Solventless DBU-promoted mannich-type reactions of α-amido β-tolylsulfones with diethyl fluoromalonates and diethyl malonates

Article abstract of DOI:10.1016/j.tet.2010.05.075

Mannich-type reactions of α-amido p-tolylsulfones with diethyl fluoromalonates and diethyl malonates, respectively in presence of catalytic amount of DBU have been developed. A variety of α-amido p-tolylsulfones prepared from aromatic and aliphatic aldehydes reacts with diethyl fluoromalonates and diethyl malonates, respectively under mild reaction conditions to afford α-fluoro β-amino esters and β-amino esters in moderate to good yield.

Full text of DOI:10.1016/j.tet.2010.05.075

Tetrahedron 66 (2010) 5647e5652
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journal homepage: www.elsevier.com/locate/tet
Solventless DBU-promoted Mannich-type reactions of a-amido p-tolylsulfones
with diethyl fluoromalonates and diethyl malonates
*
Santosh T. Kadam, Sung Soo Kim
Department of Chemistry, Inha University, Incheon 402-751, South Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 April 2010
Received in revised form 18 May 2010
Accepted 18 May 2010
Available online 25 May 2010
Mannich-type reactions of
respectively in presence of catalytic amount of DBU have been developed. A variety of
a
-amido p-tolylsulfones with diethyl fluoromalonates and diethyl malonates,
-amido p-tol-
ylsulfones prepared from aromatic and aliphatic aldehydes reacts with diethyl fluoromalonates and
diethyl malonates, respectively under mild reaction conditions to afford -fluoro -amino esters and
-amino esters in moderate to good yield.
a
a
b
b
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
a
a
-Amido p-tolylsulfones
-Fluoro -amino esters
b
N-protected imines
Mannich reaction
1. Introduction
as a catalyst.6 Electrophilic fluorinations are another popular option
for effective fluorinations. Kim et al. have utilized the phase transfer
Fluorine containing organic molecules is of great influence on
drug and pharmaceutical industry. Fluorinated compound imparts
desirable characteristic to drug by modulating both pharmacoki-
netic and pharmacodynmic properties of the drug. Therefore in-
corporation of fluorine into drug increases the metabolic stability,
lipophilicity and bioavailability.1 Thus the preparation of fluori-
nated compounds has attracted great attention in medicinal
chemistry. The catalytic method for the construction of fluorinated
molecules is a formidable synthetic challenge and various pro-
ductive progress has been made in recent years.2
catalyst for the enantioselective addition of fluorine to
ters.7 Asymmetric
-fluorinations of aldehydes have been reported
by three independent workers.8
-Amido p-tolylsulfones are considered as a precursor of N-
protected imines I. Under the basic conditions, -amido p-tol-
ylsulfones are readily converted to the N-protected imines that can
further react with various nucleophiles (Scheme 1).9aec
-Amido p-
tolylsulfones can be easily prepared by three-component coupling
of corresponding aldehyde, sodium p-toluenesulfinate and carba-
mate in presence of formic acid.9d
b-keto es-
a
a
a
a
The incorporation of fluorine can be achieved both by nucleo-
philic and electrophilic fluorinations. Nucleophilic fluo-
roalkylations have become one of the most important and fast
growing field in the fluorine chemistry. Most of the methods in-
volve the transfer of fluorinated carbanion to electrophile. Shibata
et al. have described various asymmetric fluorination methods of
O
Nu
O
R
O
Base
Nu-X
OR1
R
N
OR1
R
N
p -TolO2S
N
OR1
H
H
I
Scheme 1. Nucleophilic substitution of a-amido p-tolylsulfones through N-protected
ketones and
roalkylations of
fluorinated sulfones have been reported by Hu et al.4 Organo-
a
-amido sulfones by cinchona alkaloid.3 Fluo-
-enones, arynes and activated alkynes with
imines.
a,b
catalyzed asymmetric fluoroalkylations of
a
,
b
-unsaturated alde-
The reactions of
a
-amido p-tolylsulfones have been employed
hydes have been described with fluoromalontae by Rios et al.5
for the synthesis of N-homoallylic amines,10a enecarbamates,10b
a
a
Similarly, Wang et al. reported the asymmetric Michael reactions
-amino phosphonates,10c -amino carbonyl compounds10d and
b
of
a-fluoro ketoesters with nitroolefines by using cinchona alkaloid
-amino nitriles.10e,f Ballini et al. have reported that the Montmo-
rillonite K-10 could be an efficient catalyst for the FriedeleCrafts
reactions of
-amido p-tolylsulfones with indoles.10g Kim et al.
demonstrate the FriedeleCrafts alkylation of -amido p-tol-
ylsulfones with arenes and hetroarens.10hej Gianelli et al. have
a
a
* Corresponding author. Fax: þ82 32 867 5604; e-mail address: sungsoo@inha.ac.
kr (S.S. Kim).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.05.075

5648
S.T. Kadam, S.S. Kim / Tetrahedron 66 (2010) 5647e5652
utilized the amino catalyst for the anti-Mannich reaction of alde-
hydes with
-amido p-tolylsulfones.10k Das et al. have explored
-amido p-tolylsulfones as new substrate for aza-Moritae
%) successively offer the 28 % and 46 % yield of product in CH2Cl2
(entries 1 and 5). Further survey of reaction parameters such as
catalyst loading, reaction time and reagent ratio were performed.
