Ultrasonic promoted synthesis and antibacterial screening of some novel piperidine incorporated α-aminophosphonates

Article abstract of DOI:10.1080/10426507.2010.492363

A simple and high-yielding method was developed for the synthesis of novel -aminophosphonates from imines, obtained from 4-(piperidine-1-yl)benzaldehyde, by using triethylphosphite in the presence of dilute HCl under ultrasound irradiation. This method, w

Full text of DOI:10.1080/10426507.2010.492363

This article was downloaded by: [Anadolu University]
On: 26 December 2014, At: 16:20
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Phosphorus, Sulfur, and Silicon and the
Related Elements
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/gpss20
Ultrasonic Promoted Synthesis and
Antibacterial Screening of Some
Novel Piperidine Incorporated α-
Aminophosphonates
Priyanka G. Mandhane a , Ratnadeep S. Joshi a , Deepak R.
Nagargoje a , Asha V. Chate a & Charansingh H. Gill a
a Department of Chemistry , Dr. Babasaheb Ambedkar Marathwada
University , Aurangabad, India
Published online: 13 Jan 2011.
To cite this article: Priyanka G. Mandhane , Ratnadeep S. Joshi , Deepak R. Nagargoje , Asha V. Chate
& Charansingh H. Gill (2010) Ultrasonic Promoted Synthesis and Antibacterial Screening of Some
Novel Piperidine Incorporated α-Aminophosphonates, Phosphorus, Sulfur, and Silicon and the Related
Elements, 186:1, 149-158, DOI: 10.1080/10426507.2010.492363
To link to this article: http://dx.doi.org/10.1080/10426507.2010.492363
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Phosphorus, Sulfur, and Silicon, 186:149–158, 2011
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2010.492363
ULTRASONIC PROMOTED SYNTHESIS AND
ANTIBACTERIAL SCREENING OF SOME NOVEL
PIPERIDINE INCORPORATED α-AMINOPHOSPHONATES
Priyanka G. Mandhane, Ratnadeep S. Joshi,
Deepak R. Nagargoje, Asha V. Chate, and Charansingh H. Gill
Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University,
Aurangabad, India
GRAPHICAL ABSTRACT
Abstract A simple and high-yielding method was developed for the synthesis of novel α-
aminophosphonates from imines, obtained from 4-(piperidine-1-yl)benzaldehyde, by using tri-
ethylphosphite in the presence of dilute HCl under ultrasound irradiation. This method, which
was developed for the synthesis of α-aminophosphonates, gave excellent yields.
Supplemental materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.
Keywords α-Aminophosphonate; dilute HCl; imines; piperidine; triethylphosphite; ultrason-
ication
Received 29 March 2010; accepted 7 May 2010.
The authors are thankful to Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, for financial
support and The Head, Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-
431004 (MS), India for his valuable guidance and laboratory facility.
Address correspondence to Charansingh H. Gill, Department of Chemistry, Dr. Babasaheb Ambedkar
Marathwada University, Aurangabad 431004, India. E-mail: prof gill@rediffmail.com
149

150
P. G. MANDHANE ET AL.
INTRODUCTION
Organophosphorus compounds have found a wide range of applications in the areas
of industrial, agricultural, and medicinal chemistry owing to their biological and physical
properties as well as their utility as synthetic intermediates.1 α-Functionalized phosphonic
acids are valuable intermediates for the preparation of medicinal compounds and synthetic
intermediates.2–4 Among α-functional phosphonic acids, α-aminophosphonic acids are an
important class of compounds that exhibit a variety of interesting and useful properties. α-
Amino phosphonates are biologically and industrially important compounds. They possess
anticancer,5a anti-HIV,5b antithrombotic,5c and antibacterial properties.5d They are also
employed as enzyme inhibitors6 and peptidemimics.7 Additionally, they are utilized as
insecticides,8a herbicides,8b and fungicides.8c They are also applied as fire retardants for
cotton.9
Piperidine and its derivatives are ubiquitous building blocks in the synthesis of
pharmaceuticals and fine chemicals. The piperidine scaffold is a structural feature of many
alkaloids and drug candidates, and there have been thousands of piperidine compounds
mentioned in clinical and preclinical studies.10 The piperidine ring system is one of the most
common structural subunits in natural compounds. Along with this, interest in piperidine-
containing structures stems from their widespread occurrence in molecules that exhibited
significant biological activities. Several substituted piperidines display important biological
properties such as antiviral activity,11 antidepressant effects,12 cytotoxic activity,13 and
antimalarial activity.14
Ultrasound-accelerated chemical reactions are well known and proceed via the for-
mation and adiabatic collapse of transient cavitation bubbles. Ultrasound irradiation has
been demonstrated as an alternative energy source for organic reactions ordinarily accom-
plished by heating.15 Many homogeneous and heterogeneous reactions can be conducted
smoothly by sonication to provide improved yields and increased selectivities.16 Therefore
ultrasound irradiation has been established as an important technique in organic synthesis.
Shorter reaction time, simple experimental procedure, very high yields, increased selectivi-
ties, and clean reaction of many ultrasound-induced organic transformations offer additional
convenience in the field of synthetic organic chemistry.17
In general, α-amino phosphonates are prepared from amines and carbonyl com-
pounds or directly from the imines. However, expensive reagents, long reaction times, high
temperatures, and poor yields are the problems in many of these methods. These reactions
cannot be carried out in one step by the reaction between a carbonyl compound, an amine,
and dialkylphosphite because the amine and water present during imine formation can
decompose or deactivate the acid.18
RESULTS AND DISCUSSION
In continuation of our work19 on the development of useful synthesis methodologies,
we have synthesized, for the first time, α-aminophosphonates containing highly bioac-
tive piperdine moiety in two steps. In the first step, imine formation of 4-(piperidine-1-
yl)benzaldehyde takes place, whereas in the second step this imine is further converted into
α-amino phosphonates using triethylphosphite and dilute HCl under ultrasound irradiation.
Imines 3a–m (Scheme 1, Table 1) were prepared at room temperature from 4-(piperidine-
1-yl)benzaldehyde and substituted anilines in ethanol using a catalytic amount of acetic
acid in excellent yields and were characterized by mass spectra. α-Aminophosphonates

NOVEL PIPERIDINE INCORPORATED α-AMINOPHOSPHONATES
151
Scheme 1 Synthesis of α-aminophosphonates from imines of 4-(piperidine-1-yl)benzaldehyde.
