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Pyrolysis of methylsilyl phenyl ketones. Formation of silene in the decomposition of an intermediate silaoxetane
219
Joud of Orgunometallic Chemism, 133 (1977)214-230 9Ekevk.r SequoiaS.A.,La~~e-PrintedinTheNethedands
pyrolysis
Formation of Methylsilyl Phenyl Ketones. Silaoxetane of an Intermediate
of Silene
in
the Decomposition Wataru
and
Ando*
Akira
Sekiguchi
Department of Chemistry, The University Niiharigun, Ibaraki 300-31, Japan
of Tsukuba
(ReceivedOctober 19+.&,1976)
Abstract:
Methylsilyl
siloxyphenylcarbenes
phenyl
which
the C-H bond
of a silyl-methyl
intermediate.
The thermal
proceeded oxygen Si=O
by cleavage
bonds.
double
Gn the other
hand,
isomerized
intramolecular
group
to give
decomposition
of both
The scission
bonded
ketones
underwent
thermally
to
insertion
into
an unstable
silaoxetane
of the silaoxetane
the silicon-carbon of the Si-C bond
and the silicon-
gave
intermediate
which
trimerized
the scission
of the Si-C bond
styrene
and an
to a cyclotrisiloxane. yielded
The intermediacy of the latter benzaldehyde and an unstable silene. was supported by the occurence of a Wittig-type reaction with the starting
silyl
phenyl
Intermediates silenes,
have
convenient
postulated
Pyrolyses
method
or benzophenone.
a silicon-carbon
containing
been
mechanismsl).
ketone
frequently
to explain
of silacyclobutanes
of generation
of such
double
bond,
some reaction
have been
the most species 2) .
short-lived
Gusel'nikov and Flowers confirmed the existence of such silenes by kinetic studies and chemical trapping experiments in which reactions olefin
with water
were
used 3).
vapor, Barton
alcohols
ammonia,
and Sommer
and a conjugated
and their
coworkers
found
that copyrolysis of a silacyclobutane with an aldehyde or a ketone new olefin 4) _ yielded a cyclosiloxane and the corresponding as intermediates in these reactions They suggested silaoxetanes (eq.1 and 2). R2Si Ll
A
R
Si=CH
2
2
+
CH2=CH
2
(1)
220 R2Si=CH
+
2
R12C=0
+
*
R2Si=0
+
R’2C”CH2
121
2
However,
very
little
We have begun
studies
intramolecular previously
is known
silyl
ketones
which
were
reactions
reported
recently
to siloxycarbenes
by a variety
that
trapping
of siloxycarbenes However,
so far.
several
which
Brook
silyl
undergo
Brook
agent b
generated
to 5) _
Product
(3)
photochemically coworkers
have
are rearranged
intramolecular
/H CR2 F!e3C-CO-SiMe3 %Ke2&-F-OSiMe3
rearranged
of reagents(eq.3)
and his
ketones
by
had established
photochemically
trapped
hlJ R3SiO-E--R'
R3SiCOR.N
not observed
were
of silaoxetanes.
of silaoxetanes
of siloxycarbenes,
that
Intramolecular
the behavior
of the preparation
reactions
silo.xycarbenes,
were
about
thermally
reactions(eq.4
and
5)6'
Me -
Me
(4) OSiMe3
a
EIe2CH-CO-SiMe3 these
However, unusual known
-_)
carbene <-C-H
gintramolecular
.2
CH-C-OSiMe 3 +
intramolecular
in that
or
Me
self-insertion
reaction. bonds
would
insertion
These group(eq.6). temperature pyrolyses
Me2C=CHOSiMe3
reactions into
(51
of siloxycarbenes
(3- err-C-H
bonds
are not
is a well
A siloxycarbene not having reactive be expected to produce a silaoxetane into the-C-H
bond
by
of the silyl-methyl
considerations
led us to study
of methylsilyl
phenyl
the high
and methylsilyl
naphthyl
Xetones.
f-r-
Ph
(CH3)3SiCOPh
%
-
(CH3)3SiO-?-Ph
(6)
(CH3j2S'i-0
Result
and Discussion The reactions
were
Carried
with
a stream
of nitrogen
in a
vertical flow system through a 23 cmXl cm Pyrex tube packed The products Pyrex chips at a nitrogen rate of 30 ml/min. condensed
in a trap
ketone,&,
was pyrolyzed
by GLC afforded
and analyzed at 500".
the products
with were
Trimethylsilyl phenyl by GLC. Separation of the reaction mixture
shown
in eq-7-
221 Me3Si
5oo"
Me3SiCOPh
3 l$flOW
(Me2SiO)3
+ PhCH=CH2
1(25%)
2(33%)
of dimethylphenylsilyl
conditions
gave
\
+
C=CH2
(7)
Pb'
1 =
Pyrolysis
+ PhCHO
analogous
4(12%1
phenyl
ketone,d,
zI24%) under
similar
products(eq.8). PhMe2Si
PhMe2SiCOPh
5000
+ PhCHO
3 PhCH=CH2 N2flOW
-6
\
f
C=CH2
+
(8)
Ph'
(5%)
(8%)
1(8%)
8(17%)
1-Sila-2-oxa-cyclopent-4-ene in the pyrolysis
-10 also was obtained in 40% yield of triphenylsilyl phenyl ketone,9_, at 500".
