Efficient solvent free synthesis of tertiary α-aminophosphonates using H2Ti3O7 nanotubes as a reusable solid-acid catalyst

Article abstract of DOI:10.1039/c5nj01914a

In this paper, TiO₂ fine particles, TiO₂-P25, protonated trititanate (H₂Ti₃O₇) nanorods and nanotubes were used as recyclable solid-acid catalysts for the solvent free synthesis of tertiary α-aminopho

Full text of DOI:10.1039/c5nj01914a

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: V. G. R.
Peddiahgari, R. P. R. Bhoomireddy and N. R. Bijivemula, New J. Chem., 2015, DOI: 10.1039/C5NJ01914A.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/njc

Please do not adjust margins
New Journal of Chemistry
Page 1 of 7
View Article Online
DOI: 10.1039/C5NJ01914A
NJC
COMMUNICATION
Efficient solvent free synthesis of tertiary α-aminophosphonates
using H2Ti3O7 nanotubes as a reusable solid-acid catalyst
Bhoomireddy Rajendra Prasad Reddy,a Peddiahgari Vasu Govardhana Reddy*a and Bijivemula. N.
Reddyb
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
In this paper, TiO2 fine particles, TiO2-P25, protonated trititanate intriguing properties which are different from those of their
(H2Ti3O7) nanorods and nanotubes were used as recyclable solid- corresponding bulk materials. Metal and metal oxide
acid catalysts for the solvent free synthesis of tertiary nanoparticles characteristically have high surface area that
α-aminophosphonates through Kabachnik-Fields reaction. Among translate into more active sites per unit area and can maximize
them, H2Ti3O7 nanotubes showed the remarkable catalytic the reaction rates while minimizing the requirement of the
performance and it was due to strong and sufficient Lewis and catalyst. The easy preparation process and stability in air are
Brønsted acid sites on large nanotubular surface. More advantageous features that make the nanoparticles of metal
importantly, for the first time we reported some novel 5,8-dioxa- oxides or mixed metal oxides are widely reported and there
10-azadispiro[2.0.4.3]undecane bearing tertiary
phosphonates.
α-amino- are excellent examples of their applications as catalysts. In
recent years α-aminophosphonates are synthesized by using
metal or metal oxide nanoparticles as catalysts such as Cu-
nanoparticle,3i
3k
nanoceria,3j
nanoFe3O4,
MgFe2O4
3n
nanoparticles,3l γ-Fe2O3@SiO2-PA,3m DHAA-Fe3O4
and
Introduction
Fe/SWCNTs3o are reported in the literature. Owing to these
attractive features that of nano material catalysts, we have
focused on titanium oxide nanomaterials, since TiO2 contains
Lewis acid sites and titanium being the second most abundant
transition metal (ninth of all elements) in the Earth’s crust.
Among titanium oxide materials, one dimensional TiO2
nanostructures such as nanotubes, nanorods and nanowires4a-c
aimed much attention due to their unique properties viz., large
surface-to-volume-ratio, better dispersibility, decreased inter-
crystalline contacts and increased accessibility of Lewis and
Brønsted acid sites.5a-c Protonated trititanate nanotubes and
nanorods are synthesized by the hydrothermal treatment of
TiO2 in a basic aqueous solution, followed by H+-exchange, a
simple method requiring neither expensive apparatus nor
special chemicals. One dimensional TiO2 nanostructures have
been extensively investigated in areas such as organo catalysis,
photo catalysis, electro catalysis, sensors, and lithium
batteries.6a, 6bIn the field of catalysis, most of the studies for
the material are directed towards the utilization of the
material as a support with a large surface area. However, the
acid catalytic properties of the protonated trititanate
nanotubes and nanorods have not yet been investigated in
detail.
α-Aminophosphonate motifs have remarkable biological
activities such as antitumor agents,1a anti-leishmanial agents,1b
antitubercular agents,1c antiviral agents,1d fungicides,1e
bactericides,1f enzyme inhibitors,1g peptide mimetics,1h
herbicides,1i anti-HIV agents and plant growth regulators.1k
1j
Significant efforts have been made in the last few decades to
improve the biological features of α-aminophosphonates as
key moieties in life sciences, pharmaceuticals and agriculture.