4a–m (Scheme 1, Table 2) were then prepared in excellent yields by reacting imines 3a–m
with triethylphosphite in the presence of dil. HCl under ultrasound irradiation. Thirteen
new compounds were synthesized using this methodology in excellent yields. All the
compounds synthesized were unambiguously characterized based on analytical data.
Table 1 Synthesis of imines of 4-(piperidine-1-yl)benzaldehyde
Entry
R1
R2
R3
Time (min)
Yield (%)
Mp (◦C)
3a
3b
3c
3d
3e
3f
3g
3h
3i
H
F
H
H
F
H
H
F
H
F
F
H
OCH3
H
H
H
H
H
F
H
F
20
25
25
20
30
25
35
25
25
20
30
35
25
79
81
80
84
88
73
81
74
85
82
76
80
84
130–133
127–129
124–126
119–121
134–136
131–133
132–135
163–167
155–157
113–115
135–137
181–185
115–118
F
H
H
H
H
H
H
H
CH3
H
OCH3
OC2H5
Cl
3j
3k
3l
H
NO2
H
H
NO2
3m

152
P. G. MANDHANE ET AL.
Table 2 Ultrasound-assisted synthesis of α-amino phosphonates
Entry
R1
R2
R3
Time (min)
Yield (%)
Mp (◦C)
4a
4b
4c
4d
4e
4f
4g
4h
4i
H
F
H
H
F
H
H
F
H
F
F
H
OCH3
H
H
H
H
H
F
H
F
5
4
4
3
3
3
5
4
5
5
3
7
8
79
75
80
84
88
73
81
74
85
82
76
81
78
97–99
184–186
187–189
199–201
215–217
197–199
113–115
100–103
131–134
89–91
F
H
H
H
H
H
H
H
CH3
H
OCH3
OC2H5
Cl
4j
4k
4l
H
NO2
H
149–151
221–223
157–159
H
NO2
4m
CONCLUSION
In conclusion, a new methodology was developed for the synthesis of new α-
aminophosphonate derivatives from imines of 4-(piperidine-1-yl)benzaldehyde for first
time using dil HCl under ultrasound irradiation. All the reactions were performed under
mild reaction conditions and had shorter reaction times and quantitative yields (Table 2).
The methodology developed will be of much use to combinatorial chemists. The synthe-
sized α-aminophosphonates show excellent antibacterial activity against Gram-positive and
Gram-negative bacteria (see the Supplemental Materials, Table S1, available online).
EXPERIMENTAL
4-(Piperidine-1-yl)benzaldehyde was prepared in the laboratory by the reaction of
4-fluorobenzaldehyde and piperidine in DMF at reflux temperature and was purified by
recrystallization in aqueous ethanol. Anilines and triethylphosphite were procured from
Dodal Chemical, Aurangabad, India. Acetonitrile, N,N-dimethylformamide (DMF), abso-
lute ethanol, acetic acid, and HCl were procured from S.D. Fine-chem. Melting points were
determined in open capillaries on a Mel-Temp apparatus and are uncorrected. A Bandelin
Sonorex (35 kHz) ultrasonic bath was used for ultrasonic irradiation. 1H NMR spectra were
recorded on a Mercury Plus Varian in CDCl3/DMSO-d6 at 400 MHz using TMS as an
internal standard. IR spectra were recorded on a Perkin-Elmer FTIR using KBr discs. Mass
spectra were recorded on a Micromass Quattro II using electrospray ionization technique,
showing (m+1) peak as a base peak. The test for the purity of products and the progress of
the reactions were accomplished by TLC on Merck silica gel plates.
General Procedure: N-(4-(Piperidin-1-yl)benzylidene)benzenamine
(3a–m)
To a stirred solution of 4-(piperidine-1-yl)benzaldehyde (0.95 g, 5 mmol) in absolute
ethanol (10 mL), aniline (0.68 g, 6 mmol) and acetic acid (4 to 5 drops) were added. The
progress of the reaction was monitored on TLC (solvent system—hexane:ethyl acetate).
After completion of the reaction (20 min), water (20 mL) was added, and the solid thus

NOVEL PIPERIDINE INCORPORATED α-AMINOPHOSPHONATES
153
obtained was filtered and washed with water, dried in an oven at 50 ◦C for 5.0 h (1.35 g,
yield 79%). ES-MS: m/z 264.9 (m+1).
N-(4-(Piperidin-1-yl)benzylidene)benzenamine (3a). IR (KBr, cm−1): 1609
(C N), 845 (Ar-H). 1H NMR (CDCl3, 400 MHz, δ ppm): 1.57 (s, 2H, CH2), 1.71 (s, 4H,
CH2), 3.09 (s, 4H, CH2), 6.92 (d, 2H, Ar-H, J = 8.4 Hz), 7.34 (m, 5H, Ar-H), 7.75
(d, 2H, Ar-H, J = 8.1 Hz), 8.31 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 26.2,
29.3, 54.2, 116.4, 126.3, 127.3, 127.2, 129.3, 132.2, 152.9, 154.7, 161.2. ES-MS: m/z 264.
Elemental analysis: C18H20N2 Calc.: C: 81.78%, H: 7.63%, N: 10.60%; Found: C: 81.23%,
H: 7.91%, N: 10.86%.
N-(4-(Piperidin-1-yl)benzylidene)-2-fluorobenzenamine (3b). IR (KBr,
cm−1): 1600 (C N), 1053 (C F), 820 (Ar-H). 1H NMR (CDCl3, 400 MHz, δ ppm): 1.55
(s, 2H, CH2), 1.75 (s, 4H, CH2), 3.05 (s, 4H, CH2), 6.90 (d, 2H, Ar-H, J = 8.1 Hz),
7.13 (dd, 1H, Ar-H, J = 8 Hz, J = 2.2 Hz), 7.15 (m, 1H, Ar-H), 7.25 (dd, 1H, Ar-H, J =
8.1 Hz, J = 2.3 Hz), 7.31 (m, 1H, Ar-H), 7.61 (d, 2H, Ar-H, J = 8.5 Hz), 8.35 (s, 1H, CH).
13C NMR (CDCl3, 125 MHz, δ ppm): 26.5, 29.8, 54.1, 115.3, 117.9, 124.5, 125.7, 127.8,
130.4, 132.1, 142.3, 153.5, 156.8, 163.9. ES-MS: m/z 282. Elemental analysis: C18H19FN2
Calc.: C: 76.57%, H: 6.78%, N: 9.92%; Found: C: 76.21%, H: 6.84%, N: 10.01%.
