168

CHAPTER – IV

NANO COPPER FERRITE: A REUSABLE

CATALYST FOR THE SYNTHESIS OF β, γ-

UNSATURATED KETONES

169

Nano Copper ferrite: A reusable catalyst for the synthesis of β, γ-

Unsaturated Ketones

SECTION A: LITERATURE REVIEW

Catalysts have the remarkable property of facilitating chemical reactions

repeatedly without being consumed. Enzymes, which catalyze all aspects of cell

metabolism, are the supreme master of this art. We have used them from earlier times

for leaving bread, curdling cheese and brewing beer.

Heterogeneous catalysis plays a key role in generating the feed stock for

making the synthetic materials that we use every day, from fuels to fertilizers. New

experimental techniques have brought fresh insights into this form of catalysis, and it

now seems that there are more similarities between enzymes and heterogeneous

catalysts that initially meet the eyes.

An extensive application of heterogeneous catalysis in synthetic chemistry

can help to achieve new selective reactions to lower formation of waste and finally

render more attractive synthetic process for both environment and economic point of

view. Wender1a has described heterogeneous catalytic synthesis as “ideal synthesis” in

accordance the above.

Among the first reactions performed under heterogeneous catalysis are the

hydrogenation and, in general, the redox processes which are extensively applied in

synthetic organic chemistry. Acid - Base heterogeneous catalysis was successively

developed by exploiting the physicochemical properties of zeolities,1b clays 1c and

metal oxides.1d

Introduction to Ferrites:

The organic- Inorganic hybrid materials possess interesting functions through

the amalgamation of important properties from both components.2-5 Magnetic nano

composites possess unique physical and chemical properties compared to their bulk

counterparts due to their nano dimensions. The fast development of mobile

communication and information technology, small, inexpensive high performance

electronics devices are in high demand6. Recently, the rapid development of surface

mounting devises (SMD) using multilayer chip inductors (MLC1), which utilize

alternating coats of ferrite and electrical paste followed by co-firring.

170

Nickel ferrite nano crystals7 with octahedral structures were synthesized using

EDTA- assisted hydrothermal method under mild conditions. XRD and FTIR analyses

were used for composition and structure investigation. XRD analysis revealed a pure

ferrite phase with high crystallinity. Morphological investigations by SEM showed

octahedral nano crystals with an average size of 40 nm. The FT-IR spectrum showed υ1

and υ2 fundamental bands, corresponding to octahedral and tetrahedral sites in the

ferrite structure. Recently, it was observed that photo catalysts consist of nano

composites are efficient in utilizing visible light photons,8-12 and also observed that

such nano composite showed unprecedented high activity for photo catalytic oxidation

of water under visible light.

Jang J.S. et.al,13 describe the synthesis of Zinc ferrite(ZnFe2O4), Viz. an n-type

photo catalyst with spinel crystal structure and characterize the optical properties of

the nano crystalline zinc ferrite by using UV –Visible diffuse reflectance spectroscopy

and X-ray diffraction. Also, the photo catalytic and the photo electrochemical

performances of the material for photo current generation and CO2 production from

photo oxidation of iso propyl alcohol under visible light irradiation were investigated.

Among the nano scale inorganic materials, magnetic metal oxides and their

composites with polymers are of particular interest for their applications in various

areas like quantum computing,14 information storage media,15 sensors,16

electromagnetic wave absorption,17 modulation,18 refrigeration,19 magnetic resonance

images.20

In polymeric composites, the polymer plays the role of reducing the

aggregation of particles and imposes the upper limit on the size of inorganic particles.

The recent growth in nano materials as building blocks for general synthetic approach

to control the size and shape of inorganic nano particles. A new wet chemical method

has been reported 21, which is suitable for the direct synthesis of nano sized inorganic

oxides 22-24 in a copolymer matrix. D.R. Sharma et. al,25 reported the synthesis of a

series of nano composites of Ni-Zn ferrites in the copolymer matrix of aniline

formaldehyde and observed an interesting phase transformation including the

formation of metallic phase on pyrolysis of these materials at different temperatures

using XRD, Infrared and Mossbauer spectroscopy and transmission electron

microscopy(TEM). The spinel ferrite phase in these samples persists on heating

171

temperature to 5000C. The samples heated at 7000C, under ambient conditions, have

shown very interesting phase changes resulting the formation of Ni-Fe alloy due to the

polymer pyrolysis assisted partial reduction of spinel ferrite. Further, on heating the

sample at 7000C under Nitrogen environment results in the formation pure metallic

phase.

Liu. et al. 26 reported the high sensitivity of Cadmium ferrite(CdFe2O4) to

ethanol vapor, Reddy et. al.27 investigated Nickel ferrite(NiFe2O4) as sensor to detect

Cl2 air. Chen et al 28 revealed that Magnesium ferrite (MgFe2O4) and Cadmium

ferrite(CdFe2O4) are sensitive and selective LPG and acetylene (C2 H2).