In spite of their significance, various protocols have been
developed for their synthesis using a variety of catalysts such
as
phosphomolybdic
acid
(PMA),2a silica-supported
dodecatungstophosphoric acid (DTP/SiO2),1c graphene oxide,2b
silica-supported boron trifluoride (BF3.SiO2),2c propyl-
phosphonic anhydride (T3P),2d ytterbium triflate Yb(OTf)3,2e
molybdenum trioxide (MoO3),2f H-beta zeolite,2g zinc
dichromate trihydrate (ZnCr2O7·3H2O).2h
Recently, the use of nanoparticles as catalysts in organic
reactions has attracted much attention,3a-oowing to their
In this study, TiO2 fine particle (TFP), TiO2-P25 (TNP),
protonated trititanate (H2Ti3O7) nanorods (TNR) and
nanotubes (TNT) were used as solid acid catalysts for the
This journal is © The Royal Society of Chemistry 2015
New J. Chem., 2015, 00, 1-6 | 1
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 2 of 7
View Article Online
DOI: 10.1039/C5NJ01914A
COMMUNICATION
NJC
synthesis of tertiary α-aminophosphonates by one-pot, three- Fig. S2 and Fig. 2 displays XRD pattern of standard TFP, TNP, TNR
component coupling of aldehydes, secondary amines and and TNT. The diffraction pattern of TNT catalyst exhibited four
phosphites via Kabachnik-Fields reaction under solvent free characteristic peaks at 2θ = 10.2, 24.1, 28.3, and 48.2⁰ indicating
conditions. Further, we also extended these applications for the monoclinic structure of layered H2Ti3O7 (JCPDS No.47-0561 and
the synthesis of 5,8-dioxa-10-azadispiro[2.0.4.3]undecane 31-1329).
bearing α-aminophosphonates.
N2 adsorption-desorption isotherms of TNP, TNR and TNT are
shown in Fig. S3. Among the three catalysts TNT shows a hysteresis
Results and Discussion
loops at relative low pressure P/P0 ≥ 0.8 which indicates the
8b
presence of porous structure in nanotubues.8a, The multi-point
Characterization of TiO2 nano structured catalysts
BET surface area values of TFP, TNP, TNR and TNT listed in Table 1.
TNR and TNT were prepared by hydrothermal method7 using TFP as
The surface area of the catalyst decreases in the following order
TNT > TNP > TNR > TFP.
raw material. The nanoparticles and nanostructures of TiO2 were
characterized by HR-TEM (Fig. S1a-d, Fig. 1), XRD (Fig. S2, Fig. 2).
Pore size distribution curve of the TNT (Fig. S4) supported the
The surface area measurements and pore size of the TNP, TNR and
observation of HR-TEM image and variation in BET surface area. The
TNT were evaluated on Micromeritics ASAP 2000 equipment, using
TNT exhibited distinct pore size distribution curve, which comprised
N2 as the adsorption-desorption gas (Fig. S3). The surface area was
of two portions with peak values of ca. 2.1 to 4.2 nm and 4.2 to 23
calculated using the BET method while BJH method was used for
nm, respectively. Taking into account of the morphology of TNT, the
the pore size distribution (Fig. S4). The quantitative analysis of both
smaller pores could be attributed to the inner wall of the
Lewis and Brønsted acid sites were determined by using Ammonia-
nanotubes, with its size similar to the inner diameter of the
TPD method (Fig. S5). (Fig. S1 to Fig. S5 are associated with
nanotubes; while, the larger pores should refer to the pores
supporting information).
9b
between the nanotubes.9a,
TFP, TNP and TNR are non porous
materials.
Fig. S1a-d and Fig. 1 shows HR-TEM images of TFP, TNP, TNR and
TNT. Fig. 1a displays bundles of TNT catalysts having one
dimensional morphology with openings at both the ends. Dark
spots at random orientation reveal the overlapping of tubes with
each other. Fig. 1b confirms the one dimensional hollow tubes
having 5 layers with ∼ 2 nm diameter and length > 100 nm.
