26.07
5.8744(15)
8.040(2)
14.260(4)
74.375(4)
89.430(4)
73.780(4)
621.2(3)
236
b [ꢂ]
c [ꢂ]
a [8]
b [8]
g [8]
V [ꢂ3]
F(000)
Dx [g cmꢀ3
]
1.163
0.073
1.162
0.072
m (MoKa) [mmꢀ1
]
Transmission factors [min; max]
Scan type
2qmax [8]
0.9700; 0.9949
F and w
26.27
0.9674; 0.9835
F and w
26.07
Reflections measured
Symmetry-independent reflections
Rint
11271
2316
0.0270
6507
2438
0.0244
R1, wR2 [I ꢂ 2s (I)]
R1, wR2 (all data)
Goodness-of-fit on F2
0.0464, 0.1246
0.0684, 0.1386
1.045
0.0571, 0.1589
0.0716, 0.1714
1.023
a) Detailed X-ray crystallographic data of 4 and 8 are available from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB21EZ, UK under CCDC-635054 and -635055, respectively.
With the intention to extend this new synthesis to the preparation of 3,5-
disubstituted piperidin-2-ones, we have used triethyl orthopropanoate for the
Johnson – Claisen rearrangement. Thus, B – H alcohol 1a, on successive treatment with
triethyl orthopropanoate and CoCl2 · 6 H2O/NaBH4 according to the same procedure
(as in the case of triethyl orthoacetate) provided 5-benzyl-3-methylpiperidin-2-one (10)
in 61% yield (Scheme 3 and Table 1, Entry 9). However, the 1H- and 13C-NMR spectra
clearly indicate that this molecule is ca. 1:1 mixture of diastereoisomers. In the
1H-NMR spectrum, MeꢀC(3) appeared as two doublets of equal intensities at 1.19 and
1.23 ppm, thus indicating for 10 a 1:1 mixture of diastereoisomers. Two singlets at 6.46
and 6.50 ppm are attributed to the NH groups of the diastereoisomers. In the 13C-NMR
spectrum, two signals at 175.7 and 176.2 ppm for one C¼O, two signals at 139.2 and

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139.4 ppm for one quaternary C-atom of the Ph group, and twelve signals for six
aliphatic C-atoms clearly indicate that this compound is a mixture of diastereoisomers.
In conclusion, we have successfully developed a convenient and operationally
simple one-pot three-step procedure for the synthesis of 5-substituted and 3,5-
disubstituted piperidin-2-ones from Baylis – Hillman alcohols, by Johnson – Claisen
rearrangement, reduction, and cyclization, thus demonstrating the application of
Baylis – Hillman adducts as a versatile source for one-pot multi-step syntheses.
Experimental Part
General. M.p.: Superfit (India) capillary melting point apparatus; uncorrected. IR Spectra: JASCO-
FT-IR model 5300 spectrometer using solid samples as KBr plates, in cmꢀ1. 1H- (400 MHz) and 13C-NMR
(50 MHz) spectra: in CDCl3 on a BRUKER-AVANCE-400 and BRUKER-AC-200 spectrometer; d in
ppm, J in Hz; tetramethylsilane (TMS, 0 ppm) as internal standard. MS: Shimadzu-LCMS-2010A mass
spectrometer. Elemental analyses: Thermo-Finnigan Flash EA 1112 analyzer. X-Ray diffraction
measurements: at 298 K on a Bruker SMART APEX CCD area detector system, using graphite
monochromated MoKa radiation and fine-focus sealed tube (l ¼ 0.71073 ꢂ).
