Aluminum tris(dihydrogen phosphate) [Al(H2PO4)3]: environmentally friendly catalyst for the preparation of 1,1'-(arylmethylene)diurea and N,N'-

(arylmethylene)dibenzamide derivatives

Mohammad Reza Mohammad Shafiee* and Parvaneh Peykanpourfard Faculty of Sciences,

Islamic Azad Univercity –Najafabad Branch, Najafabad, Esfahan, Iran; P.O. Box: 517; E-mail: mohammadreza.mohammadshafiee@gmail.com

Abstract: The purpose of this investigation was to study the one-pot tri-component reaction of phenyl acetylene, aromatic aldehyde and urea in the presence of Al(H2PO4)3 as catalyst under thermal, solvent-free conditions to establish different kinds of 1,1'-(arylmethylene)diurea and N,N'-(arylmethylene)dibenzamide derivatives. The corresponding 1,1'-(arylmethylene)diurea and N,N'-(arylmethylene)dibenzamide derivatives have been obtained in good to excellent yields. The simple and efficient catalytic method represents an ecologically benign and economically attractive synthetic pathway. The effect of alkynes on the formation and establishing of 1,1'-(arylmethylene)diurea and N,N'-(arylmethylene)dibenzamide derivatives in an unusual and modified reaction and procedure has been described.

Keywords-Aluminum tris (dihydrogen phosphate) [Al(H2PO4)3; 1,1'- (arylmethylene) diurea; N,N'-(arylmethylene ) dibenzamide; Alkyne

I. INTRODUCTION One important aspect of clean technology is the use of

environmentally friendly catalysts-typically a solid catalyst that can be easily recovered when the reaction is complete. Heterogeneous organic reactions have proven useful to chemists in the laboratory as well as in the industrial context. These reactions are effected by the reagents immobilized on the porous solid supports and have advantages over the conventional solution phase reactions because of the good dispersion of active reagent sites, associated selectivity and easier work-up [1].

The development of simple, efficient and environmentally benign chemical process or methodologies for widely used pharmacophores from readily available reagents and catalysts are the major challenges for chemists’ throughout the world [2]. To plan and manage chemical reactions with “green” experimental protocol is an enormous challenge that chemists have to confront to improve the quality of the environment for present and future generations [3]. Over the past, chemists have been aware of the environmental implications of their chemistry. Nowadays, they are trying to develop new synthetic methods, reaction conditions, and uses of chemicals that reduce risks to humans and the environment. Organic solvents are high on the list of damaging chemicals because they are employed in huge amounts and are usually volatile liquids that are difficult to store [1].

Compounds bearing amide and bisamide groups is important intermediates in organic synthesis since these groups can be easily transformed into other functionalities (such as gem-diaminoalkyl and aminoalkyl group) and are of considerable interest in the synthesis of pharmacological materials such as peptidomimetic compounds [4,5]. Therefore, preparation of amides has been attracted considerable attention from the past and in recent years.

The aim of the present protocol was to summarize the data on the one-pot preparation of N,N’-alkylidene bisamide derivatives in high yield using a three-component condensation of an alkyne, aromatic aldehydes and amides/urea in the presence of Al(H2PO4)3 as catalyst under thermal, solvent-free conditions (Scheme 1).

NH

O

Y

Ar

NH

O

YAl(H2PO4)3

Solvent-free100 oC

+ Ar(R)-CHO Y NH2

O

+

Y: CH3; NH2; NHCH3 Scheme 1

II. EXPERIMENTAL All reagents were purchased from Merck and Aldrich and

used without further purification. All yields refer to isolated products after purification. Products were characterized by comparison of spectroscopic data (IR, 1H NMR spectra) and melting points with authentic samples. The NMR spectra were recorded on a Bruker Avance DPX 300 MHz instrument. The spectra were measured in DMSO-d6 relative to TMS (0.00 ppm). IR spectra were recorded on a JASCO FT-IR 460plus spectrophotometer. Melting points were determined in open capillaries with a BUCHI 510 melting point apparatus. TLC was performed on silica gel polygram SIL G/UV 254 plates. A-Preparation of Al(H2PO4)3:

The catalyst was prepared by taking a mixture of alumina (neutral) and concentrated phosphoric acid (88%) in a silica boat maintaining the molar ratio of alumina: H3PO4 as 1:3 and heating at 200-220°C on a hot sand bath. The mixture was stirred at the stipulated temperature until the swampy mass solidified and then the temperature was reduced to around 100°C. The whole was then placed in a vacuum desiccator and cooled to ambient temperature. The catalyst

