Montmorillonite clay catalyzed synthesis of enantiomerically pure 1,2,3,4-tetrahydroquinolines

Article abstract of DOI:10.1055/s-2006-942528

Arylamines undergo smooth cyclization with 2-deoxy-D-ribose on the surface of montmorillonite KSF clay under mild conditions to afford the corresponding sugar-derived chiral tetrahydroquinolines in high yields with moderate diastereoselectivity. The assignment of the stereochemistry of the product was achieved by various NMR studies. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2006-942528

PAPER
2923
Montmorillonite Clay Catalyzed Synthesis of Enantiomerically Pure
1
1
,2,3,4-Tetrahydroquinolines
a
a
a
a
b
b
Synthesis
J
.
of
E
nantiom
erically
S
Pure
1
.
,2, 3,4-Tetra
h
Y
ydroquinolines adav, B. V. S. Reddy,* Syeda Meraj, P. Vishnumurthy, K. Narsimulu, A. C. Kunwar
a
Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad 500 007, India
Centre for Nuclear Magnetic Resonance, Indian Institute of Chemical Technology, Hyderabad 500 007, India
Fax +91(40)7160387; E-mail: yadavpub@iict.res.in
b
Received 10 April 2006; revised 11 May 2006
9
organic synthesis. Heterogeneous solid acids are advan-
tageous over conventional homogeneous acid catalysts as
they can be easily recovered from reaction mixtures by
Abstract: Arylamines undergo smooth cyclization with 2-deoxy-
D-ribose on the surface of montmorillonite KSF clay under mild
conditions to afford the corresponding sugar-derived chiral tetrahy-
droquinolines in high yields with moderate diastereoselectivity. The simple filtration and can be reused after activation thereby
assignment of the stereochemistry of the product was achieved by making the process more economically viable.10 In many
various NMR studies.
cases, heterogeneous catalysts can be recovered with only
Key words: 2-deoxy sugars, solid acid, arylamines, tetrahydro- minor changes in activity and selectivity so that they can
quinolines
be conveniently used in continuous flow reactions.
Among the various heterogeneous catalysts, clays are
very attractive because of their low cost, reusability, flex-
ibility with modified acid strengths, ease of handling, en-
vironmental compatibility, nontoxicity, and experimental
simplicity.11
Tetrahydroquinolines are the core structures in various
natural products and synthetic pharmaceuticals, such as
anti-arrhythmic and cardiovascular agents, anticancer
drugs, immunosuppressants, and ligands for 5-HT1A and
NMDA receptors. The pyranoquinoline fragment is
present in many alkaloids, such as flindersine, oricine,
and veprisine, and derivatives of these alkaloids possess a
wide range of biological activities such as psychotropic,
antiallergic, anti-inflammatory, and estrogenic activities.4
Functionalized furanoquinolines are common substruc-
tures found in many biologically active natural products
such as skimmianine and halfouridine. Consequently,
many novel synthetic routes have been developed for the
synthesis of tetrahydroquinoline derivatives. Lewis acid
catalyzed aza-Diels–Alder reactions of N-arylimines with
electron-rich dienophiles are powerful synthetic tools for
the construction of nitrogen-containing heterocycles. Re-
In this report, we describe a simple and novel method for
the synthesis of sugar-based, chiral tetrahydroquinolines
from 2-deoxyribose and arylamines using montmorillo-
nite as the catalyst. Thus, treatment of aniline with 2-
deoxy-D-ribose in the presence of montmorillonite KSF
clay afforded sugar-fused tetrahydroquinolines 2a and 3a
in a combined yield of 85% (Scheme 1, Table 1).