H
A reasonable Scheme thermal step
phenyl
previously
into the proximate examples
first
ketone
rearrangement
is certainly
not many
for the formation
The proposed
1.
of the silyl reported
pathway
step
of a silyl 6) .
formed
of the products
C-H bond insertion
neighboring
effects,
in
is the therznal isomerization Similar -11. to a siloxycarbene has
ketone
Intermediate
by self-insertion
reported
is shown
to siloxyphenylcarbene
by Brook
by intramolecular group
Ph
-12 in the second of the siloxyphenylcarbene
of the silyl-methyl of the fomation of a carbene, as with
&-C-H
group.
There
of a four membered except bonds
are ring
for special of an N-alkyl
group 7) .
Scheme
1. H
P Me2SiCOPh 2
5000 N2flow
7 Me2SiO-&Ph Y..
+
Ph
R=Ph s
R=Me
5 R=Ph
Ph
I
R\ +
PhCH=CH2
/
R\ Si=O
-i-
Si=CH,
PhCHO
Me
-3
-13 F Me2SiCOPh
P
Me-Si-0 L
SiMe2R
Ph !
-15
R \ Me
The
proposed
bonds
of
third
the
Si-0
step
and
H2C=C
t---g+ 3
/
Involves
silaoxetane-
benzaldehyde
Ph
/
The
a silene,l_?,
2 R=Me 'SiMe 2 R
cleavage rupture
which
of
of
the
the
contains
Si-C
Si-0
and
bond
a Si=C
1 R=Ph
the
may
double
Si-0
give bond-
latter nay produce&_-sibyl styrene derivatives 2 and 1 by cleavage of the silaoxetane 15 which is derived from Wittig-type reactions The
of
the
silenes
The
rupture
and
the
with
of
the Si-C
starting bond
in
silyl the
phenyl
Icetones
apparently
the
into
the
double by
are C-H
bonds
insertion of
the
products
phenyl
a-
12 may give styrene Intermediates of this type
cyclotrisiloxanes
formed
1 and
silaoxetane
bond intermediate -13. the decomposition of silaoxetanes, 4) . Final products, S and 10,
when
Si=O
the
groups
of
the on
trimerize in
our
to produce
reactions
siloxyphenylcarbene
silicon(eq.9).
Although
223
th&c
are sose examples:of
arosatxc
C-E bond with
insertion
is
quite
hydrogen
effect
of
may
the
nucleophilic
It $-or
special
be
is
a silaoxetane,
electrcphilic and
as
may
be
leading
to
expect
and
in
by
the
that
et the
less
that
to
steric
the
virtue
C-H
of
of
aromatic the
attack
insertion
proximate
al.
also
not
C-H
of
the
product.
containing
bonds
proposed
reactions
resonance
by
a siloxycarbene
into
Sommer
intermediates
probably
subject
to
self-insert
Barton
silaoxetanes benzaldehyde
will
carbenes into requirements 8) , the
appears
atom
reasonable bonds
It
more
siloxycarbene,
Y-C-H
bond with
interesting.
silicon
insertions
conformational
C-H
into an aromatic
interaction ortho
intramolecular
to
form
such
silenes
with
")(eq.lO).
Me2Si=CH2
+
PhCHO
---_)
+
PhCH=CH*
Me2Si=0
+
(10)
Ph However, as
they
shown.
observed
Our
intramolecular and
Si-0
results C-H
bond
provides
scission
as
the
cleavage
suggest
insertion
cleavage
observed
only
in
evidence initial
of
step
Si-C
bond
in
a silaoxetane
the
comparable
competitive of
the
ratio. Si-C2
thermal
silaoxetanes
derived
a siloxyphenylcarbene
almost of
of
that
and
from
undergoes The
product
C2-C3
decomposition
bonds of
the
silaoxetane. I --i-O
1 -7 -CC-Ph
-E
I
)Si=O
+
PhCH=CH2
+
PhCHO
1
/
I
-Si-0
I
I -$-Ph
-7 5
3
lc-Ph
-C*
I
1
\ *
/
Si=C
Si-C ratio
224
C2-C3
Bond
scission
in a silaoxetane.intermediate
in the copyrolysis
of l,l-dimethyl-l-silacyclobutane
also was proposed 2) with acetone
(eq.11). Me2C=O B >Ie Si=CH 2 2
Me2Si-0
>Ie2Si- 0 Me-+
H2C-
LG
Me2yiOC=CHZ
-C! \
Me
silaoxetane
resulting
by cleavage Brook
from
(11)
Me
H' CH2
vinyl ether might be formed by isomerization
The silyl formed
I:' I ,MeG
i
1,5 hydrogen
migration
of the
in the biradical
of the C-C bond.
and his
coworkers
photolyses of silyl ketones in non-polar solvents involved Norrish- type 1 cleavage of the 9) The possible Si-C bond and formation of silyl and acyl radicals _ of silyl
involvement
from
Wittig-type
Scheme
radical
- Styrene
2.
ketone,
of the Si-C
rupture
the silyl
Scheme
and benzoyl _A reasonable
in our reactions. homolytic
suggested
reaction
radicals
be considered by assuming can be written
route
bond
to give
and
that
also must
followed
benzaldehyde
$-silylstyrene
with
by hydrogen and a silene
could
benzaldehyde
abstraction shown
be formed
and trimethylsilyl
in
a
by
phenyl
respectively. 2. CH3
Xe
3
5$00 \\ 3
SiCOPh
I
Me2Si*
oCOPh+
&Ie2Si=CH2
f
PhCHO
--3 PhCH=CEi2
-1 Me3SiCOPh I
I + Me Si3
CO
& *Ph
,SiMe3
H2C=C
i-
\
Me2Si=0
Ph We intended
to pyrolyze
the silyl
and benzoyl
of carbon
tetrachloride
a carbon
tetrachloride
solution
of 1 to trap
radicals.
