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Synthesis of a novel class of monobenzenoid-cage compounds
Tetrahedron LetteraNo.46,PP, 5779-5782, 1966, Printed
Per@mon
PressLtd.
in Great Britain,
SYNTHESIS OF A
CLASS OF
NVVEL
MONOBENZENOID-CAGE COMpOUNDS A. J. Hubert and M. Hubert Union Carbide European Research Associates, S.A. 95 Rue Gatti de Gamond Brussels 18, Belgium (Received 3 September 1966) A series'of dibenzenoid cage compounds (I) has been synthesized recently by internal cyclotrimerization of aromatic triynes (II) (1).
We want now to report the synthesis
of a novel class 01 monobenzenoid-cage compounds (III) which is obtained by internal cyclotrimerization of the triynes (IV) On a Ziegler catalyst (1).
(I) (n = S,4,5,8,7,8,8)
2n I s C H ( IV)
(III) (n = 4,5,6)
5779
E C H
5780
No.46
The triynes (IV) were prepared by the following steps: The W-methoxyalkylbromides
(V) were prepared by the
reaction of the corresponding Lj-methoxyalkanol with PBr3 (2) or, better. by the reaction of sodium methoxide with the a,udibromoalkanes (3). Reaction of the I&methoxyalkylbromides
(V) with Kg
according to the standard procedure gave the corresponding Grignard reagent (VI) which was treated with one equivalent (l/3 mole) of diethyl carbonate. The carbinols (VII) were obtained in good yield (~50%) and dehydrated on alumina at 250°C.
In
some attempts the dehydration occurred directly during the distillation of the carbinols and the olefins (VIII) were obtained without further treatment.
The yield of olefin was at least 65%.
Catalytic reduction in the presence of Pt at 100°C. under pressure of hydrogen (>lOO Kg) gave the tris(W-methoxyalkyl)methane (IX).
Reaction of (IX) with a saturated solution of
hydrogen bromide in acetic acid gave the tris(lr/-bromoalkyl-) methane (X) in good yield (90%). The tribromides (X) were shaken with a solution of monosodium acetylidein ammonia in an autoclave at room temperature. The tris((,./-alkynyl-) methanes(W)
were obtained in ,OEt
good yield (n, %:4, 58; 5, 90; 6, 34). o=c CB30-(CH2)n-Br Mg (V)
\ OEt
CH30-(CH2)n-MgBr
>
(VI) _I
J
HO-C (CH2)n-OCH3 3
-I-I20
>
CBQG, /OCH3 (CB2 )n,C,(CH2)n
(VII) /\
E
( CH2 ) n-l CH30
/
(VIII)
H
112 >
5781
NO.46
HBr
C
H-C
-(CH&=H3
-
1
H-C
[-(CH2)n-Br]
Cyclotrimeriaation cage-compounds
(III) (Table
under high dilution
I) as a mixture TABLE
Yield Mixture
14
5
40
6
17
(1) gave the
of isomers.
I
%
mp(1.3,5)
bp
of Isomers
4
IV,
(XI
OX)
E
3=
Pure
1,3.5
Isomer
.C
*/mm
-a+ 22* 8*+
160-185/o.
001
liq.
160-180/O.
001
155
180-190/O.
001
64
_-___--___---__-* measured
by G. L.C.
** isolated
by crystallization. The cage compounds
molecular
weight
I_Itypical
Typical
absorption
the absorption shoulder benzene
IR spectra
determination,
at 6.25
for a 1,3,5 occurs
is weaker
at 264 mu,
(IV) were
-trisubstituted at 268 mv,
c - 230
: this indicates
benzene
with the tribromide which was isolated
absorption
ring) and UV spectra.
in the case
is very
poor
probably
:
of n
q
there
4. is a
a deformation
(X) (n=4)
of the triaodium
salt of the triyne
gave a novel type of macrocyclic
by distillation
(bp 220-260*/
0.001 H
(CH2),,,-C- -@Hz),,
HC -(cH~)~-C=C \
strong
of the
ring (4). Condensation
/
by analysis,
(particularly
c - 300.
and the resolution
identified
(CH2)n-C=C (XI)
-(CH~)~-CH -(CH2)n (n = 4)
/
I
mm).
(IV) (n=4) triyne
(XI)
No.46
5782
Recrystallization
in hexane
We hope that internal
trimerization
kind of cage compound
(XII)
Cage chains
of different
u’-methoxyalkyl
magnesium
lengths
by Cr03
(VII) containing identical
similar
bromide gives
described
has been prepared
The spectra
:
synthesized
Reaction
The triyne Others
The other
a
steps
(IV) (m = 5, are under
carbinol are
n = 4,
n
q
preparation
properties
A. J.
of these
will be investigated.
Hubert,
Glasgow
Chemical
(1965).
(2)
L.I..
Smith,
(3)
H.T.
(4)
D. J. Cram
Clarke,
Society
J. Chem.
J.A.
Sprung,
J.Chem.Soc. and Counkers,
Sot.
Anniversary 1966,
Meeting,
000.
J.Amer.Chem.Soc. 1913.
-103,
J.Amer.Chem.
1943,
65,
1279.
1703. Sot.
4)
and
REFERENCES. (i)
in
m-methoxyalkyl
units gives
and the chemical
groups
which is oxidized
with another
chains.
of
n methylene
alcohol
m # n methylene
by this procedure.
will be trimerieed.
(XI) will give a novel
to (III) but with polymethylene
Reaction
above.
at 176’.
investigated.
a secondary
in acetone. containing
melting
(VI) containing
(m, n, n) polymethylene
to those
compounds
this is being
are now being
magnesium
bromide
;
(2.3%)
of the triyne
compounds
the chain with ethyl formate to the ketone
gave crystals
1959.81,
5971.