2
3
The reaction proceeded smoothly at room temperature
and the products were obtained as a mixture of 2a and 3a
in a 1:1 ratio. The isomers 2a and 3a were easily separated
by column chromatography. The product 2a was charac-
terized by extensive NMR experiments using nuclear
Overhauser effect spectroscopy (NOESY), double quan-
tum filtered correlation spectroscopy (DQFCOSY), heter-
onuclear single quantum correlation spectroscopy
5
6
7
cently, tetrahydroquinoline derivatives have been synthe-
sized in a one-pot operation by 1:2 coupling of arylamines
with cyclic enol ethers or hemiacetals using acid cata-
(
HSQC) and heteronuclear multiple bond correlation
spectroscopy (HMBC) experiments. The presence of the
bridgehead methylene groups of a bicyclononene-like
structure was supported by d = 27.9 (C2) and 1.98
8
lysts. Recently, the use of solid acids such as clays, zeo-
lites, heteropoly acids, and ion-exchange resins as
catalysts has received great attention in different areas of
[
H2
] and 1.67 [H
], and the small couplings be-
(
pro-R)
2(pro-S)
H
O
H
H
O
H
O
HO
KSF
OH
OH
+
+
OH
MeCN, r.t.
N
H
NH2
N
OH
H
1
2a
3a
Scheme 1
SYNTHESIS 2006, No. 17, pp 2923–2926
x
x.
x
x
.
2
0
0
6
Advanced online publication: 25.07.2006
DOI: 10.1055/s-2006-942528; Art ID: Z07606SS
Georg Thieme Verlag Stuttgart · New York
©

2
924
J. S. Yadav et al.
PAPER
Table 1 Montmorillonite Clay Promoted Synthesis of Fused Tetrahydroquinolines
R4
R4
R1
R4
R3
R2
H
O
H
R3
R2
H
O
H
R3
O
HO
OH
+
OH
+
OH
NH2
R2
N
OH
N
H
R1
H
R1
1
2
3
Arylamine
Time (h)
Productsa
Yield(%)b
R1
H
R2
R3
H
R4
H
1
1
1
1
1
1
1
1
1
1
1
1
1
a
b
c
d
e
f
H
5.0
6.0
5.0
9.0
7.0
6.0
7.0
9.5
7.5
6.5
7.0
6.5
8.0
2a
85
80
87
70
81
85
75
70
86
81
86
80
72
3
a
H
H
Cl
Me
F
H
H
H
H
H
H
H
H
H
H
2b
3
b
H
H
2c
3
c
H
H
2d
3
d
H
Cl
Me
H
H
2e
3
e
H
H
2f
3
f
g
h
i
Cl
H
Cl
F
2g
3
g
Cl
Me
H
2h
3
h
Cl
Cl
Me
Me
Cl
H
2i
3
i
j
H
2j
3
j
k
l
H
H
2k
3
k
H
H
Me
Cl
2l
3
l
m
H
Cl
2m
3
m
a
Products were obtained as a mixture of 2 and 3 in 1:1 ratio.
Yield refers to pure products after chromatography.
b
tween these methylene protons and bridge protons H1 and the NOE cross peak between H2(pro-R)–H4 as well as the
H3, JH1–H2(pro-R) = 3.4 Hz, JH1–H2(pro-S) = 1.9 Hz, JH2(pro-R)–H3 coupling JH4–H5 = 10.9 Hz (Figure 1). The structure was
.4 Hz, and JH2(pro-S)–H3 = 4.8 Hz. The fusion of bicy- further confirmed by molecular mechanics calculations.
=
1
2
2
clononene and the aromatic ring at C1–C6 and C3–NH
was confirmed by the presence of HMBC peaks between
H1–C6, H1–C7, H1–C11, H7–C1 and NOE’s between
H1–H7 and NH–H3. The two six-membered rings of the
bicyclononene moiety have different conformations, the
one containing an oxygen is in a chair form, whereas the
other with a nitrogen and fused to the aromatic ring exists
in a half-chair form. The chair conformation of the oxy-
gen-containing six-membered ring is further supported by
The structure of 3a was obtained as discussed for 2a
Figure 2). It was well supported by the small coupling
(
constants JH1–H2(pro-R) = 3.3 Hz, JH1–H2(pro-S) = 1.9 Hz,
JH2(pro-R)–H3 = 2.3 Hz, and JH2(pro-S)–H3 = 4.1 Hz, d = 23.1
(
C2), 2.45 [H2(pro-R)], and 1.25 [H2(pro-S)]. The very large
upfield shift of H2(pro-S) (d = 1.25) and H4 (d = 3.27) due
to the ring current effect of the aromatic p-electrons fur-
ther confirmed the structure. Characteristic NOE interac-
tions between H1–H7, NH–H10, and NH–H4 as well as
Synthesis 2006, No. 17, 2923–2926 © Thieme Stuttgart · New York

PAPER
Synthesis of Enantiomerically Pure 1,2,3,4-Tetrahydroquinolines
2925
OH
R1
R2
KSF Clay
OH
O
HO
MeCN, r.t.