However, the total decomposition at 500° made this approach unfeasible.
A mechanisn! involving radicals is unlikely since the benzoyl radical would
easily
conditions.
decarbonylate In
addition,
before the
hydrogen
formation
4-enes -8 and 10 provides support that a siloxycarbene.
of
abstraction
under
these
1-sila-2-oxa-cyclopent-
the reaction
proceeds
through
225 A photochemical When
a benzene
pressure was
reaction
solution
mercury
lamp
of a silyl
of 1 was
ketone
irradiated
for 24 hr, almost
with
examined.
also_was
a 4OOW high
all of the starting
material
recovered.
This indicates that the siloxycarbene generated photochemically may revert to -1 5)*g) since it has activation energies not enough to insert into the C-H bond leading to the silaoxetane. Further support the copyrolysis
for the formation
of & with
an excess
+ Ph 2 CO ,$&$
Me3SiCOPh
Ph2C=CH2
-1
derived
from
the silene those
the diene
(Me2SiO)3
a result
compound
2-naphthyl pyrolysis sitilar
-17
ketone
than
were and
of A.
of the higher toward
extended
products(eq.13).
However,
+ PhCHO
(12)
(27%)
an attempt
Products at
The silene
was
reactivity
of
50Q0
formed were
trapped a silene
to trap in the identical
by 1, not toward
a diene. phenyl
2-naphthyl E
-19(25%)
from
of the silaoxetane
failed.
to similar
triethylsilyl
of trimethylsilyl
comes
(32%)
2,3-dimethyl-1,3-butadiene
of the pyrolysis
Our-studies
by cleavage
olefin
+ PhCH=CH2
(24%)
and benzophenone.
a conjugated
of -1 with as
a carbonyl
is formed
the silene
with
copyrolysis with
+
-16(17%)
l,l-Diphenylethylene
of the silene,lQ,
of benzophenone(eq.12).
pyrolyses ketone.
ketone,=,
of trimethylsilyl Gas phase at 500" gave
20(7%) -
(13)
226
Their
formatiomcan
be rationalized
of the siloxycarbene
as shown
products, Er -19 and the silene, to produce 20. Pyrolysis of triethylsilyl
which
unidentified
which
but very
polymeric
strong
styrene
reacts
ketone,=,
with
to Ffive
ketone
afforded
had no carbonyl -I at 1003-1100 cm .
absorption
and trans,4%),
of isomerization
then decomposes
again
phenyl
products,
Si-O-C
(cis,3%,
in terms
to a si'laoxetane which
allylbenzene(4%)
-17
mainly
absorption, Some P-methyl-
and benzaldehyde
(4%)
Since
also were obtained as minor products. -methylstyrene ? did not isomerize to allylbenzene under the reaction conditions, the Ia.tter may have been formed via cleavage of the Si-C bond of
silaoxetane
the
cleavage. have
been
followed
A long-range expected
Et3SiCOPh
from
5000 UZflow>
by 1,3 hydrogen
insertion
product
the siloxycarbene
Et3SiO=&Ph
migration
and C-O
such as 24, which
, was not obtained(eq.14).
+3 Ph
Et2Si, Y- 0
-21
-24
?
? 1
Me
/L
Et2Si f 0X
?
polymer
might
.e Et Sk 2l 0L
Ph
l
-
PhCEi=CEMe
(14)
22 -
Ph
0
Et2Si=CH2
+
1,3 hydrogen J PhCH2CH=CH2
PhCHO
migration
-23
Experl"menta1 General: Nmr data were
obtained
spectra
were
obtained
using
sPectra
were
obtained
either
at 7OeV.
Preparative
Separation
stainless
with
columns
10% P_piezon Grease
JEOL
GLC was
chromatography. with
on a Varian a Hitachi
A-60D
EP-l-G3
JNF-07
or Hitachi
accomplished
was
15% SF-96 on Celite
spectrometer.
Infrared
spectrometer_
using
RMU-7M
a Ohkura
Mass spectromete: gas
done by 2 m X5 mm or 30 cm X5 mm and 1.5 my5 545.
Yields
mm stainless were
column
done by.GLC.
227 A known
amount
and used
of standard
to calculate
sample
was
added
to the reaction
mixture
yield.
Reagents: Silyl
ketones
were
dibromide
with
the Brook
methodlo)
Me3SiCOPh:
prepared
acetate
m-p. m-p.
in 97% yield
51-53O'in
97-99O
67% yield
in 88% yield
b-p.
Et3SiCOPht
106-1G9°/4mmHg
14G"/2mmHg
system
(lit. b.p.
(lit. m.p.
{lit. m.p.
in 57% yield
61°/lmmHg1G)); 10) 1;
103Oll));
(lit. 113°/0.1mmHg12));
in 61% yield.