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2011 2nd International Conference on Environmental Science and Technology IPCBEE vol.6 (2011) © (2011) IACSIT Press, Singapore

B

N

thus preparedsample vial [6

B-X-ray diffraPowder X

using D8 Adcompany in Gof 0.02 and asource generawere preparedsample holder70° and phaspatterns to enware. The frepattern is presthe actual phaand Al2PO4(O

C-Typical ProTo a mixtu

and phenyl (0.025 g) and the appropriatwas monitoremass was cooboiling ethanfiltration. Solwas purified solvent (ethanAll the produNMR:

N-BenzoyEntry 1): 1H-NMR (301H), 7.29-7.5= 7.7 Hz, 2H59.6, 127.4, 1ppm; IR (KB

d was finally tr6].

action (XRD) X-ray diffractiodvance diffracGermany. Scaa counting timated at 40 kV d by compactir. Data was coses were iden

ntries in the Dish catalyst wasented in Figuases were Al(HOH)3

Figure 1. XRD

ocedure: ure of benzaldacetylene (1 mixture was

te time (Tableed by TLC. Aoled to 25 oC nol. The catlvent was conby recrystall

nol 40% or dieucts were char

ylamino(pheny

00 MHz, DMS8 (m, 11H), 7

H) ppm; 13C 128.4, 128.5,

Br, cm-1): 3285

ransferred and

on measuremect meter madans were takenme of 1.0s usi

and 30 mA. ion in to a glaollected over antified by maiffractplus versias characterizeure 1. As it waH2PO4)3 (hexa

D pattern of Al(H

dehyde (1 mmmmol) was

heated at 100 e 1). The progAfter completand the mixtu

talyst was rencentrated anlization proceethyl ether). acterized by I

yl)methyl ben

SO-d6): δ = 77.92 (d, J = 7.1

NMR (75 M129.2, 132.5, 5, 3088, 1651

d stored in an

ents were perde by a Brukn with a 2θ sting Cu Kα raSpecimens fo

ass-backed alua 2u range fromatching experiion 6.0 indexied by XRD anas shown in Fiagonal), AlPO

H2PO4)3

mol), urea (2.5 added Al(H

oC in an oil bgress of the rtion of the reure was dissoemoved by

nd the solid pedure in appr

IR, 1H NMR a

nzamide (Ta

7.05 (t, J = 71 Hz, 4H), 9.0

MHz, DMSO-d134.7, 141.1

1, 1543, 1497

airtight

formed ker axs tep size adiation or XRD uminum m 48 to imental ing soft nd their igure 1, 4.xH2O

mmol) H2PO4)3 bath for eaction eaction, lved in simple

product ropriate

and 13C

able 1,

7.7 Hz, 03 (d, J d6): δ= , 166.5 , 1342,

12NN,En1H6HHzpp123013475.N,En1H6HHzpp(22980reN,En1H6HHz8.M142910C1

N,1H= 2HDMIR134.27

A-ca

co

269, 1137, 104, 8.51; C21H18

N,N-(4-nitrophentry 2):

H-NMR (300 H), 6.20 (br, 2z, 2H), 7.56 (pm; 13C NMR28.2, 147.3, 15072, 3040, 29352, 1304, 1267.05; H, 5.45;38; N, 24.90 %

N,N-(4-chloropntry 3):

H-NMR (300 H), 6.02 (br, 2z, 2H), 7.31 (pm; 13C NMR2C), 132.3, 14942, 1638, 15807, 734; Foundquires C, 48.8

N,N-(3-nitrophentry 4):

H-NMR (300 H), 6.13 (br, 2z, 2H), 7.62 (12 (d, J = 7.9

MHz, DMSO-d46.4, 148.5, 15959, 1645, 15059, 989, 82111H15N5O4 req

N,N-(4-nitropheH-NMR (300 M

8.2 Hz, 1H), H), 8.21 (d, JMSO-d6): δ=

R (KBr, cm-1):348, 1269, 11447; N, 27.79

7.66 %].