DBU (10 mol %) and 3.0 equiv of 2 under solvent-free condition
have been found to be the choice of reaction conditions (entry 13).
a
a
a
BayliseHillman reaction through DABCO as efficient catalyst.10l
Mannich reactions are fundamental method for the carbone
carbonbond formationadjacent tonitrogenatom.11 Thekeyelement
in the Mannich reactions is an iminium intermediate, which is
susceptible to nucleophilic attack by various nucleophiles such as
enolised ketones. Due to the synthetic utility of the products, tre-
mendous efforts have been made for Mannich reactions.12 The use of
carbamate-protectedalkyloraryliminesin Mannichreactions raises
problem due to their instability.13,14c This problem can be overcome
by the use of gradual and in situ generated carbamate protected
The reactions of aromatic, aliphatic and heteroaromatic
p-tolylsulfones have been investigated to produce the fluorinated
amino esters (Table 2). The aromatic -amido p-tolylsulfones bearing
a-amido
b-
a
electron-donating and electron-withdrawing substituents show the
clean reaction under the reaction conditions (entries 1e7). Electron-
donatingp-Meandp-MeOsubstituents in4shows 80and 78%yieldof
the products, respectively (entries 2 and 4). Relative to p-Me, o-Me
gives the lower yield (67%) due to the steric hindrance (entry 3).
iminesfromstable
Deng et al.14b Ricci et al.14c and Ananthanawat et al.14d have dem-
onstrated Mannich reaction of -amido sulfones with enolizable
carbonyl nucleophiles such as 1,3-diketones, diethyl malonate and
-keto esters. On the basis of their reports the fluorine containing
enolizable carbonyl compounds like diethyl fluoromalonate may
react with in situ generated N-carbamate imines from -amido
sulfones. The development of Mannich reactions of fluoromalonates
with -amido p-tolylsulfones yet to be reported.
a
-amido p-tolylsulfones. RecentlySchaus et al.,14a
Table 2
Mannich-type reactions of various
a
-amido p-tolylsulfones with diethyl fluo-
a
romalonate 2a
NHCbz
O
O
NHCbz
O
b
O
S
DBU
R
O
O
R
O
F
O
rt
a
F
O
O
4
2
5a-5i
a
DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) is well-known as
sterically hindered, non-nuleophilic, strong amine base.15a,15b Re-
cently DBU has been widely used as the catalyst for various organic
transformations such as cyanoacylation of ketones,15c amidation of
cyanoacetates,15d benzylation of nitrogen oxygen or sulfur atoms,15e
Entry
R in 4
Time (h)
5aei
Yieldb (%)
1
2
2
2
5a
5b
74
80
synthesis of 2H-1-chromenes,15f
b-hydroxy a-diazo carbonyl com-
pounds15g and synthesis of tetramic acid.15h
Me
2. Results and discussions
In continuation of new synthetic application of
ylsulfones,10gej the DBU-catalyzed Mannich reactions of diethyl
fluoromalonates and -amido p-tolylsulfones are herein described.
The optimization of reaction conditions has been performed be-
tween -amido p-tolylsulfone 1 and diethyl fluoromalonate 2 in
presence of various amino bases as shown in Table 1. The organic
bases such as DABCO (1,4-diazabicyclo[2.2.2]octane), Guanidino-
benzimidazole and tBuTMG (2-tBu-1,1,3,3-tetramethylguanidine)
are unable to give the product even after 4 h reaction time (Table 1,
entries 2e4). TMG (1,1,3,3-tetramethylguanidine) and DBU (50 mol
a-amido p-tol-
3
4
5
6
7
8
2
2
2
4
4
2
2
5c
5d
5e
5f
67
78
65
58
61
78
55
Me
a
a
MeO
Br
Table 1
Mannich-type reactions of
a-amido p-tolylsulfones 1 with diethyl fluoromalonates 2
in presence of various bases and solventsa
NC
O2N
NHCbz
O
O
O
NHCbz
O
5g
5h
5i
O
Solvent, rt
Base
O
O
S
F
O
O
F
O
1
2
3
2 (equiv) Solvent Time (h) Yieldb (%)
N
Entry Base (mol %)
1
2
3
4
5
6
7
8
TMG (50)
DABCO (50)
Guanidinobenzimidazole (50) 1.0
1.0
1.0
CH2Cl2 4.0
CH2Cl2 4.0
CH2Cl2 4.0
CH2Cl2 4.0
CH2Cl2 4.0
28
NR
NR
NR
46
Trace
NR
NR
68
67
68
70
75
9
tBuTMG (50)
DBU (50)
DBU (50)
DBU (50)
DBU (50)
DBU (50)
DBU (30)
DBU (10)
DBU (10)
DBU (10)
1.0
1.0
1.0
1.0
1.0
2.0
2.0
2.0
2.0
3.0
a
Reagent and condition: 4 (0.5 mmol), 2 (3.0 mmol) and 10 mol % of DBU at rt
without using solvent.
THF
CH3CN 4.0
DMF 4.0
4.0
b
Isolated yield.
9
CH2Cl2 3.0
CH2Cl2 3.0
CH2Cl2 3.0
a
-Amido p-tolylsulfone having bromine atom offers the product
10
11
12
13
in lower yield because of electron-withdrawing power (entry 5).
This trend becomes even augmented with p-CN and p-NO2 (entries
6 and 7). a-Amido p-tolylsulfone derived from 2-pyridinecarbox-
yladehyde also reacts with diethyl fluoromalonte 2 to yield the
Neat
Neat
2.0
2.0
a
Reagent and conditions: 1 (0.5 mmol), 2 (xmmol) at rt.