Y. Atassi et al.29 prepared Mg-Cu-Zn ferrite through a wet synthetic method by

a self-combustion reaction directly from citrate-precursor. The synthesized powders

were sintered at 7500C for 2 hours. XRD patterns and FTIR spectra confirmed the

formation of single phase Mg-Cu-Zn ferrite after combustion. This is the first time that,

Mg-Cu-Zn ferrite is sintered at such a low temperature. The sintered process increased

the crystalinity of the solid and domain sizes. Tania Jahanbin et al 30 presented nano

crystalline nickel Zinc Ferrite (Ni0.8Zn0.2Fe2O4) has been synthesized by co-precipitation

technique. The dried powder has passed into the toroid and pellet forms, then

sintering them at sintering temperatures of 11000, 12000 and 13000C. The samples were

characterized employing X-ray diffraction, initial permeability and relative loss factor.

The initial permeability values were in the range of 10-17 due to the small particle size.

The relative loss factor was in the order 10-3 –10 -5 in the frequency range of 1 MHz to 1

GHz.

The materials of choice for many microwave applications are cubic ferrites, of

the cubic spinel ferrites two classes of materials are significant; The Mn-Zn and the Ni-

Zn ferrite materials. Mn-Zn ferrite is typically limited to frequencies <500 KHz owing

to their relatively low resistivities (0.02-20. –m) ; Ni-Zn ferrite materials have very large

resistivites (101-107 –m), high neel temperatures above 5000C and tunable magnetic

inductions making them potential candidates for much higher frequency (1-300 MHz)

applications.31 N. Rezhescu et al,32 presented some spinel ferrites, MFe204 (M=Cu,Cd

and Zn), having sub-micron grain sizes (0.1-0.7μm) were prepared by sol-gel-self

combustion and their sensing properties to reducing gases were investigated. By gas

sensitivity measurements it was found that copper ferrite(CuFe2O4) has a good

172

sensitivity to reducing gases at optimum working temperature of 3000C. Better

sensitivity to LPG of copper ferrite (CuFe2O4) cannot be explained by morphology

changes. Zinc ferrite (ZnFe2O4) having the highest porosity and largest surface area, is

sensitive to ethanol only.

The palladium catalyzed coupling reaction between aryl halide and olefins

often known as the Heck Reaction33 has become an important C-C coupling reaction in

modern organic synthesis due to the broad availability of substrates. (Aryl -Iodides, -

bromides, -Chlorides) and the tolerance to the wide range of functional groups.

In recent years, much attention has given to overcome the problems on

homogeneous ‘Pd’ catalysts, by employing many heterogeneous Pd systems,34 such as

Pd supported on different supports like carbon,35 mesoporous silica,36 zeolites,37

metaloxides,38 clays,39 polymer,40 diatomic,41 ionic liquids,42 and surface modified

nickel ferrite43. Ferrite is a family of oxide that plays an important role in the field of

heterogeneous catalyst and proved to be a suitable support44. Nickel ferrite with an

inverse spinel structure showed ferromagnetism and therefore it can be easily

separated from reaction mixture by employing an external magnetic field.

Sanjay R Borhade et al,45 presented the palladium supported on Nickel ferrite

found to be highly active catalyst for the Heck olefination of aryl iodides and activated

aryl bromides providing an excellent yield under aerobic condition & in shorter

reaction time and presented in Scheme-1.

X +

R

RPd-Nickel Ferrite

TEA , DMF

1300

X= I, Br, Cl. R= COOEt, Ph, COOH, CONH2 etc.

Scheme -1

1,2,3-Triazoles were synthesized in water using magnetically recoverable

heterogeneous Cu catalyst via one-pot multi component reaction using MW irradiation

was reported by R. S. Varma et al46(Scheme-2). The advantages of this protocol are easy

recovery of the catalyst using an external magnet, efficient recycling, and the high

stability of the catalyst renders the protocol economic and sustainable.

173

Ph

Br

+ Ph + NaN3

nano-FGT-Cu Catalyst

MW,120oC,10 min

NN

N

PhPh

Scheme -2

Y. V. D. Nageswar47 and his co-workers reported that a simple and efficient

procedure for the synthesis of diaryl selenides employing copper ferrite nanoparticle

catalyzed reaction of aryl iodides/aryl bromides with diphenyl diselenide in the

presence of base and solvent at 120 °C. The copper ferrite nanoparticles were

magnetically separated, recycled, and reused up to three cycles. This was presented in

Scheme-3

Ph I + PhSeSePhCuFe2O4 nanoparticles

KOH, DMSO, N2, 120 oC, 18hPh

SePh

Scheme -3

M.L.Kantham et al 48 presented magnetically recoverable and reusable copper

ferrite nanoparticles for asymmetric hydrosilylation of several ketones and represented

in Scheme-4. The copper ferrite nanoparticles were magnetically separated, and the

efficiency of the catalyst remains almost unaltered up to three cycles.

O

Br

CuFe2O4 nano particlesPMHS, BINAP

toulene, rt, 12h Br

OH

Scheme -4

An efficient three-component coupling of aldehydes, amines and alkynes has

been developed to prepare propargylamines in nearly quantitative yields using

magnetically separable copper ferrite nanoparticles as catalyst which was reported by

174

M.L.Kantam49.The advantage of this reaction is, it does not require any co-catalyst. It

was presented in Scheme-5

Ph ONH

Ph

++CuFe2O4

toulene, 80oC, 4hN

Ph

Ph

Scheme -5

The effectiveness of magnetic CuFe2O4 powder as adsorbent/catalyst for the

removal of azo-dye Acid Red B (ARB) from water by adsorption and subsequent

catalytic combustion was studied by R. Wu and co-workers 50. Magnetic

CuFe2O4 powder showed excellent adsorption properties towards ARB at pH<5.5, and

it could be conveniently recovered by magnetic separation technology after

adsorption(Scheme-6).