II- Optimizationatalyst

To improvonditions, the

47, 875, 802, 8N2O2 requiresenyl)methyl)d

MHz, DMSO2H), 6.20 (t, J(d, J = 8.4 Hz

R (75 MHz, D51.7, 158.4 pp946, 1639, 169, 1177, 107 N, 24.97; C1

%]. henyl)methyl)

MHz, DMSO2H), 6.13 (t, J(d, J = 8.5 HzR (75 MHz, D42.9, 158.4 pp84, 1488, 125d: C, 48.91; H80; H, 5.58; Nenyl)methyl)d

MHz, DMSO2H), 6.22 (t, J(t, J = 7.8 Hz,9 Hz, 1H), 8.d6): δ= 27.1, 558.4 ppm; IR 586, 1527, 11, 699 Foundquires C, 46.97enyl)methyl)dMHz, DMSO-6.99 (d, J = 8J = 8.6 Hz, 259.6, 124.2, 1: 3454, 3304, 43, 1106, 841; C9H11N5O4

II. RESULTS

n of the temp

ve the yielde reaction w

702; Found: s C, 76.34; H,di(N′-methyl)u

O-d6): δ = 2.5J = 7.9 Hz, 1Hz, 2H), 8.19 (d

DMSO-d6): δ= pm; IR (KBr, 605, 1584, 18, 876, 854, 8

11H15N5O4 req

)di(N′-methyl

O-d6): δ = 2.5J = 8.2 Hz, 1Hz, 2H), 7.38 (dDMSO-d6): δ=pm; IR (KBr, c2, 1212, 1173

H, 5.65; N, 20.N, 20.70 %]. di(N′-methyl)u

O-d6): δ = 2.5J = 7.9 Hz, 1H, 1H), 7.76 (d.15 (s, 1H) pp59.7, 121.4, 12

(KBr, cm-1): 424, 1347, 1

d: C, 47.05; H7; H, 5.38; N,

diurea (Table 1-d6): δ = 5.81

8.2 Hz, 2H), 72H) ppm; 13C128.2, 147.3, 2962, 1671, , 779, 742; Forequires C, 4

S AND DISCUSS

perature and

d and optimwas carried o

C, 76.39; H, 5.49; N, 8.48

urea (Table

56 (d, J = 4.3H), 6.91 (d, J =d, J = 8.7 Hz,27.1, 59.8, 1

cm-1): 3361, 31516, 1492, 1825, 739; Founquires C, 46.9

l)urea (Table

54 (d, J = 4.4H), 6.73 (d, J =d, J = 8.5 Hz,

= 27.1, 59.7, 1cm-1): 3322, 3

3, 1088, 1014,.77; C11H15ClN

urea (Table

55 (d, J = 4.3H), 6.94 (d, J =d, J = 7.4 Hz, pm; 13C NMR22.8, 130.5, 13378, 3301, 3

1251, 1206, 1H, 5.47; N, 2 24.90%]. 1, Entry 5): (br, 4H), 6.17.57 (d, J = 8.5

C NMR (75 M158.6, 160.5 p1609, 1561, 1ound: C, 42.742.69; H, 4.38

SIONS the amount of

mize the reaout using ph

5.55; 8 %].

1,

3 Hz, = 8.1 , 2H) 24.1,

3311, 1418, nd: C, 7; H,

e 1,

4 Hz, = 8.2 , 2H) 128.8 3031, 859, N4O2

1,

3 Hz, = 8.0 1H),

R (75 33.9,

3168, 1165, 4.99;

7 (t, J 5 Hz, MHz, ppm; 1514, 6; H, 8; N,

of the

action henyl

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acetylene, benAl(H2PO4)3 atemperature oAt 80 oC, thcomplete conincrease in tereaction. TheroC (giving sho

+ Ph-

Figure 2Benzoylamino

Then we tthis reaction. was efficient the amount of(Fig. 3). Fina0.025 g of Al(

Figure 3. Th

nzaldehyde anas catalyst (Scon rate of the rhe reaction pnversion of emperature to refore, we keport reaction tim

-CHO Ph N

O

+

S

2. Effect of tempo(phenyl)methyl b

tried to optimIt should be enough to catf catalyst did nally, we achiev(H2PO4)3 as th

he effect of amouBenzoylamino(p

nd benzamidecheme 2). Inreaction was iproceeded smproduct was100 oC incre

pt the reactionme and high y

Al(H2PO4)H2 Solvent-fre

Scheme 2

mperature for the pbenzamide using (0.05 g)

mize the amounnoted that 0.0talyze the reacnot improve thved an optimihe catalyst and

unt Al(H2PO4)3 inphenyl)methyl ben

e in the preseitially, the efinvestigated (F

moothly and s observed. Feased the raten temperature yield).