Isolated yield.
b
product in 78 % yield (entry 8). In addition to aromatic and

S.T. Kadam, S.S. Kim / Tetrahedron 66 (2010) 5647e5652
5649
heteroaromatic
also applicable for Mannich reactions of aliphatic
ylsulfones. -Amido p-tolylsulfone bearing aliphatic chain have
shown the somewhat moderate yield (55%) of the adduct (entry 9).
The Mannich-type reactions between -amido p-tolylsulfones
and diethyl malonate under the same reaction conditions are also
performed (Table 3). -Amido p-tolylsulfone containing no sub-
stituent at the benzene ring gives 90% yield of product (entry 1).
-Amido p-tolylsulfones containing electron-donating MeOe and
a
-amido p-tolylsulfones, this catalytic protocol is
p-NO2 group require quite longer reaction time with lower yield
(entry 8). -Amido p-tolylsulfone derived from acid-sensitive het-
erocyclic 2-pyridinecarboxyladehyde undergoes smoothly for the
formation of the Mannich product (81%) (entry 9). Aliphatic ana-
a
-amido p-tol-
a
a
a
logues of a-amido p-tolylsulfones are moderately reactive towards
the Mannich reactions with quite lower yield (entries 10 and 11).
The electron-withdrawing power of fluorine of diethyl fluo-
romalonates dominates over the statistical factor for diethyl mal-
onates to give the higher yield for the former (compare entry 1 of
Table 2, and entry 1 of Table 3, etc.). The reaction conditions are
also proved to be equally effective in Mannich-type reactions of N-
Boc amido p-tolylsulfones with diethyl fluoromalonate and diethyl
malonate, respectively (Scheme 2). The N-Boc amido p-tol-
ylsulfones show the similar yield of Mannich adducts relative to
N-Cbz amido p-tolylsulfone under identical reaction conditions.
a
a
Mee groups in the benzene ring are successfully converted into the
Mannich adducts with quite high yield (73e90%) (entries 2e5).
Table 3
Mannich-type reactions of various
a
-amido p-tolylsulfones with diethylmalonatea
NHCbz
O
O
NHCbz
O
O
S
DBU
O
O
O
R
O
R
O
O
rt
O
O
O
NH
O
HN
O
O
O
O
O
6
4
7a-j
O
O
DBU
rt
O
S
R
O
O
R
Entry
1
R in 4
Time (h)
7
Yieldb (%)
90
8
2, 6
9 a-b
2 : R=H
6 : R= F
2
2
7a
9 a R=H: 2 h, 68 %
9 b R=F: 2 h, 70 %
Scheme 2. The Mannich-type reactions of 2 and 6 with N-Boc amido p-tolylsulfones.
2
7b
7c
7d
7e
7f
78
73
88
90
80
70
62
81
Although several other catalytic methods of carbonecarbon
Me
bond formation at the
a-position of amine have been reported,
present protocol is simple and efficient in terms of reaction con-
dition such as lower temperature and strong Lewis acid.13a,16
3
2
2
2
2
2
5
2
DBU-catalyzed Mannich-type reactions of
ylsulfones are also applicable with 1,3-diketone,
a
b
-amido p-tol-
-keto ester and
Me
cyclic diketone (Table 4). Acetylacetone shows quite high reactivity
towards -amido p-tolylsulfone in presence of 10 mol % of DBU
(50 min and 94%) (entry 1). Ethylacetoacetate gives the 81% yield of
Mannich products within 2 h. But cyclic 1,3-dicarbonyl compound
produces somewhat lower yield relative long chain 1,3-dicarboyl
substrate under the same reaction conditions (79%, 3 h).
4
a
MeO
MeO
5
MeO
OMe
Table 4
Mannich-type reactions of
a
-amido p-tolylsulfones 4 with 1,3-diketone,
b
-keto ester
and cyclic diketonea
6
Br
Cl
NHCbz
2
NHCbz
R
O
O
O
DBU
R
S
R
O
R1
R2
O
7
7g
7h
7i
rt, Solventless
R1
11a-11c
O
10a-10c
4
Entry
1
10aec
11aec
Time (h)
50 min
Yieldb (%)
94
8
O2N
O
O
11a
9
N
O
O
2
11b
2
81
10
2
2
7j
55
62
O
11
7k
a
Reagent and condition: 4 (0.5 mmol), 6 (3.0 mmol) and 10 mol % of DBU at rt
without using solvent.
79c
O
3
11c
3
b
Isolated yield.
O
a
Reagent and condition: 1 (0.5 mmol), 8 (2.0 mmol) and 10 mol % of DBU at rt
p-Bromo and p-chloro substituted benzene ring present in 4
without using solvent.
b
(entries 6 and 7) shows 80 and 70% yield, respectively.
a-Amido p-
Isolated yield.
c
tolylsulfone with aromatic ring substituted with deactivating
CH2Cl2 was used at rt.

5650
S.T. Kadam, S.S. Kim / Tetrahedron 66 (2010) 5647e5652
Plausible mechanism and role of DBU are shown in Scheme 3.
128.6, 128.5, 128.4, 128.1, 122.3, 67.2, 63.1, 62.8, 57.7, 57.3, 13.7, 13.6.
HRMS-FAB: [MH]þ calcd for C22H25FNO6: 418.1666, found: 418.1667.
