Vapor phase synthesis of annelated pyridines over metal modified zeolite beta

Article abstract of DOI:10.1007/s10562-015-1598-0

Vapor phase synthesis of annelated pyridines from cyclic ketones, aldehydes and ammonia was carried out over various zeolite molecular sieves like Hβ, HZSM-5 (240), HZSM-5 (40), HY, HX, HMCM-41 and Mordenite. The preliminary screening of catalyst clearly shows that Hβ catalyst was found to be more active for the vapor phase synthesis of annelated pyridines. Hβ was further modified with transition metals like Fe, Cu, Pb, Mo, Zn, Ni, Co, Ce, W and Sn to get higher yields.

Full text of DOI:10.1007/s10562-015-1598-0

Catal Lett
DOI 10.1007/s10562-015-1598-0
Vapor Phase Synthesis of Annelated Pyridines over Metal
Modified Zeolite Beta
Arun Kumar Macharla1 Mahender Reddy Marri1 Swamy Peraka1
•
•
•
Naresh Mameda1 Srujana Kodumuri1 V. V. Krishna Mohan Kandepi1
Narender Nama1
•
•
•
Received: 2 June 2015 / Accepted: 24 July 2015
Ó Springer Science+Business Media New York 2015
Abstract Vapor phase synthesis of annelated pyridines
from cyclic ketones, aldehydes and ammonia was carried
out over various zeolite molecular sieves like Hb, HZSM-5
(240), HZSM-5 (40), HY, HX, HMCM-41 and Mordenite.
The preliminary screening of catalyst clearly shows that
Hb catalyst was found to be more active for the vapor
phase synthesis of annelated pyridines. Hb was further
modified with transition metals like Fe, Cu, Pb, Mo, Zn, Ni,
Co, Ce, W and Sn to get higher yields.
1 Introduction
Annelated pyridines and their derivatives are an important
class of organic compounds. They provide valuable syn-
thetic templates for the preparation of new compounds with
specific biological (anti-inflammatory agents [1, 2], anti-
bacterial agents [3], inhibitors of gastric acid secretion [4]
and calcium channel blockers [5]) or material properties.
Octahydroacridines and its derivatives are a class of com-
pounds with pharmacological interest [6–9] as illustrated
by the preparation of hydrogen-bonding synthetic receptors
and polydentate ligands from 1,2,3,4,5,6,7,8-octahy-
droacridine (3a) and 9-substituted octahydroacridine
derivatives [10]. They also play an important role in the
preparation of alkaloids, dyes, drugs and other biologically
active compounds with intriguing pharmacological and
therapeutic properties [11–13]. 1,2,3,5,6,7-hexahydrodicy-
clopenta[b,e] pyridine (3f) is an important anti-ulcer agent
[14].
Graphical Abstract
R
O
O
Zeolite, 350 oC
+
+
H
NH3
R
0.5 h-1 W.H.S.V
n
n
N
n
n = 1/2/3
R = H/Alkyl
Keywords Cyclization Á Annelated pyridines Á
Heterogeneous catalysis Á Impregnation Á Zeolites
Annelated pyridines are commonly prepared by the
condensation of cyclic ketones with an appropriate nitro-
gen containing species to build up the pyridine ring. Thus,
the Friedlander condensation of cyclopentanone or cyclo-
hexanone with b-aminoacrolein affords 2,3-fused pyridines
[7]. Conventionally, diannelated pyridines are prepared by
the partial hydrogenation of isooxazole over Raney nickel
catalyst to b-amino acrolein, further on Friedlander con-
densation with cyclopentanone gives 2,3-fused pyridines
[15]. bis-Annelated pyridines were synthesized in multi-
step by Tabyaoui et al. [16] using cycloalkane carbox-
aldehyde-NaN3-triphenylphosphines. Pilato et al. elabo-
rated a multi-step synthesis of octahydroacridines via
condensation of cyclohexanone with formaldehyde [10].
Electronic supplementary material The online version of this
article (doi:10.1007/s10562-015-1598-0) contains supplementary
material, which is available to authorized users.