The NH3 desorption spectrum of TNT and TNR (Fig. S5) consists of
two unresolved peaks (at 160.9oC and 302 C for TNT; at 148.8 oC
o
(very low intense peak) and 326.1 oC for TNR).The low temperature
peak can be assigned to NH3 desorption from weakly acidic
Brønsted sites, while high-temperature peak is related to NH3
desorption from strongly acidic Lewis sites10a-d, whereas TFP and
TNP showed NH3 desorption peak at 288oC and 276.8oC (Fig. S5)
respectively which correspond to Lewis acidic sites.11a, 11bFurther
the quantity of NH3 desorption were depicted in Table 1. The
enhancement of NH3 desorption quantity confirms the formation of
nanotubular structure with high surface area and higher
concentration of Brønsted and Lewis acid sites.
Catalytic activity
Fig. 1 HR-TEM image of TNT.
After the successful preparation and characterization of the TFP,
TNP, TNR and TNT, we examined their catalytic activity in the
Kabachnik-Fields reaction. In order to establish the optimal
condition, the catalytic activities of TFP, TNP, TNR and TNT were
examined in a model reaction using benzaldehyde, morpholine and
diethyl phosphite under solvent free condition and at room
temperature for 15 min via
a three-component reaction.
Encouragingly, all the reactions led to the desired product with
variable yields, the highest yield has been observed with TNT
catalyst (Table 1). Superior results with TNT are due to the presence
of high concentration of Lewis and Brønsted acid sites on large
surface area. Ranu et al.12a and Rao et al.12b etc. reported that Lewis
acidity is a primary requisite for Kabachnik-Fields reaction. Similarly,
Fuchide et al.13 demonstrated Brønsted acid-mediated Kabachnik-
Fields reaction. Above reports illustrate that Brønsted and Lewis
acidity is responsible for this reaction. In contrast, no product was
detected in the absence of a TiO2 catalyst, thus suggesting the
essential role of TiO2 catalyst in the Kabachnik-Fields reaction.
Fig. 2 XRD pattern of TNT.
2 | New J.Chem., 2015, 00, 1-6
This journal is © The Royal Society of Chemistry 2015
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 3 of 7
View Article Online
DOI: 10.1039/C5NJ01914A
NJC
COMMUNICATION
The catalytic performance can be explained in terms of catalytic all the three-component coupling reactions were performed under
active Lewis and Brønsted acid sites and surface area of the catalyst solvent free conditions.
(Table 1). Both TFP and TNP mainly composed of anatase phase, the
higher surface area and higher Lewis acid sites of TNP beneficial for
obtaining higher yield than TFP. Though surface area of TNR is
nearly 50% lower than TNP, TNR exhibited higher activity due to
H2Ti3O7 crystal structure, one dimensional morphology, less
agglomeration and more acid sites than TNP catalyst. Likewise, TNT
catalyst has similar crystal structure but one dimensional
morphology with hollow inner space evidenced higher surface area
than TNR itself. Surface area of TNT is about 11 folds higher than
TNR and having high concentration of Lewis and Brønsted acid sites
are responsible for better catalytic activity of TNT than TNR.
Table 1. Physical properties of various Ti-O based nanostructures
and catalytic activity for Kabachnik-Fields reaction
Acid concentrationb
Fig. 3 Investigation of TNT loading on Kabachnik-Fields reaction
Catalyst
TFP
SBET (m2 g-1)
5.1
Yield (%)a
15
BASc
LASd
Table 2. Optimization of solvents.
n.d.
0.006
Entry
1.
Solvent
Yield (%)a
97
TNP
TNR
TNT
A.Ce
51
24
n.d.
0.046
1.613
---
0.445
1.510
2.162
---
35
57
95
0
Toluene
Acetonitrile
Ethanol
DMF
2.
3.
4.
5.
6.
7.
80
50
5
286
---
Reaction conditions: Catalyst (5 mol%), benzaldehyde (0.5 mmol),
morpholine (0.5 mmol), diethyl phosphite (0.5 mmol), and solvent free
DMSO
0
a
b
(5mL). Product yield measured after the reaction at rt, 15 min. The acid
Water
0
concentrations of the titania nanostructures were estimated from the NH3-
TPD in mmol.g-1
c
d
Neat
95
.
Brønsted acid sites. Lewis acid sites. n.d. = not
detected. A.C = Absence of catalyst. eReaction continued up to 12 h.