The reaction includes the formation of N-acylimine by the elimi-
nation of benzensulfinate. The intermediate N-acylimine un-
dergoes the nucleophilic addition with enolate of dicarbonyl
compound or diethyl malonate to give the corresponding addition
product. Finally benzensulfinate abstracts the proton from DBUþH
to release DBU and benzensulfinic acid. This mechanism consists of
DBU (5 mol %) catalyzed intramolecular cyclization reaction of
o-alkynylbenzoic acid (0.3 mmol).17
3.2.2. Compound 5b. IR (KBr): 3426, 3320, 2817, 1742, 1685, 1581,
1278, 1128, 1011, 780, 627 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d:
7.30e7.24 (m, 7H), 7.12 (d, J¼7.6 Hz, 2H), 5.79e5.70 (m, 2H), 5.11 (d,
J¼12.0 Hz,1H), 5.00 (d, J¼12.4 Hz,1H) 4.23 (q, J¼3.0 Hz, 2H), 4.10 (q,
3.0 Hz, 2H), 2.31 (s, 3H), 1.23 (t, J¼7.0 Hz, 3H), 1.09 (t, J¼7.1 Hz, 3H);
13C NMR (50 MHz, CDCl3)
d: 164.53, 164.00, 163.83, 163.33, 155.0,
p -TOl-SO2H
138.3, 136.0, 132.6, 129.0, 128.3, 128.0, 127.2, 122.1, 67.0, 63.0, 62.6,
57.4, 57.0, 21.0, 13.6, 13.5. HRMS-FAB: [MH]þ calcd for C23H27FNO6:
432.1822, found: 432.1824.
N
NHCbz
N
SO2-Tol-p
R
p-TOl-SO2
DBU H
DBU
3.2.3. Compound 5c. IR (KBr): 3436, 3318, 1752, 1680, 1571, 1248,
1131, 1008, 770, 650 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d: 7.39e7.14
NHCbz
(m, 9H), 6.08e6.01 (m, 1H), 5.59 (d, J¼10 Hz, 1H), 5.10 (d, J¼12 Hz,
1H), 4.98 (d, J¼12.0 Hz,1H), 4.26 (q, J¼3.0 Hz, 2H), 4.04 (q, J¼3.0 Hz,
2H), 2.54 (s, 3H), 1.28 (t, J¼7.0 Hz, 3H), 1.02 (d, J¼7.0 Hz, 3H); 13C
R
O
O
NCbz
R''
O
p-TOl-SO2
DBU H
R
NMR (50 MHz, CDCl3) d: 176.0,155.5, 137.1, 136.0, 130.7, 128.5, 128.4,
128.1, 128.0, 126.5, 122.4, 67.1, 36.2,62.7, 19.8, 13.8, 13.4. HRMS-FAB:
OH
O
O
[MH]þ calcd for C23H27FNO6: 432.1822, found: 432.1823.
R'
R'
3.2.4. Compound 5d. IR (KBr): 3426, 3289, 2847, 1765, 1690, 1577,
1238, 1191, 1042, 748 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d: 7.30e7.25
R: Alkyl, Aryl
R': H, F
(m, 7H), 6.83 (d, J¼8.8 Hz, 2H), 5.70 (s, 2H), 5.10 (d, J¼12.0 Hz, 1H),
5.00 (d, J¼12.0 Hz, 1H), 4.22 (q, J¼3.3 Hz, 2H), 4.10 (q, J¼3.0 Hz, 2H),
3.77 (s, 3H), 1.23 (t, J¼7.0 Hz, 3H), 1.11 (t, J¼7.0 Hz, 3H); 13C NMR
Scheme 3. Plausible mechanism for Mannich-type reaction of
a-amido p-
tolylsulfones.
(100 MHz, CDCl3) d: 176.5, 160.3, 130.1, 129.0, 128.7, 128.1, 122.6,
14.5, 67.7, 63.7, 63.4, 55.8, 14.3.
DBU-catalyzed Mannich-type reactions of diethyl fluo-
romalonates and diethyl malonates with in situ generated carba-
mate protected imines from a-amido p-tolylsulfones are developed.
The present process is efficiently catalyzed by readily available base
under solvent-free conditions. This strategy is extended to diethyl
malonate, 1,3-dicarbonyl compound and b-keto ester too.
3.2.5. Compound 5e. IR (KBr): 3436, 3318, 2845, 1752, 1680, 1571,
1248, 1131, 1008, 770, 664 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d: 7.42
(d, J¼8.4 Hz, 2H), 7.38e7.25 (m, 7H), 5.81 (d, J¼10.0 Hz, 1H),
5.73e5.66 (m, 1H), 5.10 (d, J¼12.0 Hz, 1H), 5.00 (d, J¼12.0 Hz, 1H),
4.22 (q, J¼3.0 Hz, 2H), 4.10 (d, J¼3.0 Hz, 2H), 1.21 (t, J¼7.2 Hz, 3H),
1.11 (t, J¼7.2 Hz, 3H); 3C NMR (100 MHz, CDCl3)
d: 176.0, 164.4,
164.0, 163.7, 163.2, 155.0, 143.7, 136.0, 134.4, 131.7, 130.0, 128.5,
128.2, 128.1, 123.0, 67.3, 63.3, 63.0, 57.2, 56.8, 13.8, 13.7. HRMS-FAB:
[MH]þ calcd for C22H24BrFNO6: 496.0771, found: 496.0772.
3. Experimental section
3.1. General
3.2.6. Compound 5f. IR (KBr): 3328, 3358, 2913, 1690, 1645, 1571,
In all cases the 1H NMR (400 MHz) spectra were recorded with
Varian Gemini 4000 spectrometer. Chemical shifts are reported in
parts per million in CDCl3 with tetramethylsilane as an internal
standard. 13C NMR data were collected on a Varian Gemini 2000
spectrometer (50 MHz).