1964,g,
5722.
Per@mon
PressLtd.
in Great Britain,
SYNTHESIS OF A
CLASS OF
NVVEL
MONOBENZENOID-CAGE COMpOUNDS A. J. Hubert and M. Hubert Union Carbide European Research Associates, S.A. 95 Rue Gatti de Gamond Brussels 18, Belgium (Received 3 September 1966) A series'of dibenzenoid cage compounds (I) has been synthesized recently by internal cyclotrimerization of aromatic triynes (II) (1).
We want now to report the synthesis
of a novel class 01 monobenzenoid-cage compounds (III) which is obtained by internal cyclotrimerization of the triynes (IV) On a Ziegler catalyst (1).
(I) (n = S,4,5,8,7,8,8)
2n I s C H ( IV)
(III) (n = 4,5,6)
5779
E C H
5780
No.46
The triynes (IV) were prepared by the following steps: The W-methoxyalkylbromides
(V) were prepared by the
reaction of the corresponding Lj-methoxyalkanol with PBr3 (2) or, better. by the reaction of sodium methoxide with the a,udibromoalkanes (3). Reaction of the I&methoxyalkylbromides
(V) with Kg
according to the standard procedure gave the corresponding Grignard reagent (VI) which was treated with one equivalent (l/3 mole) of diethyl carbonate. The carbinols (VII) were obtained in good yield (~50%) and dehydrated on alumina at 250°C.
In
some attempts the dehydration occurred directly during the distillation of the carbinols and the olefins (VIII) were obtained without further treatment.
The yield of olefin was at least 65%.
Catalytic reduction in the presence of Pt at 100°C. under pressure of hydrogen (>lOO Kg) gave the tris(W-methoxyalkyl)methane (IX).
Reaction of (IX) with a saturated solution of
hydrogen bromide in acetic acid gave the tris(lr/-bromoalkyl-) methane (X) in good yield (90%). The tribromides (X) were shaken with a solution of monosodium acetylidein ammonia in an autoclave at room temperature. The tris((,./-alkynyl-) methanes(W)
were obtained in ,OEt
good yield (n, %:4, 58; 5, 90; 6, 34). o=c CB30-(CH2)n-Br Mg (V)
\ OEt
CH30-(CH2)n-MgBr
>
(VI) _I
J
HO-C (CH2)n-OCH3 3
-I-I20
>
CBQG, /OCH3 (CB2 )n,C,(CH2)n
(VII) /\
E
( CH2 ) n-l CH30
/
(VIII)
H
112 >
5781
NO.46
HBr
C
H-C
-(CH&=H3
-
1
H-C
[-(CH2)n-Br]
Cyclotrimeriaation cage-compounds
(III) (Table
under high dilution
I) as a mixture TABLE
Yield Mixture
14
5
40
6
17
(1) gave the
of isomers.
I
%
mp(1.3,5)
bp
of Isomers
4
IV,
(XI
OX)
E
3=
Pure
1,3.5
Isomer
.C
*/mm
-a+ 22* 8*+
160-185/o.
001
liq.
160-180/O.
001
155
180-190/O.
001
64
_-___--___---__-* measured
by G. L.C.
** isolated
by crystallization. The cage compounds
molecular
weight
I_Itypical
Typical
absorption
the absorption shoulder benzene
IR spectra
determination,
at 6.25
for a 1,3,5 occurs
is weaker
at 264 mu,
(IV) were
-trisubstituted at 268 mv,
c - 230
: this indicates
benzene
with the tribromide which was isolated
absorption
ring) and UV spectra.
in the case
is very
poor
probably
:
of n
q
there
4. is a
a deformation
(X) (n=4)
of the triaodium
salt of the triyne
gave a novel type of macrocyclic
by distillation
(bp 220-260*/
0.001 H
(CH2),,,-C- -@Hz),,
HC -(cH~)~-C=C \
strong
of the
ring (4). Condensation
/
by analysis,
(particularly
c - 300.
and the resolution
identified
(CH2)n-C=C (XI)
-(CH~)~-CH -(CH2)n (n = 4)
/
I
mm).
(IV) (n=4) triyne
(XI)
No.46
5782
Recrystallization
in hexane
We hope that internal
trimerization
kind of cage compound
(XII)
Cage chains
of different
u’-methoxyalkyl
magnesium
lengths
by Cr03
(VII) containing identical
similar
bromide gives
described
has been prepared
The spectra
:
synthesized
Reaction
The triyne Others
The other
a
steps
(IV) (m = 5, are under
carbinol are
n = 4,
n
q
preparation
properties
A. J.
of these
will be investigated.
Hubert,
Glasgow
Chemical
(1965).
(2)
L.I..
Smith,
(3)
H.T.
(4)
D. J. Cram
Clarke,
Society
J. Chem.
J.A.
Sprung,
J.Chem.Soc. and Counkers,
Sot.
Anniversary 1966,
Meeting,
000.
J.Amer.Chem.Soc. 1913.
-103,
J.Amer.Chem.
1943,
65,
1279.
1703. Sot.
4)
and
REFERENCES. (i)
in
m-methoxyalkyl
units gives
and the chemical
groups
which is oxidized
with another
chains.
of
n methylene
alcohol
m # n methylene
by this procedure.
will be trimerieed.
(XI) will give a novel
to (III) but with polymethylene
Reaction
above.
at 176’.
investigated.
a secondary
in acetone. containing
melting
(VI) containing
(m, n, n) polymethylene
to those
compounds
this is being
are now being
magnesium
bromide
;
(2.3%)
of the triyne
compounds
the chain with ethyl formate to the ketone
gave crystals
1959.81,
5971.
1964,g,
5722.