OH
O
OH
4
R = OH; R' = H = 2-deoxy-D-glucose
R = H; R' = OH = 2-deoxy-D-galactose
Scheme 2
Figure 1
Important NOE relationships and energy-minimized
structure of compound 2a.
Other lactols such as 2-hydroxytetrahydro-2H-pyran and
-hydroxytetrahydrofuran smoothly underwent cycliza-
2
tion with arylamines on the surface of montmorillonite
KSF to give tetrahydropyranoquinoline and hexahydrofu-
8
ro[3,2-c]quinoline derivatives, respectively. A possible
mechanism may be addition of aniline to the a,b-unsatur-
ated position of the conjugated aldehyde formed in situ
from the 2-deoxyribose and the acidic clay. Thus the ini-
tially formed Michael adduct undergoes a tandem
Friedel–Crafts intramolecular cyclization resulting in the
formation of the chiral tricyclic amine (Scheme 3).
Figure 2 Important NOE relationships and energy-minimized
structure of compound 3a.
The scope and generality of this process is illustrated with
respect to various arylamines and 2-deoxy-D-ribose and
the results are presented in Table 1.
the very small values for JH4–H5 = 1.0 Hz and JH4–H5 = 2.0
Hz indicated the presence of single rotamer about C4–C5.
In summary, we disclose a novel procedure for the synthe-
sis of sugar-derived chiral tetrahydroquinolines from 2-
Encouraged by the results obtained with aniline, we deoxy-D-ribose and arylamines using an inexpensive and
turned our attention towards various amines and lactols. readily available solid acid, montmorillonite KSF clay.
Interestingly, a wide range of arylamines including ortho-, This method is quite simple and straightforward leading to
meta-, and para-substituted anilines worked well under sugar-fused heterocycles in a single-step operation.
the reaction conditions. However, the reaction did not pro-
ceed with 2,6-disubstituted anilines such as 2,6-dichloro-
aniline and 2,6-dimethylaniline under similar conditions.
1H NMR and 13C NMR spectra were recorded on an Inova-500
spectrometer in CDCl using TMS as an internal standard. High-
3
These results clearly indicated that one of the ortho-posi- resolution mass spectra were recorded on a Finnigan MAT 1020
tions of aniline should be unsubstituted for the reaction to mass spectrometer operating at 70 eV.
succeed. Furthermore, 2-deoxy-D-glucose and 2-deoxy-
D-galactose did not react with arylamines to give the cor-
responding cycloadducts. Instead, both 2-deoxy-D-
glucose and 2-deoxy-D-galactose underwent cyclodehy-
Sugar-Fused Heterocycles 2 and 3; General Procedure
A mixture of 2-deoxy-D-ribose (2 mmol), aniline (3 mmol), and
montmorillonite KSF (1 g) in MeCN (10 mL) was stirred at r.t. for
the time specified in Table 1, as required to take the reaction to com-
dration on the surface of clay resulting in the formation of
pletion as indicated by TLC. The mixture then was filtered and
-furylethane-1,2-diol 4 in 60% and 45% yields, respec- washed with EtOAc (2 × 10 mL). The combined organic layers
2
tively (Scheme 2).
were dried (anhyd Na SO ), concentrated in vacuo, and purified by
2 4
column chromatography [silica gel (Merck, 100–200 mesh],
OH
O
OH
montmorillonite
OHC
H+
HO
OH
aniline
OH
HO
+
N
OH
H
OH
+
O
H
OH2
H
O
H
H
O
H
H+
: OH
+
N
OH
N
H
–
H2O
OH
N
H
N
H
OH
: OH
H
OH
Scheme 3
Synthesis 2006, No. 17, 2923–2926 © Thieme Stuttgart · New York

2
926
J. S. Yadav et al.
PAPER
(2R,3R,5R)-3-Acetoxy-1,2,3,5-tetrahydro-2,5-methano-4,1-
EtOAc–hexane, 1:9) to afford the pure tetrahydroquinoline deriva-
tive.