SO3Na

OH

NN

SO3Na

CuFe2O4

water, pH<5.5,

150 -300oC

SO2 + CO2 + nitrate

Scheme-6

Previous methods for the allylatioin of carbonyl compounds:

β, γ – Unsaturated Ketones are versatile synthons in the synthesis of natural

products51. In general acylation of olefins produces β, γ – unsaturated ketones, but α,

β– unsaturated ketones may also be generated52 . The synthesis is complicated by a

tendency towards prototropic rearrangement producing conjugated α, β– unsaturated

ketones53.

Y. Ishino et al54 reported that treatment of acid chlorides with allyl chlorides in

the presence of zinc dust and a catalytic amount of chlorotrimethylsilane (TMSCl) in

THF brought about highly facile and effective coupling to give the corresponding gem-

bisallylation products, 4-hydroxy-penta-1,6-dienes, in good to excellent yields. These

reactions are assumed to proceed through allylzinc intermediates generated in situ.It

was represented in Scheme 7.

175

Ph Cl

O

+Cl Zn, Me3SiCl

THF,50 o, 3h

Ph

HO

Scheme 7

Indium-mediated allylation of α-chlorocarbonyl compounds with various allyl

bromides in aqueous media gave the corresponding homoallylic chlorohydrins, which

could be transformed into the corresponding epoxides in the presence of a base was

described by J.A.Shin and co-workers55 presented in Scheme 8 . These reactions were

strongly dependent upon both the substituents at the carbon bearing chlorine and the

allyl bromides used.

Ph

O

ClBr+

PhCl

OH O Ph

In

aq.THF

DBU

THF , rt

Scheme-8

Y.-M. Zhang et al56 presnted that ytterbium can react with allyl bromide

smoothly in the presence of methyliodide to form allylytterbium bromide(Scheme 9),

which further reacts with diselenides, aldehydes and ketones to afford allylselenides

and homoallylic alcohols respectively in good yields under mild and neutral

conditions.

Br

Yb, MeI

THF, 0o

YbBr

(i) PhSePh,THF

15o, 30 min

(ii) HCl

SePh

(i) PhCHO,THF,25o,1h

(ii) HCl OH

Ph

Scheme- 9

T. H. Chan et al57 reported that commercial antimony can be used directly for

the allylation of carbonyl compounds in aqueous media in the presence of fluoride

salts.(Scheme 10)

176

Br + PhCHOaq. KF, Sb

20o, 16hPh

OH

Scheme 10

Regio- and diastereoselective carbonyl allylations of 1-halobut-2-enes with

tin(II) halides are described by Y. Masuyama et al58. In this reation, Tin(II)bromide in a

dichloromethane−water biphasic system is an effective reagent for unusual α-

regioselective carbonyl allylation of 1-bromobut-2-ene to produce 1-substituted pent-3-

en-1-ols (Scheme 11). The addition of tetrabutylammonium bromide (TBABr) to the

biphasic system produces 1-substituted 2-methylbut-3-en-1-ols via usual γ-addition

which is opposite to the α-addition without TBABr. The γ-addition to aromatic

aldehydes exhibits anti-diastereoselectivity, while that to aliphatic aldehydes is not

diastereoselective.

Br + PhCHO

A) SnBr2, CH2Cl2

H20, 25oC, 24 hrs

or

B) SnBr2, Bu4NBr

CH2Cl2, H2O, 25oC,24 hrs

Ph

OH

+ Ph

OH

Scheme 11

H.Suzuki et al59 reproted that in the presence of allyl halide, aromatic aldehydes

readily underwent a Barbier-type allylation when milled together with bismath shot to

afford the corresponding homoallyl alcohols in good yield (Scheme 12). In contrast to

the failure in solution reaction, aromatic ketones also underwent allylic carbonyl

addition under solvent-free conditions to give the expected tertiary homoallyl alcohols

in moderate to good yield

Br + PhCHOBi shot

ball mill,1.5 hPh

OH

Scheme 12

Tin-mediated allylation of aldehydes or ketones in distilled water gives rise to

the corresponding homoallyl alcohols in high yield without assistance such as heat,

supersonic and acidic media was reported by Z.Y.Wang and his co workers60 (Scheme

13).

177

Br + PhCHOSn, H2O

rt, 13hPh

OH

Scheme 13

A highly efficient electroallylation of carbonyl compounds in aqueous

electrolyte in a divided cellwith a catalytic amount of zinc consumption was reported

by J.-M. Huang et al61 (Scheme 14).

Br + PhCHO

Zn Cathode/Pt anode

NH4Cl-THF,LiClO4

H2O, 30 mA,rtPh

OH

Scheme 14

M. D. Preite et al 62 repoted that a new protocol, amenable to be used in large-

scale preparations, using an economical form of indium metal and mild warming is

reported for the Barbier allylation of aldehydes and ketones with allyl bromide in N,N-

dimethylformamide (Scheme 15).

