Some novel synthesis of biologically active benzopyran...

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Mandal, T. K.: Some novel synthesis of……

Review Article

Some novel synthesis of biologically active benzopyran derivatives

Tapas Kumar Mandal

Assistant Professor, Department of Chemistry, Fakir Chand College, Diamond Harbour, 24

Pgs (S), Pin – 743331.

Correspondence should be addressed to Tapas K. Mandal: tapasmanda83@gmail.com

Abstract

Compounds containing pyran, benzopyran and benzothiopyran ring systems display

interesting biological activities such as antiallergic, antitumor, antiviral, antioxidant and

antiinflammatory etc. The aim of the present paper was to review the various synthetic

approach of this type of compounds on this field.

Key words: Benzopyran derivatives

Indroduction

Heterocycles play an important role in the design and discovery of new

physiological/pharmacologically active compounds. Chemically, chromones (4H-chromen-4-

ones) are heterocyclic compounds with the benzopyrone framework. Molecules containing the

chromone or benzopyranone ring have a wide range of biological activities1-6. They have been

shown to be tyrosine and protein kinase inhibitors, as well as anti-inflammatory, antiviral,

antioxidant7, and antihypertensive agents. Chromone derivatives are also active at

benzodiazepine receptors, and on lipoxygenase and cyclooxygenase. In addition to this, they

have been shown to be anticancer agents8, possessing antimutagenic properties and the ability

to inhibit electron transport through inhibition at NADH. The main objectives of benzopyran

derivatives synthesis are not only for the development of more diverse and complex bioactive

compounds for biological activity and structure-activity relationship studies but also for other

applications in Medicinal Chemistry.

Prajnan O Sadhona ……., Vol. 4, 2017

Synthesis of 4H-1-Benzopyran Derivatives

Scheme 1

Rovis et al9. developed a highly enantio- and diastereoselective intramolecular Stetter

reaction. Subjection of α,α-disubstituted Michael acceptors to an asymmetric intramolecular

Stetter reaction results in a highly enantioselective conjugate addition. The reaction is

heterocyclic carbene catalyzed stereoselective cyclization.

Scheme 1

Scheme 2

Pawar et al10. synthesised flavones, a benzopyran derivative using recyclable ionic

liquid under microwave irradiation condition.

Scheme 2

Scheme 3

Lokenande et al11. developed dimethylsulfoxide- iodine catalysed one-pot oxidative

deallylation of 2′-Allyloxychalcones which undergo undergo deprotection and subsequent

oxidative cyclisation to give flavones.

Scheme 3

Scheme 4

Kabalka et al12. developed Cu (II) catalyzed MW assisted cyclization of enol. They

synthesised functionalized flavones and chromones via the cyclization of 1-(2-hydroxyaryl)-

3-aryl-1,3-propanedione .

Scheme 4

Tolune, 25oC, 24 hr

(50-95%)

MW (22-50 Sec)

[EtNH3]NO3

(80-90%)

R2 I2, DMSO

130oC, 30 min.

(85-97%)

CuCl2, EtOH

MW,80oC,5 min.

O(86-98%)

Scheme 5

Mukaiyama and coworkers13 explored base-catalyzed [2,3]-Wittig rearrangement of

silyl enolates in DMF solvent at room temperature to produce α-allyloxy ketones in good yield.

Scheme 5

Scheme 6

Yang et al14. developed Pd-catalyzed copper-free carbonylative Sonogashira coupling

reaction which was utilized to synthesize flavones from terminal alkynes and aryl iodides by

using water as solvent. The reaction was carried out at room temperature under balloon pressure

of CO with Et3N as a base.

Scheme 6

Scheme 7

Ahmed et al15 . explored Silica gel supported InBr3 or InCl3 (15–20 mol %) as a new

solid-support catalysts for the facile and efficient oxidation, under solvent free conditions, of

2′-hydroxychalcones and flavanones to yield the corresponding flavones in >80% yield. The

catalysts are easily prepared, stable, and efficient under mild reaction conditions.