N-(4-(Piperidin-1-yl)benzylidene)-3-fluorobenzenamine (3c). IR (KBr,
cm−1): 1615 (C N), 1051 (C F), 811 (Ar-H). 1H NMR (CDCl3, 400 MHz, δ ppm): 1.53
(s, 2H, CH2), 1.78 (s, 4H, CH2), 3.06 (s, 4H, CH2), 6.52 (d, 2H, Ar-H, J = 8.7 Hz),
7.11 (s, 1H, Ar-H), 7.13 (m, 2H, Ar-H), 7.26 (t, 1H, Ar-H, J = 8.1 Hz), 7.67 (d, 2H, Ar-H,
J = 8.3 Hz), 8.34 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 26.1, 29.7, 54.8,
111.4, 115.8, 116.1, 119.3, 125.1, 131.4, 133.9, 152.1, 156.5, 161.3, 165.4. ES-MS: m/z
282. Elemental analysis: C18H19FN2 Calc.: C: 76.57%, H: 6.78%, N: 9.92%; Found: C:
76.24%, H: 6.94%, N: 10.14%.
N-(4-(Piperidin-1-yl)benzylidene)-4-fluorobenzenamine (3d). IR (KBr,
cm−1): 1620 (C N), 1056 (C F), 780 (Ar-H). 1H NMR (CDCl3, 400 MHz, δ ppm): 1.54
(s, 2H, CH2), 1.77 (s, 4H, CH2), 3.11 (s, 4H, CH2), 6.64 (d, 2H, Ar-H, J = 8.3 Hz),
7.17 (d, 2H, Ar-H, J = 8 Hz), 7.34 (d, 2H, Ar-H, J = 8.6 Hz), 7.67 (d, 2H, Ar-H, J = 8.4
Hz), 8.31 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 26.3, 29.1, 54.5, 115.4, 118.8,
124.1, 125.9, 132.4, 149.2, 135.4, 162.6, 164.7. ES-MS: m/z 282. Elemental analysis:
C18H19FN2 Calc.: C: 76.57%, H: 6.78%, N: 9.92%; Found: C: 76.33%, H: 6.81%, N:
9.98%.
N-(4-(Piperidin-1-yl)benzylidene)-2,3-difluorobenzenamine
(3e). IR
(KBr, cm−1): 1618 (C N), 1040 (C F), 840 (Ar-H). 1H NMR (CDCl3, 400 MHz, δ ppm):
1.51 (s, 2H, CH2), 1.73 (s, 4H, CH2), 3.14 (s, 4H, CH2), 6.92 (d, 2H, Ar-H, J = 8.1
Hz), 7.09 (dd, 1H, Ar-H, J = 8.4 Hz, J = 2.3 Hz), 7.14 (dd, 1H, Ar-H, J = 8.2 Hz, J =
2.4 Hz), 7.21 (t, 1H, Ar-H, J = 8.7 Hz), 7.64 (d, 2H, Ar-H, J = 8.5 Hz), 8.33 (s, 1H,
CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 26.1, 29.9, 54.1, 115.4, 116.6, 121.3, 124.6,
128.7, 132.1, 143.3, 144.5, 151.9, 153.4, 162.3. ES-MS: m/z 300. Elemental analysis:
C18H18F2N2 Calc.: C: 71.98%, H: 6.04%, N: 9.33%; Found: C: 71.45%, H: 6.21%, N:
9.47%.
N-(4-(Piperidin-1-yl)benzylidene)-2,3,4-trifluorobenzenamine
(3f). IR
(KBr, cm−1): 1650 (C N), 1045 (C F), 815 (Ar-H). 1H NMR (CDCl3, 400 MHz, δ ppm):
1.55 (s, 2H, CH2), 1.78 (s, 4H, CH2), 3.09 (s, 4H, CH2), 6.52 (d, 2H, Ar-H, J = 8.5
Hz), 6.84 (d, 1H, Ar-H, J = 8.2 Hz), 7.07 (d, 1H, Ar-H, J = 8.6 Hz), 7.66 (d, 2H, Ar-H,
J = 7.8 Hz), 8.31 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 26.4, 29.5, 54.3,
115.6, 116.4, 122.5, 125.9, 131.8, 138.1, 142.4, 145.3, 151.8, 156.9, 160.3. ES-MS: m/z

154
P. G. MANDHANE ET AL.
318. Elemental analysis: C18H17F3N2 Calc.: C: 67.91%, H: 5.38%, N: 8.80%; Found: C:
67.74%, H: 5.43%, N: 8.93%.
N-(4-(Piperidin-1-yl)benzylidene)-4-methylbenzenamine (3g). IR (KBr,
cm−1): 1610 (C N), 801 (Ar-H). 1H NMR (CDCl3, 400 MHz, δ ppm): 1.51 (s, 2H, CH2),
1.79 (s, 4H, CH2), 2.54 (s, 3H, CH3), 3.02 (s, 4H, CH2), 6.51 (d, 2H, Ar-H, J = 8.3
Hz), 7.21 (d, 2H, Ar-H, J = 8.1 Hz), 7.24 (d, 2H, Ar-H, J = 8.3 Hz), 7.61 (d, 2H, Ar-H,
J = 8.2 Hz), 8.31 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 25.4, 26.6, 29.8, 54.1,
116.1, 123.4, 124.2, 131.8, 132.7, 138.9, 151.7, 153.6, 161.5. ES-MS: m/z 278. Elemental
analysis: C19H22N2 Calc.: C: 81.97%, H: 7.97%, N: 10.06%; Found: C: 81.62%, H: 8.14%,
N: 10.24%.