benzoxazepine-3-methanol (Ac-3a)
1
H NMR (500 MHz, DMSO-d ): d = 7.05 (ddd, J
= 8.2 Hz,
6
H9–H10
(
2R,3R,6R)-1,3,4,6-Tetrahydro-2,6-methano-2H-5,1-benzox-
JH8–H9 = 7.2 Hz, JH7–H9 = 1.5 Hz, 1 H, H9), 7.02 (dd, JH7–H8 = 7.2 Hz,
JH7–H9 = 1.5 Hz, 1 H, H7), 6.58 (d, JNH–H3 = 4.4 Hz, NH), 6.55 (dd,
azocin-3-ol (2a)
1
H NMR (500 MHz, DMSO-d ): d = 6.99 (ddd, JH9–H10 = 8.1 Hz,
JH9–H10 = 8.2 Hz, JH8–H10 = 1.0 Hz, 1 H, H10), 6.51 (td, JH7–H8
JH8–H9 = 7.2 Hz, JH8–H10 = 1.0 Hz, 1 H, H8), 4.63 (dd, JH1–H2(pro-S)
=
=
6
JH8–H9 = 7.4 Hz, J
= 1.3 Hz, 1 H, H9), 6.93 (dd, JH7–H8 = 7.4 Hz,
H7–H9
JH7–H9 = 1.3 Hz, 1 H, H7), 6.61 (dd, JH9–H10 = 8.1 Hz, JH8–H10 = 1.2
Hz, 1 H, H10), 6.44 (td, JH8–H9 = JH7–H8 = 7.4 Hz, JH8–H10 = 1.2 Hz,
1.6 Hz, JH1–H2(pro-R) = 3.5 Hz, 1 H, H1), 4.40 (ddd, JH3–H4 = 4.1 Hz,
JH4–H5 = 2.1 Hz, JH4–H5¢ = 1.0 Hz, 1 H, H4), 3.58 (ddt, JH2(pro-S)–H3
=
1
H, H8), 6.07 (d, JNH–H3 = 4.1 Hz, 1 H, NH), 4.73 (d, JOH–H4 = 5.6
Hz, OH), 4.53 (dd, JH1–H2(pro-R) = 3.4 Hz, JH1–H2(pro-S) = 1.9 Hz, 1 H,
H1), 3.59 (ddt, JH3–H4 = 3.0 Hz, JOH–H4 = 5.6 Hz, JH4–H5¢
4.1 Hz, JH2(pro-R)–H3 = 2.9 Hz, JH3–H4 = JH3–NH = 4.4 Hz, 1 H,
H3), 3.49 (dd, JH5–H5¢ = 13.2 Hz, JH4–H5¢ = 1.0 Hz, 1 H, H5¢),
3.23 (dd, JH5–H5¢ = 13.2 Hz, JH4–H5 = 2.1 Hz, 1 H, H5), 2.29 (ddd,
JH2(pro-R)–H2 (pro-S) = 12.8 Hz, JH1–H2(pro-R) = 3.5 Hz, JH2(pro-R)–H3 = 2.9
=
JH4–H5 = 10.9 Hz, 1 H, H4), 3.44 (dddd, JNH–H3 = 4.1 Hz, JH3–H4 = 3.0
Hz, JH2(pro-R)–H3 = 2.4 Hz, JH2(pro-S)–H3 = 4.8 Hz, 1 H, H3), 3.43 (dd,
Hz, 1 H, H2(pro-R)), 2.08 (s, 3 H, OAc), 1.39 (ddd, JH2(pro-R)–H2 (pro-S)
=
JH4–H5¢ = 5.6 Hz, JH5–H5¢ = 10.9 Hz, 1 H, H5¢), 2.77 (t, JH4–H5
JH5–H5¢ = 10.9 Hz, 1 H, H5), 1.98 (ddd, JH1–H2(pro-R) = 3.4 Hz,
JH2(pro-R)–H3 = 2.4 Hz, JH2(pro-R)–H2(pro-S) = 12.9 Hz, 1 H, H2(pro-R)), 1.67
=
12.8 Hz, JH2(pro-S)–H3 = 4.1 Hz, JH1–H2(pro-S) = 1.6 Hz, 1 H, H2(pro-S)).
13
C NMR (75 MHz, CDCl ): d = 144.3, 130.8, 129.9, 118.3, 117.9,
3
1
12.9, 71.3, 68.4, 60.8, 45.3, 29.6, 21.2.