Reaction conditions: Benzaldehyde (0.5 mmol), morpholine (0.5 mmol) and
diethyl phosphite (0.5 mmol), solvent (3 mL), r.t and TNT (5 mol%) quenched
after 15 min.a Isolated yield.
Besides this, we observed that the concentration of the catalyst
played a major role in catalyzing the one-pot three component
Kabachnik-Fields reaction. Upon varying the concentration of TNT
by using the model reaction as described above, it was observed
from Fig. 3 that 5 mol% of the TNT afforded the optimum reaction
rate and yield. When 2, 3 and 4 mol% of TNT respectively was used,
the reaction was incomplete. However, no significant improvement
was observed with 6 mol% of TNT.
With the optimized conditions in hand, the activity of the TNT
catalyst in the Kabachnik-Fields reaction of a number of aldehydes,
secondary amines and dimethyl/diethyl phosphites was
investigated (Table 3). As shown, benzaldehyde delivered good to
excellent yields of the corresponding α-aminophosphonates (Table
3, entries 1, 2 and 11-16). Aromatic aldehydes substituted at the
phenyl ring with MeO, Me, Cl and Br were all converted into the
corresponding α-aminophosphonates efficiently, indicating no
remarkable electronic and position effects of the substituents on
the reaction (Table 3, entries 3-6). Cinnamaldehyde and furan-2-
carbaldehyde were successfully coupled with morpholine and
To check the solvent effect on the outcome of the reaction, the
above model reaction was performed with 5 mol% of TNT in various
solvents such as toluene, acetonitrile, ethanol, DMF, DMSO, and
water at room temperature (Table 2). From Table 2, it is evidenced
that toluene is the best solvent (Table 2, entry 1), whereas
acetonitrile affords a lower yield (Table 2, entry 2). Moderate yields
were obtained when the reaction was performed in ethanol (Table
2, entry 3) and a poor result was observed with DMF (Table 2, entry
4). DMSO and water did not afford desired product (Table 2, entries
5 and 6). It is quite interesting to note that the reaction also took
place smoothly under solvent free conditions and generated the
corresponding α-aminophosphonate in excellent yield. To avoid the
use of volatile solvents and to reduce the environmental pollution,
dimethyl
phosphite
to
afford
the
corresponding
α-aminophosphonates smoothly (Table 3, entries 7 and 8). It is
noteworthy that pivalaldehyde and cyclohexanecarbaldehyde
(aliphatic aldehydes) afforded the desired products in good yields as
well (Table 3, entries
9 and 10). Several types of aliphatic
cyclic/acyclic secondary amines can be used in this study. The
coupling (except for entry 15) proceeded smoothly to lend the
corresponding α-aminophosphonates in good to excellent yields
This journal is © The Royal Society of Chemistry 2015
New J.Chem., 2013, 00, 1-6 | 3
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 4 of 7
View Article Online
DOI: 10.1039/C5NJ01914A
COMMUNICATION
NJC
Table 3. Synthesis of tertiary α-aminophosphonates by the reaction high efficiency of TNT catalyst for the preparation of broad range of
of various aldehydes, secondary amines and dimethyl/diethyl α-amino- phosphonates.
phosphites in the presence of TNT.
R2
R1
R3
O
R2
R3
+
N
TNT (5 mol%)
R1 CHO
+
N
H
R4O P H
OR4
OR4
Neat, R.T, 15 min
P
O
OR4
Entry
1
R1
R2R3NH
Morpholine
R4
Yield (%)a, Ref
9515,16
Ph
Me
2
3
Ph
Morpholine
Morpholine
Morpholine
Morpholine
Morpholine
Morpholine
Morpholine
Morpholine
Morpholine
Pyrrolidine
Piperidine
R2,R3 = Me
R2,R3 = Et
R2,R3 = i-Pr
R2,R3 = Bn
S3
Et
Me
Et
9517
9718
9517
9717
8917
9316
8716
8916
9016
8515
9217
9519
9517
017
4-OMe-C6H4
4
4-Me-C6H4
5
4-Cl-C6H4
Et
Fig. 4 The recycling experiment of TNT in Kabachnik-Fields reaction
6
3-Br-C6H4
Et
for Table 3 and entry 2; carried out at r.t for 15 min.