N-(4-(Piperidin-1-yl)benzylidene)-3-methoxybenzenamine (3h). IR (KBr,
1
cm−1): 2810 (O CH3), 1617 (C N), 745 (Ar-H). H NMR (CDCl3, 400 MHz, δ ppm):
1.53 (s, 2H, CH2), 1.77 (s, 4H, CH2), 3.07 (s, 4H, CH2), 3.94 (s, 3H, OCH3), 6.63
(d, 2H, Ar-H, J = 8.6 Hz), 6.91 (s, 1H, Ar-H), 6.95 (dd, 2H, Ar-H, J = 8.1 Hz, J = 2.2 Hz),
7.32 (t, 1H, Ar-H, J = 8.5 Hz) 7.69 (d, 2H, Ar-H, J = 8.1 Hz), 8.34 (s, 1H, CH). 13C NMR
(CDCl3, 125 MHz, δ ppm): 26.8, 29.9, 54.5, 57.6, 111.3, 114.2, 115.6, 116.7, 124.4, 131.9,
133.5, 152.5, 155.6, 161.7, 163.8. ES-MS: m/z 294. Elemental analysis: C19H22N2O Calc.:
C: 77.52%, H: 7.53%, N: 9.52%; Found: C: 77.23%, H: 7.61%, N: 9.63%.
N-(4-(Piperidin-1-yl)benzylidene)-4-methoxybenzenamine (3i). IR (KBr,
1
cm−1): 2840 (O CH3), 1607 (C N), 790 (Ar-H). H NMR (CDCl3, 400 MHz, δ ppm):
1.59 (s, 2H, CH2), 1.79 (s, 4H, CH2), 3.01 (s, 4H, CH2), 3.94 (s, 3H, OCH3), 6.63
(d, 2H, Ar-H, J = 8.6 Hz), 6.91 (d, 2H, Ar-H, J = 8.7 Hz), 7.41 (d, 2H, Ar-H, J = 8.7 Hz)
7.61 (d, 2H, Ar-H, J = 8.1 Hz), 8.33 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm):
26.9, 29.1, 54.6, 57.6, 111.3, 114.3, 115.6, 116.7, 124.4, 131.9, 133.5, 152.5, 155.6, 161.7,
163.8. ES-MS: m/z 294. Elemental analysis: C19H22N2O Calc.: C: 77.52%, H: 7.53%, N:
9.52%; Found: C: 77.19%, H: 7.71%, N: 9.61%.
N-(4-(Piperidin-1-yl)benzylidene)-4-ethoxybenzenamine (3j). IR (KBr,
cm−1): 1604 (C N), 825 (Ar-H). 1H NMR (CDCl3, 400 MHz, δ ppm): 1.41 (t, 3H, CH3),
1.62 (s, 2H, CH2), 1.81 (s, 4H, CH2), 3.91 (s, 4H, CH2), 4.01 (q, 2H, OCH2), 6.91
(d, 2H, Ar-H, J = 8.3 Hz), 6.93 (d, 2H, Ar-H, J = 7.9 Hz), 7.41 (d, 2H, Ar-H, J = 8.1 Hz),
7.92 (d, 2H, Ar-H, J = 8.1 Hz), 8.48 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm):
15.4, 26.8, 29.7, 54.8, 65.7, 115.4, 116.3, 123.8, 124.7, 133.4, 143.3, 147.1, 159.2, 162.8.
ES-MS: m/z 308. Elemental analysis: C20H24N2O Calc.: C: 77.89%, H: 7.84%, N: 9.08%;
Found: C: 77.64%, H: 7.97%, N: 9.23%.
N-(4-(Piperidin-1-yl)benzylidene)-4-chlorobenzenamine (3k). IR (KBr,
cm−1): 1620 (C N), 810 (Ar-H), 728 (C Cl). 1H NMR (CDCl3, 400 MHz, δ ppm): 1.67
(s,2H, CH2),1.83 (s, 4H, CH2), 3.33 (s, 4H, CH2), 6.92 (d, 2H, Ar-H, J = 8.4 Hz), 7.12
(d, 2H, Ar-H, J = 8.7 Hz), 7.31 (d, 2H, Ar-H, J = 7.3 Hz), 7.75 (d, 2H, Ar-H, J = 8.1 Hz),
8.28 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 26.1, 29.2, 54.4, 116.4, 124.5,
125.5, 131.1, 133.5, 134.7, 152.8, 154.5, 163.8. ES-MS: m/z 298.5. Elemental analysis:
C18H19ClN2 Calc.: C: 72.35%, H: 6.41%, N: 9.37%; Found: C: 72.63%, H: 6.55%, N:
9.45%.
N-(4-(Piperidin-1-yl)benzylidene)-3-nitrobenzenamine (3l). IR (KBr,
1
cm−1): 1618 (C N), 1345 (C NO2), 830 (Ar-H). H NMR (CDCl3, 400 MHz, δ ppm):
1.59 (s, 2H, CH2), 1.88 (s, 4H, CH2), 3.91 (s, 4H, CH2), 6.57 (d, 2H, Ar-H, J = 8.1
Hz), 7.54 (d, 2H, Ar-H, J = 8.3 Hz), 7.62 (t, 1H, Ar-H, J = 8.7 Hz), 7.91 (dd, 1H, Ar-H,
J = 8.4 Hz, J = 2.3 Hz), 8.27 (s, 1H, Ar-H), 8.31 (dd, 1H, Ar-H, J = 8.2 Hz, J = 2.5 Hz),
8.30 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 26.2, 29.3, 54.5, 115.4, 118.9,

NOVEL PIPERIDINE INCORPORATED α-AMINOPHOSPHONATES
155
121.7, 124.3, 129.3, 131.4, 133.1, 151.9, 153.2, 156.7, 163.4. ES-MS: m/z 309. Elemental
analysis: C18H19N3O2 Calc.: C: 69.88%, H: 6.19%, N: 13.58%; Found: C: 69.56%, H:
6.25%, N: 13.75%.
N-(4-(piperidin-1-yl)benzylidene)-4-nitrobenzenamine: (3m). IR (KBr,
1
cm−1): 1610 (C N), 1333 (C NO2), 770 (Ar-H). H NMR (CDCl3, 400 MHz, δ ppm):
1.72 (s, 2H, CH2), 1.82 (s, 4H, CH2), 3.95 (s, 4H, CH2), 6.61 (d, 2H, Ar-H, J = 8.0
Hz), 7.56 (d, 2H, Ar-H, J = 7.9 Hz), 7.61 (d, 2H, Ar-H, J = 8.4 Hz), 8.31 (d, 2H, Ar-H,
J = 8.4 Hz, J = 2.5 Hz), 8.41 (s, 1H, CH). 13C NMR (CDCl3, 125 MHz, δ ppm): 26.5,
29.4, 54.7, 116.3, 123.4, 124.3, 125.9, 132.7, 148.6, 153.7, 161.5, 163.6. ES-MS: m/z
309. Elemental analysis: C18H19N3O2 Calc.: C: 69.88%, H: 6.19%, N: 13.58%; Found: C:
69.61%, H: 6.27%, N: 13.64%.