(
1
ddd, JH1–H2(pro-S) = 1.9 Hz, JH2(pro-S)–H3 = 4.8 Hz, JH2(pro-R)–H2(pro-S)
2.9 Hz, 1 H, H2(pro-S)).
=
1
3
Acknowledgment
C NMR (75 MHz, DMSO-d ): d = 147.6, 130.4, 129.4, 119.2,
6
1
15.1, 112.9, 69.6, 67.4, 62.5, 48.8, 27.9.
S.M. and P.V.M. thank CSIR, New Delhi for the award of fel-
lowships.
HRMS: m/z calcd for C H NO : 191.0946; found: 191.0951.
1
1
13
2
(
2R,3R,6R)-3-Acetoxy-1,3,4,6-tetrahydro-2,6-methano-2H-5,1-
benzoxazocine (Ac-2a)
References
1
H NMR (500 MHz, CDCl ): d = 7.15 (ddd, JH9–H10 = 7.8 Hz,
3
(1) IICT Communication No. 060501.
JH8–H9 = 7.3 Hz, J
= 1.6 Hz, 1 H, H9), 7.11 (dd, JH7–H8 = 7.3 Hz,
H7–H9
(2) (a) Buonora, P.; Olsen, J. C.; Oh, T. Tetrahedron 2001, 57,
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JH8–H10 = 1.1 Hz, 1 H, H8), 6.62 (dd, JH9–H10 = 7.8 Hz, JH8–H10 = 1.1
Hz, 1 H, H10), 4.93 (ddd, JH4–H5 = 11.0 Hz, JH4–H5¢ = 6.0 Hz,
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.6 Hz, 1 H, H1), 4.46 (br s, NH, 1 H), 3.77 (ddd, JH2(pro-R)–H3 = 2.1
Hz, JH3–H4 = 3.1 Hz, JH2(pro-S)–H3 = 4.7 Hz, 1 H, H3), 3.75 (dd,
=
(
(
3) Ramesh, M.; Mohan, P. S.; Shanmugam, P. Tetrahedron
3
1984, 40, 4041.
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JH5–H5¢ = 11.0 Hz, 1 H, H5), 2.24 (ddd Hz, JH2(pro-R)–H2(pro-S) = 13.1
Hz, JH1–H2(pro-R) = 3.6 Hz, JH2(pro-R)–H3 = 2.1 Hz, 1 H, H2(pro-R)), 2.08
(
4
=
1177. (c) Johnson, J. V.; Rauckman, B. S.; Baccanari, D. P.;
s, 3 H, OAc), 1.96 (ddd, JH2(pro-R)–H2(pro-S) = 13.1 Hz, JH2(pro-S)–H3
.7 Hz, JH1–H2(pro-S) = 2.0 Hz, 1 H, H2(pro-S)).
=
Roth, B. J. Med. Chem. 1989, 32, 1942. (d) Mohamed, E.
A. Chem. Pap. 1994, 48, 261; Chem. Abstr., 1995, 123,
9315x.
1
3
C NMR (75 MHz, CDCl ): d = 145.6, 130.5, 129.8, 118.9, 117.2,
3
1
12.9, 72.4, 67.6, 58.8, 46.5, 28.0, 21.1.
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(
(
2R,3R,5R)-1,2,3,5-Tetrahydro-2,5-methano-4,1-benzox-
(6) Katritzky, A. R.; Rachwal, S.; Rachwal, B. Tetrahedron
1996, 52, 15031.
(7) (a) Povarov, L. S. Russ. Chem. Rev. 1967, 36, 656.