& V. V. Krishna Mohan Kandepi
krizmohan@yahoo.com
& Narender Nama
narendern33@yahoo.co.in
Regas et al. described
a multi-step synthesis of
1
1,2,3,4,5,6,7,8-octahydro-9-methylacridine via an intra-
I&PC Division, CSIR-IICT, Hyderabad 500 007, India
123

A. K. Macharla et al.
R
N
shape selective character can promote a specific selectivity.
In addition to shape and size selective catalysis, the gen-
eration of acidic sites within the zeolite pores gives rise to a
highly efficient solid acid catalysis. The acid site formed,
behaves as a classic Brønsted acid site. Previously, syn-
thesis of a number of N-containing heterocyclic com-
pounds and annelated pyridines over zeolites has been
reported from our laboratory [20–23].
O
O
Zeolite, 350 oC
0.5 h-1 W.H.S.V
+
NH3
+
H
R
n
n
n
n = 1/2/3
R = H/Alkyl
Scheme 1 Synthesis of annelated pyridines
molecular hetero Diels–Alder reaction of vinyl allenes and
imines, followed by catalytic transfer hydrogenation of the
cyclic intermediate product [17]. Acridine substituted at C9
position with an alkyl or aryl group yielded all the three
hydrogenation products upon treatment with an Ni–Al
alloy in hydrochloric acid [18]. Recently, Borowski et al.
reported the synthesis of tetrahydro and octahydroacridines
by hydrogenation of acridines using bis(dihydrogen)
ruthenium complex [19].
In the present study we have synthesized the annelated
pyridines over zeolites in vapor phase conditions
(Scheme 1). Vapor phase synthesis using heterogeneous
catalysts is gaining importance due to many advantages in
comparison to homogenous catalysts such as continuous
production, simplified product recovery, easy catalyst
recovery and regeneration without liquid waste.
Unfortunately, most of the methods reported earlier
required several steps and the yields are very low. Obviously
an eco-friendly, single step synthetic method, which allows
entry into these annelated systems is highly desirable.
Indeed, there is substantial attention to design hetero-
geneous catalytic systems towards eco-friendly, selective
and shape selective reactions. In particular, microporous
solids like zeolites, besides their natural acidity and the
2 Experimental Section
2.1 Reagents and Materials
Zeolite b in ammonia form (NH4b) with SiO2/Al2O3 = 38
was purchased from Alfa Aesar. Ketones and aqueous
formaldehyde (37 %) were purchased from Sigma-Aldrich.
Table 1 Synthesis of 1,2,3,4,5,6,7,8-octahydroacridine: Variation of catalysta
Entry
Catalyst
TOS (h)
Conversion (%)b
Selectivity (%)b
3a
4a
Others
1
2
3
4
5
6
7
Hb
1
4
1
4
1
4
3
4
1
4
1
4
1
4
83
74
39
–
63
60
28
–
12
15
9
25
25
63
–
H-ZSM-5(240)
H-ZSM-5(40)
HY
–
99
66
82
79
67
66
99
99
54
54
41
34
43
40
27
14
32
39
67
65
6
53
59
51
52
56
70
57
44
25
25
6
6
8
HX
17
16
11
17
8
HMCM-41
Mordenite
10
Bold values are the best results under tested conditions
a
Cyclohexanone:Formaldehyde:Ammonia (1:1:5), Catalyst (4 g), Temperature = 350 °C, W.H.S.V = 0.5 h-1
Products were quantified by GC
b
123

Vapor Phase Synthesis of Annelated Pyridines over Metal Modified Zeolite Beta
Table 2 Synthesis of 1,2,3,4,5,6,7,8-octahydroacridine: effect of metal modified Hb zeolitea
Entry
Catalyst
TOS (h)
Conversion (%)b
Selectivity (%)b
3a
4a
Others
