α,β-unsaturated ketones by cathodic addition of benzotrichloride to ketones

I Dieses Manuskript ist This manuscript is to be cited as I zu zitieren als

Angew. Chem. Suppl. Angew. Chern. Suppl. 1982,137-146 1982,137-146 I 0 Verlag Chemie GmbH. D-6940 Weinheim, 1982 0721 4227/82/01010137102.50/0

1

u,D-Unsaturated Ketones by Cathodic Addition of Benzotri-

chloride to Ketones

Michael Steiniger and Hans J. SchZfer"

Organic halides can be added reductively to activated double

bonds to form cyclopropanes/l/ or to carbonyl compounds to

yield carbinols/2/ or olefins/3/. We found that by cathodic

reduction of benzotrichloride in the presence of ketones

.r,U-unsaturated phenylketones 3 (eq. 1 ) can be prepared in

one Step and good yields (Table 1 ) . The main side product

is bentalchloride ( z ) , whose formation can be reduced by adding sodlum hydride to the electrolyte.

*Dipl. Chem. M. Steiniqer, P r o f . D r . H.J. SchZfer

Organisch-Chemlsches Institut der UniversitBt

Or16ansrlng 2 3 , D - 4 4 0 0 Miinster

- 137 -

( 1 ) 0 I1

+2e C6H5-CC13 -

-c1'

C ~ H ~ C H C C ~ ~ 1 2

4

The followlng pathway seems reasonable (eq. 2 ) :

1 is reductively cleaved to the anion 1. which adds to the ketone to yield 5. This adduct cyclizes to the oxirlne 6 ,

whose heterolysls leads to the intermediate oation I , which

rearranges to g / 5 / , that is deprotonated to 2. The direct conversion of 6 to 8 has also been proposed/6/. 4 is probab- ly formed by protonation of 2, partially by protons from the anolyte.

The formation of g as intermediate is supported by the adducts '1-14 with norcamphor (eq. 3 ) and Table 2 .

-

- -

-

1

lj m

m X

I

m 3 u

urn U P

LI=u I \

- - ' 7

3-'J Z i m

X

< > W

I N I

i a , x c s o u c

1 3 2 " s m a

- 139 -

I ,

a m

- 138- - 140 -

H-NMR

Compound 5 r Ppm, CDC13, TI44 3C-NMR

BFpm, CDC13]

- 141 -

& 6‘5 1 1 _- _ _

&c6H5 Hb _- 12 Hc _-

__ 13 _-

These products are best explained y& the two equilibrating

norbornyl cations 2 and 10 as intermediates, because 14 and the corresponding acetate of ‘3 are also formed in the ace-

tolysis of ~ - 2 - b e n z o y l - ~ - 2 - n o r b o r n y l m e s y l a t e / 7 / .

Ha,Hb: 2.05-2.6 (m.3H);

Hc: 2.85-3.1 (m,lH)

Ha,Hb: 3.0-3.2 (m,lH),

3.4-3.6 (m,lH);

HC: 6.65 (d, 1H) -

H ~ : 4 . 4 - 4 . 7 (m,l~) -

With %,%-unsaturated ketones and with aldehydes the addition

ends mainly at the intermediate products 5 or 6 (Table 3 ) .

Preparation of 1-Benzoyl-1-cvclopentene: 1.0 y (5 mOl) ben-

zotrichloride and 0.85 g (10 mmol) cyclopentanone are dis-

solved in 50 ml catholyte (0.5 m LiC104 in tetrahydrofuran)

subsequently so much sodium hydride was added under Stirring

to get a good suspension but a small coverage of the mercury

surface. At - 0 . 8 V (Marple) and 0 ” C was electrolyzed until

965 Cb were consumed. Controlling the pH between 5 to 7 the

catholyte was added to 300 ml icewater and extracted with

10 0 V x

0

2 0 U

‘0

m

m W

0 Y

Y

Y

U

Y

m C

a

:: c s

a 0 Y

Q a .* U 4 5:

-3 U Y

s B w 0 C .* Y .r(

a m 0

a z

U

.rl

m I

i m - a x c c a 0 0

; g u u

- 2: N

X . . - E

a m

- -

7 -

; 5 4 - m L n I

7 - 0

- w m . . .

. .. .. n u

C X X

m

- - E X - - - - E X

a a - . - 0 . . a a F j u r

I

m m m N P . O l r

N r N N . . . . : .. ..

u a X X X

a n O N

U J

0-u-u I N

m c , tn (D

=, U

- 143 -

0 N

x c1 X . . - -N urn X

U z i m 2 I 3 -u -32 X

I ni

- X -

- m

N X 4

u o=u m m Ln

xw % % u u

I

- 142 - - 144 -

ether (3x100 mlj. The ether layer was washed ( 5 0 ml H20),

dried (MgS04j and evaporated at room temperature. Column

filtration (Sil1caqel/CH2Cl2) of the crude product (1.6 g )

afforded a product mixture (1.1 g ) , which was separated by

HPLC (CH2C12 : C2H502CCH3. 20 : 11 to afford 0.17 q 122 % )

4 and 0.559 ( 6 4 % ) 1-benzoyl-1-cyclopentene.