7
C6H5-CH=CH
Me
Me
Me
Me
Me
Et
8
2-Furan
9
t-Bu
10
11
12
13
14
15b
16
17
18
19
20
Cy
Ph
Ph
Ph
Me
Et
Ph
Ph
Et
Ph
2-Thiophene
2-Thiophene
S1
Et
9517
95
Et
S3
n-Bu
n-Bu
Et
93
S3
86
S2
S3
80
Fig. 5 NH3-TPD of (a) Fresh TNT and (b) Reused TNT after seventh
Reaction conditions: Aldehyde (0.5 mmol), amine (0.5 mmol) and dialkyl
phosphite (0.5 mmol), solvent free, r.t and 5 mol% TNT quenched after 15
cycle.
a
b
min. Isolated yield; reaction continued up to 12 h. S1, S2 and S3 are 2,6-
dimethoxynicotinaldehyde, 3-(pyrimidin-5-yl)benzaldehyde and 5,8-dioxa-
10-azadispiro[2.0.4.3]undecane respectively.
To evaluate the reactivity and reusability of the TNT nanocatalyst
during the reaction, in the next study a series of seven consecutive
runs of the Kabachnik-Fields reaction of benzaldehyde, morpholine
and diethyl phosphite were performed. To do this, after the
completion of reaction, the reaction mixture was dissolved in EtOAc
(2mL), centrifuged to precipitate the TNT and decanted the organic
layer containing the desired product. The obtained precipitate was
washed twice with EtOAc to avoid loss of product, dried at 100oC
and reused in a subsequent reaction. Smooth loss of activity was
observed from fifth time of reuse i.e incomplete conversion of
reactants was observed after 15 min. It was due to the decrease in
concentration of acid sites (Fig. 4 and Fig. 5). After seventh cycle,
(Table 3, entries 1-14). However, when N, N-diisopropylamine was
used as the substrate, the desired α-amino phosphonate could not
be obtained (Table 3, entry 15). N, N-dibenzylamine was also shown
to indicate in the three-component coupling reaction affording the
corresponding α-amino phosphonate in high yield (Table 3, entry
16). The applicability of optimized reaction conditions was further
extended to the synthesis of novel tertiary α-aminophosphonates
with 5,8-dioxa-10-azadispiro [2.0.4.3]- undecane (Table 3, entries
17-20). This 5,8-dioxa-10-azadispiro[2.0.4.3]undecane was prepared
as per reported literature.14 These observations successfully verify
4 | New J.Chem., 2015, 00, 1-6
This journal is © The Royal Society of Chemistry 2015
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 5 of 7
View Article Online
DOI: 10.1039/C5NJ01914A
NJC
COMMUNICATION
the concentration of Brønsted and Lewis acid sites of TNT were Associate Professor, Department of Material Science
&
observed at 0.734 mmol.g-1 and 1.537 mmol.g-1 respectively.
Nanotechnology, Yogi Vemana University, Kadapa, Andhra Pradesh
for his fruitful discussions.
Conclusion
Notes and References
In summary, protonated trititanate nanotubes function as a highly
active heterogeneous catalyst for the synthesis of tertiary
α-aminophophonates via Kabachinik-Fields reaction. This
remarkable activity was observed due to presence of higher
population of Brønsted and Lewis acid sites on the large
nanotubular catalyst surface. The simple procedure adopted for
catalyst preparation, easy recovery and reusability of the catalyst
are expected to contribute its utilization for the development of
α-aminophophonates. These contributions are also cost effective,
environmental friendly and possess high generality that makes the
present methodology suitable for industrialization.
1
(a) L. Gu and J. Cheng, Org. Biomol. Chem., 2012, 10, 7098-
7102; (b) S. Bhagat, P. Shah, S. K. Garg, S. Mishra, P. K. Kaur, S.
Singh and A. K. Chakraborti, Med. Chem. Commun., 2014, 5,
665-670; (c) S. A. R. Mulla, M. Y. Pathan, S. S. Chavan, S. P.
Gample and D. Sarkar, RSC Adv., 2014, 4, 7666-7672; (d) N.
Long, X. J. Cai, B. A. Song, S. Yang, Z. Chen, P. S. Bhaduri, D. Y.
Hu, L. H. Jin and W. Xue, J. Agric. Food Chem. 2008, 56, 5242-
5246; (e) M. V. N. Reddy, B. Sivakumar, A. Balakrishna, C. S.