1
2
5wt% Feb
5wt% Cub
5wt% Pbb
5wt% Mob
5wt% Znb
5wt% Nib
5wt% Cob
5wt% Ceb
5wt% Wb
5wt% Snb
1
4
2
4
1
4
1
4
1
4
2
4
2
4
1
4
1
4
2
4
89
77
83
70
94
92
96
86
73
71
83
82
82
79
94
86
94
89
85
90
67
62
71
67
88
84
62
62
72
59
63
60
63
61
62
57
59
54
61
64
11
16
20
17
7
22
21
9
16
5
3
6
10
22
20
19
35
19
23
26
27
26
29
23
30
24
18
4
16
18
8
5
6
6
18
16
11
12
12
14
18
16
15
18
7
8
9
10
Bold values are the best results under tested conditions
a
Cyclohexanone:Formaldehyde:Ammonia (1:1:5), Catalyst (4 g), Temperature = 350 °C, W.H.S.V = 0.5 h-1
Products were quantified by GC
b
Table 3 Synthesis of 1,2,3,4,5,6,7,8-octahydroacridine: effect of reaction temperaturea
Entry
Temperature (°C)
TOS (h)
Conversion (%)b
Selectivity (%)b
3a
4a
Others
1
2
3
4
250
300
350
400
1
4
1
4
1
4
2
4
40
15
56
37
94
92
95
92
47
29
63
49
88
84
56
58
35
33
8
18
38
29
23
5
28
7
6
10
26
26
18
16
Bold values are the best results under tested conditions
a
Cyclohexanone:Formaldehyde:Ammonia (1:1:5), 5wt% Pbb (4 g), W.H.S.V = 0.5 h-1
b
Products were quantified by GC
Ammonia was used in the form of gas through manometer
impregnation using the metal precursors (Fe(NO3)3Á9H2O,
Cu(NO3)2Á3H2O, Pb(NO3)2, (NH4)6Mo7O24Á4H2O, Zn(NO3)3Á
6H2O, Ni(NO3)2Á6H2O, Co(NO3)2Á6H2O, Ce(NO3)3Á6H2O,
(NH4)6H2W12O40ÁXH2O and SnCl4Á5H2O) with various per-
centages (1, 3, 5, 7 and 10 wt%). Zeolite Hb was added to the
aqueous solution of corresponding metal salt (The ratio of
weight of the zeolite to the volume of distilled water used to
(Calibrated with flow meter).
2.2 Preparation of Catalyst
The zeolite NH4b was calcined at 500 °C for 10 h to obtain
zeolite Hb. Metal modified zeolite Hb was prepared by wet
123

A. K. Macharla et al.
Table 4 Synthesis of 1,2,3,4,5,6,7,8-octahydroacridine: Effect of molar ratioa
Entry
Molar ratio (1a:2a:NH3)
TOS (h)
Conversion (%)b
Selectivity (%)b
3a
4a
Others
1
2
3
4
5
6
7
8
9
10
1:0.5:5
1:1:5
1
4
1
4
1
4
2
4
3
4
3
4
3
4
2
4
3
4
2
4
82
81
94
92
93
89
99
85
99
99
73
66
85
83
86
87
79
82
68
60
68
60
88
84
55
53
49
49
53
47
59
55
67
61
56
54
52
50
55
46
15
16
24
5
15
7
6
10
25
31
36
39
32
38
28
37
15
19
27
28
33
37
34
43
1:1.5:5
1:2:5
20
16
15
12
15
15
13
8
1:2.5:5
1:0.5:3
1:1:3
18
20
17
18
15
13
11
11
1:1.5:3
1:2:3
1:1:1
Bold values are the best results under tested conditions
a
5wt% Pbb (4 g), Temperature = 350 °C, W.H.S.V = 0.5 h-1
Products were quantified by GC
b
overnight at 100 °C and calcined at 450 °C for 6 h in the
presence of static airflow before using it for the reaction. After
modification, each zeolite was pelleted, crushed and sized to
18-30 mesh.
100
80
60
40
20
0
2.3 Characterization of Catalysts
The temperature programmed desorption (TPD) of
ammonia of Hb and Pbb samples were measured using an
Auto Chem 2910 (Micromeritics, USA). In a typical
method about 0.1 g of calcined sample was degassed at
200 °C for 3 h in helium at a flow rate of 30 mL min-1.
After degassing the sample was saturated with 10 % NH3
(balance helium) at 60 °C, at a flow rate of 50 mL min-1
and subsequently flushed with helium gas at 60 °C for 1 h.
The TPD measurements were carried out from 60 to
700 °C at a ramping rate of 10 °C min-1. The amount of
desorbed NH3 was calculated using GRAMS/32 software.