1278, 1124, 1155, 1018, 780 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d: 7.55
(d, J¼7.6 Hz, 2H), 7.45 (d, J¼8.0 Hz, 2H), 7.26e7.22 (m, 5H), 5.95 (d,
J¼9.6 Hz, 1H), 5.77e5.68 (m, 1H), 5.06 (d, J¼12.4 Hz, 1H), 4.95 (d,
J¼12.0 Hz, 1H), 4.20 (q, J¼3.2 Hz, 2H), 4.10 (q, J¼3.0 Hz, 2H), 1.18 (t,
J¼7.0 Hz, 3H), 1.10 (t, J¼7.0 Hz, 3H); 13C NMR (100 MHz, CDCl3)
d:
164.7,164.2,164.1, 155.6, 141.1,136.2,132.8,129.7,129.0, 128.9, 128.7,
122.8, 118.5, 113.1, 68.0, 64.0, 63.8, 57.8, 57.4, 14.3, 14.2. GCeMS:
ꢁ
m/z: 443 [Mþ ], 221, 107, 106, 91.
3.2. Experimental procedure for the Mannich-type reaction
of a-amido p-tolylsulfones with diethyl fluoromalonates and
diethyl malonates
3.2.7. Compound 5g. IR (KBr): 3346, 3318, 2895, 1782, 1647, 1544,
1248, 1138, 1157, 770, 685 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d: 8.12
(d, J¼7.6 Hz, 2H), 7.53 (d, J¼7.6 Hz, 2H), 7.25e7.20 (m, 5H),
To a mixture of a-amido p-tolylsulfone (0.5 mmol) and diethyl
5.88e5.71 (m, 2H), 4.25e4.19 (m, 2H), 4.10e4.07 (m, 2H), 1.19e1.07
malonate or diethyl fluoromalonate (3.0 mmol), DBU (10 mol %) was
added and stirred at rt. The progress of the reaction mixture was
monitored by TLC. After completion of reaction the crude product
was subject to column chromatography to obtain the pure product.
1H, 13C NMR data HRMS and IR values for all products are given
below.
(m, 6H); 13C NMR (100 MHz, CDCl3)
d: 204.2, 203.6, 157.5, 129.4,
128.4, 128.0, 122.4, 120.6, 110.9, 74.5, 55.2, 41.5, 30.4, 28.3, 26.7, 11.5;
HRMS-FAB: [MH]þ calcd for C22H24FN2O8: 463.1517, found:
463.1522.
3.2.8. Compound 5h. IR (KBr): 3385, 3018, 2877, 1738, 1675, 1578,
3.2.1. Compound 5a. IR (KBr): 3414, 3330, 2841, 1728, 1690, 1590,
1228, 1176, 1048, 784, 650 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d: 8.43
(s, 1H), 7.54 (t, J¼7.6 Hz, 2H), 7.28e7.23 (m, 5H), 7.13 (d, J¼7.5 Hz,
1H), 6.19 (d, J¼9.2 Hz, 1H), 5.79e5.82 (m, 1H), 5.00 (s, 12H),
4.26e4.23(m, 2H), 4.18e4.13 (m, 2H), 1.24e1.12 (m, 6H); 13C NMR
1218, 1131, 1008, 745, 657 cmꢀ1
;
1H NMR (400 MHz, CDCl3)
d:
7.37e7.31 (m,10H), 5.77e5.75 (m,1H), 4.22 (q, J¼2.8 Hz, 2H), 4.09 (q,
J¼2.8 Hz, 2H), 1.23 (t, J¼7.2 Hz, 3H), 1.09 (t, J¼7.0 Hz, 3H); 13C NMR
(50 MHz, CDCl3)
d: 175.8, 164.5, 164.0, 163.3, 155.0, 135.9, 135.3,
(100 MHz, CDCl3) d: 176.0, 157.0, 149.0, 143.7, 136.7, 136.2, 128.5,

S.T. Kadam, S.S. Kim / Tetrahedron 66 (2010) 5647e5652
5651
128.5, 128.2, 128.1, 123.3, 67.2, 66.8, 63.2, 57.7, 13.8, 13.9. GCeMS:
(100 MHz, CDCl3)
d
: 168.0, 166.6, 155.5, 137.6, 136.1, 133.4, 128.6,
ꢁ
m/z: 418 [Mþ ], 241, 197, 107, 91.
128.3, 128.0, 127.6, 6.8, 62.1, 61.7, 56.3, 53.3, 13.8, 13.7. HRMS-FAB:
[MH]þ calcd for C22H25ClO6N: 434.1370, found: 434.1370.
3.2.9. Compound 5i. IR (KBr): 3245, 3342, 2755, 1760, 1635, 1590,
1247, 1210, 1008, 847, 760, 645 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d:
3.2.17. Compound 7h. IR (KBr): 3353, 3325, 1642, 1630, 1470, 1254,
7.34e7.25 (m, 5H), 5.00e4.99 (m, 2H), 4.64e4.53 (m,1H), 4.30e4.15
(m, 2H), 4.16e4.13 (m, 2H), 1.05e1.18 (m, 14H), 0.84 (t, J¼13.2 Hz,
1131, 1011, 860, 725 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d: 8.15 (d,
J¼7.6 Hz, 2H), 7.50 (d, J¼7.6 Hz, 2H), 7.33e7.25 (m, 5H), 6.55 (d,
J¼8.0 Hz, 1H), 5.60 (d, J¼3.2 Hz, 1H), 5.10e5.05 (m, 2H), 4.21e4.10
(m, 4H), 3.89 (d, J¼3.2 Hz, 1H), 1.2e1.09 (m, 6H); 13C NMR
3H); 13C NMR (100 MHz, CDCl3)
d: 175.8, 164.6, 155.6, 136.1, 128.3,
127.9, 127.9, 122.5, 66.7, 62.7, 54.2, 53.8, 31.4, 29.7, 28.6, 25.3, 22.3,
13.9, 13.6. HRMS-FAB: [MH]þ calcd for C22H33FNO6: 426.2292,
found: 426.2290.