Nmr(CC14):
The pyrolyses diameter,3
cm;
of a 28 cmX1 by syringe,
were
performed
length,33 cm Pyrex was
of the appratus
cm).
at a rate
with
The pyrolysate
with
was
Trimethylsilyl at 500".
trapped
The sample
was
phenyl
cooling.
benzaldehyde(l2%)
ice-acetone
was passed
Separation
by comparison
of their
nmr,
through
identified
by its nmr,
mixture
5-57 and
Irtneat): M+ 176(relresolution
3050, iat. mass:
5.78(2H,d,J=3Hz,C=CH2) 2950,
1490,
1410,
162(15),
801, m,?e Calcd
tube
as
by GLC
styrene(33%),
and retention
spectra.
in the gas phase
the reaction
were
times 14)
d-Trimethylsilylstyrene
ir and mass
nitrogen
GLC.
was pyrolyzed
of the product
ir spectra
the Pyrex
was 1.4 sec.
x-trimethylsilylstyrene(24%). 13) , styrene and benzaldehyde
of authentic*samples.
in using
or a liquid
hexamethylcyclotrisiloxane(25%), and
(inside
of the oven was measured
time of the sample
ketoneiG.486g)
H,9.16.
consisted
through
Hexamethylcyclotrisiloxane
SiMe),
Calcd
oven
dripped
passing
The temperature
in a dry
One ml of benzene
after
four products,
those
2950,
chips.
and then separated by preparative trap, concentrated, Pyrolysis of Trimethylsilyl phenyl ketone:
gave
G-7-1.2
The upper end cap for sample introduction
of nitrogen
The residence
tube
apparatus
Pyrex
a rubber
inlet.
a stream
of 30 ml/min.
by a thermocouple.
a vertical
The pyrolysis
equipped
with
using
tube packed
and a nitrogen
a one ml syringe
a wash
x
fr(neat):
2875, 1612 (C=O), 1590, 1578 and 1210 cm-'. Anal. for C13H2001Sil: C,70.85; H.9.15: Found: C,70.79; Pyrolysis Procedure:
General
using
54-55"
7.2-7.9(5H,m,ArH).
(15R,m,SiCH2CH3),
tube
of the corresponding
rll).
2-ClGH,COSiMe3: b-p.
by hydrolysis
in water-acetone-ethanol
61-65°/lmmHg
b.p.
PhMe2SFCOPh: Ph3SiCOPh:
silver
identified
with was
Nmr(CC14):g0.15(9H,s,
and 6.9-7.4(5H,m,ArH).
1249 and
161(1OG),
for C11H16Silz
932 cm-l,
135(30)
and
176.1021;
Mass: 73163);
Found:
m/e, high
176.1009.
.
228 Pyrolysis
of Dimethylphenylsilyl
Dimethylphenylsilyl The products
were
phenyl
phenyl
analyzed
x
Calcd
for
is, mass
Ir(neat)r
3055,
C16H18Sil:
2945,
C,80.29;
elemental
1250,
1135,
MT 240(100), mass:
m/e
8 was
analyses.
6.08(lH,s,_Ar-CH-0) 1490,
and
1249,
1110
Found:
of
and
and
934
by
6.8-7.6(10H, an
its
nmr,
for C15H1601Sil:
fr(neat):
Found:
Anal.
_
ir,
mass
3045,
1590,
Mass:
m/e,
high resolution
and 105(18);
240.0970;
-1
0.48(3H,s,SiMe),
and 1015 cm -'(Si-O-C). 165(30)
Nmr(CC14):
H,6.99.
7 0.42(3H,s,SiMe),
6.8-7.7(9H,m,ArH).
225(43),
!
and
analyses.
C,80.02;
identified
?Znr(&14):
104O(Si-O-C)
239(88),
Calcd
1427, H,7.19:
l-Sila-2-oxa-cyclopent-Gene ans
and elemental
5.62 and 5_92(2H,d,J=3Hz,C=CH2)
0.38(6H,s,SiMe),
at 500".
the formation
$-Dimethylphenylsilylstyrene
g(l?%).
by its nmr,
was pyrolyzed
showed
d-dimethylphenylsilylstyrene(8%)
I-sila-2-oxa-cyclopent-4-ene
rn,&H).
ketone(0.956g)
by GLC, which
s_;yrene(5%), benzaldehyde(8%), spas identified
ketone:
240.0945.
Anal.
Calcd.: C,74_95; H,6.71: Found: C,74.72; H,6.85. Pyrolysis of Triphenylsilyl phenyl ketone: A benzene pyrolyzed
solution
at 500".
GLC as resinous and
of triphenylsilyl
phenyl
ketone(0.550g)
1-Sila-2-oxa-cyclopent-4-ene
liquid
in 40% yield.
6.9-7.9(19H,m,ArH)-
Ir(CC14):
1122 and 1010 cm -'(Si-O-C); 364.1283;
high
Found:
Nmr(CC14): 3060,
1590,
resolution
364.1296.