Scheme 7

DMF, rt, 1 hr

OSiMe3

+ R'-C C H

CO, 25oC, 24 hr

PdCl2, PPh3, Et3N, H2O O

O(35-91%)

Aryl-IPd(0)

Aryl-Pd-ICO

Aryl-CO-Pd-IR-C C-H

Aryl-CO-Pd R

Aryl-C

R1 InBr3 or InCl3O

Solvent-free Condition

Scheme 8

Seijas et al16. synthesised flavanone derivatives by microwave irradiation of

phloroglucinol and β-ketoesters under solvent free condition. The reaction goes through a

cycloaddition of an α-oxo ketene intermediate followed by an uncatalyzed thermal Fries

rearrangemen.

R1, R2, R3, R4 =H. OH. OMe, NO2

Scheme 8

Scheme 9

J. I. Lee et al17. synthesised flavones from1-(2-methoxyphenyl)-3-phenyl- 1,3-

propanediones. The cyclization was successfully accomplished by heating with hydriodic acid

in glacial acetic acid. The cyclization accompanied by the cleavage of the 2-methoxy group of

1-(2-methoxyphenyl)-3-phenyl-1,3- propanedione with 47% HI proceeded well in glacial

acetic acid for 1.5 h at 100 o C to afford flavone in 78% yield.

Scheme 9

Scheme 10

Choudary et al18. designed and developed a nano heterogeneous catalyst for the

Claisen–Schmidt condensation (CSC) of benzaldehydes with 2-hydroxyacetophenone to yield

substituted chalcones followed by isomerization to afford flavanones with excellent yields.

Scheme 10

R4OCH3

HI / HOAc

100oC, 2 hr

R2(60-78%)

80oC, Ethanol

NAP-MgO

(50-90%)

Scheme 11

Chandrasekhar et al19. used L-Proline as an efficient organocatalyst for the synthesis of

substituted flavanones and chalcones in good yields. The efficiency of the catalyst was proved

with a variety of substrates ranging from electron-deficient to electron-rich aryl aldehydes and

2-hydroxyacetophenones.

Scheme 11

Scheme 12

A novel and conveient one‐pot synthesis of 3‐aroyl‐7‐hydroxy‐6‐nitroflavones from

2′,4′‐dihydroxy‐5′‐nitroacetophenone and (substituted)benzoyl chlorides in refluxing dry

acetone in the presence of anhydrous potassium carbonate was developed20.

Scheme 12

Scheme 13

Larock et al21. synthesised iodine substituted chromone derivatives by using

interhalogen compound ICl. They developed ICl induced cyclization of heteroatom-

substituted alkynones which provides a simple, highly efficient approach to various 3-

iodochromones, iodothiochromenones, iodoquinolinones and analogues in good to excellent

yields.

Scheme 13

L-Proline

DMF, 80oC, 18 hr

(60-73%)

K2CO3, acetone

reflux, 35-46 hr

CH2Cl2

ICl, -78oC or rt

X = O, S, NMe2

96-99%

Scheme 14

Raghunathan et al22. Studies on synthesis of novel polycyclic thiopyrano

coumarin/chromone frameworks through intramolecular domino Knoevenagel hetero Diels–

Alder reactions of 4-hydroxycoumarin and its benzo-analogous with suitable S-prenylated

pyrazole aldehydes.

Scheme 14

Scheme 15

Fillio et al23. synthesised chromanone derivative by Yb(OTf)3 catalysed annulation

reaction of phenol with5-alkylidene Meldram’s acids. Conjugate addition followed by

cyclization occurs here. (only electron rich phenols react to give corresponding product).

Scheme 15

Scheme 16

Skouta et al24. synthesized Isoflavone derivatives rapidly via the annulation of

salicylaldehyde and arylacetylenes followed by IBX/DMSO oxidation of the isoflavanones.