Reddy, S. K. Naik and C. D. Reddy, Arkivoc., 2007, 246-254; (f)
S. Shafakat, N. Ali, S. Zakhr, M. Patel and M. Farooqui, Eur. J.
Med. Chem., 2012, 50, 39-43; (g) S. D. Lombaert, L. Blanchard,
T. Tan, Y. Sakane, C. Berry and R. D. Ghai, Bioorg. Med. Chem.
Lett. 1995, 5, 145-150; (h) B. Lejczak, P. Kafarski, H. Sztajer
and P. J. Mastarlerz, Med. Chem., 1986, 29, 2212-2217; (i) D.
Bonarska, J. Sarapuk and H. Kleszczynska, Pol. J. Food Nutr.
Sci., 2003, 12/53, 17-19; (j) J. A. Sikosrki, M. J. Miller, D. S.
Braccolino, D. G. Cleary, S. D. Corey, J. E. Ream, D. Schnur, A.
Shah and M. C. Walker, Phosphorus, Sulfur Silicon Relat. Elem.,
1993, 76, 375-378; (k) L. Maier and H. Spoerri, Phosphorus,
Sulfur Silicon Relat. Elem., 1991, 61, 69-75.
Experimental
Hydrothermal preparation of H2Ti3O7 nanotubes and H2Ti3O7
nanorods
As received chemicals were used for catalyst synthesis and used
without further purification. In a typical synthesis process, TiO2 fine
particles (2.5 g) dispersed in 10 M NaOH aqueous solution (200 mL)
and cooked either at 130°C/20 h (for nanotubes) or 180°C/20 h (for
nanorods) in Teflon-lined autoclave (capacity 250 mL).7 The white
precipitate obtained was subjected to washing (twice) with distilled
water (800 mL) followed by dil. HCl (0.1 N, 200 mL), finally washed
with ethanol (200 mL), and dried at 80°C for 12 h. The obtained
materials were denoted as TNT and TNR respectively.
2
(a) P. S. Reddy, P. V. G. Reddy and S. M. Reddy, Tetrahedron
Lett., 2014, 55, 3335-3339; (b) T. Bhattacharya, B. Majumdar,
D. Dey and T. K. Sarma, RSC Adv., 2014, 4, 45831-45837; (c)
M. V. Reddy, S. D. Dindulkar and Y. T. Jeong, Tetrahedron
Lett., 2011, 52, 4764-4767; (d) M. Milen, P. A. Balogh, A.
Dansco, D. Frigyes, L. Pongo and G. Keglevich, Tetrahedron
Lett., 2013, 54, 5430-5433; (e) Y. Heo, D. H. Cho, M. K. Mishra
and D. O. Jang, Tetrahedron Lett., 2012, 53, 3897-3899; (f) K.
Alagiri, P. Devadig and K. R. Prabhu, Tetrahedron Lett., 2012,
53, 1456-1459; (g) V. H. Tillu, D. K. Dumbre, R. D. Wakharkar
and V. R. Choudhary, Tetrahedron Lett., 2011, 52, 863-866; (h)
S. Sobhani and M. F. Maleki, Synlett., 2010, 383-386.
General procedure for TNT- catalyzed Kabachnik-Fields reaction
A mixture of aldehyde (1.0 mmol) and amine (1.0 mmol) was taken
in a 10 ml round bottom flask at room temperature and then added
dialkyl phosphite (1.0 mmol). Further, 5 mol % TNT was added to
the reaction mixture and again stirred for 15 min. The reaction
mixture was dissolved in EtOAc (2mL) and the catalyst was
separated by centrifugation and subsequent washing with EtOAc.
The recovered catalyst was reused for next cycle. The filtrate were
washed with brine, then dried over anhydrous Na2SO4, filtered and
concentrated on a rotary evaporator and the resulting residue was
purified by silica gel column chromatography (70:30, hexane/EtOAc)
to afford the pure α-aminophosphonate. The novel
α-aminophosphonates were structurally assigned by their IR, NMR
(1H, 13C & 31P) and mass spectra analysis. The known compounds
spectral data were found to be consistent with authentic samples.
