Palladium-catalyzed oxidation of alcohols via their allyl carbonates under neutral conditions

Tetrahedron Letters,Vol.25,No.26,pn Printed in Great Britain

2791-2792,1984

PALLADIUM-CATALYZED

OXIDATION

ALLYL

UNDER

CARBONATES

0040-4039/84 $3.00 + .oo 01984 Pergamon Press Ltd.

OF ALCOHOLS NEUTRAL

VIA THEIR

CONDITIONS

Jiro Tsuji,* Ichiro Minami, and Isao Shimizu Tokyo Institute of Technology, Meguro, Tokyo 152, JAPAN Summary:

Treatment

of alkyl allylcarbonates

derived from various alcohols

with a palladium catalyst in MeCN affords ketones and aldehydes in high yields. This new method

of oxidation

of alcohols

can be applied to various

alcohols

except simple primary alcohols. Oxidation of alcohols to the corresponding ketones and aldehydes is one of A number of oxidation methods are known,

the most important synthetic methods.

mainly by using inorganic reagents such as Cr and Mn salts, and the separation of inorganic compounds is sometimes a problem.') method

of palladium-catalyzed

oxidation

We now wish to report a new

of alcohols

via their allylcarbon-

ates, which are prepared easily by the reaction of alcohols with ally1 chloroformate. As expressed by the following scheme, the reaction produces only CO2 and propene as by-products, and hence the reaction is very clean.

R H

;+“-pd+*

Pd(O)

ocof-4

-co2

R'f

’

-C3H6

[

I

B

R R’ >-

As shown

in the table,

’

1

the reaction

;F”

A. Pd-Phosphine-free. B.

Pd-PPh3.

0-

can be applied

to various

alcohols

except simple primary alcohols, which give somewhat lower yields, and a considerable amount of alcohols is recovered (entry 4). The phosphine-free palladium is an active formation

catalyst.

In the presence

of PPh3, the decarboxylation-ether

takes place without undergoing the oxidation.2)

biallylic carbonates are subjected to the oxidation,

When unsymmetrical

(entries 2,3, and 5), the

less hindered simple ally1 group is cleaved to form CY.,~-unsaturatedketones or aldehydes. Several types of palladium-catalyzed

oxidation of alcohols are known.3-5)

Only the ally1 carbonate method reported in this paper can be carried out under neutral conditions.

2791

2792

Tablea)

Entry

Ally1

Carbonate

Product

Yieldb)

1

PhCH20C02CH2CH=CH2

PhCHO

2

"C3H7CH=CHCH20C02CH2CH=CH2

"C3H7CH=CHCH0

3

PhCH=CHCH20C02CH2CH=CH2

PhCH=CHCHO

69%

4

nC1,jH210C02CH2CH=CH2

nCgH1gCHO

(27%)

"ClOH21OH

(73%)

76% (95%)

oco*-

Phd

5

88%

o= 0

(76%)

(96%)

oco,-

0

0

l3 a) Reaction MeCN

Conditions;

(5 cm3)

Allylic

carbonate

at 80 OC for l-2 h under

(1 mmol),

Pd(OAc)2

b) Isolated

argon.

77%

(0.1 mmol),

yields,

dry

GLC yields

in

parenthesis.

This

Acknowledgment: for Scientific

research

Research,

and Encouragement

58110005,

of Education,

Science

was

A, No.

financially

57430030,

of Young

supported

for Special

Scientist,

by the Grant-in-Aids Project

No. 58750681

Research,

from

No.

the Ministry

and Culture.

References: 1)

For

a

Synthetic Guibe,

(1967).

Y. Tamaru,

1401;

on

Y. S. M'Leux,

32, 2814 5)

review

Reactions"

4)

the

oxidation

pp 257-421,

48, 1286

(1983).

(Received

in Japan

alcohols,

see,

H.

0.

House,

Inc., California,

"Modern

1972.

ibid 22, 3591 (1981). 3) W. G. Lloyd, J. Org. _:r H. Nagashima, J. Tsuji, Chem. Lett., 1981, 1171.

Y. Yamamoto,

Y. Tamaru,

of

W. A. Benjamin

Y. Yamada,

Y. Yamada, K. Inoue,

28 February

1984)

Z. Yoshida, Y. Yamamoto,

Tetrahedron Z. Yoshida,

Lett.,

2)

F.

Chem.,

1979,

J. Org. Chem.,