5-Benzylpiperidin-2-one (2). To a stirred soln. of propanenitrile 1a (1 mmol, 0.159 g) in triethyl
orthoacetate (¼1,1,1-triethoxyethane; 1 ml) was heated at 1458 in the presence of a cat. amount of
propanoic acid (3 drops) for 2 h. Excess orthoester (along with propanoic acid) was distilled off under
reduced pressure. The residue was diluted with MeOH (8 ml), and CoCl2 · 6 H2O (2 mmol, 0.476 g) was
added. The resulting soln. was cooled to 08, and NaBH4 (10 mmol, 0.38 g) was added in three portions
within 15 min (H2 gas evolution was observed). The mixture (black formed precipitate) was stirred for
30 min at 08, and then allowed to warm to r.t. and stirred for further 6 h. MeOH was removed under
reduced pressure. Then, the residue was diluted with 4n HCl (15 ml) and extracted with AcOEt (3 ꢁ
20 ml). The combined org. layers were washed with H2O (20 ml) and dried over anh. Na2SO4. After
evaporation of the solvent, the residue was purified by CC (SiO2; AcOEt) to furnish 5-benzylpiperidin-2-
one (2) as a colorless solid in 60% (0.114 g) yield. M.p. 107 – 1098. IR: 3300 – 2800 (multiple bands), 1662.
1H-NMR: 1.46 – 1.60 (m, 1 H); 1.85 – 1.96 (m, 1 H); 2.00 – 2.15 (m, 1 H); 2.25 – 2.49 (m, 2 H); 2.55 – 2.70
(m, 2 H); 2.95 – 3.04 (m, 1 H); 3.20 – 3.29 (m, 1 H); 6.27 (br. s, 1 H, D2O exchangeable); 7.14 (d, J ¼ 6.8,
2 H); 7.19 – 7.34 (m, 3 H). 13C-NMR: 26.9; 30.7; 35.1; 39.6; 47.3; 126.5; 128.6; 128.9; 139.2; 172.6. LC-MS:
190 ([M þ H]þ). Anal. calc. for C12H15NO: C 76.16, H 7.99, N 7.40; found: C 76.18, H 8.04, N 7.45.
5-(2-Methylbenzyl)piperidin-2-one (3). Yield: 58%. M.p. 103 – 1058. IR: 3300 – 2800 (multiple
1
bands), 1666. H-NMR: 1.49 – 1.64 (m, 1 H); 1.83 – 1.97 (m, 1 H); 2.00 – 2.12 (m, 1 H); 2.25 – 2.50 (m,
5 H); 2.63 (d, J ¼ 7.2, 2 H); 2.97 – 3.07 (m, 1 H); 3.21 – 3.30 (m, 1 H); 6.35 (br. s, 1 H, D2O exchangeable);
7.05 – 7.20 (m, 4 H). 13C-NMR: 19.4; 27.0; 30.6; 33.9; 36.7; 47.2; 125.9; 126.5; 129.7; 130.5; 135.9; 137.5;
172.7. LC-MS: 204 ([M þ H]þ). Anal. calc. for C13H17NO: C 76.81, H 8.43, N 6.89; found: C 76.67, H 8.49,
N 6.93.
5-(4-Methylbenzyl)piperidin-2-one (4). Yield: 64%. M.p. 111 – 1138. IR: 3200 – 2850 (multiple
1
bands), 1662. H-NMR: 1.45 – 1.58 (m, 1 H); 1.85 – 1.94 (m, 1 H); 1.99 – 2.10 (m, 1 H); 2.25 – 2.49 (m,
5 H); 2.51 – 2.65 (m, 2 H); 2.94 – 3.03 (m, 1 H); 3.20 – 3.28 (m, 1 H); 6.19 (br. s, 1 H); 7.03 (d, J ¼ 7.6, 2 H);
7.10 (d, J ¼ 7.6, 2 H). 13C-NMR: 21.0; 26.8; 30.6; 35.2; 39.2; 47.2; 128.7; 129.2; 135.9; 136.1; 172.6. LC-MS:
204 ([M þ H]þ). Anal. calc. for C13H17NO: C 76.81, H 8.43, N 6.89; found: C 76.70, H 8.41, N 7.00.