3
(a) M. Zhu and G. Diao, J. Phys. Chem. C., 2011, 115, 24743-
24749; (b) J. Xu, A. R. Wilson, A. R. Rathmell, J. Howe, M. Chi
and B. J. Wiley, J. ACS Nano., 2011, 5, 6119-6127; (c) G. B.
Dharma Rao, M. P. Kaushik and A. K. Halve, Tetrahedron Lett.,
2012, 53, 2741-2744; (d) A. Behr, Y. Brunsch and A. Lux,
Tetrahedron Lett., 2012, 53, 2680-2683; (e) J. Mondal, T. Sen
and A. Bhaumik, Dalton Trans., 2012, 41, 6173-6181; (f) M. C.
Hong, M. C. Choi, Y. W. Chang, Y. Lee, J. Kim and H. Rhee, Adv.
Synth. Catal., 2012, 354, 1257-1263; (g) P. Zhao, M. Grillaud,
L. Salmon, J. Ruiz and D. Astruc, Adv. Synth. Catal., 2012, 354,
1001-1011; (h) M. Oberholzer, R. Gerber and C. M. Frech, Adv.
Synth. Catal., 2012, 354, 627-641; (i) M. Kidwai, S. Bhardwaj,
N. K. Mishra, A. Jain, A. Kumar and S. Mozzumdar, Catal. Sci.
Technol., 2011, 1, 426-430. (j) S. M. Agawane and J. M.
Nagarkar, Tetrahedron Lett., 2011, 52, 3499-3504; (k) V. S.
Reddy, A. S. Kumar, A. V. Ganesh and G. G. K. S. N. Kumar,
Tetrahedron Lett., 2011, 52, 1359-1362; (l) M. Sheykhan, H.
Mohammadnejad, J. Akbari and A. Heydari, Tetrahedron Lett.,
2012, 53, 2959-2964; (m) S. Sobhani, Z. M. Falatoonia and M.
Honarmand, RSC Adv., 2014, 4, 15797-15806; (n) S. S.
Acknowledgments
We are grateful for financial support from the Department of
Atomic Energy (DAE) Board of Research in Nuclear Sciences (BRNS),
Mumbai, India (2012/37C/33/BRNS). B. R. P. Reddy thanks to the
UGC-CSIR, New Delhi, India for the award of Junior Research
Fellowship. The authors also thankful to Dr. M. V. Shankar,
This journal is © The Royal Society of Chemistry 2015
New J.Chem., 2013, 00, 1-6 | 5
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 6 of 7
View Article Online
DOI: 10.1039/C5NJ01914A
COMMUNICATION
Cheraghi, S. Mahdudi, j. Akbar and Heydari, Tetrahedron
NJC
16 M. Sheykhana, L. M. Mani, A. Ebrahimi and A. Hyderi, J. Mol.
Catal. A., 2011, 335, 253-261.
Lett., 2013, 54, 6403-6406; (o) H. Sharghi, S.
Ebrahimpourmoghaddam and M. M. Doroodmand,
Tetrahedron., 2013, 69, 4708-4724.
17 S. L. McDonald and Q. wang, Angew. Chem. Int. Ed., 2014, 53,
1867-1871
4
5
(a) T. Kasuga, M. Hiramatsu, A. Hoson, T. Sekino and K.
Niihara, Langmuir., 1998, 14, 3160-3163; (b) X. Chen and S. S.
Mao, Chem. Rev., 2007, 107, 2891-2959; (c) C. N. R. Rao, A.
Govindaraj, F. L. Deepak, N. A. Gunari and M. Nath, Appl.
Phys. Let., 2001, 78, 13-26.
18 S. Bhagat and A. K. Chakraborti, J. Org. Chem., 2008, 73, 6029-
6032.
19 A. Atmani, J. C. Combert, C. Malhiac and K. Mulengi,
Tetrahedron Lett., 2000, 41, 6045-6048.
(a) M. Kitano, K. Nakajima, J. N. Kondo, S. Hayashi and M.
Hara, J. Am. Chem. Soc., 2010, 132, 6622–6623; (b) M. Kitano,
E. Wada, K. Nakajima, S. Hayashi, S. Miyazaki, H. Kobayashi
and M. Hara, Chem. Mater., 2013, 25, 385-393; (c) E. Wada,
M. Kitano, K. Nakajima and M. Hara, J. Mater. Chem. A., 2013,
1, 12768-2774.