0.00
0.25
0.50
0.75
1.00
1.25
WHSV
Conversion of 1a
Selectivity of 3a
Others
Selectivity of 4a
Fig. 1 Effect of WHSV on the cyclization of 1a with 2a and NH3.
Catalyst = 5 wt% Pbb; reaction
1a:2a:NH3 = 1:1:5 (mole ratio); time on stream = 1 h
temperature = 350 °C;
2.4 General Procedure for the Synthesis
of Annelated Pyridines
dissolve the metal salt was 1:3), then it was mixed homoge-
nously with glass rod and was placed on hot plate to remove
excess water. After impregnation, the catalyst was dried
All the experiments were carried out in a fixed-bed Pyrex
glass reactor (20 mm inner diameter and 60 cm height)
123

Vapor Phase Synthesis of Annelated Pyridines over Metal Modified Zeolite Beta
100
reactants mixture. The products from the reactor were
cooled using ice-cold water and periodically collected at
the bottom. The products were analyzed by gas chro-
matography using SE-30 (30 %) column and purified by
column chromatography over silica gel (100–200 mesh).
90
80
70
60
50
40
30
20
10
0
1
All the products were characterized by H NMR and 13C
NMR spectroscopy.
3 Results and Discussion
3.1 Catalyst Screening
3.1.1 Synthesis of 1,2,3,4,5,6,7,8-octahydroacridine (3a)
Over Unmodified Zeolites
0
2
4
6
8
10
Wt% of Pb
The cyclization reaction of cyclohexanone (1a),
formaldehyde (2a) and ammonia was carried out over
various catalysts such as Hb, H-ZSM-5(240), H-ZSM-
5(40), HY, HX, HMCM-41 and Mordenite (Table 1).
Based on the preliminary studies carried out over these
catalysts, Hb showed 83 % conversion of 1a with 63 % of
3a selectivity. However, H-ZSM-5(40) and HMCM-41
afforded relatively higher conversions with lower product
selectivity. The results of 4th hour time on stream were
also given for all the catalysts for comparison.
Conversion of 1a
Selectivity of 3a
Selectivity of 4a
Others
Fig. 2 Effect of wt% of Pb over Hb zeolite on the cyclization of 1a
with
2a
and
NH3;
reaction
temperature = 350 °C;
1a:2a:NH3 = 1:1:5 (mole ratio); WHSV = 0.5 h-1
stream = 1 h
;
time on
100
80
60
40
20
0
Large pore zeolites like Hb, is having Brønsted acid
sites inside their micropores and on the external surface as
well, whereas Lewis acid sites predominantly located at the
internal surface due to local defects [24]. Higher selectivity
obtained over Hb catalyst indicates the presence of suitable
acid sites for the formation of 3a. Thus the total acidity,
acid site strength and the pore size of the zeolite were
governing the activity and selectivity of the cyclization
reaction.
3.1.2 Synthesis of 1,2,3,4,5,6,7,8-octahydroacridine Over
Modified Hb-Zeolite
0
2
4
6
8
10
Time (h)
Although many zeolitic structures are extensively investi-
gated, metal modified zeolite b has not been yet widely
explored [25]. It is well acknowledged that the metal ion
modification in zeolite manipulates the total acidity, acid
site strength and the nature of acid sites [26]. Next, our
efforts focused on achieving the highest conversion of 1a
and selectivity of 3a.
Conversion of 1a
Selectivity of 3a
Selectivity of 4a
Fig. 3 Effect of time on stream on the cyclization of 1a with 2a and
NH3. Catalyst = 5 wt% Pbb; reaction temperature = 350 °C;
1a:2a:NH3 = 1:1:5 (mole ratio); WHSV = 0.5 h-1
Then we investigated cyclization reaction using Hb
zeolite modified with various transition metal ions and
results are presented in Table 2. It is, however, clear from
this table that Pbb exhibits much higher activity than that
with other transition metal modified Hb zeolites (Table 2,
entry 3).
with a continuous down flow. The amount of catalyst taken
for all reactions was 4 g. The catalyst bed temperature was
measured with a thermocouple placed in the middle of the
catalyst bed. The reactants mixture was fed from the top of
the reactor using a syringe pump (B.Braun, USA).