5-[4-(1-Methylethyl)benzyl]piperidin-2-one (5). Yield: 56%. M.p. 95 – 968. IR: 3320 – 2850 (multiple
1
bands), 1664. H-NMR: 1.23 (d, J ¼ 6.8, 6 H); 1.45 – 1.59 (m, 1 H); 1.86 – 1.95 (m, 1 H); 1.99 – 2.12 (m,
1 H); 2.25 – 2.67 (m, 4 H); 2.83 – 3.04 (m, 2 H); 3.21 – 3.28 (m, 1 H); 6.11 (br. s, 1 H, D2O exchangeable);
7.06 (d, J ¼ 7.8, 2 H); 7.15 (d, J ¼ 7.8, 2 H). 13C-NMR: 24.0; 26.9; 30.6; 33.7; 35.1; 39.2; 47.2; 126.5; 128.8;
136.5; 146.9; 172.7. LC-MS: 232 ([M þ H]þ). Anal. calc. for C15H21NO: C 77.88, H 9.15, N 6.05; found: C
77.96, H 9.17, N 6.03.
5-(2-Chlorobenzyl)piperidin-2-one (6). Yield: 53%. M.p: 106 – 1088. IR: 3200 – 2950 (multiple
1
bands), 1672. H-NMR: 1.48 – 1.60 (m, 1 H); 1.85 – 1.96 (m, 1 H); 2.01 – 2.14 (m, 1 H); 2.27 – 2.50 (m,

Helvetica Chimica Acta – Vol. 93 (2010)
1185
2 H); 2.54 – 2.70 (m, 2 H); 2.94 – 3.05 (m, 1 H); 3.21 – 3.30 (m, 1 H); 6.05 (br. s, 1 H); 7.08 (d, J ¼ 7.6, 1 H);
7.11 – 7.33 (m, 2 H); 7.36 (d, J ¼ 8.0, 1 H). 13C-NMR: 26.9; 30.6; 33.7; 37.0; 47.2; 126.8; 128.0; 129.8; 131.1;
134.2; 137.1; 172.5. LC-MS: 224 ([M þ H]þ), 226 ([M þ 2 þ H]þ). Anal. calc. for C12H14ClNO: C 64.43, H
6.31, N 6.26; found: C 64.57, H 6.39, N 6.25.
5-(4-Chlorobenzyl)piperidin-2-one (7). Yield: 55%. M.p: 109 – 1118. IR: 3300 – 2950 (multiple
1
bands), 1657. H-NMR: 1.45 – 1.59 (m, 1 H); 1.83 – 1.93 (m, 1 H); 1.98 – 2.12 (m, 1 H); 2.24 – 2.49 (m,
2 H); 2.52 – 2.68 (m, 2 H); 2.92 – 3.03 (m, 1 H); 3.18 – 3.29 (m, 1 H); 6.15 (br. s, 1 H); 7.06 (d, J ¼ 8.0,
2 H); 7.27 (d, J ¼ 8.0, 2 H). 13C-NMR: 26.7; 30.5; 35.0; 38.8; 47.1; 128.6; 130.2; 132.2; 137.7; 172.5. LC-MS:
224 ([M þ H]þ), 226 ([M þ 2 þ H]þ). Anal. calc. for C12H14ClNO: C 64.43, H 6.31, N 6.26; found: C
64.28, H 6.30, N 6.21.
5-(3-Phenylpropyl)piperidin-2-one (8). Yield: 59%. M.p. 88 – 908. IR: 3300 – 2840 (multiple bands),
1664. 1H-NMR: 1.29 – 1.50 (m, 3 H); 1.56 – 1.95 (m, 4 H); 2.26 – 2.47 (m, 2 H); 2.56 – 2.66 (m, 2 H); 2.88 –
2.97 (m, 1 H); 3.28 – 3.38 (m, 1 H); 6.06 (br. s, 1 H); 7.13 – 7.31 (m, 5 H). 13C-NMR: 26.9; 28.6; 30.6; 32.6;
33.0; 35.8; 47.4; 125.7; 128.2; 141.9; 172.6. LC-MS: 218 ([M þ H]þ). Anal. calc. for C14H19NO: C 77.38, H
8.81, N 6.45; found: C 77.55, H 8.81, N 6.48.