(100 MHz, CDCl3) d: 175.0, 155.2, 148.6, 141.5, 131.7, 128.8, 128.2,
124.0, 67.0, 62.2, 62.0, 55.3, 13.0. HRMS-FAB: [MH]þ calcd for
C22H25O8N2: 445.1611, found: 445.1613.
3.2.10. Compound 7a. IR (KBr): 3436, 3318, 1752, 1680, 1571, 1248,
1131, 1008, 780 cmꢀ1
;
1H NMR (400 MHz, CDCl3)
d: 7.33e7.25 (m,
3.2.18. Compound 7i. IR (KBr): 3376, 3348, 3052, 1752, 1680, 1470,
10H), 6.50 (d, J¼8.4 Hz, 1H), 5.55 (d, J¼4.4 Hz, 1H), 3.7 (d, J¼4.4 Hz,
1274, 1162, 1001, 860, 758 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d: 8.42
1H), 4.20e4.09 (m, 4H), 1.21e1.09 (m, 6H); 13C NMR (100 MHz,
(d, J¼4.8 Hz, 1H), 7.60 (t, J¼7.6 Hz, 1H), 7.31e7.22 (m, 6H), 7.13e7.10
(m,1H),6.35 (d, J¼8.0 Hz,1H), 5.61e5.59 (m,1H), 5.13e5.06 (m, 2H),
4.41 (d, J¼5.2 Hz,1H), 4.19e4.10 (m, 4H),1.24e1.14 (m, 6H); 13C NMR
CDCl3) d: 175.9, 167.9, 155.6, 139.1, 136.3, 128.5, 128.4, 128.0, 127.7,
126.2, 66.8, 62.0, 61.6, 56.7, 53.8, 13.8. HRMS-FAB: [MH]þ calcd for
C22H26NO6: 400.1760, found: 400.1758.
(100 MHz, CDCl3)
d
: 175.8, 168.5, 158.1, 148.7, 136.7, 128.4, 127.9,
ꢁ
122.4, 121.5, 66.8, 61.7, 54.8, 13.8. GCeMS: m/z: 419 [Mþ ], 307, 197,
3.2.11. Compound 7b. IR (KBr): 3325, 3250, 2730, 1740, 1645, 1584,
107, 91.
1247, 1110, 1048, 783 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d: 7.31e7.29
(m, 5H), 7.23 (d, J¼8.6 Hz, 2H), 7.15 (d, J¼8.6 Hz, 2H), 6.47 (d,
3.2.19. Compound 7j. IR (KBr): 3346, 3323, 2928, 1627, 1605, 1570,
J¼7.6 Hz, 1H), 5.51 (s, 1H), 5.11e5.03 (m, 2H), 4.20e3.88 (m, 4H),
1230, 1131, 1021, 860, 746 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d:
2.30 (s, 3H), 1.17e1.09 (m, 6H); 13C NMR (100 MHz, CDCl3)
d: 168.0,
7.31e7.24 (m, 5H), 5.79 (d, J¼40.4 Hz, 1H), 5.03 (q, J¼10.4 Hz, 2H),
4.22e4.15 (m, 2H), 4.09e4.04 (m, 2H), 3.67 (d, J¼4.0 Hz, 1H),
1.82e1.59 (m, 8H), 1.40e1.38 (m, 2H), 1.26e1.25 (m, 1H), 1.24e1.10
167.0, 155.7, 137.3, 136.4, 136.2, 129.2, 128.4, 128.0, 126.2, 66.8, 61.9,
61.6, 56.8, 53.7, 21.0, 14.0, 13.8. HRMS-FAB: [MH]þ calcd for
C23H28O6N: 414.1917, found: 414.1924.
(m, 6H); 13C NMR (100 MHz, CDCl3)
d: 175.1, 168.6, 156.1, 136.6,
128.3, 127.8, 66.4, 61.5, 55.6, 52.4, 41.2, 30.0, 29.4, 25.9, 25.8, 25.6,
13.8,13.6. HRMS-FAB: [MH]þ calcd for C22H32O6N: 406.2230, found:
406.2232.
3.2.12. Compound 7c. IR (KBr): 3315, 3302, 2865, 1789, 1675, 1510,
1267, 1145, 1035, 827 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d: 7.30e7.23
(m, 6H), 7.15 (d, J¼8.4 Hz, 3H), 6.50 (d, J¼8.4 Hz, 1H), 5.72 (q,
J¼4.2 Hz, 1H), 5.03 (q, J¼13.2 Hz, 2H), 4.18e4.02 (m, 4H), 3.75 (d,
J¼4.8 Hz, 1H), 2.46 (s, 3H), 1.20e1.08 (m, 6H); 13C NMR (100 MHz,
3.2.20. Compound 7k. IR (KBr): 3246, 3215, 2845, 1640, 1675, 1570,
1212, 1145, 1047, 840, 730 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d:
CDCl3)
d
: 168.0, 167.0, 155.4, 137.4, 136.3, 135.0, 130.6, 128.3, 128.0,
7.33e7.28 (m, 5H), 5.65 (d, J¼1.0 Hz, 1H), 5.06 (s, 2H), 4.30e4.11 (m,
127.6, 126.1, 125.6, 66.7, 62.0, 61.6, 55.2, 50.8, 19.0, 13.8, 13.7.
