Deprotection of benzaldehyde diacetates by ceric ammonium nitrate coated on silica

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TenahedronLews.Vol. 33,No.27.p~.3855-3858.1992 PrintedinGren~ Britain

DEPROTECTION

OF BENEALDEHYDE

DIACLTATES

BY CERIC

AMMONIUM

NITRATE

COATED

Philippe

Cotelle*

and Jean-Pierre

ON SILICA

Catteau

Laboratoire de Chimie Organique Physique associ6 au CNRS Universit& des Sciences et Technologies de Lille 59655 Villeneuve d'Ascq

Benzaldehyde diacetates ABSTRKT: corresponding benzaldehydes using on sibica in dichloromethane.

F'or decades I Nitra?.e organic to

(CAN)

chemistryI.

has

also

For

of

has

used

been

protected diacetate

ideal

been

nitration

oxidising

shown the

and

reagent

because

employed

to

and

selectively converted to the Ammonium Nitrate (CAN) coated

properties extremely

of

benzylic

of the on

deprotection

of

Ammonium

in

synthetic

dimethyl

oxidation3-E,

mild

gel

of

ethers CAN

conditions

silica

oxidation

Ceric

useful

of hydroquinone

for

adsorbed

arenes6

effect

has

involved.

for

oxidative

hydroquinones7.

CAN

have

been

ketones

which

or

1,3-dithianes'. The benzaldehyde has been successfully used by Tomita and ~011,'

protection reaction.

be

oxidation

1,3-dithiolanes

as

to

quinonesl

polynuclear

but has not yet become acylation

strong

been

thl; corresponding

proveri to be an

It

the

have

were Ceric

FRANCE

a useful

method

due to the unselectivity

of the

Recently,

we have used this protection to modify selectively the orientation of the nitration of 2,5dimetboxybenzaldehydelO. In this paper, we wish to report the use of CAN cn silica7 for the selective deprotection of benzaldehyde diacetstes. We

reacted

benzaldehydes

several

in acetic

dichloromethanell

benzaldehyde anhydride

diacetates

l(prepared

quantitativelyl')

(Table, scheme 1).

3855

with

from

cAN/Si02

the in

3856

R’

R’ CHO

Scheme 1 occurs

beprotection diacetates protection,

lb

and

which

diacetoxybenzene

Ic

nitroh,ydroquinone

without

was

reacts and

selectively previously

with

CAN

has

of

4-acetoxybenzaldehyde the

reported

in

acetate

Chawlal'

methanol/acetic

acid

to

(1,4give

1,4_Diacetoxybenzene does not (All attempts to cleave aromatic and

failed). These

differences

because of the drastic conditions used by Chawla. nitration Whereas for dimethoxybenzenes13, dichlcromethane

phenolic

by

hydroquinone).

react in the presence of CAN/SiO2 alipha,tic acetates

cleavage

on

are

not unexpected

with

CAN/Si02

occurred giving good yields of mononitrated

in

compounds,

no nitrated compound was obtained for la. la showed

no sign of reaction

with silica

in methylene

chloride

and w:*s thus completely recovered from the reaction mixture, but reaction of la with CAN in an acetonitrile/water solution afforded the benzoquinone-1,4-aldehyde

diacetate'

2 (scheme 2) attempts to deprotect 2 proved to be futile).

la

Scheme 2

in

96%

yield

(all

3857

Th+ mixture

addition

of

lml

of

water

(CAN/SiO2 in methylene

dimethoxybenzaldehyde Th+se results

or methanol

to

the

deprotection

chloride) gave a mixture

of 2 and 2,5-

(10/90) from la (90% yield).

show that for deprotection it is necessary to coat onto silica. When oxidative demethylation can

Ceric AriunoniumNitrate the reaction

occur,

must

be carried

out in the

absence

of

a protic

solvent to avoid the formation of benzoquinone. Table: oeprotection

of benzaldehyde diacetates

1 and benzoquinone-1,4-

aldehydcr!diacetate 2 by cAN/Sio2 RX

R2

R3

R4

la14

0CH3

H

0CH3

H

92

lb15

H

0COCH3

H

H

98

lC15 ld"

H

OCOCH3

OCH3

H

0CH3

H

90 94

1918

OCH3

NO2 H

0CH3 OCH3

NO2

95

Substra*:.e

Yield(%)"

Ob

2 a. Yieltls of pure compounds. b. 2 wa::.recovered To proves

sum

up,

useful

diacetayes

in 95% yield. we

have

for

the

found

that

selective

to give benzaldehydes.

CAN/Si02

deprotection

Rev.,

1992,

Synthesis, 92,

aprotic of

in

acidic16

REFERENCES AND NOTES 1973, 347-354. See also G.A.

solvent

benzaldehyde

The aryl acetate function

not lb and react whereas lo) does conditions, it is readily cleaved.

1. T.L. HO,

in an

or

(compounds alkaline17

MOLANDER,

Chem.

29-68

2. P. JACOB, P.S. CALLERY, A.T. SHULGIN, N. CASTAGNOLI,

J. Org. Chem.,

1976, 4.1. , 3627-3629 3. s. DTNCTURK,

J.H. RIDD, J. Chem.

Sot.

Perkin

Trans.

2,

1982, 961-

964 4. K. Ii;OBE, N. TAKEDA, K. MOHRI, Y. TSUDA, Chem.

Pharm.

Bull ., 1989,

37, 339(1-3392 5. W.S. TRAHANOVSKY,

L.B. YOUNG, J. Org. Chem., 1966, 31, 2033-2035 6. H.M. CHAWLA, R.S. MITTAL, Synthesis, 1985, 70-72 7. A. FISCHER, G.N. HENDERSON, Synthesis, 1995, 641-643

3858

8. T,L, Ho, H.C. HO, C.H. WONG, J. Chem. Sot.,

Chem.

Commun.,

1972,

INUBUSHI,

Chem.

791 9. M. TOMITA, T. KIKUCHI, K. BESSHO, Pharm. Bull., 1963, 11, 1484-1490

HORI,

T.

Y.

10. E. COTELLE, J.P. CATTEAU, Synth. Commun., in press 11. '!'ypicalprocedure: Substituted benzaldehyde diacetate in

dichloromethane

(15ml)

is

(6.94g, 2.lmmol of Ce(IV)). residue is filtered. The Evaprration Addition

of

evapcration

of

solvent hexane

gives

added

The

washed

from

the

with

mixture

stirring

to

is stirred

with combined

(1, lmmol)

the

for

dichloromethane filtrates

the acetic (to remove benzaldehyde which is found

and

(2*15ml).

gives

(2*15ml)

substituted

CAN/SiO2

15 min an

oil.

acid) and to be pure

by lP-N.M.R. 12. Y. CHAUDHURI, H.M. CHAWLA, curr. Sci., 1986, 55, 852-853 13.

The

nitration

of

dimethoxyphenyl

derivatives

will

be

published

soon. 14. l'.R. PREUSS, R. MENZEL, Arch. Pharm., 1958, 291, 377-380; C.A. 53, 5175 (1959) 15. All new compounds give satisfactory spectroscopic data. 16. (:. BiiCHI, S.M. WEINREB, J. Am. Chem. Sot., 1971, 93, 746-752 17. E. HASLAM, G.K. MAKINSON, M.O. NAUMANN, J. CUNNINGHAM, J. Chem. sot. 1964, 2137-2146

(ReceivedinFrance 12 March 1992)