5-Octylpiperidin-2-one (9). Yield: 65%. M.p. 59 – 618. IR: 3300 – 2800 (multiple bands), 1674.
1H-NMR: 0.88 (t, J ¼ 6.8, 3 H); 1.20 – 1.51 (m, 15 H); 1.71 – 1.80 (m, 1 H); 1.84 – 1.95 (m, 1 H); 2.24 – 2.48
(m, 2 H); 2.89 – 2.98 (m, 1 H); 3.29 – 3.38 (m, 1 H); 6.19 (br. s, 1 H, D2O exchangeable). 13C-NMR: 14.1;
22.7; 27.0; 27.1; 29.3; 29.5; 29.7; 30.8; 31.9; 33.1; 47.7; 172.8. LC-MS: 212 ([M þ H]þ). Anal. calc. for
C13H25NO: C 73.88, H 11.92, N 6.63; found: C 73.69, H 11.99, N 6.60.
5-Benzyl-3-methylpiperidin-2-one (10). Yield: 61%. M.p. 84 – 868. IR: 3300 – 2900 (multiple bands),
1
1658. H-NMR: 1.19, 1.23 (2d, J ¼ 6.8, 3 H); 1.60 – 2.78 (m, 6 H); 2.92 – 3.05 (m, 1 H); 3.15 – 3.30 (m,
1 H); 6.46, 6.50 (2 br. s, NH of diastereoisomers, 1 H); 7.05 – 7.38 (m, 5 H). 13C-NMR: 17.1; 18.5; 31.7;
1
33.8; 34.3; 35.7; 35.9; 36.3; 39.2; 40.3; 46.9; 47.9; 126.3; 128.5; 128.8; 139.2; 139.4; 175.7; 176.2. H- and
13C-NMR data clearly indicate that this product is a mixture of 1:1 diastereoisomers.
We thank DST (New Delhi) for funding this project. R. J. R. thanks CSIR (New Delhi) for his
research fellowship. D. V. L. thanks UGC (New Delhi) for his research fellowship. We thank UGC (New
Delhi) for support and providing some instrumental facilities. We thank the National Single Crystal X-
Ray Facility funded by DST. We also thank Professor S. Pal, School of Chemistry, University of
Hyderabad for helpful discussions regarding X-ray data analysis.
REFERENCES
[1] D. Basavaiah, D. V. Lenin, B. Devendar, Tetrahedron Lett. 2009, 50, 3538; D. Basavaiah, R. J. Reddy,
Org. Biomol. Chem. 2008, 6, 1034; D. Basavaiah, R. J. Reddy, J. Srivardhana Rao, Tetrahedron Lett.
2006, 47, 73; D. Basavaiah, J. Srivardhana Rao, R. J. Reddy, J. Org. Chem. 2004, 69, 7379; D.
Basavaiah, D. S. Sharada, A. Veerendhar, Tetrahedron Lett. 2004, 45, 3081; D. Basavaiah, T.
Satyanarayana, Chem. Commun. 2004, 32; D. Basavaiah, A. Jaganmohan Rao, Chem. Commun.
2003, 604; D. Basavaiah, A. Jaganmohan Rao, Tetrahedron Lett. 2003, 44, 4365; D. Basavaiah, R. M.
Reddy, N. Kumaragurubaran, D. S. Sharada, Tetrahedron 2002, 58, 3693; D. Basavaiah, T.
Satyanarayana, Org. Lett. 2001, 3, 3619; D. Basavaiah, M. Bakthadoss, S. Pandiaraju, Chem.
Commun. 1998, 1639.
[2] S. Kumar, C. Flamant-Robin, Q. Wang, A. Chiaroni, N. A. Sasaki, J. Org. Chem. 2005, 70, 5946; D. S.