4H), 3.55 (d, J¼4.4 Hz, 1H), 1.57e1.49 (m, 2H), 1.29e1.19 (m, 14H),
ꢁ
GCeMS: m/z: 414 [Mþ ], 254, 210, 117, 90.
0.86 (t, J¼6.2 Hz, 3H); 13C NMR (100 MHz, CDCl3)
d: 175.8, 168.3,
167.7, 155.8, 136.5, 128.3, 127.8, 66.5, 61.7, 61.4, 54.8, 50.7, 33.6, 31.5,
ꢁ
3.2.13. Compound 7d. IR (KBr): 3245, 3342, 2755, 1760, 1635, 1590,
28.8, 26.1, 22.4, 13.9, 13.8. EIMS: m/z: 408 [Mþ ], 322, 278, 106, 90.
1247, 1210, 1008, 847 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d: 7.35e7.20
(m, 7H), 6.84 (d, J¼8.4 Hz, 2H), 6.46 (d, J¼9.2 Hz, 1H), 5.53e5.46 (m,
3.2.21. Compound 9a. IR (KBr): 3323, 3304, 2945, 1615, 1600, 1540,
1H), 5.08e5.05 (m, 2H), 4.16e4.09 (m, 4H), 3.79 (s, 3H), 1.22e1.10
1230, 1145, 1042, 870, 762 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d:
(m, 6H); 13C NMR (100 MHz, CDCl3)
d: 167.9, 166.8, 158.8, 155.5,
7.29e7.25 (m, 5H), 6.11e6.21 (m, 1H), 5.59e5.62 (m, 1H), 4.30e4.10
(m, 4H), 3.94 (s, 1H), 1.41 (s, 9H), 1.38 (t, J¼6.4 Hz, 3H), 1.14 (t,
136.3, 128.3, 127.9, 127.3, 113.8, 66.7, 61.8, 61.5, 56.7, 55.1, 53.3, 13.8.
HRMS-FAB: [MH]þ calcd for C23H28O7N: 429.1788, found: 429.1783.
J¼6.4 Hz, 3H); 13C NMR (100 MHz, CDCl3)
d: 175.9, 154.5, 135.6,
128.4, 127.4, 126.1, 79.5, 61.8, 61.00, 56.8, 62.7, 56.8, 28.1, 13.9, 13.7.
3.2.14. Compound 7e. IR (KBr): 3376, 3348, 1652, 1680, 1570, 1274,
HRMS-FAB: [MH]þ calcd for C19H28O6N: 366.1917, found: 366.1911.
1131, 1011, 860 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d: 7.36e7.26 (m,
5H), 6.49 (d, J¼7.2 Hz, 2H), 5.48e5.42 (m, 1H), 5.09 (s, 2H),
3.2.22. Compound 9b. IR (KBr): 3391, 3062, 2950, 2913, 1680, 1570,
4.20e4.05 (m, 4H), 3.81 (s, 9H), 1.25 (t, J¼3.0 Hz, 3H), 1.10 (t,
1230, 1131, 1021, 860, 746 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d:
J¼3.0 Hz, 3H); 13C NMR (100 MHz, CDCl3)
d
: 153.3, 128.4, 128.1,
7.34e7.25 (m, 5H), 5.65e5.62 (m,1H), 5.42e5.46 (m,1H), 4.33e4.25
(m, 4H), 4.14e4.08 (m, 4H), 3.84e3.82 (m, 1H), 1.37e1.30 (m, 12H),
103.2, 67.0, 62.1, 61.7, 60.8, 56.07,15.3,14.0. HRMS-FAB: [MH]þ calcd
for C25H32O9N: 489.1999, found: 489.2003.
1.12 (t, J¼6.4 Hz, 3H); 13C NMR (100 MHz, CDCl3)
d: 175.8, 154.2,
135.6,128.4,128.2, 80.2, 63.0, 62.7, 57.2, 56.8, 28.0,13.8,13.6. HRMS-
3.2.15. Compound 7f. IR (KBr): 3350, 3328, 1614, 1660, 1548, 1525,
FAB: [MH]þ calcd for C19H27FO6N:384.1822, found: 384.1821.
1234, 1107, 1028, 850, 670 cmꢀ1 1H NMR (400 MHz, CDCl3)
; d:
7.46e7.33 (m, 7H), 7.44 (d, J¼8.4 Hz, 2H), 7.39e7.33 (m, 4H), 7.19 (d,
J¼8.4 Hz, 2H), 6.50 (d, J¼8.0 Hz,1H), 5.47 (d, J¼3.2 Hz,1H), 5.12e5.04
(m, 2H), 4.1e4.08 (m, 4H), 3.82 (d, J¼3.6 Hz, 1H), 1.21e1.12 (m, 6H);
3.2.23. Compound 11a. IR (KBr): 3325, 3012, 2940, 2910, 1630,
1545, 1230, 1021, 860; 1H NMR (400 MHz, CDCl3)
d
: 7.25e7.19 (m,
10H), 6.0 (s, 1H), 5.18 (s,1H), 5.01 (d, J¼8.8 Hz, 2H), 4.15 (d, J¼5.6 Hz,
1H), 2.11e2.00 (m, 6H); 13C NMR (100 MHz, CDCl3)
: 202.2, 202.1,
13C NMR (100 MHz, CDCl3)
d
: 176.0, 156.2, 131.7, 128.5, 128.0, 124.0,
d
67.0, 62.2, 62.0, 55.3, 13.0, 13.8; EIMS (m/z): [MþH]þ: 389.2.