Diethyl(phenylamino)(4-(piperidin-1-yl)phenyl)methylphosphonate
(4a–m)
To a mixture of N-(4-(piperidin-1-yl)benzylidene)benzenamine (0.001 mol) and tri-
ethylphosphite (0.0035 mol), a catalytic amount of dilute hydrochloric acid (5 mol%) was
added. Then the reaction mixture was irradiated under ultrasound waves. The progress of
the reaction was monitored on TLC using hexane:ethyl acetate (8:2) as the solvent system.
After the completion of reaction, ice cold water was added to it, and the mixture was
extracted with ethyl acetate and dried over anhydrous sodium sulfate. Then the solvent was
evaporated under reduced vacuum pressure.
4a: IR (KBr, cm−1): 1245 (P O), 1045 (P O C). 1H NMR (CDCl3, 400 MHz, δ
ppm): 1.17 (t, 3H, CH3), 1.28 (t, 3H, CH3), 1.58 (s, 2H, CH2), 1.78 (s, 4H, CH2),
3.18 (s, 4H, CH2), 3.67 (d, 1H, NH CH P O), 3.97 (m, 2H, O CH2), 4.15 (m, 2H,
O CH2), 5.01 (d, 1H,CH NH Ph), 6.57 (d, 2H, Ar-H), 6.65 (t, 1H, Ar-H), 6.97 (s, 2H,
Ar-H), 7.14 (t, 2H, Ar-H), 7.36 (d, 2H, Ar-H). 13C NMR (CDCl3, 125 MHz, δ ppm): 14.8,
25.5, 25.9, 52.4, 56.5, 62.3, 113.5, 114.3, 117.6, 125.9, 127.6, 129.5, 148.2. ES-MS: m/z
402. Elemental analysis: C22H31N2O3P Calc.: C: 65.65%, H: 7.76%, N: 6.96%; Found: C:
65.72%, H: 7.93%, N: 7.04%.
4b: IR (KBr, cm−1): 1234 (P O), 1032 (P O C). 1H NMR (CDCl3, 400 MHz, δ
ppm): 1.15 (t, 3H, CH3), 1.25 (t, 3H, CH3), 1.54 (s, 2H, CH2), 1.76 (s, 4H, CH2),
3.11 (s, 4H, CH2), 3.76 (d, 1H, NH CH P O), 4.17 (m, 2H, O CH2 CH3), 4.22 (m,
2H, O CH2 CH3), 5.03 (d, 1H,CH NH Ph), 6.61 (d, 2H, Ar-H), 6.92 (dd, 1H, Ar-H),
7.01 (dd, 1H, Ar-H), 7.11 (d, 2H, Ar-H), 7.33 (dd, 1H, Ar-H), 7.41 (m, 1H, Ar-H). 13C
NMR (CDCl3, 125 MHz, δ ppm): 13.6, 25.4, 26.3, 54.2, 55.6, 63.2, 115.3, 117.2, 120.1,
122.3, 129.2, 130.1, 133.9, 136.1, 149.3, 157.8. ES-MS: m/z 420. Elemental analysis:
C22H30FN2O3P Calc.: C: 62.84%, H: 7.19%, N: 6.66%; Found: C: 62.92%, H: 7.27%, N:
6.68%.
1
4c: IR (KBr, cm−1): 1230 (P O), 1022 (P O C). H NMR (CDCl3, 400 MHz, δ
ppm): 1.17 (t, 3H, CH3), 1.27 (t, 3H, CH3), 1.51 (s, 2H, CH2), 1.78 (s, 4H, CH2),
3.09 (s, 4H, CH2), 3.91 (d, 1H, NH CH P O), 4.13 (m, 2H, O CH2 CH3), 4.21 (m,
2H, O CH2 CH3), 5.01 (d, 1H,CH NH Ph), 6.70 (d, 2H, Ar-H), 6.79 (s, 1H, Ar-H),
6.91 (dd, 1H, Ar-H), 6.96 (d, 1H, Ar-H), 7.04 (d, 2H, Ar-H), 7.15 (dd, 1H, Ar-H). 13C
NMR (CDCl3, 125 MHz, δ ppm): 15.3, 26.2, 27.1, 54.2, 58.6, 63.1, 105.1, 106.3, 116.3,
123.4, 128.7, 129.7, 134.2, 149.6, 151.2, 165.3. ES-MS: m/z 420. Elemental analysis:
C22H30FN2O3P Calc.: C: 62.84%, H: 7.19%, N: 6.66%; Found: C: 62.88%, H: 7.25%, N:
6.69%.

156
P. G. MANDHANE ET AL.
4d: IR (KBr, cm−1): 1224 (P O), 1033 (P O C). 1H NMR (CDCl3, 400 MHz, δ
ppm): 1.16 (t, 3H, CH3), 1.20 (t, 3H, CH3), 1.53 (s, 2H, CH2), 1.81 (s, 4H, CH2),
3.21 (s, 4H, CH2), 4.03 (d, 1H, NH CH P O), 3.98 (m, 2H, O CH2 CH3), 4.13 (m,
2H, O CH2 CH3), 4.98 (d, 1H,CH NH Ph), 6.67 (d, 2H, Ar-H), 7.01 (d, 2H, Ar-H),
7.16 (d, 2H, Ar-H), 7.24 (d, 2H, Ar-H). 13C NMR (CDCl3, 125 MHz, δ ppm): 15.4, 27.2,
29.5, 54.2, 59.5, 65.3, 116.3, 121.1, 125.3, 135.7, 137.9, 145.3, 151.4, 154.8. ES-MS: m/z
420. Elemental analysis: C22H30FN2O3P Calc.: C: 62.84%, H: 7.19%, N: 6.66%; Found:
C: 62.89%, H: 7.21%, N: 6.71%.