6
7
(a) S. H. Kang, S. H. Choi, M. Kang, J. Y. Kim, H. S. Kim, T.
Hyeon and Y. E. Sung, Adv. Mater., 2008, 20, 54-58; (b) H. Zhu
and Q. Li, Nanoscale Res Lett., 2013, 8, 230-235.
(a) D. P. Kumar, M. V. Shankar, M. M. Kumari, G. Sadanandam,
B. Srinivas and V. Durgakumari, Chem. Commun., 2013,49,
9443-9445; (b) D. P. Kumar, N. L. Reddy, M. M. Kumari, B.
Srinivas, V. Durgakumari, B. Sreedhar, V. Roddatis, O.
Bondarchuk, M. Karthik, B. Nepolian and M. V. Shankar, Sol.
Energ. Mat. Sol. C., 2015, 136, 157-166; (c) H. Zhang, G. R. Li,
L. P. An, T. Y. Yan, X. P. Gao and H. Y. Zhu, J. Phys. Chem. C.;
2007, 111, 6143-6148.
8
9
(a)C. Liao, H. P. Wang and H. P. Lin, Int. J. Photoenergy.,
2013, 2013, 1-7; (b) R. Doong, S. Chang and C. Tsai, appl.
Catal. B., 2013, 129, 48-55.
(a) D. V. Bavykin, V. N. Parmon, A. A. Laokin and F. C. Walsh, J.
Mater. Chem., 2004, 14, 3370-3377; (b) S. Zu, A. Du, J. Liu, J.
Ng and D. D. Sun, Int. J. Hydrogen Energy., 2011, 36, 6560-
6568.
10 (a) L. Chmielarz, P. Kustrowski, M. Zbroja, W. Lasocha and R.
Dziembaj, Catalysis today., 2004, 90, 43-49; (b) T. Matsuda,
M. Asanuma and E. Kikuchi, Appl. Catal., 1988, 38, 289-299;
(c) C. Gannoun, R. Delaigle, P. Eloy, D. P. Debecker, A. Ghorbel
and A. E. Gaigneaux, Catal. comm., 2011, 15, 1-5; (d) C.
Gannouna, A. Turkia, H. Kochkara, R. Delaiglec, P. Eloyc, A.
Ghorbela and E. M. Gaigneauxca, Appl. catal. B., 2014, 147,
58-64.
11 (a) M. E. Manriquez, T. Lopez, R. Gomez and Navarrete, J. Mol.
catal. A., 2004, 220, 229-237; (b) A. V. Grigorieva, V. V.
Yuschenko, I. I. Ivanova, E. A. Goodilin and Y. D. Tretyakov, j.
Nanomaterials., 2012, 2012, 7 pages.
12 (a) B. C. Ranu, A. Hajra and U. Jana, Org. Lett. 1999, 1, 1141-
1143; (b) A. Manjula, B. V. Rao and P. Neelakantan, Synth.
Commun., 2003, 33, 2963-2969.
13 T. Akiyama, M. Sanada and K. Fuchide, Synlett., 2003, 1463-
1464.
14 S. Y. Kim, H. B. Park, J. H. Cho, K. H. Yoo and C. H. Oh, Bioorg.
Med. Chem. Lett., 2009, 19, 2558-2561.
15 F. Babudri, V. Fiandanese, R. Musio, F. Naso, O. Sciavovelli and
Scilimati, Synthesis., 1991, 225-228.
6 | New J.Chem., 2015, 00, 1-6
This journal is © The Royal Society of Chemistry 2015
Please do not adjust margins

Page 7 of 7
New Journal of Chemistry
View Article Online
DOI: 10.1039/C5NJ01914A
Graphical Abstract
Efficient solvent free synthesis of tertiary α-aminophosphonates using H2Ti3O7
nanotubes as a reusable solid-acid catalyst
Bhoomireddy Rajendra Prasad Reddya, Peddiahgari Vasu Govardhana Reddy*a and Bijivemula. N. Reddyb
Kabachnik-Fields reaction was applied to synthesis of α-aminophosphonates from aldehydes, secondary amines
and dialkyl phosphites in presence of H2Ti3O7 nanotubes as reusable solid-acid catalyst.