155.7, 139.5, 136.0, 128.7, 128.5, 128.3, 128.0, 127.8, 127.7, 126.3, 71.4,
66.9, 54.2, 30.2, 29.9.
3.2.16. Compound 7g. IR (KBr): 3361, 3288, 1672, 1660, 1515, 1520,
1274, 1131, 1011, 855 cmꢀ1; 1H NMR (400 MHz, CDCl3)
d
: 7.41e7.24
3.2.24. Compound 11b. IR (KBr): 3338, 3310, 2854, 2951,1627,1552,
(m, 9H), 6.62 (d, J¼8.8 Hz, 1H), 5.60e5.56 (m, 1H), 5.16e5.09 (m,
1260, 1021, 827; 1H NMR (400 MHz, CDCl3)
d
: 7.28e7.21 (m, 10H),
2H), 4.25e4.13 (m, 4H), 3.94 (s, 1H), 1.27e1.18 (m, 6H); 13C NMR
6.54e6.39 (m, 1H), 5.60e5.50 (m, 1H), 5.05e5.00 (m, 2H),

5652
S.T. Kadam, S.S. Kim / Tetrahedron 66 (2010) 5647e5652
4.09e3.99 (m, 3H), 2.12 (s, 3H), 1.03 (t, J¼7.0 Hz, 3H); 13C NMR
hedron 2007, 63, 8525e8528; (e) Shibata, N.; Mizuta, S.; Kawai, H. Tetrahedron:
Asymmetry 2008, 19, 2633e2644; (f) Shibata, N.; Ishimaru, T.; Nakamura, S.;
Takeshi, T. J. Fluorine Chem. 2007, 128, 469e483; (g) Fukuzumi, T.; Shibata, N.;
Sugiura, M.; Nakamura, S.; Toru, T. J. Fluorine Chem. 2006, 127, 548e551.
4. Ni, C.; Zhang, L.; Hu, J. J. Org. Chem. 2008, 73, 5699e5713.
(100 MHz, CDCl3) d: 202.9, 202.7, 168.3, 166.8, 155.6, 155.5, 139.2,
139.1, 136.1, 128.5, 128.2, 128.0, 127.8, 127.5, 126.4, 126.0, 66.7, 64.0,
61.6, 54.2, 30.3, 13.6; HRMS-FAB (m/z): [MþH]þ calcd for
C21H24O5N: 370.1654, found: 370.1655.
5. Companyo, X.; Hejnova, M.; Kamlar, M.; Vesely, J.; Moyano, A.; Rios, R. Tetra-
hedron Lett. 2009, 50, 5021e5024.
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C. F., III. Angew. Chem., Int. Ed. 2005, 44, 3706e3710.
3.2.25. Compound 11c. IR (KBr): 3335, 3022, 2870, 2932, 1665,
1545, 1228, 1021, 852; 1H NMR (400 MHz, CDCl3)
d
: 7.35e7.23 (m,
10H), 6.20 (d, J¼9.6 Hz, 2H), 5.10 (d, J¼12.8 Hz, 2H), 2.30e2.16 (m,
4H), 1.05 (s, 6H); 13C NMR (100 MHz, CDCl3)
: 192.9, 167.7, 157.2,
d
9. (a) Petrini, M. Chem. Rev. 2005, 105, 3949e3977; (b) Petrini, M.; Torregiani, E.
Synthesis 2007, 159e186; (c) Cote, A.; Charette, A. B. J. Org. Chem. 2005, 70,
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Lett. 2007, 48, 7930e7933; (b) Mecozzi, T.; Peterin, M. Synlett 2000, 73e74; (c)
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lová, S.; Reme, M.; Císaová, I.; Veselý, J. Eur. J. Org. Chem. 2009, 6277e6280; (e)
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(i) Thirupathi, P.; Kim, S. S. Eur. J. Org. Chem. 2010, 1798e1808; (j) Kadam, S. T.;
Thirupathi, P.; Kim, S. S. Tetrahedron 2009, 65, 10383e10389; (k) Gianelli, C.;
Sambri, L.; Carlone, A.; Bartoli, G.; Melchiorre, P. Angew. Chem., Int. Ed. 2008, 47,
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157.9, 136.6, 134.1, 133.4, 129.0, 128.6, 128.5, 113.9, 113.8, 61.4, 59.8,
55.1, 55.0, 49.3, 13.7; HRMS-FAB: [MH]þ calcd for C23H26O4N:
380.1862, found: 380.1863.
Acknowledgements
The authors thank the Center for Biological Modulators of the
KRICT for the financial support. Thanks are also due to BK 21 ad-
ministrated by Korea Research Council.
Supplementary data
11. (a) Marques, M. M. B. Angew. Chem., Int. Ed. 2006, 45, 348e352; (b) Kobayshi, S.;
Ishitani, H. Chem. Rev. 1999, 99, 1069e1094; (c) Benaglia, M.; Cinquini, M.; Cozzi,
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Supplementary data associated with this article can be found in
the online version at doi:10.1016/j.tet.2010.05.075.
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