A new synthesis of β-keto-phenylsulfoxides

TetrahedronLetters No. 11, pp 921 - 924, 1975.

A NEW SYNTHESIS

OF

B-KETO-PHENYLSULFOXIDES

HUGO J. MONTEIBO* DEPABTAMENTO

AND JOffO P. DE SOUZA

DE QUIMICA, 70.000

Pereamon Prers. Printed in &eat Britain.

UNIVERSIDADE

- BRASILIA,

DE BBASILIA

D.F., BRAZIL.

(Receivedin USA 29 Dotober 1974; received in BK for Publication10 Fsbruary1975)

B-Keto-sulfoxides chemistry

as synthetic

preparation

intermediates'.

of such compounds

alkyl phenylsulfoxides appropriate

The most common method of

involves the reaction

with sodium methylsulfinylmethide*. have also been prepared

organic

have been widely used in

More recently

via rearrangement with alkyl lithium3

esters

B-Keto-sulfoxides

of 1-chloro-2-hydroxy or oxidation

of

-

the

B-ketothioethers 3*4 . In the course of our researches

develop a convenient

synthetic method

sulfoxide moiety alpha to a carbonyl a new method of preparation When carbonyl

of

it became necessary

for the introduction group. We now wish

an active

at room temperature,

amounts of methyl benzenesulfinate5

of the

to report

with

methylene equimolar

and sodium hydride in anhydrous

ether, a smooth reaction took place. After the conventional up the corresponding

to

2-keto-phenylsulfoxides.

compounds bearing

group were stirred overnight,

good yields

of

2-keto-phenylsulfoxides

(see table).

921

work

could be isolated in

922

Ro. 11

+

C6H5S02Me

'OC6'5

In a typical reaction,

a suspension of

sodium

hydride (0.370 g, 15.4 mmoles) in 70 ml of anhydrous ether was treated with a mixture of cyclohexanone 14.1 mmoles)

ethyl

(1.38 g ,

and methyl bensenesulfinate (2.40 g, 15.4 mmoles)

with vigorous stirring, at

room temperature under nitrogen.

After stirring overnight the resulting slurry was cooled in

an

ice bath, acidified with 10% sulfuric acid and the ethereal layer separated. The water layer was extracted with ether ml

x

(20

sodium

2) and the combined extracts washed with 10%

bicarbonate, brine, and dried over sodium sulfate. Evaporation of the solvent under vacuum gave a crystalline residue which was recrystallized from ether to give

a-phenylsulfinyl-cyclo-

hexanone (2,3 g, 74%). As shown by the examples in the table procedure allows the direct preparation of

the

B-keto-sulfoxides

derived from cyclanones, which are not readily available other means. The generality of the method is presently investigation in our laboratory.

new

by under

lo.

11

923

TABLE The Reaction of Methyl Bensenesulfinate with Carbonyl Compounds Carbonyl Compounds

Product (isolated yield, rn.~./Et~C>~ 0

+ @

0

(65%, 82-83O) 'OC6?15

W

0

(70%, 70-71°, SOC6H5 l&70.5-71.S0)

0

0

0

0

(74%, 104-105O)

SOC6H5 0

0

c)r;

0

(83%, 0i1)~ SOC6H5

0

(60%, 95-97')

m

a

0

SOC6H5

0

(50%, 112-113°)b'C

SOC6H5 L

a - All new compounds exhibited spectral and analytical data in agreement with the proposed structures. b-

In a preliminarly experiment methyl p-toluenesulfinate was used with similar results.

c - n-Hexane used as crystallization solvent.

I

no.

924

AKNONLEDGEMENT

This work was financially supported by

the National

Research Council of Brazil.

REFERENCES

1.

L. Field, Synthesis, 101 (1972).

2.

H.-D. Becker and G.A. Russel, J. Am. Chem. Sot., as, 3410 (1963); E. J. Corey and M. Chaykovsky, ibid., 86,

1639,

(1964). 3.

I. Kuwajima and Y. Fukuda, Tetrahedron Letters, 327 (1973).

4.

B. M. Trost and T. N. Salzmann, J. Am. Chem. Sot., E,

6840

(1973). 5.

L. Field and J. M. Locke, Org. Synth., 46,

6.

F. A. Carey and 0. Hernandez, J. Org. Chem., 2,

62 (1966). 2670(1973).

11