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