CHOBr+

In

DMF, 40 -50oC, 2h

OH

Scheme 15

Jagir S. Sandhu et al63 described a new and efficient method for the preparation

of β,γ-unsaturated ketones has been achieved by a simple reaction of an acid chloride

with allyl and crotyl bromide and cadmium powder in absolute tetrahydrofuran

(Scheme 16)

R Cl

O

BrR1+

Cd, THF

R

O

R1

Scheme 16

An efficient procedure for the preparation of β,γ-unsaturated ketones has been

developed by a simple reaction of an acid chloride with allyl bromide and commercial

zinc dust in ether was reported by B.C. Ranu et al64 (Scheme 17) .

178

Br1.Zn , ether

2. RCOClR

O

Scheme 17

A mild and efficient method for the preparation of β,γ unsaturated ketones by

a simple reaction on acid chloride with allyl, crotyl, prenyl bromide and indium in

DMF was described by J.S. Yadav et al65 (Scheme 18).

R Cl

O

R2

R1

Br

, In

DMF / H2O

R

O

R1 R2

Scheme 18

A series of allyl ketones were synthesized from the mixture of zinc, nitrile and

allyl bromide in the presence of AlCl3 via Barbier-type reaction condition was

reported by Li-Shin Lin et al66 (Scheme 19). When crotyl bromide was used for the

allylation, only the γ-adduct was produced via the SE2′ pathway under the reaction

condition.

R CN +Br Zn/AlCl3 (4eq./0.4eq.),THF

2M HCl (5mL/ eq.)R

O

Scheme 19

Vernal J. Bryan et al67 reported that Indium mediated coupling of allylic

bromide with acyloyl-imidazoles or pyrazoles in aqueous media gives the

corresponding tertiary alcohols or ketones in good yield (Scheme 20). The reaction

provides a facile regioselective synthesis of β,γ-unsaturated ketones and its usefulness

is demonstrated by the synthesis of the monoterpene artemesia ketone.

N N

O

Ph + BrR1

In

H2ON NR

R1

O In

R

O

R1

Scheme 20

179

Yoshiro Masuyama and his coworkers68 reported that Carbonyl allylations by

allylic chlorides either with tin(IV) iodide and tetrabutylammonium iodide (TBAI) in

dichloromethane or with tin(IV) iodide and sodium iodide in 1,3-

dimethylimidazolidin-2-one at room temperature produced the corresponding

homoallylic alcohols (Scheme 21). The carbonyl allylations probably proceeded via the

reduction of tin(IV) iodide to tri iodostannate(II) species with iodide sources such as

TBAI and NaI, which led to the construction of a tin(IV)-catalytic cycle based on

regeneration of tin(IV) iodide via the transmetalation of homoallyloxytriiodotin to

homoallyloxytrimethylsilane with iodotrimethylsilane.

SnI4MI

-I2reduction

M+SnI3

Cl

-MClSnI

R

OH

RCHO

R

OSnI3H3O+

StoichiometrticMe3SiI

transmetalationcatalytic

SnI4+R

OSiMe3

R

OH

MI -I2, reduction

Scheme 21

Richard C. Larock et al69 reported that allylic mercuric iodides undergo

efficient acylation with allylic rearrangement upon reaction with acyl chlorides and

aluminium chloride to provide a convenient synthesis of allylic ketones (Scheme 22).

Artemisia ketone was prepared in two steps by this approach.

H2C=C(CH3)CH2HgI + n-C3H7COCl

AlCl3/ CH2Cl2

0oC, 10 minn-C3H7COCH2C(Cl)(CH3)2

Scheme 22

Allylations of N-benzyl and N-methyl cyclic imides were accomplished

successfully under mild Barbier type conditions using zinc metal, allyl bromide and

catalytic amount of PbBr2 was described by Sung Hoon Kim and his co-workers70

(Scheme 23). Subsequent coupling reactions with some carbon nucleophiles afforded

1,2- and 1,4-addition products in moderate to high yields.

180

Y

N

YO

OR1

R1 = CH3,CH2Ph

Y-Y: CH2-CH2,C6H4

+ BrZn

PbBr2 cat

Y

N

Y

O

OH

R1

Carbon nucleophileAlkylated product

Scheme 23

Huanfeng Jiang et al71 reported the regioselective synthesis of β, γ-unsaturated

ketones from terminal alkynes is achieved by cooperative action of tris(acetonitrile)

pentamethyl cyclopentadiene rutheni hexafluorophosphate [Cp*Ru(MeCN)3+ PF6-]

and para-toluenesulfonic acid catalysts (Scheme 24).

R + H2O

Cp* Ru(MeCN)3 + PF6- (4 mol%)

p-TSA H2O (15 mol %), dioxane, r.t

RR

O

Scheme 24

Teruaki Mukaiyama et al72 reported that various Π- allylnickel halides were

found to react with 2-pyridyl carboxylates to give β, γ- unsaturated ketones chemo

specifically in good yields (Scheme 25).

R X+

Ni(cod)2

toulene R

+NiX

X

Ni

R

+N

R'CO2

DMF R' R

O

R'R

O

+

Scheme 25

Minoru Uemura et al73 reported that reaction of acid chlorides with lithium

pentamethyl cyclopentadienide afforded the corresponding pentamethyl

cyclopentadienyl ketones in high yield. These ketones were treated with an

allylaluminum reagent to form the corresponding 3-butenyl alcohols. Removal of

pentamethyl cyclopentadiene upon heating or treatment with a catalytic amount of

trichloroacetic acid yields the corresponding β, γ -unsaturated ketones in good yields

(Scheme 26).

