The structure of arylketoximes and their iminoxy radicals

The structure of arylketoximes and their iminoxy radicals

TetrahedronLetters No.27, pp. 2345-2348,1970. THE STRUCTURE OF ARYLKETOXIMES Franz Max-Planck-Institut A. PergamonPress. Printed in Great Britai...

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TetrahedronLetters No.27, pp. 2345-2348,1970.

THE

STRUCTURE

OF ARYLKETOXIMES

Franz Max-Planck-Institut

A.

PergamonPress. Printed in Great Britain.

AND

THEIR

IMINOXY

RADICALS

Neugebauer

ftir Medizinische

Forschung,

Heidelberg,

West

Germany

(Receivedin VK 4 May 1970; accepted for publication14 May 1970)

In view

of current

interest

of arylazoketoximes trans-anti

formazans

appeared

isomer

intramolecular

in the hydrogen

(‘>,

desirable.

a linear

hydrogen

trans-syn

bridge

bonding

in oximes,

One can conceive isomer

(3) in analogy -

(3

1

to the red trans-syn

/”

N=C

\

N=C HO ’

N=N \

structures,

a linear

isomer

with a strong

isomers

‘.

-3

'N=N

of the

\ C6H5

/N-N%C_R H *. / ‘N=N

/

4

/ H5C6

H5C3

corresponding

2

‘N=N

/

IR spectra

/”

SH5

H/“-N\\^_R

of 2,

6 and 7 (table -

to the stretching

tetrachloride

stretching

of three

of the structure

(5).

1

carbon

the study

and a trans-syn

HO

The

1)

vibration

solution of free

1) in the solid

vibrations only

bands

hydroxy-groups

phase

of strongly at 357a/cm . These

2345

show strong

associated are

near

hydroxy-groups.

observed,

results

bands

exclude

corresponding the structure

32oo/cm

In i-9 % to the 3.

2346

No.21

Arylazcketoximes bridges

associate

and probably

The chemical distinguish

in the solid phase via strong

give dimers

in the form

for the trans-anti

isomer

of -1 and -2: in DMSO

1 and g.

supported

(3

two different

1.

OH-signals

OH-

one to

12.66

6,H=

are mixtures

(5) and phenylazo-methyl-

This assignment

of H and OH at ,‘C = N ,3

allows

z (table 1) is a mixture of 1 and

- 9.38

is additionally = 3.28

[ppm],

‘4).

OH

,LOH) assoc.

3575/cm

326a/cm

12.66

6

H3C

‘)

3575/cm

32oo/cm

12.58

7

H5C6

‘)

3570/cm

33 1o/cm

12.52,

iminoxy

tetra-acetate

of these oximes

radicals, in methylene

in benzene at 40°C

which can also be generated dichloride

solution

1 and table 2) show two large

nitrogen

Surprisingly,

the mixture

of trans-anti

H5C6

by l5 N labeling

8)

splittings

HO-N=C-15N=N-C6H5

(2: 1)

radical

7)

with lead

. The ESR spectra

in the range of 20 and 12 gauss. isomers

The assignment

of arylazo-aryl-ketoximes of the nitrogen

splittings

8 and 9.

C6H4N02-

I

11.35

by di-p-tolylaminyl

in a flow system

in the oximes

d[wml

by oxidation of the oximes

and trans-syn

only one type of iminoxy radicals.

been accomplished

-8

arylazo-aryl-ketoximes

isomers. J

(DMSO)

shift of the OH proton is expected

are abtained.

V (OH)free

H 5,

The dehydrogenation

generates

sulfoxide

oximes 2) .

IR and NMR data

5

(figure

chemical

OH * * * N hydrogen

rings like simple

phenylazc+formaldoxime

in the case of -5 by the difference

R

yields

A larger

turned out to be ptire trans-anti

typical for a cis arrangement

Table

in dimethyl

3) . As with most oximes,

2 in the ratio of 2: 1. Surprisingly, ketoxime

of six-membered

shift of the OH protons of oximes

between structure

intermolecular

HO-

15

(4)

I

N=C-N=N-C6H5

9

has

Ho.27

2341

The iminoxy radical unlabeled spl Ming

radical.

from 8 yields

The labeling

into a 27.2

Consequently

derived

15

gauss

the smaller

the same

ESR spectrwn

of the oxime nitrogen

in 9 changes

15N 14N a / a = 1.38

N-splittings

12 gauss nitrogen splitting

obtained from the the 19.7

gauss

(gyromagnetic

is due to the azenitrogen

14N -

ratio

1.40).

ccnnected

with the aryl group.

8

0

IO Gauss

‘6”6 Figure

1.

ESR spectrum generated

Table

2.

of the iminoxy radical

from

phenylazo-formaldoxime

by me oxidation of the oxime by lead tetra-acetate

in CH2C12 solution.

N-Oa

ESR data R3-C

44 \

N=N’ ‘R1 aN’

aN4

Solvent

R’

R3

CH2Cl2

C6H5

H

lo.9

19.3

CH 6 6

C6H5

C6H5

11.6

19.8

C6H5

11.8

20.3

C6H5

11.4

19.8

12.3

19.7

11.9

19.8

C6H6

C6H4N02

C6H6

C6H4mH3

- (4 ) - (4)

C6H6

C6H6

C6H4N02

C6H6

‘gH5

C6H4mH3

- (4) - (4)

aH 0.8

(5J

[gauss]

No.27,

2348

The

very

high spin

structures This

and suggests

cyclic

radicals

density

at the nitrogen

a cyclic

conformation

primarily

represented

formed.

as a hybrid

//Cl

trans-syn

The energeticly

of the structures

..

of MO

G -orbital, and which

1ies in the nodal

plane

reorientation

species.

of linear

conformation

:Y .:

iminoxy

can be

y l\

:O*

N

b

C -

spin densities

are

radical

//CL

l

components

linear

I

:g: .’k, -

the measured

excludes

the iminoxy

cyclic

N

-

main

fast

group

-b and -c.

4)J

:N\

theory,

whose

prefered E,

a

In terms

of a very

for

I //CL

t;’ _

:O.

to the aryl

conformation

be the result

I

:y

10

could

adjacent

orbitals

imply

that the unpaired

on the 0 atom

electron

and the adjacent

is in a

N atoms,

of the %-system.

References

1) D.S.Jackson, 2)

K.Nakamoto,

3)

G.G.Kleinspehn,

4)

A.J.Durbetaki Society,

5) M. Busch

J.Chem.Soc.

(B),

M.Margoshes

and R.E.Rundle,

J.A.Jung

1964,

E.Bamberger

7)

F.A.Neugebauer,

8)

B.C.Gilbert

148th National

Abstracts

and E .Meussdorffer,

6)

J.Amer.Chem.Soc.

and S.A.Studniarz,

and C.Miles,

Chicago,

19s_S, 785. ----

and W.Pemsel, Tetrahedron

and R.O.C.Norman,

J.org Meeting

.Chemistry, of the American

zz,

6480

32, -_

460 (1967).

Chemical

A-47.

J.prakt.Chem.

22,

Ber.dtsch.chem.Ges., Letters

1968, ====

J.Chem.Soc.

121 (1907). 36,

53,

2129. (B),

1966, ====

86.

62,

85 (19o3).

(1955).