Ammonia gas was fed into the reactor parallel to the
123

A. K. Macharla et al.
Table 5 Synthesis of annelated pyridines with various aldehydesa
Entry
R
TOS (h)
Conversion (%)b
Selectivity (%)b
Yield (%)c
3
4
Others
3
4
1
2
3
4
5
a
H (2a)
1
4
1
4
1
4
1
4
1
4
94
92
88
96
90
89
92
91
91
89
88 (3a)
84
7 (4a)
10
5
79
72
44
43
19
16
18
13
12
16
5
6
7
CH3 (2b)
55 (3b)
49
27 (4b)
28
18
23
39
44
43
37
84
79
21
24
31
25
29
38
–
CH3CH2 (2c)
CH3CH2CH2 (2d)
CH3CH(CH3) (2e)
24 (3c)
20
37 (4c)
32
22 (3d)
17
35 (4d)
46
16 (3e)
21
– (4e)
–
–
Cyclohexanone:Aldehyde:Ammonia (1:1:5), 5 %Pbb (4 g), Temperature = 350 °C, W.H.S.V = 0.5 h-1
Products were quantified by GC
b
c
Isolated yields
Table 6 Synthesis of annelated pyridines with various ketonesa
O
O
n
5 wt% Pb Beta
+
+
NH
3
+
H
H
350 oC
n
n
n
N
3
n
N
4
0.5 h-1 w.H.S.V
2a
1
Entry
n
TOS (h)
Conversion (%)b
Selectivity (%)b
3
4
Others
1
2
3
a
1 (1b)
2 (1a)
3 (1c)
1
4
1
4
1
4
72
56
94
92
95
91
49 (3f)
51
18 (4f)
33
34
5
15
88 (3a)
84
7 (4a)
10
6
86 (3g)
73
5 (4g)
4
9
23
Ketone:Formaldehyde:Ammonia (1:1:5), 5 % Pbb (4 g), Temperature = 350 °C, W.H.S.V = 0.5 h-1
Products were quantified by GC
b
Pbb catalyst at 0.5 h-1 WHSV in the temperature range of
250-400 °C. The conversions of 1a were 40, 56, 94 and
95 % and the selectivity of 3a were 47, 63, 88 and 56 % at
reaction temperatures 250, 300, 350 and 400 °C, respec-
tively (Table 3). The conversion of 1a was increased with
increase in reaction temperature from 250 to 400 °C and
higher selectivity of 3a was observed at 350 °C.
3.2 Optimization of Reaction Conditions
The effect of other parameters like reaction temperature,
feed molar ratio, space velocity and metal content was
studied further using Pbb to optimize the reaction condi-
tions. The experimental data regarding the effect of reac-
tion temperature was presented in Table 3. The cyclization
reaction was carried out using 1:1:5 molar ratio of cyclo-
hexanone, formaldehyde and NH3 (feed) over 4 g of 5 %
The effect of molar ratio of the feed over 5 % Pbb
catalyst was listed in Table 4. The results indicate that the
123

Vapor Phase Synthesis of Annelated Pyridines over Metal Modified Zeolite Beta
1–5), whereas the increase in concentration of ammonia
resulted in higher selectivity of the desired product 3a
(Table 4, entries 2, 7, 10).
The effect of WHSV on the cyclization of 1a with 2a
and NH3 was studied from 0.25 to 1 h-1 and the results are
shown in Fig. 1. The maximum selectivity of the product
3a was obtained at 0.5 h-1 WHSV. Upon further increase
in WHSV, conversion of cyclohexanone (1a) and selec-
tivity of 3a were decreased. This might be due to the less
contact time between the reactant and the catalyst.
The reaction was carried out over 1, 3, 5, 7 and 10 wt%
Pb-modified Hb zeolites and the results are shown in
Fig. 2. The 5 wt% Pb-modified Hb zeolite was found to be
more active for this cyclization reaction to form 3a. Further
increase in the wt% of Pb decreased the both catalytic
activity and selectivity. This might be due to the blocking
of active sites by excess loading.
The time on stream was studied at 350 °C and 0.5 h-1
WHSV for 10 h duration and the results are shown in
Fig. 3. The conversion of 1a and selectivity for 3a is stable
for the initial 4 h and slowly decreased with time. Deac-
tivation of the catalyst is observed over the time, this might
be because of accumulation of coke on active sites.