Scheme 16

54-91%

Yb(OTf)3

CH3NO2,

100oC, 1.5 hr

(71-83%)

R2AuCN

Toluene, 150oC, 36 hr

IBX/DMSO85oC,

45-63%

Scheme 17

Zhang et. al25. synthesized a series of 2-methylchromanone derivatives by using

palladium-catalyzed Wacker-type oxidative cyclization, in which a 1,5-hydride alkyl to

palladium migration and a direct chirality transfer were involved.

Scheme 17

Scheme 18

Nguyen et al26.carried out acid-mediated ring-transformations of 5-alkylidene-2,5-

dihydropyrrol-2-ones, available by cyclization of 1,3-diketone dianions with bis(imidoyl)

dichlorides of oxalic acid, resulted in formation of functionalized pyran-4-ones, such as 5,6-

dihydrobenzo[h]chromones and 5,6,7,8-tetrahydrochromones.

Scheme 18

Scheme 19

Šket et al27. synthesised flavanone derivative by photochemical reaction of 2-halo-

substituted 1,3-diarylpropan-1,3-dione. The photochemical behaviour of this type of

compounds grately depend on the natutre og halogen and electron donating group present in

aromatic ring. In this reaction 2-choloro-2-fluro derivatives resulted 3-fluoroflavanone. 2-

chloro-1,3-diphenylpropan-1,3-dione cyclized to flavanones.

X= H, F

Scheme 19

OPd(OAc)2, K2CO3

EtOH, H2O, 35oC, 24 hr

H H(D)

OLi OLi N

HCl, THF O

(37-95%)

(45-55%)

Scheme 20

Oxidative cyclization of 2′-hydroxychalcones by employing FeCl3.6H2O–methanol

under mild conditions for the synthesis of flavone derivatives was developed by K. H. Kumar

et al28.

Scheme 20

Scheme 21

Médebielle et al29. sythesized fluorinated 4H-benzo[h]chromen-4-one and 4H-

pyrano[3,2-h]quinolin-4-one derivatives in moderate to good yields, through a one-pot

aldolization–intramolecular SNAr process from the tetrakis(dimethylamino)ethylene (TDAE)

mediated reductive cleavage of two N,N-dimethylamino-bis-chlorodifluoroacetyl substrates in

the presence of heteroaryl aldehydes.

Scheme 21

Scheme 22

Bennardi et al30. reported the use of bulk and silica-supported Wells-Dawson acid

(H2P2W18O62.24H2O) as reusable, heterogeneous catalysts to obtain substituted flavones and

chromones. The cyclization of 1-(2-hydroxyphenyl)-3-aryl-1,3-propanediones was carried out

RFeCl3.6H2O

FeCl3.6H2O

Reflux, 8-10 hrs Where X= OH.

Where X= NH2

Reflux, 5-7 hrs

(55-62%)

(55-78%)

COCF2Cl

CF2ClTDAE

ArCHOX

COCF2CHOHAr

Y = COCF2CHOHAr

18-65%

by the catalst. In the reaction toluene was used as solvent. The catalysts were easily recycled

and reused without loss of their catalytic activity. The presented synthetic method is a simple,

clean and environmentally friendly alternative for synthesizing substituted flavones and

chromones.

Scheme 22

Scheme 23

Muthukrishnan et al31. synthesized bis-spirochromanones from 4,6-diacetyl resorcinol

in one-pot by carrying out the Kabbe condensation in room temperature ionic liquid.

Scheme 23

Scheme 24

A series of fluorinated flavanone derivatives were synthesized by S. Zhu et al32. with

excellent diastereoselectivities under mild reaction conditions via one pot tandem procedure

procedure involving a proline-catalyzed Knoevenagel condensation, a Michael addition, and

an electrophilic fluorination by NFSI.