Ar Cl

O Cp*Li

Ar Cp*

O

Ar

OH

Cp*THF, 0oC

30 min

AlMe2

THF, -20oC1hr

toulene

reflux Ar

O

Scheme 26

Yoshiro Masuyama et al74 presented that carbonyl allylations by allylic

chlorides either with tin(IV) iodide and tetrabutylammonium iodide (TBAI) in

181

dichloromethane or with tin(IV) iodide and sodium iodide in 1,3-

dimethylimidazolidin-2-one at room temperature produced the corresponding

homoallylic alcohols (Scheme 27). The carbonyl allylations probably proceeded via the

reduction of tin(IV) iodide to triiodostannate(II) species with iodide sources such as

TBAI and NaI, which led to the construction of a tin(IV)-catalytic cycle based on

regeneration of tin(IV) iodide via the transmetalation of homoallyloxytriiodotin to

homoallyloxytrimethylsilane with iodotrimethylsilane.

R H

O

+ ClSnI4, TABI

CH2Cl2, r.tR

OH

Scheme 27

Z. Wang et al reported75 a novel mediation system, Zn-InCl3(cat.)/NH4Cl was

employed in the Barbier–type allylation (Scheme 28). As a result, the allylation with

allyl chloride in water took place smoothly under mild conditions. Various aldehydes

and even ketones could be employed to afford the corresponding alcohols in high

yields.

R1

O

R2

+R3 Cl

Zn-InCl3

sat.NH4Cl R1

OH

R2R3

Scheme 28

Akio Baba et al 76 reported that allylation of acid chlorides was achieved by

allyltributyltin in presence of catalytic amount of dibutyltin di chloride (Scheme 29).

Bu3Sn + R Cl

OBu2SnCl2

Additive

R

O

+ Bu3SnCl

Scheme 29

Samarium(II)-induced77 coupling of acid chlorides with allylic halides gave

diallylated tertiary alcohols. Monoallylated allylic ketones could not be obtained.

Cl + R Cl

OR

OH

SmI2

THF

Scheme 30

182

SECTION-B: PRESENT WORK

Introduction

Despite the advantages of homogeneous metal catalysts, difficulties in

recovering the catalyst from the reaction mixture severely inhibit their use in industry.

Heterogeneous catalysis results in easy separation and recycling of catalyst. Recent

reports reveal that magnetic nanoparticles are efficient catalysts and they can be easily

separated from reaction mixture 78. The high surface area to volume ratio of metal

oxide nanoparticle is mainly responsible for their catalytic performance79. Copper

ferrite nano material is one such reusable catalyst which shows profound catalytic

activity in organic synthesis80.

Thus it is clearly evident that the need for the development of new and flexible

protocols is required in such a way that they should be more economic and

environmentally benign. Here in, we report nano copper ferrite as a reusable catalyst,

for the allylation of acid chlorides with shorter reaction times (than reported) in good

to moderate yields. The general synthetic Scheme is presented in Scheme-I & II.

183

1a-j 3a-j

= Copper ferrite nano particle.

R = (a)C6H5,

(b) 2-ClC6H4

(c) 2-Br,5-F,C6H3

(d) 2-Br,5-F,C6H3,

(e) Furanyl

(f) 5-Phenyl,3-Methyl,4-Isoxazolyl,

(g) 5-(2,5-dichloro)Phenyl,3-Methyl,4Isoxazolyl,

(h) (CH3)3C-,(i)C11H23-(j)C15H31-,

Scheme-I: Synthesis of β, γ-unsaturated ketone using Allyl Bromide.

2a – d 4a – d

= Copper ferrite nano particle

R = (a) C6H5,

(b) 2-ClC6H4,

(c) Furanyl,

(d) – CH (CH3)2

Scheme-II: Synthesis of β, γ-unsaturated ketone employing Cinnamyl Chlorides

184

Preparation of the nano catalyst:

The catalyst is synthesized by citrate gel precursor method81. Copper (II)

nitrate and iron (III) nitrate are taken in stoichiometric proportions and minimum

amount of deionized water is added to produce clear cationic solution. Citric acid

solution is then prepared in stoichiometric ratio. Aqueous solutions with 1:1 molar

ratio of metal ion solutions are mixed and citric acid is added in equimolar ratio to the

above mixed metal ion solution. pH is adjusted to 7 by adding ammonia solution. The

aqueous mixture is kept for stirring to form a highly viscous gel. The gel is then

heated gradually up to 90oC to evolve reddish brown gases and become dried gel

which is finally treated at 350oC for 1 hr to observe whether the dry gel burnt out in

self-propagating manner to form loose powder. The finely powdered particles are

calcinated at 600oC. The powder is then characterized.