Support of this work by the Arbeitsqemeinschaft Industriel-

ler Forschungsvereiniqungen and the Fonds der chemischen

Industrie is gratefully acknowledged.

References

/1/ M.M. Baizer, J.L. Chruma, J.Org.Chem. 37, 1951 (1972).

/ 2 / F. Karrenbrock, H.J. Schafer, Tetrahedron Lett. 1978, 1521; T. Shono, H. Ohmizu, S . Kawakami, 5. Nakano,

N. Kise, Tetrahedron Lett. 1981, 871; Cathodic reduc- tion of 1.1.1-trichlorethane at -1.1 to -1.3 v (VS.

Marple) in the presence of aldehydes RCHO ( R : CqH9,

C6H5) or ketones R1R2C=0 (R1: CH3, R2: C2H5, R1,R2 =

-(CH215-) produces 1.1-Dichloroethylcarbinols in 2 0 to

34 % yield, M. Steiniger, Diplomarbeit Miinster 1980.

/ 3 / F. Karrenbrock, H.J. Schgfer, I. Langer, Tetrahedron

Lett. 1979, 2915; J.M. v. Tilborq, C.J. Smit, Recl.Trav.

Chim. Pays-Bas 2, 202 (1980).

/4/ L.W. Marple, Anal. Chem. 2, 844 (1967). /5/ K. Griesbaum. H. Keul, R. Kibar, B. Pfeffer, M. Spraul,

Chem. Ber. 114, 1858 (1981).

- 145 -

/ 6 / R.N. McDonald, T.E. Tabor, J.Amer.Chem.Soc. 89, 6573 (1967); R.N. McDonald, Mechanisms of Molecular Migra-

tions (B.S. Thyagarajan) Vol. 3 , p . 67, Wiley-Inter-

science, New York 1971.

/7/ X. Creary, J.Amer.Chem.Soc. 103, 2463 (1981).

Received: July 3 0 , 1981 /z 969 s/

Dieses Manuskript ist zu zitieren als Angew. Chem. Suppl.

This manuscript is to be cited as Angew. Chem. Suppl.

1982,147-152 1982,147-152

Overlag Chemie GmbH. D-6940 Weinheim. IS82 0721 4227/82/01010147602.50/0

Oxanickelacyclopenten-Derivate Bus Nickel ( 0 ) , Kohlendioxid und Alkinen

Von Georg Burkhart und Heinz Hoberg+

Von C02 abzuleitende Hetero-1,Z-diene lassen sich an Nickel-

(0)-Verbindungen in vielfgltiger Weise umwandeln. So werden

Phenylisocyanat gespalten/l/, Diphenylketen dimerisiert/2/

und Diarylcarbodiimide trimerisiert/3/ oder auch mit Alkinen

zu Pyridinderivaten umeesetzt/4/.

Wir haben unsere Untersuchungen nun auch auf das Kohlen-

dioxid ausgedehnt.

Es zeigte sich, daR ein stark basischer, chelatisierender

Ligand, wie N,N,N' ,N' -Tetramethylethylendiamin (TMEDA) , Reaktionen von Kohlendioxid an Nickel ( 0 ) ermBglicht . t Prof. Dr. H. Hoberg, Dr. G. Burkhart

Max-Planck-Institut fiir Kohlenforschung, Postfach 01 13 25,

D-4330 MUlheim a.d. Ruhr 1

- 147 -

So erfolgt bei Umsetzung von COP mit (CDT)Ni(O) (CDT-Cyclo-

dodecatrien-l,5,9) in TMEDA eine Disproportionierung des

Kohlendioxids zu (TMEDA)Ni(COJ) (2) und Ni(C0)4 gem8A:

5 (CDT)Ni t 8 C02 +TMEDA - 4 (TMEDA)Ni(C03) t Ni(CO),, -CDT

1

Filhrt man die gleiche Reaktion i n Gegenwart eines Alkins,

z.B. 2-Butin durch, so kann keine Disproportionierung mehr

beobachtet werden. Stattdessen wird der Komplex 2 erhalten, in dem Kohlendioxid und 2-Butin C-C-verknilpft sind und rnit

dem (TMEDA) Ni-Rest eine Nickelaverbindung bilden. CH \ 3 FHX

,C"i ' (CDT)Ni t H3CCICCH + C02 +TMEDA+ (TMEDA)Ni I

-CDT 3

g fBllt als gelboranees Pulver an und ist in Toluol oder Diethylather nur wenig 1Sslich. In Methylenchlorid und Di-

methylformamid erfolgt rasche Zersetzung. Thermisch ist g bis 170 OC stabil.

Das Infrarotspektrum (KBr) zeigt charakteristische Banden

bei 1620 und 500 cm-', die einer C-0-Doppelbindung bzw.

einer Ni-0-Bindung zuzuordnen sind.

Die Protonolyse von 2 liefert 2-Methylcrotons&ure, mit Koh-

- 146 - - 148 -