C25H2001Sil' H,5.53: Found: C,82.12; H,5.37. Copyrolyses of Trimethylsilyl phenyl
1430,
mass:
Anal.
ketone
was
-10 was obtained by p 5-27(J_H,s,Zz-CH-0) 1267,
m/e Calcd
Calcd.:
with
1185, for
C,82.38;
Benzophenone
and
2,3-Dimethyl-1,3-butadiene: A mixture and 2.54g(14m
of 0.435g(2.44m
mol)
l,l-Diphenylethylene
mol)
of benzophenone was obtained
hexamethylcyclotrisiloxane(l4%), l,l-Diphenylethylene
was
of trimethylsilyl
was pyrolyzed in 17% yield styrene(32%)
identified
together
were
identical
with
also was
those
done
of the pyrolysis
ketone
of its nmr,
at 500°.
an excess
Products
of trimethylsilyl
of
-l-(
2_naphthyl)ethylene(7%)
were
obtained
phenyl
4 1 1 2
at 5OOO.
and I-trimethylsilyl
by GLC-
1
and yield7
ketone.
2_naphthaldehyde(25%)
i
ir spectr i
Pyrolysis of Trimethylsilyl 2-naphthyl ketone: Trimethylsilyl 2-naphthyl ketone(O-22g) was Pyrolyzed 2_Vinylnaphthalene(20%),
’
with
and benzaldehyde(27%).
by comparison
and retention time with tho'se of an authentic sample, Copyrolysis of trimethylsily phenyl ketone with 2,3-dimethyl-1,3-butadiene
phenyl
at 500'.
2-Vinylnaphthalenej
[ ]
229
1it.l') 60-62O)
(m-p. 61-6Z", lit.16) 59-62O) with
those
were
of
-ethylene
identified
authentic
was
m/e,
5.63
m/e
has
only
the
small
Calcd been
of
were
the
by
and
and
mass
930
nmr
152(52)
226-1178:
the
above
and
ir
Nmr(CC14):
and 890
and
7.1-8.1(7H,-
cm-'.
Mass:
73(100);
Found:
high
226.1181.
spectroscopic
resolution
The
means
.
spectra
2 -naphthyl)
spectra.
and
product
because
of
reaction of
pyrolyzed
P_methylstyrene(cis,3%, The
material
which
p-Methylstyrene
Trimethylsilyl
cm
high
GLC;
was
had
strong not
500".
and
major
did
at
trans,d%),
product
Si-O-C
Four
was
an
absorption
isomerize
to
allylbenzene
conditions.
Trimethylsilyl 8 mm ~30
ketone:
ketone(0.569g)
benzaldehyde(4S).
polymeric -1 cm .
1000-1100
Photolysis
in
ir
1250,
phenyl
phenyl
found
unidentified
a 4OOW
their
5.87(2H,d,J=3Hz,C=CH2) 2950,
by
Triethylsilyl
allylbenzene(4%)
under
nmr,
153(23),
identified
of
I-Trimethylsilyl-l-(
C15H18Sil:
Triethylsilyl
at
comparison
yield,
Pyrolysis products
and
211(27), for
by
its
3050,
Ir(CC14):
M + 2266613,
mss:
by
(m.p. 58-60",
2-naphthaldehyde
samples.
identified
0.25(9H,s,SiMe),
s
m,Np-H).
and
phenyl
phenyl
Pyrex
and
tube,
pressure
mercury
of
trimethylsilyl
phenyl
1.
W.Ando,
T.Hagiwara
W.Ando,
A.Sekiguchi,
ketone
in Benzene:
ketone(0.199g) then
lamp
and
the
for
ketone(868)
3 ml
mixture
24 hr. and
of
was GLC
benzene
was
irradiated
showed
the
placed
with presence
benzaldehyde(g%).
References
commun., W.Ando, and
(1975)
T.Migita,
J.
Amer.
J.Ogiwara
and
T.Migita,
S.Kammura,
M.Jones,Jr., and
T.Migita,
J.
A,Sekiguchi
and
T.Migita,
Chem.
and
(1975)
H.Shechter,
and
Lett_,
V.M.Vdovin,
G.M.Maryanoff
3818:
Chem.
Lett.,
Tetrahedron
N.S.Nametkin
and
L.E.Gusel'nikov
Sot-,
g
(1975)
(1976)
779;
(1975)
2061.
Act.
Chem.
Res.,
L.E.Gusel'nikov.
J.
Chem.
Sot.,
and
J.
Chem.
sot.
M.C.Flowers,
(B) Chem.
(1968)
419;
Commun.,
864:
N.S.Nametkin, Akad.
95 (1973) 7518; Sot. Chem.
18.
3. M.C.Flowers
(1967)
Sot:, Chem.
(1975)
Amer.
A.Sekiguchi
W.Ando,
L.E.Gusel'nikov,
J-
M-Green,
_, g
W.Ando,
8
Chem.
T.Migita,
145;
A.Sekiguchi,
R.L.Kreeger 2.
and
Nauk
L.E.Gusel'nikov, SSSR,
201
(1971)
R.L.Ushakova 1365.
and
V.M.Vdovin,
Dokl.
7159;
280 dA.
D.N.Roark
and L.H.Sommer,
T_J_Barton,
E-A-Kline
Orqanosilicon _cliem.,80
Chem.
(1973) 167;
the 3rd Int, Sympo&ium
Wisconsin,
G.D.Homer
Commun.,
on
(1972);
and L.H.Sommer,
J, organometal.