Fig. 4 NH3-TPD profiles: a Pbb b Hb
Table 7 Desorption of ammonia of Hb and 5 % Pbb at different
acidic regionsa
Catalysts Aciditya (mmol/g) Acidic sitesbdistribution
LT-peakc MT-peakc HT-peakc
3.3 Cyclization of Cyclohexanone with Various
Aldehydes
Hb
0.47
25.4
55.3
74.6
41.6
–
5 % Pbb 0.63
3.1
This strategy has been extended by varying the aldehyde.
Surprisingly, increase in alkyl chain length of the aldehyde,
the selectivity of corresponding 9-substituted octahy-
droacridines (3) were decreased and 6-substituted octahy-
drophenanthridines (4) were increased (Table 5). This may
be due to the restriction of the transition state by the
channels of the zeolites [27], i.e., the transition state for the
reactions that yields 9-substituted octahydroacridines were
too large to be accommodated within the pores of the
zeolites used in this reaction.
a
Total acidity amount determined by NH3-TPD
The NH3-TPD (%) distribution of acidic sites
b
c
LT-peak represents weak acid sites (150–250 °C), MT-peak rep-
resents medium acid sites (250–550 °C) and HT-peak represents
strong acid sites (550–650 °C)
Table 8 Synthesis of 1,2,3,4,5,6,7,8-octahydroacridine: Catalyst
reusability studya
Entry Cycle
TOS (h) Conversion (%)b Selectivity (%)b
3a 4a Others
3.4 Cyclization with Various Cyclic Ketones
1
2
3
a
1st use
2nd use
3rd use
1
4
1
4
1
4
94
92
95
97
93
91
88
84
85
84
86
83
7
8
9
7
5
9
5
8
6
9
9
8
This novel method for the cyclization reaction was applied
to a variety of cyclic ketones over 5 wt% Pbb catalyst. As
shown in Table 6, cyclopentanone (1b), cyclohexanone
(1a) and cycloheptanone (1c) undergo cyclization to pro-
vide the corresponding annelated pyridines in moderate to
excellent selectivities.
Cyclohexanone:Formaldehyde:Ammonia (1:1:5), 5wt% Pbb (4 g),
Temperature = 350 °C, W.H.S.V = 0.5 h-1
b
Products were quantified by GC
3.5 Temperature Programmed Desorption
of Ammonia (NH3-TPD)
optimum molar ratio of 1a, 2a and ammonia is 1:1:5. At
this molar ratio, the highest selectivity of 3a was obtained
(Table 4, entry 2). Higher concentration of 2a resulted in
lower selectivity of the desired product 3a (Table 4, entries
The TPD-NH3 profiles of Hb and 5 % Pbb catalysts are
given in Fig. 4 and the respective results of total acidity are
shown in Table 7. As can be seen from Table 7, total
123

A. K. Macharla et al.
Scheme 2 The plausible
reaction mechanism
acidity and acid site strength are enhanced upon modifi-
Similar reaction mechanism could be practiced to other
products by varying the number of carbon atoms in the
cyclic ketones and aldehyde.
cation of Hb with Pb metal ion.
3.6 Reusability of the Catalyst
The Pbb catalyst was regenerated by calcined at 400 °C for
4 h under air flow and reused. The catalyst was tested for
three cycles and reproducible results were obtained. The
results were depicted in Table 8.
4 Conclusion
In conclusion, the present protocol demonstrates Pbb zeolite
as an effective catalyst for the synthesis of 1,2,3,4,5,6,7,8-
octahydroacridine, 9-substituted octahydroacridines and
other annelated pyridines using simple reactants such as
cyclic ketones, aliphatic aldehydes and ammonia under
vapor phase conditions. Notable advantages offered by this
method are single step (step economic) synthesis of anne-
lated pyridines, inexpensive and environmentally friendly
catalysts and commercially available reactants makes this
method valuable from a preparative point of view.
3.7 Reaction Mechanism
Proposed reaction mechanism for the formation of anne-
lated pyridines via intermolecular cyclization of
cyclopentanone, formaldehyde and ammonia is depicted in
Scheme 2. The Brønsted acidic centers present at the
intersections of the zeolites are expected to be active sites
for the formation of hemiaminal (I). The carbonyl group of
the cyclopentanone is protonated by zeolite, which leads to
the formation of hemiaminal (I) via nucleophilic addition.