1
4e: IR (KBr, cm−1): 1232 (P O), 1035 (P O C). H NMR (CDCl3, 400 MHz, δ
ppm): 1.15 (t, 3H, CH3), 1.27 (t, 3H, CH3), 1.61 (s, 2H, CH2), 1.77 (s, 4H, CH2),
3.13 (s, 4H, CH2), 4.11 (d, 1H, NH CH P O), 4.23 (m, 2H, O CH2 CH3), 4.27
(m, 2H, O CH2 CH3), 5.07 (d, 1H,CH NH Ph), 6.56 (dd, 1H, Ar-H), 6.78 (dd, 1H,
Ar-H), 6.91 (d, 2H, Ar-H), 7.08 (dd, 1H, Ar-H), 7.23 (d, 2H, Ar-H). 13C NMR (CDCl3, 125
MHz, δ ppm): 15.7, 26.3, 30.9, 53.1, 61.2, 63.5, 108.5, 116.3, 118.2, 127.5, 128.6, 129.7,
142.1, 146.2, 151.3, 154.8. ES-MS: m/z 438. Elemental analysis: C22H29F2N2O3P Calc.:
C: 60.27%, H: 6.67%, N: 6.39%; Found: C: 60.31%, H: 6.74%, N: 6.41%.
1
4f: IR (KBr, cm−1): 1227 (P O), 1031 (P O C). H NMR (CDCl3, 400 MHz, δ
ppm): 1.13 (t, 3H, CH3), 1.25 (t, 3H, CH3), 1.59 (s, 2H, CH2), 1.71 (s, 4H, CH2),
3.07 (s, 4H, CH2), 4.11 (d, 1H, NH CH P O), 4.27 (m, 2H, O CH2 CH3), 4.31 (m,
2H, O CH2 CH3), 5.09 (d, 1H,CH NH Ph), 6.46 (d, 1H, Ar-H), 6.79 (d, 2H, Ar-H),
6.89 (d, 1H, Ar-H), 7.27 (d, 2H, Ar-H). 13C NMR (CDCl3, 125 MHz, δ ppm): 15.3, 27.4,
31.5, 52.6, 62.2, 64.8, 115.3, 116.5, 118.2, 127.3, 128.5, 130.4, 141.6, 143.7, 147.3, 151.9.
ES-MS: m/z 456. Elemental analysis: C22H28F3N2O3P Calc.: C: 57.89%, H: 6.18%, N:
6.14%; Found: C: 57.91%, H: 6.21%, N: 6.18%.
4g: IR (KBr, cm−1): 1237 (P O), 1028 (P O C). 1H NMR (CDCl3, 400 MHz, δ
ppm): 1.12 (t, 3H, CH3), 1.26 (t, 3H, CH3), 1.57 (s, 2H, CH2), 1.73 (s, 4H, CH2),
2.78 (s, 3H, CH3), 3.12 (s, 4H, CH2), 4.17 (d, 1H, NH CH P O), 4.24 (m, 2H,
O CH2 CH3), 4.31 (m, 2H, O CH2 CH3), 5.03 (d, 1H,CH NH Ph), 6.44 (d, 2H,
Ar-H), 6.78 (d, 2H, Ar-H), 7.18 (d, 2H, Ar-H), 7.31 (d, 2H, Ar-H). 13C NMR (CDCl3, 125
MHz, δ ppm): 15.5, 25.2, 27.9, 29.3, 54.1, 59.9, 60.4, 115.3, 116.2, 127.4, 128.7, 130.9,
132.1, 146.3, 149.2. ES-MS: m/z 416. Elemental analysis: C23H33N2O3P Calc.: C: 66.33%,
H: 7.99%, N: 6.73%; Found: C: 66.37%, H: 8.03%, N: 6.77%.
4h: IR (KBr, cm−1): 1235 (P O), 1035 (P O C). 1H NMR (CDCl3, 400 MHz, δ
ppm): 1.13 (t, 3H, CH3), 1.21 (t, 3H, CH3), 1.61 (s, 2H, CH2), 1.82 (s, 4H, CH2),
3.09 (s, 4H, CH2), 3.73 (s, 3H, OCH3), 3.98 (d, 1H, NH CH P O), 4.08 (m, 2H,
O CH2 CH3), 4.12 (m, 2H, O CH2 CH3), 5.03 (d, 1H,CH NH Ph), 6.31 (s, 1H, Ar-
H), 6.43 (dd, 1H, Ar-H, J = 8.1 Hz, J = 2.3 Hz), 6.51 (dd, 1H, Ar-H, J = 8.4 Hz, J = 2.1 Hz),
6.96 (d, 2H, Ar-H, J = 7.9 Hz), 7.13 (d, 2H, Ar-H, J = 8.3 Hz). 13C NMR (CDCl3, 125 MHz,
δ ppm): 15.4, 23.3, 27.5, 30.3, 53.2, 57.9, 59.3, 65.5, 101.6, 105.1, 109.2, 117.4, 127.5,
129.6, 133.4, 149.3, 151.1, 163.6. ES-MS: m/z 432. Elemental analysis: C23H33N2O4P
Calc.: C: 63.87%, H: 7.69%, N: 6.48%; Found: C: 63.92%, H: 7.73%, N: 6.51%.
1
4i: IR (KBr, cm−1): 1237 (P O), 1028 (P O C). H NMR (CDCl3, 400 MHz, δ
ppm): 1.17 (t, 3H, CH3), 1.26 (t, 3H, CH3), 1.56 (s, 2H, CH2), 1.79 (s, 4H, CH2),
3.11 (s, 4H, CH2), 3.92 (s, 3H, OCH3), 4.01 (d, 1H, NH CH P O), 4.16 (m, 2H,
O CH2 CH3), 4.21 (m, 2H, O CH2 CH3), 5.01 (d, 1H,CH NH Ph), 6.49 (d, 2H,
Ar-H), 6.64 (d, 2H, Ar-H), 6.89 (d, 2H, Ar-H), 7.14 (d, 2H, Ar-H). 13C NMR (CDCl3, 125
MHz, δ ppm): 15.6, 24.7, 27.9, 54.2, 57.1, 58.3, 64.6, 116.9, 117.1, 118.8, 127.1, 129.4,

NOVEL PIPERIDINE INCORPORATED α-AMINOPHOSPHONATES
157
141.5, 149.2, 151.7. ES-MS: m/z 432. ES-MS: m/z 432. Elemental analysis: C23H33N2O4P
Calc.: C: 63.87%, H: 7.69%, N: 6.48%; Found: C: 63.89%, H: 7.71%, N: 6.50%.