(1974) 37;
T.J.Barton,
G.Marquardt
and J.A.Kilgour,
J. Organometal.
Chem.,
(1975) 317;
T.J.Bartou 5.
Sot.
and P.M.Darvey, Madison,
C.M.Golino,_
R-D-Bush,
&j
Chem.,
J. Chem.
A-G-Brook
and J.A.Kilgour, and
J-M-Duff
Z.M.Duff,
and A;G.Brook,
A.G.Brook,
H.W.Kucera
A-G-Brook,
R-Pearce
J. Amer,
g- Amer. Can.
Chem.
Chen.
Sot.,
98
J. Chem.,
g
89 (1967) 454; (1973) 2869;
and R.Pearce,
Can.
J. Chem.,
and J-B-Pierce,
Can.
J_ Chem,
6.
A.R.Bassindale,
7.
9d (1975) C6. E-J-Corey and A-M-Felix,
A-G-Brook
8.
J.A.Myers,
R.C.Joines
and J-Harris,
49 42
J. Organometal.
J. -Amer. Chem.
and W.M.Jones,
(1976) 7231.
Sot.,
Sot.,
J. Amer.
g
(1971) 1618; (1971) 1622. Chem.,
(1965) 2518.
Chem.
Sot.,
92
(1970)
4740; C.Mayor 9.
and C.Wentrup,
C.Wentrup A-G-Brook A.G.Brook, A-G-Brook A.G.Brook,
10. A-G-Brook, .J. Fmer. 12. H.Bock,
P.J.Dillon J-B-Pierce
Can.
Sot.., g
(1975) 7467:
Sot.,
J, Amer.
H.Alt
Can. J. Chem.,
J. Chem-,
and J.M.Duff,
M.A.Quigley,
G-J-D-Peddle,
z
49 'Z (1973) 352;
Can. J. Chem., N.V.Schwartz
53
(1971) 133; (1975) 2874.
and C.M.Warner,
g (1960) 5102. Chem. Sot., 73 (1957) 4373.
and H.Seidl,
13. W.Patnode
and D.F.Wilcock,
14.. P_Cazeau,
E.Frainnet,
g
Chem.
and R-Pearce,
and J-M-Duff,
Chem.
11. A.G.Brook,
J. Amer.
and K.Wilczek, Helv. Chim. Acta., 53 (1970) 1459. and J_M.Duff, J. Amer. Chem. Sot., z (1969) 2118;
J. Peer.
Chem.
Sot.,
g
(1969) 355.
J. Amer.
Chem.
Sot.,
68
(1946) 358.
J_Dunogues
and R_Calas,
J. Organometal,
(1972) Cll.
15. C.J.Pouchert, Ardrich
16. C.J.Pouchert, Ardrich
The Aldrich
Chemical
Co.,
The Aldrich
Chemical
co,,
Library
of Infrared
Spectra,
435A,
of Infrared
Spectra,
688A,
(1970). Libsary
(1970).
Chem.
Joud of Orgunometallic Chemism, 133 (1977)214-230 9Ekevk.r SequoiaS.A.,La~~e-PrintedinTheNethedands
pyrolysis
Formation of Methylsilyl Phenyl Ketones. Silaoxetane of an Intermediate
of Silene
in
the Decomposition Wataru
and
Ando*
Akira
Sekiguchi
Department of Chemistry, The University Niiharigun, Ibaraki 300-31, Japan
of Tsukuba
(ReceivedOctober 19+.&,1976)
Abstract:
Methylsilyl
siloxyphenylcarbenes
phenyl
which
the C-H bond
of a silyl-methyl
intermediate.
The thermal
proceeded oxygen Si=O
by cleavage
bonds.
double
Gn the other
hand,
isomerized
intramolecular
group
to give
decomposition
of both
The scission
bonded
ketones
underwent
thermally
to
insertion
into
an unstable
silaoxetane
of the silaoxetane
the silicon-carbon of the Si-C bond
and the silicon-
gave
intermediate
which
trimerized
the scission
of the Si-C bond
styrene
and an
to a cyclotrisiloxane. yielded
The intermediacy of the latter benzaldehyde and an unstable silene. was supported by the occurence of a Wittig-type reaction with the starting
silyl
phenyl
Intermediates silenes,
have
convenient
postulated
Pyrolyses
method
or benzophenone.
a silicon-carbon
containing
been
mechanismsl).
ketone
frequently
to explain
of silacyclobutanes
of generation
of such
double
bond,
some reaction
have been
the most species 2) .
short-lived
Gusel'nikov and Flowers confirmed the existence of such silenes by kinetic studies and chemical trapping experiments in which reactions olefin
with water
were
used 3).
vapor, Barton
alcohols
ammonia,
and Sommer
and a conjugated
and their
coworkers
found
that copyrolysis of a silacyclobutane with an aldehyde or a ketone new olefin 4) _ yielded a cyclosiloxane and the corresponding as intermediates in these reactions They suggested silaoxetanes (eq.1 and 2). R2Si Ll
A
R
Si=CH
2
2
+
CH2=CH
2
(1)
220 R2Si=CH
+
2
R12C=0
+
*
R2Si=0
+
R’2C”CH2
121
2
However,
very
little
We have begun
studies
intramolecular previously
is known
silyl
ketones
which
were
reactions
reported
recently
to siloxycarbenes
by a variety
that
trapping
of siloxycarbenes However,
so far.