Middleton, A. R. MacKenzie, S. D. Newman, M. Corless, A. Warren, A. P. Marchington, B. Jones,
Bioorg. Med. Chem. Lett. 2005, 15, 3957; T. R. Elworthy, E. R. Brill, C. C. Caires, W. Kim, L. K.
Lach, J. L. Tracy, S.-S. Chio, Bioorg. Med. Chem. Lett. 2005, 15, 2523; F. Yokokawa, A. Inaizumi, T.
Shioiri, Tetrahedron 2005, 61, 1459; H. K. Lee, J. S. Chun, C. S. Pak, Tetrahedron 2003, 59, 6445;
A. R. MacKenzie, A. P. Marchington, D. S. Middleton, S. D. Newman, B. C. Jones, J. Med. Chem.
2002, 45, 5365; L. M. Nogle, T. R. Williamson, W. H. Gerwick, J. Nat. Prod. 2001, 64, 716; N.
Yamazki, T. Ito, C. Kibayashi, Tetrahedron Lett. 1999, 40, 739; R. Bonjouklian, T. A. Smitka, A. H.
Hunt, J. L. Occolowitz, T. J. Perun Jr., L. Doolin, S. Stevenson, L. Knauss, R. Wijayaratne, S.
Szewczyk, G. M. L. Patterson, Tetrahedron 1996, 52, 395.

1186
Helvetica Chimica Acta – Vol. 93 (2010)
[3] P. M. Weintraub, J. S. Sabol, J. M. Kane, D. R. Borcherding, Tetrahedron 2003, 59, 2953; K. Takasu,
´
N. Nishida, M. Ihara, Synlett 2004, 1844; R. G. Arrayas, A. Alcudia, L. S. Liebeskind, Org. Lett. 2001,
3, 3381; E. Jao, P. B. Slifer, R. Lalancette, S. S. Hall, J. Org. Chem. 1996, 61, 2865; T. Fujji, S. Yoshifuji,
Tetrahedron 1970, 26, 5953.
[4] C. E. Aroyan, A. Dermenci, S. J. Miller, Tetrahedron 2009, 65, 4069; V. Declerck, J. Martinez, F.
Lamaty, Chem. Rev. 2009, 109, 1; V. Singh, S. Batra, Tetrahedron 2008, 64, 4511; D. Basavaiah, K. V.
Rao, R. J. Reddy, Chem. Soc. Rev. 2007, 36, 1581; D. Basavaiah, A. Jaganmohan Rao, T.
Satyanarayana, Chem. Rev. 2003, 103, 811; P. Langer, Angew. Chem., Int. Ed. 2000, 39, 3049; E.
Ciganek, in ꢃOrganic Reactionsꢄ, Ed. L. A. Paquette, Wiley, New York, 1997, Vol. 51, p. 201; D.
Basavaiah, P. Dharma Rao, R. Suguna Hyma, Tetrahedron 1996, 52, 8001; S. E. Drewes, G. H. P.
Roos, Tetrahedron 1988, 44, 4653.
´
˜
[5] A. Trofimov, V. Gevorgyan, Org. Lett. 2009, 11, 253; E. J. Lenardao, J. de Oliveiros Feijo, S. Thurow,
G. Perin, R. G. Jacob, C. C. Silveira, Tetrahedron Lett. 2009, 50, 5215; N. Abermil, G. Masson, J. Zhu,
J. Am. Chem. Soc. 2008, 130, 12596; M. Shi, X.-G. Liu, Org. Lett. 2008, 10, 1043; P. Shanmugam, V.
Vaithiyanathan, K. Selvakumar, Tetrahedron Lett. 2008, 49, 2119; M. Bakthadoss, N. Sivakumar, G.