1
4j: IR (KBr, cm−1): 1241 (P O), 1032 (P O C). H NMR (CDCl3, 400 MHz, δ
ppm): 1.13 (t, 3H, CH3), 1.21 (t, 3H, CH3), 1.29 (t, 3H, CH3), 1.51 (s, 2H, CH2),
1.77 (s, 4H, CH2), 3.17 (s, 4H, CH2), 3.99 (d, 1H, NH CH P O), 4.13 (m, 2H,
O CH2 CH3), 4.28 (m, 2H, O CH2 CH3), 5.04 (d, 1H,CH NH Ph), 6.44 (d, 2H, Ar-
H, J 8.2 Hz), 6.59 (d, 2H, Ar-H, J = 7.8 Hz), 6.97 (d, 2H, Ar-H, J = 8.1 Hz), 7.11 (d, 2H,
Ar-H, J = 7.6 Hz). 13C NMR (CDCl3, 125 MHz, δ ppm): 15.2, 25.5, 27.8, 54.3, 59.3, 64.6,
67.8, 115.4, 115.5, 118.3, 127.3, 130.4, 141.6, 147.7, 149.2. ES-MS: m/z 446. Elemental
analysis: C24H35N2O4P Calc.: C: 64.56%, H: 7.90%, N: 6.27%; Found: C: 65.72%, H:
7.93%, N: 7.04%.
4k: IR (KBr, cm−1): 1245 (P O), 1025 (P O C). 1H NMR (CDCl3, 400 MHz, δ
ppm): 1.16 (t, 3H, CH3), 1.23 (t, 3H, CH3), 1.58 (s, 2H, CH2), 1.74 (s, 4H, CH2),
3.13 (s, 4H, CH2), 4.05 (d, 1H, NH CH P O), 4.14 (m, 2H, O CH2 CH3), 4.21 (m,
2H, O CH2 CH3), 5.07 (d, 1H,CH NH Ph), 6.49 (d, 2H, Ar-H), 6.63 (d, 2H, Ar-H),
7.09 (d, 2H, Ar-H), 7.23 (d, 2H, Ar-H). 13C NMR (CDCl3, 125 MHz, δ ppm): 15.7, 26.4,
27.3, 53.4, 57.3, 63.7, 115.7, 116.3, 124.1, 127.8, 129.9, 131.2, 147.3, 151.5. ES-MS: m/z
436.5. Elemental analysis: C22H30ClN2O3P Calc.: C: 60.48%, H: 6.92%, N: 6.41%; Found:
C: 60.54%, H: 6.98%, N: 6.47%.
4l: IR (KBr, cm−1): IR (KBr, cm−1): 1245 (P O), 1045 (P O C). 1H NMR (CDCl3,
400 MHz, δ ppm): 1.17 (t, 3H, CH3), 1.23 (t, 3H, CH3), 1.57(s, 2H, CH2), 1.77 (s, 4H,
CH2), 3.17 (s, 4H, CH2), 3.93 (d, 1H, NH CH P O), 4.07 (m, 2H, O CH2 CH3),
4.14 (m, 2H, O CH2 CH3), 5.01 (d, 1H,CH NH Ph), 6.59 (d, 2H, Ar-H), 6.99 (dd,
1H, Ar-H), 7.10 (d, 2H, Ar-H), 7.35 (dd, 1H, Ar-H), 7.51 (s, 1H, Ar-H), 8.05 (dd, 1H,
Ar-H). 13C NMR (CDCl3, 125 MHz, δ ppm): 15.4, 26.6, 27.9, 54.3, 58.7, 63.5, 110.3,
115.3, 116.1, 121.5, 127.9, 129.2, 132.5, 143.5, 149.6, 151.2. ES-MS: m/z 447. Elemental
analysis: C22H30N3O5P Calc.: C: 59.05%, H: 6.76%, N: 9.39%; Found: C: 59.09%, H:
6.79%, N: 9.41%.
4m: 1247 (P O), 1031 (P O C). 1H NMR (CDCl3, 400 MHz, δ ppm): 1.14 (t, 3H,
CH3), 1.21 (t, 3H, CH3), 1.55 (s, 2H, CH2), 1.71 (s, 4H, CH2), 3.15 (s, 4H, CH2),
3.96 (d, 1H, NH CH P O), 4.14 (m, 2H, O CH2 CH3), 4.23 (m, 2H, O CH2 CH3),
5.06 (d, 1H,CH NH Ph), 6.58 (d, 2H, Ar-H), 6.96 (d, 2H, Ar-H), 7.11 (d, 2H, Ar-H),
8.23 (d, 2H, Ar-H). 13C NMR (CDCl3, 125 MHz, δ ppm): 15.7, 26.3, 27.8, 54.9, 56.8,
63.2, 115.3, 116.7, 124.5, 127.9, 129.1, 139.7, 151.4, 156.3. ES-MS: m/z 447. Elemental
analysis: C22H30N3O5P Calc.: C: 59.05%, H: 6.76%, N: 9.39%; Found: C: 59.11%, H:
6.82%, N: 9.44%.
REFERENCES
1. (a) Engel, R.; Chem. Rev. 1977, 77, 349; (b) Hiratake, J.; Oda, J. Biosci. Biotechnol. Biochem.
1997, 61, 211; (c) Schug, K. A.; Lindner, W. Chem. Rev. 2005, 105, 64; (d) Moonen, K.;
Laureyn, I.; Stevens, C. V. Chem. Rev. 2004, 104, 6177; (e) Palacios, F.; Alonso, C.; de los
Santos, J. M. Curr. Org. Chem. 2004, 8, 1481.
2. Dingwall, J. G.; Campell, C. D.; Baylis, E. K. UK Patent Appl. 1,542,938 (1979); Chem. Abstr.
1979, 88, 105559j.
3. Kafarski, P.; Lejczak, B.; Tyka, R.; Koba, L.; Pliszczak, E.; Wieczorek, P. J. Plant Growth Regul.
1995, 14, 199.