Characterization of the catalyst:

XRD studies were carried out to the synthesized nano ferrite and XRD spectrum

is presented in Fig 4.1. From the XRD data it is observed that the copper ferrites are

spinal crystals. From the XRD data, size of the copper ferrite particles is calculated by

using sheerer formulae & particle size is found to be 20 nm. This shows that the

synthesized powder has nano size crystalline. The scanning electron microscope

studies are carried out on the copper ferrite sample at 600oC, and it is presented in Fig

4.2. The TEM image was recorded and presented in Fig 4.3. The lump size with

irregular morphology is observed and it is found at 400 µm at 600oC. From the above

study we observed it possess less number of pores with smaller lump size, resulting

fine grained microstructure with respect to ferrites.

Fig 4.1: XRD Spectrum of CuFe2O4 at 600oC

185

Fig 4.2: SEM image CuFe2O4 Fig 4.3: TEM image of CuFe2O4

Results & Discussions:

In a typical experiment, allylhalide and acid chloride are mixed in presence of

catalytic amount of copper nano ferrite in stoichiometric portions using

tetrahydrofuran as solvent and stirred at room temperature. The completion of the

reaction is monitored by thin layer chromatographic technique (n-hexane and ethyl

acetate as elute). In our initials efforts to optimise the reaction condition, we screened

various solvents like tetrahydrofuran, diethylether, dichloromethane and acetonitrile

for this reaction. We found the reaction was efficient in tetrahydrofuran compared to

the other solvents tested. The results are listed in Table 1. From Table 1 it is clearly

evident that a significant decrease in yields and longer reaction times are noted for the

solvents other than THF, whereas in the presence of tetrahydrofuran the yields are

promising and shorter reaction times are noted.

Table-1: Allylation of acid chlorides under different solvent systems

S.No Catalyst Solvent Time(hrs

)

Yield*

1 CuFe2O4 THF 1.5 95

2 CuFe2O4 (C2H5)2O 3.5 78

3 CuFe2O4 Dichloromethane 6 63

4 CuFe2O4 MeCN 12 Trace

*Isolated yields

186

After completion of the reaction, the catalyst is recovered by magnetization

and washed with diethyl ether and the recovered catalyst is reused for few more

cycles. During washing with the solvent, it is clearly evident that there is no leaching

of catalyst and is confirmed by performing the reaction with the filtrate. Atomic

absorption spectroscopy is employed to determine the copper content of copper ferrite

nano particles and it is found to be 27.3%. The leaching of metal after three cycles is

found to be 0.156%. From our investigations, we observe that nano catalyst shows

excellent to good reactivity with promising yields even for the next three cycles in the

same reaction. Since, there is no observable loss in the yield percentage; the further

reusability of nano catalyst is regretted. The results are listed in table-2.

Table-2: Reusability of nano catalyst

a: Catalyst recovered by membrane filtration and washed with diethyl ether and then

by distilled water

b: yields compared to isolated products

It is noticed that in some reactions the catalyst needs co-catalysts/additives.

Some reactions need the acidic /basic workup to get the product. But here in with the

present nano sized copper ferrite catalyst; there is no need of additives, ligands, co-

catalysts and no need of activation for its reusability. The notable advantages of this

method are (i) lesser reaction times and (ii) reusable than the earlier reported methods.

The results are tabulated in Table 3.

S.No Catalyst Recoverya (%) Yeildb(%)

1 -------- 95

2 97 89

3 86 82

4 80 78

187

Table-3: Reaction times by different catalysts for the allylation of acid chlorides

* Reaction times related to the synthesis of allyl phenyl ketone.

Synthesis of β, γ-unsaturated ketone from allylbromide (3a):

In a typical procedure, allyl bromide (1 mmol) in absolute THF (5ml) is added

to a stirring suspension of copper nano ferrite (10 mol %) and stirring is continued for

30 min at room temperature. Benzoyl Chloride (1 mmol) is then added in THF (10 ml)

to the reaction mixture and then the reaction is continued for a certain period of time

as required for completion (monitored by TLC). The reaction mixture is then filtered

to separate the catalyst and the filtrate was quenched with a few drops of water and

the product is extracted with dichloromethane and the solvent is removed under

reduced pressure. Further purification is attained by column chromatography, a color

less crystalline compound is formed and recrystallized from ethanol. The pure

compound is then characterized by spectroscopic techniques.

The allyl bromide & cinnamyl chloride reacted with a wide variety of 10 acid

chlorides under the above optimized conditions and the results are summarized in

table 4. From the table 4 it is observed that when the reaction proceeded with aliphatic

long chain acid chlorides, the formation of allyl ketone was not found. It appears that

neither electronic effects nor steric effects are important factors in acylation of allyl

halides by nano catalyst. All the acylation reactions proceed with allylic

rearrangement, 82 so that the double bond was removed from the conjugation. The

mechanism, in which electrophillic attack of nano ferrite occurs at the γ carbon atom of

allylic moiety, generated insitu, will react with the acyl halides results the title

compounds. The formation of stable allyl ketone is confirmed by IR & NMR spectral

studies. In 1HNMR spectra, the chemical shift at δ 4.01-5.39, as doublet of doublet,

S.No Catalyst Time*(hrs)

1 Ni(Cod)2 [72] 15

2 Zn [64] 3

3 Cd [63] 3

4 In [65] 3

5 BuSnCl2+Additive [76] 2

6 CuFe2O4 1.5

188

confirms the presence of formation of stable olefinic bond. This indicates allylation

takes place at carbonyl carbon without any prototropic rearrangement. From 13CNMR

data the chemical shift for carbonyl carbon is observed at 162-175 ppm and 132.5-143.92

ppm corresponds to the β carbon and chemical shift at 105.07-111.82 ppm for the γ

carbon. This indicates the tolerance to the double bond.