Scheme 24

Scheme 25

Capretta et al33. synthesized flavanone derivatives using Palladium complexes of

1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phosphaadamantane which was effective catalytic

systems facilitating the sequential application of a microwave-assisted Sonogashira and

carbonylative annulation reaction for the preparation of substituted flavanones.

Scheme 25

R + H C C R1

Pd2 (dba)3 / Pa-Ph

DMF, DBU

MW, 30 min

ArH2P2W18O62

.24 H2O

110oCTolune,

(82-88%)

H3COCN

Cyclic or acyclic ketoneOO

(58-84%)

+ R3CHO

i) Proline, EtOH, rt

ii) NFSI, Na2CO3

Scheme 26

X. Zhu et al34. described an efficient, mechanically activated solid-state synthesis of

flavones from 1-(2-hydroxyphenyl)-3-aryl-1,3-propanediones using high-speed ball milling.

This method has notable advantages in terms of good yield, short reaction time, and neat

conditions.

Scheme 26

Scheme 27

L-G Meng et al35. developed a facile synthesis of 2-alkyl-substituted chromanones

from ortho-acylphenols and terminal alkynoates. The method contains two

Scheme 27

consecutive processes in one-pot reaction through a DABCO-catalyzed condensation reaction

and a KOBut-mediated intramolecular cycloaddition to afford the desired products

Scheme 28

C. S. López et al36. developed a method of synthesis of chroman derivative from aryl

3-methy-2-butenoate esters through biphasic base catalysis-mediated photo-Fries

rearrangement reaction in good to high yield and in short reaction times (30–120 min) in a one-

pot photochemical reaction.

Scheme 28

HSBM O

DABCO (10 mol%)

KOBut, DMF, rt, 2.5 hr

38-76%

OCyclohexane, KOH

OLight

Photo-FriesRearrangement

Intramolecular oxa-Michael cyclisation

Scheme 29

Vedachalam et al37. developed an efficient strategy for the carbon-carbon bond

formation between aldehyde and nitrile intramolecularly using an N-heterocyclic carbene

catalyst. They described the formation of 3-amino chroman derivatives in good to eccellent

yields(80-90%)

Scheme 29

Scheme 30

E. A. Hillard et al38. Synthesized cytotoxic ferrocenyl flavones via a ferricenium-

mediated 1,6-oxidative cyclization of 2′-hydroxyferrocenyl chalcones. An oxidation of the

ferrocenyl group of 2′-hydroxyferrocenyl chalcones activates the β-position of the unsaturated

ketone to nucleophilic attack to yield the first examples of ferrocenyl flavones.

Scheme 30

Scheme 31

Mallik et al39. developed synthesis flavanones starting either from 2′-hydroxychalcones

using anhydrous potassium carbonate as an inexpensive, safe, and efficient basic catalyst. The

favored reaction condition was either refluxing in a solvent with added catalyst or microwave

irradiation on the catalyst.

Scheme 31

DBU, 10 mol %

CH2Cl2, rt

NH280-95%

NaH, AgOTf

THF, rt

80-90%

Anhydrous K2CO3

Acetone, reflux (3-5 hr.)

Anhydrous K2CO3

MW(3-5 min.)

Scheme 32

Venkatesan and Maruthavanan synthesized chroman derivatives containing heteroaryl

moiety in C-2 position by oxidative cyclization of 2’-hydroxy chalcone using DDQ/DMSO-I2

/diphenyl disulfide40. The biological activity of flavone has been enhanced by introducing

heteroaryl moiety in C-2 position of chromone derivatives. Thus, 2-(1H-Indol-3-yl)-4H-

chromen-4-one derivatives and 2-(2- chloroquinolin-3-yl)-4H-chromen-4-one derivatives

were synthesized from corresponding chalcone. Both the compounds have biological activity.