(b) Boger, D. L.; Weinreb, S. M. Hetero-Diels–Alder
Methodology in Organic Synthesis; Academic: San Diego,
1987, Chap. 2 and 9.
(8) (a) Dy(III)-catalyzed: Batey, R. A.; Powell, D. A.; Acton,
A.; Lough, A. J. Tetrahedron Lett. 2001, 42, 7935.
(b) Montmorillonite clay catalyzed: Yadav, J. S.; Reddy, B.
V. S.; Sadasiv, K.; Reddy, P. S. R. Tetrahedron Lett. 2002,
azepine-3-methanol (3a)
1
H NMR (500 MHz, DMSO-d ): d = 7.00 (ddd, JH7–H9 = 1.4 Hz,
6
JH8–H9 = 7.4 Hz, J
= 8.1 Hz, 1 H, H9), 6.97 (dd, JH7–H9 = 1.4
H9–H10
Hz, JH7–H8 = 7.4 Hz, 1 H, H7), 6.51 (dd, JH8–H10 = 1.2 Hz, JH9–H10 = 8.1
Hz, 1 H, H10), 6.46 (td, JH8–H10 = 1.2 Hz, JH7–H8 = JH8–H9 = 7.4 Hz,
1
H, H8), 6.29 (d, JNH–H3 = 4.6 Hz, NH, 1 H), 4.88 (br s, OH), 4.54
dd, JH1–H2(pro-S) = 1.9 Hz, JH1–H2(pro-R) = 3.3 Hz, 1 H, H1), 3.40 (ddt,
JH2(pro-R)–H3 = 2.3 Hz, JH2(pro-S)–H3 = 4.1 Hz, JH3–H4 = JNH–H3 = 4.6 Hz,
H, H3), 3.36 (dd, JH4–H5 = 1.2 Hz, JH5–H5¢ = 12.4 Hz, 1 H, H5), 3.27
ddt, JH4–H5 = 1.2 Hz, JH4–H5¢ = 2.0 Hz, JH3–H4 = 4.6 Hz, 1 H, H4),
.15 (dd, JH4–H5¢ = 2.0 Hz, JH5–H5¢ = 12.4 Hz, 1 H, H5¢), 2.45 (ddd,
(
1
(
3
43, 3853. (c) In Cl -catalyzed: Zhang, J.; Li, C.-J. J. Org.
Chem. 2002, 67, 3969. (d) In Cl -catalyzed: Li, Z.; Zhang,
3
3
JH2(pro-R)–H3 = 2.3 Hz, JH1–H2(pro-R) = 3.3 Hz, JH2(pro-R)–H2(pro-S) = 12.7
Hz, 1 H, H2(pro-R)), 1.25 (ddd, JH1–H2(pro-S) = 1.9 Hz, JH2(pro-S)–H3 = 4.1
Hz, JH2(pro-R)–H2(pro-S) = 12.7 Hz, 1 H, H2(pro-S)).
J.; Li, C.-J. Tetrahedron Lett. 2003, 44, 153.
(9) Clark, J. H. Acc. Chem. Res. 2002, 35, 791.
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(b) Kozhevnikov, I. V. Catal. Rev. Sci. Eng. 1995, 37, 311.
1
3
C NMR (75 MHz, DMSO-d ): d = 145.7, 130.1, 128.9, 118.0,
6
(
11) (a) Balogh, M.; Laszlo, P. In Organic Chemistry using Clay;
1
14.6, 112.2, 68.7, 67.7, 62.9, 46.9, 23.1.
Springer-Verlag: New York, 1993. (b) Laszlo, P. Science
+
MS (EI): m/z = 191 [M ], 162, 145, 119, 72, 57, 43.
1987, 235, 1473. (c) Laszlo, P. Pure Appl. Chem. 1990, 62,
HRMS: m/z calcd for C H NO : 191.0946; found: 191.0949.
2027. (d) Cornélis, A.; Laszlo, P. Synlett 1994, 155.
12) Molecular mechanics calculations were carried out using
1
1
13
2
(
Sybyl 6.8 programme on a silicon graphics O workstation.
2
Synthesis 2006, No. 17, 2923–2926 © Thieme Stuttgart · New York