Ph

NH

O

Ph)3

ee

preparation of N-Al(H2PO4)3 as ca

nt of the catal025 g of Al(Hction, and incrhe yield signifized conditiond 100 °C.

n the preparation onzamide

ence of ffect of Fig. 2). almost

Further of the as 100

NH

O

Ph

h

atalyst

lyst for H2PO4)3 reasing ficantly n using

of N-

efsyTh

En

aIs

prcrprpr

he(adepropmcavi

Nath

Using these fficiency of ynthesis of a whe results are s

TABLE I. N,N'-(AR

ntry Ald

1 Benza

2 Nitroben

3 Chlorobe

4 Nitroben

5 Nitroben

solated yields.

The work-uroducts were irystallization frotocol avoidsrocess, making

In conclusieterogeneous carylmethylene)erivatives in aresent protocperational sim

mild reaction catalysts which ew of environ

We are thajafabad Bran

his research

[1] (a) R. supportevol: 1, p

[2] a) W. BTheory Laszlo, AcademSupportChiches

[3] (a) K. TVCH, W

[4] (a) C. AFebruary

optimized reathese proced

wide variety osummarized in

PREPARATION OFRYLMETHYLENE)

dehyde

aldehyde Be

4-nzaldehyde

N

4-enzaldehyde

N

3-nzaldehyde

N

4-nzaldehyde

up procedure isolated and pfrom aqueous s the use of g it superior to

IV. Cion, a rapid catalytic proto)diurea and N,a one-pot proccol features

mplicity, high yconditions, us

make it a usenmental and ec

ACKNOW

ankful to thnch Research C

REFE

S. Varma, “Sed reagents and pp. 43-55, FebruaBannwarth, B. Hi

to Application; Preparative Ch

mic Press, Inc., Sts and Catalyst ister, 1992. Tanaka, G. KauppWeinheim, 2009.Alemán, J. Puiggay 1995; (b) H

action conditidures were of substitutedn Table 1.

F 1,1'-(ARYLMETH)DIBENZAMIDE DE

Amide Tim(mi

enzamide 80

N-methyl urea

5

N-methyl urea

8

N-methyl urea

7

urea 25

is very cleapurified by sim ethanol (or ddry media du

o the reactions

CONCLUSION and enviro

ocol for the pN,N'-(arylmethycedure has bee

with mainyields, short rse of low coseful and attracconomical poi

WLEDGMENTS he Islamic ACouncil for the

ERENCES Solvent-free org

microwave irradary 1999. inzen, CombinatWiley/VCH, W

hemistry Using San Diego, 1987in Organic Synt

p, Solvent-free org

ali, J. Org. ChemH. R. Shaterian,

ons, the scopeexplored for

d urea (Schem

HYLENE)DIUREA AERIVATIVES

me in)

Yield (%)a

0 76

64

63

67

5 65

ar-cut; that ismple filtrationdiethyl ether).uring the rea

s that use solve

onmentally bepreparation of ylene)dibenzaen developed.

n advantagesreaction timest and eco-frie

ctive process iints.

Azad Universie partial suppo

anic syntheses diation” Green C

torial Chemistry: Weinheim, 2006;

Supported Rea7; (c) K. Smith, thesis, Ellis Hor

ganic synthesis, W

m. vol. 60, pp. 91, H. Yarahmad

e and r the

me 1).

AND

m.p. (°C) 234-236 207-209 196-198 202-203 185-187

s the n and . Our action ent.

enign f 1,1'-amide . The s of s, and endly in the

ity –ort of

using Chem.,

From (b) P.

agents, Solid

rwood,

Wiley-

0-924, di, M.

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Ghashang, Bioorg. Med. Chem. Lett. vol. 18, 788-792, January 2008.

[5] Pallai, P. V.; Struthers, R. S.; Goodman, M.; Moroder, L.; Wunsch, E.; Vale, W. Biochemistry, vol. 24, pp. 1933-1941, April 1985.

[6] (a) F. d’Yvoire, Bull. Soc. Chim. Fr. 2277, pdf file no.00-014-0546, 1961; (b) H. R. Shaterian, M. Ghashang, N. Tajbakhsh Riki and M. Asadi, “An efficient method for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS) catalyzed by aluminum tris(dihydrogen phosphate) under solvent-free and ambient conditions” Can. J. Chem. Vol: 86, pp. 841-845, August 2008.

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