158
P. G. MANDHANE ET AL.
4. Ishiguri, Y.; Yamada, Y.; Kato, T.; Sasaki, M.; Mukai, K. Eur. Patent Appl. EP 82–301905 (1982);
Chem. Abstr. 1983, 98, 102686u.
5. (a) PCT Int. Appl. WO 2007045496 (2007); (b) Alonso, E.; Alonso, E.; Solis, A.; del Pozo,
C. Synlett 2000, 698; (c) Meyer, J. H.; Barlett, P. A. J. Am. Chem. Soc. 1998, 120, 4600;
(d) Atherton, F. R.; Hasall, C. H.; Lambert, R. W. J. Med. Chem. 1986, 29, 29.
6. (a) Allen, M. C.; Fuhrer, W.; Tuck, B.; Wade, R.; Wood, J. M. J. Med.Chem. 1989, 32, 1652;
(b) Bartlett, P. A.; Hanson, J. E.; Giannousis, P. G. J. Org. Chem. 1990, 55, 6268.
7. Kafarski, P.; Lejezak, B. Phosphorus, Sulfur Silicon Relat. Elem. 1991, 63, 193.
8. (a) Emsley, J.; Hall, D. The Chemistry of Phosphorus; Harper and Row: London, (1976); (b) Kle-
sezynska, H.; Bornarska, D.; Bielecki, K.; Sarapak, J. Cell Mol. Biol. Lett. 2002, 7, 929; (c) Smith,
W. W.; Bartlett, P. A. J. Am. Chem. Soc. 1998, 120, 4622.
9. Birum, G. H. U.S. Patent 4,032,601 (1977).
10. Watson, P. S.; Jiang, B.; Scott, B. Org. Lett. 2000, 2, 3679.
11. Finke, P. E.; Oates, B.; Mills, S. G.; MacCoss, M.; Malkowitz, L.; Springer, M. S.; Gould, S. L.;
Demartino, J. A.; Carella, A.; Carver, G.; Holmes, K.; Danzeisen, R.; Hazuda, D.; Kessler, J.;
Lineberger, J.; Miller, M.; Schleif, W. A.; Emini, E. A. Bioorg. Med. Chem. Lett. 2001, 11, 2475.
12. Trabaco, A. A.; Aerts, N.; Alvarez, R. M.; Andres, J. I.; Boeckx, I.; Fernandez, J.; Gomez, A.;
Janssens, F. E.; Leenaerts, J. E.; Lucas, A. I. D.; Matesanz, E.; Steckler, T.; Pullan, S. Bioorg.
Med. Chem. Lett. 2007, 17, 3860.
13. (a) Kobayashi, J.; Ishibashi, M. Heterocycles 1996, 42, 943; (b) Ninomiya, I.; Kiguchi, T.; Naito,
T. Alkaloids 1998, 50, 317.
14. (a) Murata, K.; Takano, F.; Fushiya, S.; Oshima, Y. J. Nat. Prod. 1998, 61, 729; (b) Kobayashi,
S.; Ueno, M.; Suzuki, R.; Ishitani, H.; Kim, H. S.; Wataya, Y. J. Org. Chem. 1999, 64, 6833;
(c) Takaya, Y.; Tasaka, H.; Chiba, T.; Uwai, K.; Tanitsu, M.; Kim, H. S.; Wataya, Y.; Miura, M.;
Takeshita, M.; Oshima, Y. J. Med. Chem. 1999, 42, 3163.
15. Shelke, K. F.; Sapkal, S. B.; Shingare, M. S. Chin. Chem. Soc. 2009, 20, 283.
16. (a) Gaplovsky, A.; Gaplovsky, M.; Toma, S.; Luche, J. L. J. Org. Chem. 2000, 65, 8444;
(b) Suslick, K. S. Ultrasound, Its Chemical, Physical and Biological Effects; VCH: Weinheim,
Germany, 1988; (c) Rajagopal, R.; Jarikote, D. V.; Srinivasan, K. V. Chem. Commun. 2002, 616;
(d) Deshmukh, R. R.; Rajagopal, R.; Srinivasan, K. V. Chem. Commun. 2001, 1544.
17. (a) Mason, T. J.; Lorimer, J. P. In E. Horwood, Ed., Sonochemistry: Theory, Application and Uses
of Ultrasound in Chemistry; John Wiley, New York, 1988; (b) Suslick, K. S., Ed., Ultrasound,
Its Chemical, Physical and Biological Effects; VCH: Weinheim, Germany, 1988; (c) Gaplovsky,
A.; Gaplovsky, M.; Toma, S.; Luche, J. L. J. Org. Chem. 2000, 65, 8444; (d) Deshmukh, R. R.;
Rajagopal, R.; Srinivasan, K. V. Chem. Commun. 2001, 1544; (e) Rajagopal, R.; Jarikote, D. V.;
Srinivasan, K. V. Chem. Commun. 2002, 616; (f) Cravotto, G.; Cintas, P. Chem. Soc. Rev. 2006,
35, 180; (g) Shaabani, A.; Rezayan, A. H.; Rahmati, A.; Sharifi, M. Monatsh. Chem. 2006, 137,
77; (h) Pereira, C. M. P.; Stefani, H. A.; Guzen, K. P.; Orfao, A. T. G. Lett. Org. Chem. 2007, 4,
43; (i) Li, J. T.; Zhang, X. H.; Lin, Z. P. Bailest. J. Org. Chem. 2007, 3, 13.
18. Zon, J. Pol. J. Chem. 1981, 55, 643.
19. (a) Mandhane, P. G.; Joshi, R. S.; Nagargoje, D. R.; Gill, C. H. Tetrahedron Lett. 2010, 51, 1490;
(b) Joshi, R. S.; Mandhane, P. G.; Diwakar, S. D.; Gill, C. H. Ultrason. Sonochem. 2010, 17,
298; (c) Jadhav, G. R.; Shaikh, M. U.; Kale, R. P.; Gill, C. H. Chin. Chem. Letts. 2009, 20,
292; (e) Jadhav, G. R.; Kale, R. P.; Shaikh, M. U.; Gill, C. H. Chin. Chem. Lett. 2009, 20, 535;
(f) Mandhane, P. G.; Joshi, R. S.; Ghawalkar, A. R.; Jadhav, G. R.; Gill, C. H. Bull. Korean
Chem. Soc. 2009, 30(12), 2969.