4.1. Synthesis of allylketones from Cinnamyl chloride:

The results with allyl bromide encouraged us to extend the reaction with cinnamyl

chloride. The synthetic route is presented in Scheme-II. The reaction is done under

above said optimized conditions. The results are listed in Table 4.

Spectral Characterization of 1-(2-chloro phenyl) but-3-en-1-one (table4 entry 2) 3b:

In the IR spectrum the peaks at 1715, 1680, 3071, 776 cm-1 represents the

carbonyl group, alkenyl group, =C-H stretching and C- Cl stretchings respectively. In

1HNMR spectrum (Fig 4.4), the chemical shift at δ 3.33 -3.50 (as a broad singlet)

assigned for CH2 protons, a multiplet at δ 4.76-5.11 for the CH proton, a doublet of

doublet at δ 4.23 for the =CH2 protons and aromatic protons appeared at δ 7.42 -7.93

confirms the formation of compound. In 13 C NMR (Fig 4.5) chemical shifts at δ 166.64,

132.30, 131.70, 131.38, 130.73, 126.96, 119.67, 37.40 were in accordance with the

structure.

Spectral Characterization of 1-(5-methyl-3-phenyisoxazol-4-yl) but-3-en-1-one (table

4 entry 6) 3f:

After completion of the reaction, the crude product was characterized by

advanced spectroscopic techniques. The IR spectrum of compound 3f was presented

in Fig 4.6. From the figure, the peaks at 1719, 1599, 3108, 1678 & 1058 cm-1 corresponds

to carbonyl group, stretching of C=C of allyl group , =C-H group stretching , C=N

stretching of isoxazole moity and C-O-N group respectively . In 1HNMR spectrum

(Fig 4.7) chemical shift at δ 8.18-8.22 represents the aromatic protons, a doublet at δ

3.67 corresponds to the CH2 protons attached to the carbonyl group, a characteristic

multiplet observed at δ 6.29 for the allyl proton (=CH), a doublet of doublet at δ 4.96-

5.04 for the end methylene protons, and a singlet at δ 2.49 for the methyl proton. From

the 13CNMR spectrum (Fig 4.8) chemical shifts at δ 174.9, 162.16, 160.53, 132.88, 131.09,

129.15, 128.38, 126.87, 109.92, 42.30, 12.82 confirms the formation of compound.

189

Fig 4.4 1H NMR spectrum of 1-(2-chloro phenyl) but-3-en-1-one (3b)

190

Fig 4.5 13C NMR spectrum of 1-(2-chloro phenyl) but-3-en-1-one (3b)

191

Fig 4.6 IR spectrum of 1-(5-methyl-3-phenyisoxazol-4-yl) but-3-en-1-one 3f

192

Fig 4.7 1H NMR spectrum of 1-(5-methyl-3-phenyisoxazol-4-yl) but-3-en-1-one 3f

193

Fig 4.8 13C NMR spectrum of 1-(5-methyl-3-phenyisoxazol-4-yl) but-3-en-1-one 3f

194

Table-4: Synthesis of allyl ketones Using copper ferrite nano particles

S.NO R - COCl PRODUCT TIME(hrs)

1

2

3

4

5

6

7

8

10

Cl

Br

F

Br

MeO

O

N

O

C6H5

N

O

C6H3(2,5-Cl)

C(CH3)3

H23C11

C15H31

O

1.5 95

1a3a

OCl

O

Br

F

O

Br

MeO

O

O

N

O

C6H5O

N

O

(Cl-5,2)C6H3O

C(CH3)3

O

ALLYL HALIDE

9

1b 3b

1c3c

1d 3d

1e 3e

1f3f

1g3g

1h 3h

1i

NR

1j

NR

Br

2.3 86

2.0 84

3.081

2.575

3.0 82

3.580

3.075

YIELD(%)

195

11

12

13

Cl

O

O

2a 4a

2b

Cl

OCl

O

O

(CH3)2CH(H3C)2HC

O

2.0 81

2.5 80

2.5 75

3.0 7214

4b

2c

4c

2d4d

*Yields compared to isolated products and characterized by IR &NMR studies

compared with authentic samples

NR: No Reaction

196

Conclusions

In conclusion, we report here for the first time an efficient protocol in the

synthesis of β, γ-unsaturated ketones using copper ferrite nano material. The notable

advantages are inexpensive, heterogeneous reusable catalyst; mild reaction conditions,

high yields of products, shorter reaction times, no isomerization during the reaction

and easy workup.

This work was published in “Journal of Chemical Sciences” Vol. 124, No. 3, May

2012, pp. 639–645.

197

Spectral characterization of selected Compounds:

1-phenyl but-3-en-1-one (table 4 entry 1)3a:83

O

IR (υmax, KBr Pellet in cm- 1): 1701, 1669, 3009 ; 1HNMR

(90MHz, CDCl3/TMS): 7.25-8.4 (ArH,m), 3.89(2H, d),

5.82- 6.09(1H, m), 5.09-5.39(2H, dd); 13 C NMR (22.5MHz,

CDCl3/TMS) δ171.94, 133.77, 130.2, 129.4, 128.41,105.07,

42.28.