several
which
Brook
silyl
undergo
Brook
agent b
generated
to 5) _
Product
(3)
photochemically coworkers
have
are rearranged
intramolecular
/H CR2 F!e3C-CO-SiMe3 %Ke2&-F-OSiMe3
rearranged
of reagents(eq.3)
and his
ketones
by
had established
photochemically
trapped
hlJ R3SiO-E--R'
R3SiCOR.N
not observed
were
of silaoxetanes.
of silaoxetanes
of siloxycarbenes,
that
Intramolecular
the behavior
of the preparation
reactions
silo.xycarbenes,
were
about
thermally
reactions(eq.4
and
5)6'
Me -
Me
(4) OSiMe3
a
EIe2CH-CO-SiMe3 these
However, unusual known
-_)
carbene <-C-H
gintramolecular
.2
CH-C-OSiMe 3 +
intramolecular
in that
or
Me
self-insertion
reaction. bonds
would
insertion
These group(eq.6). temperature pyrolyses
Me2C=CHOSiMe3
reactions into
(51
of siloxycarbenes
(3- err-C-H
bonds
are not
is a well
A siloxycarbene not having reactive be expected to produce a silaoxetane into the-C-H
bond
by
of the silyl-methyl
considerations
led us to study
of methylsilyl
phenyl
the high
and methylsilyl
naphthyl
Xetones.
f-r-
Ph
(CH3)3SiCOPh
%
-
(CH3)3SiO-?-Ph
(6)
(CH3j2S'i-0
Result
and Discussion The reactions
were
Carried
with
a stream
of nitrogen
in a
vertical flow system through a 23 cmXl cm Pyrex tube packed The products Pyrex chips at a nitrogen rate of 30 ml/min. condensed
in a trap
ketone,&,
was pyrolyzed
by GLC afforded
and analyzed at 500".
the products
with were
Trimethylsilyl phenyl by GLC. Separation of the reaction mixture
shown
in eq-7-
221 Me3Si
5oo"
Me3SiCOPh
3 l$flOW
(Me2SiO)3
+ PhCH=CH2
1(25%)
2(33%)
of dimethylphenylsilyl
conditions
gave
\
+
C=CH2
(7)
Pb'
1 =
Pyrolysis
+ PhCHO
analogous
4(12%1
phenyl
ketone,d,
zI24%) under
similar
products(eq.8). PhMe2Si
PhMe2SiCOPh
5000
+ PhCHO
3 PhCH=CH2 N2flOW
-6
\
f
C=CH2
+
(8)
Ph'
(5%)
(8%)
1(8%)
8(17%)
1-Sila-2-oxa-cyclopent-4-ene in the pyrolysis
-10 also was obtained in 40% yield of triphenylsilyl phenyl ketone,9_, at 500".
H
A reasonable Scheme thermal step
phenyl
previously
into the proximate examples
first
ketone
rearrangement
is certainly
not many
for the formation
The proposed
1.
of the silyl reported
pathway
step
of a silyl 6) .
formed
of the products
C-H bond insertion
neighboring
effects,
in
is the therznal isomerization Similar -11. to a siloxycarbene has
ketone
Intermediate
by self-insertion
reported
is shown
to siloxyphenylcarbene
by Brook
by intramolecular group
Ph
-12 in the second of the siloxyphenylcarbene
of the silyl-methyl of the fomation of a carbene, as with
&-C-H
group.
There
of a four membered except bonds
are ring
for special of an N-alkyl
group 7) .
Scheme
1. H
P Me2SiCOPh 2
5000 N2flow
7 Me2SiO-&Ph Y..
+
Ph
R=Ph s
R=Me
5 R=Ph
Ph
I
R\ +
PhCH=CH2
/
R\ Si=O
-i-
Si=CH,
PhCHO
Me
-3
-13 F Me2SiCOPh
P
Me-Si-0 L
SiMe2R
Ph !
-15
R \ Me
The
proposed
bonds
of
third
the
Si-0
step
and
H2C=C
t---g+ 3
/
Involves
silaoxetane-
benzaldehyde
Ph
/
The
a silene,l_?,
2 R=Me 'SiMe 2 R
cleavage rupture
which
of
of
the
the
contains
Si-C
Si-0
and
bond
a Si=C
1 R=Ph
the
may
double
Si-0
give bond-
latter nay produce&_-sibyl styrene derivatives 2 and 1 by cleavage of the silaoxetane 15 which is derived from Wittig-type reactions The
of
the
silenes
The
rupture
and
the
with
of
the Si-C
starting bond
in
silyl the
phenyl
Icetones
apparently
the
into
the
double by
are C-H
bonds
insertion of
the
products
phenyl
a-
12 may give styrene Intermediates of this type
cyclotrisiloxanes
formed
1 and
silaoxetane
bond intermediate -13. the decomposition of silaoxetanes, 4) . Final products, S and 10,
when
Si=O
the
groups
of
the on
trimerize in
our
to produce
reactions
siloxyphenylcarbene
silicon(eq.9).