Sivakumar, G. Murugan, Tetrahedron Lett. 2008, 49, 820; F. C. Pigge, R. Dhanya, E. R. Hefgen,
Angew. Chem., Int. Ed. 2007, 46, 2887; S. Chuprakov, D. A. Malyshev, A. Trofimov, V. Gevorgyan, J.
Am. Chem. Soc. 2007, 129, 14868; D. Basavaiah, K. Ramesh Reddy, N. Kumaragurubaran, Nat.
Protoc. 2007, 2, 2665; A. Kattuboina, P. Kaur, C. Timmons, G. Li, Org. Lett. 2006, 8, 2771; M. E.
Krafft, J. A. Wright, Chem. Commun. 2006, 2977; L. Navarre, S. Darses, J.-P. Genet, Adv. Synth.
Catal. 2006, 348, 317; V. Singh, G. P. Yadav, P. R. Maulik, S. Batra, Tetrahedron 2006, 62, 8731; G. W.
`
Kabalka, B. Venkataiah, C. Chen, Tetrahedron Lett. 2006, 47, 4187; J. Srivardhana Rao, J.-F. Briere, P.
Metzner, D. Basavaiah, Tetrahedron Lett. 2006, 47, 3553; M. Dadwal, R. Mohan, D. Panda, S. M.
Mobin, I. N. N. Namboothiri, Chem.Commun. 2006, 338; S. C. Kim, S. Gowrisankar, J. N. Kim,
Tetrahedron Lett. 2006, 47, 3463; P. V. Ramachandran, S. Madhi, L. Bland-Berry, M. V. R. Reddy,
M. J. OꢄDonnell, J. Am. Chem. Soc. 2005, 127, 13450; M. Shi, L.-H. Chen, C.-Q. Li, J. Am. Chem. Soc.
2005, 127, 3790; K. Matsui, S. Takizawa, H. Sasai, J. Am. Chem. Soc. 2005, 127, 3680; T. Turki, J.
´
Villieras, H. Amri, Tetrahedron Lett. 2005, 46, 3071; L. S. Santos, C. H. Pavam, W. P. Almeida, F.
Coelho, M. N. Eberlin, Angew. Chem., Int. Ed. 2004, 43, 4330; D. Basavaiah, A. K. D. Bhavani, S.
Pandiaraju, P. K. S. Sarma, Synlett 1995, 243; D. Basavaiah, S. Pandiaraju, P. K. S. Sarma,
Tetrahedron Lett. 1994, 35, 4227; D. Basavaiah, V. V. L. Gowriswari, P. K. S. Sarma, P. Dharma
Rao, Tetrahedron Lett. 1990, 31, 1621.
[6] A. M. M. Castro, Chem. Rev. 2004, 104, 2939; P. Wipf, in ꢃComprehensive Organic Synthesisꢄ, Eds.
B. M. Trost, I. Fleming, L. Paquette, Pergamon Press, New York, 1990, Vol. 5, p. 827; W. S. Johnson,
L. Werthemann, W. R. Bartlett, T. J. Brocksom, T.-T. Li, D. J. Faulkner, M. R. Petersen, J. Am.
Chem. Soc. 1970, 92, 741.
[7] a) D. Basavaiah, S. Pandiaraju, Tetrahedron Lett. 1995, 36, 757; b) D. Basavaiah, S. Pandiaraju, M.
Krishnamacharyulu, Synlett 1996, 747; c) B. Das, A. Majhi, J. Banerjee, Tetrahedron Lett. 2006, 47,
7619.
[8] J. O. Osby, S. W. Heinzman, B. Ganem, J. Am. Chem. Soc. 1986, 108, 67; S. W. Heinzman, B. Ganem,
J. Am. Chem. Soc. 1982, 104, 6801; T. Satoh, S. Suzuki, Y. Suzuki, Y. Miyaji, Z. Imai, Tetrahedron
Lett. 1969, 10, 4555.
[9] D. Basavaiah, V. V. L. Gowriswari, Synth.Commun. 1987, 17, 587.
Received October 5, 2009