1-(2-chloro phenyl) but-3-en-1-one (table4 entry 2) 3b :

O

Cl

IR (υmax, KBr Pellet in cm- 1): 1715,1680, 3071, 776; 1HNMR

(90MHz, CDCl3/TMS) : δ 7.42-7.93 (ArH, m), 3.33 (2H,

d),4.76-5.11 (1H, m), 4.23(2H,dd); 13CNMR(22.5MHz,

CDCl3/TMS): δ 166.64, 132.30, 131.70, 131.38, 130.73,

126.96, 119.67, 37.40

1-(furan-2-yl) but-3-en-1-one (table 4 entry 5) 3e:

O O

IR (υmax, KBr Pellet in cm- 1): 1717, 1648, 3127, 1077;

1HNMR (90MHz, CDCl3/TMS) :δ7.53 - 7.33 & 6.78(3H, m) ,

3.6(2H, d), 6.57-6.55(1H, m), 4.365.22 (2H, dd);

13CNMR(22.5MHz,CDCl3/TMS):δ178.28, 162.32, 147.19,

143.92,119.39,112.21,111.82, 27.67.

1-(5-methyl-3-phenyisoxazol-4-yl) but-3-en-1-one (table 4 entry 6) 3f :

N

O

O

CH3

IR(υmax, KBr Pellet in cm- 1): 1719, 1599, 3108 , 1678, 1058 ;

1HNMR (90MHz, CDCl3 /TMS) : 8.18-8.22 (ArH, m), 3.67

(2H, d), 6.29 (1H, m), 4.96-5.04 (2H, dd), 2.49 (3H, s);

13CNMR (22.5MHz, DMSO / TMS) : 174.9, 162.16,

160.53, 132.88, 131.09, 129.15, 128.38, 126.87, 109.92,

42.30, 12.82.

198

1-(3-(2,6-dichlorophenyl)-5-methylisoxzol-4-yl)but-3-en-1-one (table 4 entry 7) 3g:

N

O

O

ClCl

CH3

IR(υmax, KBr Pellet in cm- 1): 1712, 1637, 3060, 1645, 1069,

717; 1HNMR (90MHz,CDCl3/TMS): 7.78-8.34 (ArH, m),

3.97 (2H, d), 6.48 (1H, m), 4.23-4.54 (2H, dd), 2.57 (3H, s) ;

13CNMR (22.5MHz, CDCl3 /TMS ) : 175.74, 162.12,

158.67, 134.65, 131.97, 128.10, 109.93, 42.29, 12.80.

1, 4-Diphnyl-but-- 3- en-1 one (table 4 entry 11)4a 84:

O

IR (υmax, KBr Pellet in cm- 1): 1450,1598,1679,3062 ;

1HNMR (90MHz, CDCl3/TMS): 3.89(2H, br S), 5.82-

6.09(1H, m), 5.09-5.39(1H, dd), 7.25-8.4(ArH,m); 13 C

NMR (22.5MHz, CDCl3/TMS): δ171.94, 133.77,

130.2,129.4, 128.41,105.07, 42.28

1-(2-Chloro phenyl)-4-phenyl-but-3-en-1-one (table 4 entry 12)4b:

O

Cl

IR (υmax, CHCl3 in cm- 1): 725,1249,1443,1593,1724,3020 ;

1HNMR (90MHz, CDCl3/TMS): 3.53(2H, br S), 6.33-

6.53(1H, m), 5.11(1H, d/d) ,7.32-7.83(ArH,m); 13 C NMR

(22.5MHz, CDCl3/TMS): 165.00,132.98,132.87, 132.01,

130.84, 130.51, 130.00, 129.4, 128.00, 127.13, 126.18,

125.54, 44.87.

1-Furan-2yl-4-phenyl-but-3en-1-one (table 4 entry 13)4c:

OO

IR (υmax, CHCl3 in cm- 1): 1014, 1116, 1473, 1581, 1701,

2877, 3016 ; 1HNMR (90MHz, CDCl3/TMS): 3.85(2H,br

S) , 6.08 (1H,m), 6.26-6.41(1H,dd),6.53-6.71(3H,m),7.31-

7.67(ArH, m); 13 C NMR (22.5 MHz, CDCl3 /TMS) :

160.34,146.09, 144.07, 135.41,133.51,1238.08, 126.16,

124.38, 118.91, 111.16, 44.87

199

2-Methyl-6-phenyl-hex-5-en-3-one (table 4 entry 14)4d:

O

H3C

H3C

IR (υmax, CHCl3 in cm- 1): 1438,1593,1724,3020 ; 1HNMR

(90MHz, CDCl3/TMS): 1.13-1.21 (6H,d),2.13-2.55 (1H,m),

3.85(2H,br S), 6.16 (1H, m), 6.26-6.41(1H,dd), 6.26-6.54

(1H,dd), 6.54-6.71(ArH, m), 7.30-7.38(ArH, m); 13CNMR

(22.5MHz, CDCl3/TMS) : 181.64, 135.63,133.81, 128.33,

127.94, 126.39, 125.00, 124.3, 45.07, 31.98, 23.18, 21.75,

18.47.

200

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