Scheme 32

Scheme 33

Jarho et al41.synthesized a series of bilogically active chroman derivatives. They

synthesized the derivatives in a one step procedure including a base catalyzed aldol

condeasation using microwave irradiation.

Scheme 33

Scheme 34

Taheri et al42. synthesized a series of chroman derivatives by using sulfone-containing

Brønsted acid ionic liquid as catalyst. The reactions were performed under solvent-free

conditions, and the only by-product was water. The Brønsted acid ionic liquid could be

recovered and reused without significant loss of its activity.

Scheme 34

Piperidine / EtOH

DMSO / I2

Ph-S-S-Ph

DIPA, EtOH

170oC, 1 h, MWR

CF3SO3-

Scheme 35

Synthesis of a series of chroman derivatives was described by Y. Zhou et al43. They

described the chroman synthesis via a one-pot reaction of phenol, paraformaldehyde, and 5-

benzylimidazolidin-4-one mediated by p-nitrobenzoic acid.The chroman derivatives

containing spirocyclic N,O-acetal skeleton can be obtained in moderate to good yields (up to

89%) with good to excellent diastereoselectivities.

Scheme 35

Scheme 36

Zhang et al. synthesized 4-carbonyl chroman derivatives with high yield . A Rh-

catalyzed intramolecular aromatic C–H insertion of α-diazo β-ketoesters was developed in this

process44.

Scheme 36

Scheme 37

Kamat et al45. described in the synthsis 2-substituted or 2,2-disubstituted chromans and

4-aryl-3,4-dihydrobenzopyran-2-ones via [3+3] cyclocoupling. For the synthesis of chromans,

phenols and allylic alcohols were refluxed in chloroform in presence of 20 mol % I2 while

[3+3] cyclocoupling of phenols and cinnamic acids proceeded to give 4-aryl-3,4-

dihydrobenzopyran-2-ones using 30 mol % I2. Later reaction occurs via a tandem

hydroarylation–esterification process at 120–130 °C under solvent free conditions. Chromans

were obtained in 20–92% yields and substituted 4-aryl-3,4-dihydrobenzopyran-2-ones were

obtained in 5–85% yields.

Scheme 37

+ (HCHO)n +

p-nitrobenzoic acid

30 mol % I2

CHCl3, reflux

ArCOOH

20mol % I2

120o-130oC

Scheme 38

Arumugam et al46. described the easy method for the regioselective synthesis of internal

alkenes through a dehydrative cross-coupling and direct coupling procedure using the

environmentally benign Ca(II) catalyst. Several alkenes and alcohols underwent the coupling

reaction under solvent-free conditions in a short time to produce the desired alkenes. Applying

this protocol they synthesized novel benzopyran molecules through a cascade strategy.

Scheme 38

Scheme 39

A facile photochemical preparation of 5-, 6-, and 7-substituted chroman-4-ones from

aryl 3-methyl-2-butenoate esters were described by S.M. Bonesi et al47.

Scheme 39

Scheme 40

Luthma et al48. synthesized tricyclic N-benzylated chroman-4-one

tetrahydropyrimidine derivatives through a multi-component reaction between various 2-

substituted chroman-4-one derivatives, N-methylenebenzylamine and a catalytic amount of

proline under mild reaction conditions.

Scheme 40

+Ca(OTf)2

X=H, R1 = Me

Ohv, cyclohexane

KOH, 10% aq., 25oC, Ar

BnN NBn

Conclusion

4H-1-Benzopyran derivatives show vast array of biologically activity and have been

used in traditional eastern medicine for thousands of years The importance and vastness of the

areas of biological activities, development of newer synthesis of different benzopyran

derivatives and different transformations of benzopyran derivatives are very much important.

Acknowledgment

The author acknowledges Prof. Asok Kumar Mallik, Research guide, Department of

Chemistry, Jadavpur University, for giving valuable suggestions during writing this review.

Author also thanks departmental colleague for their support.

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Some novel synthesis of biologically active benzopyran...

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