However, hemiaminal is an intermediate for the formation
of imine, due to strong basic condition of the reaction
mixture, it further reacts with another ketone to afford the
intermediate N-(1-cyclopentenyl)-N-cyclopentylidenamine
(II). The p electrons from the intermediate (II), reacts with
the carbocation formed by the protonation of aldehyde by
zeolite. Further loss of water and hydrogen afford the final
product 1,2,3,5,6,7-hexahydrodicyclopenta[b,e] pyridine.
Acknowledgments We thank the CSIR Network project CSC-0123
for financial support. M.A.K., M.M.R. and M.N., thank the CSIR and.
P.S. and K.S. the UGC, India for a fellowship.
References
1. Maruyama Y, Anami K, Kotoh Y (1978) Arzneim Forsch
28:2102
2. Maruyama Y, Anami K, Terasawa M, Goto K, Imayoshi T,
Kodobe Y, Mizushima Y (1981) Arzneim Forsch 31:1111
123

Vapor Phase Synthesis of Annelated Pyridines over Metal Modified Zeolite Beta
3. Rival Y, Grassy G, Michel G (1992) Chem Pharm Bull 40:1170
4. Kaminski JJ, Wallmark B, Andersson BM (1991) J Med Chem
34:533
16. Tabyaoui B, Aubert T, Farniar M, Guilard R (1988) Synth
Commun 18:1475
´
17. Regas D, Afonso MM, Palenzuela JA (2004) Synthesis 5:757
5. Sanfilippo PJ, Urbanski M, Press JB, Dubinsky B, Moore JB
(1988) J Med Chem 31:2221
18. Kamata K, Tominaga Y, Tori-i A, Thiemann T, Mataka S (1998)
Heterocycles 48:1663
6. Wainwright M (2001) J Antimicrob Chemother 47:1
7. Chiron J, Galy J-P (2003) Heterocycles 60:1653
8. McKenna MT, Proctor GR, Young LC, Harvey AL (1997) J Med
Chem 40:3516
19. Borowski AF, Vendier L, Sabo-Etienne S, Rozycka-Sokolowskab
E, Gaudynb AV (2012) Dalton Trans 41:14117
20. Narender N, Srinivasu P, Kulkarni SJ, Raghavan KV (2001) J
Catal 202:430
9. Wang S-J, Huang C-C (1996) Neuroscience 70:409
10. Pilato ML, Catalano VJ, Bell TW (2001) J Org Chem 66:1525
11. Canas-Rodriguez A, Canas RG, Mateo-Bernardo A (1988) Chem
Abstr 108:112191t
21. Narender N, Suresh Kumar Reddy K, Krishna Mohan KVV,
Kulkarni SJ (2009) Catal Lett 130:367
22. Krishna Mohan KVV, Suresh Kumar Reddy K, Narender N,
Kulkarni SJ (2009) J Mol Catal A 298:99
12. Adrien A (1951) Acridines; their preparation, physical, chemical
and biological properties and uses. Interscience Publishers Ltd.,
London
13. Acheson RM, Orgel LE (1956) Acridines. Interscience Publishers
Inc., New York
14. Curran ACW (Wyth, John and Brother Ltd.) U.S. 3,963,722 (CL.
260-283 R; C07 D 215/16), June 1976 (Chem. Abstr. 86 (1977)
5334)
23. Krishna Mohan KVV, Narender N, Kulkarni SJ (2007) Microp-
orous Mesoporous Mater 106:229
24. Jansen JC, Creyghton EJ, Njo SL, Van Koningsveld H, Van-
Bekkum H (1997) Catal Today 38:205
25. Armor JN (1998) Microporous Mesoporous Mater 22:451
26. Cruz-Cabeza AJ, Esquivel D, Jimenez-Sanchidrian C, Romero-
Salguero FJ (2012) Materials 5:121
27. Weitkamp J, Puppe L (eds) (1999) Catalysis and zeolites: fun-
damentals and applications. Springer-Verlag, Berlin, p 343
15. Thummel RP, Kohli DK (1977) J Org Chem 421:2742
123