Although
223
th&c
are sose examples:of
arosatxc
C-E bond with
insertion
is
quite
hydrogen
effect
of
may
the
nucleophilic
It $-or
special
be
is
a silaoxetane,
electrcphilic and
as
may
be
leading
to
expect
and
in
by
the
that
et the
less
that
to
steric
the
virtue
C-H
of
of
aromatic the
attack
insertion
proximate
al.
also
not
C-H
of
the
product.
containing
bonds
proposed
reactions
resonance
by
a siloxycarbene
into
Sommer
intermediates
probably
subject
to
self-insert
Barton
silaoxetanes benzaldehyde
will
carbenes into requirements 8) , the
appears
atom
reasonable bonds
It
more
siloxycarbene,
Y-C-H
bond with
interesting.
silicon
insertions
conformational
C-H
into an aromatic
interaction ortho
intramolecular
to
form
such
silenes
with
")(eq.lO).
Me2Si=CH2
+
PhCHO
---_)
+
PhCH=CH*
Me2Si=0
+
(10)
Ph However, as
they
shown.
observed
Our
intramolecular and
Si-0
results C-H
bond
provides
scission
as
the
cleavage
suggest
insertion
cleavage
observed
only
in
evidence initial
of
step
Si-C
bond
in
a silaoxetane
the
comparable
competitive of
the
ratio. Si-C2
thermal
silaoxetanes
derived
a siloxyphenylcarbene
almost of
of
that
and
from
undergoes The
product
C2-C3
decomposition
bonds of
the
silaoxetane. I --i-O
1 -7 -CC-Ph
-E
I
)Si=O
+
PhCH=CH2
+
PhCHO
1
/
I
-Si-0
I
I -$-Ph
-7 5
3
lc-Ph
-C*
I
1
\ *
/
Si=C
Si-C ratio
224
C2-C3
Bond
scission
in a silaoxetane.intermediate
in the copyrolysis
of l,l-dimethyl-l-silacyclobutane
also was proposed 2) with acetone
(eq.11). Me2C=O B >Ie Si=CH 2 2
Me2Si-0
>Ie2Si- 0 Me-+
H2C-
LG
Me2yiOC=CHZ
-C! \
Me
silaoxetane
resulting
by cleavage Brook
from
(11)
Me
H' CH2
vinyl ether might be formed by isomerization
The silyl formed
I:' I ,MeG
i
1,5 hydrogen
migration
of the
in the biradical
of the C-C bond.
and his
coworkers
photolyses of silyl ketones in non-polar solvents involved Norrish- type 1 cleavage of the 9) The possible Si-C bond and formation of silyl and acyl radicals _ of silyl
involvement
from
Wittig-type
Scheme
radical
- Styrene
2.
ketone,
of the Si-C
rupture
the silyl
Scheme
and benzoyl _A reasonable
in our reactions. homolytic
suggested
reaction
radicals
be considered by assuming can be written
route
bond
to give
and
that
also must
followed
benzaldehyde
$-silylstyrene
with
by hydrogen and a silene
could
benzaldehyde
abstraction shown
be formed
and trimethylsilyl
in
a
by
phenyl
respectively. 2. CH3
Xe
3
5$00 \\ 3
SiCOPh
I
Me2Si*
oCOPh+
&Ie2Si=CH2
f
PhCHO
--3 PhCH=CEi2
-1 Me3SiCOPh I
I + Me Si3
CO
& *Ph
,SiMe3
H2C=C
i-
\
Me2Si=0
Ph We intended
to pyrolyze
the silyl
and benzoyl
of carbon
tetrachloride
a carbon
tetrachloride
solution
of 1 to trap
radicals.
However, the total decomposition at 500° made this approach unfeasible.
A mechanisn! involving radicals is unlikely since the benzoyl radical would
easily
conditions.
decarbonylate In
addition,
before the
hydrogen
formation
4-enes -8 and 10 provides support that a siloxycarbene.
of
abstraction
under
these
1-sila-2-oxa-cyclopent-
the reaction
proceeds
through
225 A photochemical When
a benzene
pressure was
reaction
solution
mercury
lamp
of a silyl
of 1 was
ketone
irradiated
for 24 hr, almost
with
examined.
also_was
a 4OOW high
all of the starting
material
recovered.
This indicates that the siloxycarbene generated photochemically may revert to -1 5)*g) since it has activation energies not enough to insert into the C-H bond leading to the silaoxetane. Further support the copyrolysis
for the formation
of & with
an excess
+ Ph 2 CO ,$&$
Me3SiCOPh
Ph2C=CH2
-1
derived
from
the silene those
the diene
(Me2SiO)3
a result
compound
2-naphthyl pyrolysis sitilar
-17
ketone
than
were and
of A.
of the higher toward
extended
products(eq.13).
However,
+ PhCHO
(12)
(27%)
an attempt
Products at
The silene
was
reactivity
of
50Q0
formed were
trapped a silene
to trap in the identical
by 1, not toward
a diene. phenyl
2-naphthyl E
-19(25%)
from
of the silaoxetane
failed.
to similar
triethylsilyl
of trimethylsilyl
comes
(32%)
2,3-dimethyl-1,3-butadiene
of the pyrolysis
Our-studies
by cleavage
olefin
+ PhCH=CH2
(24%)
and benzophenone.
a conjugated
of -1 with as
a carbonyl
is formed
the silene
with
copyrolysis with
+
-16(17%)
l,l-Diphenylethylene
of the silene,lQ,
of benzophenone(eq.12).
pyrolyses ketone.
ketone,=,
of trimethylsilyl Gas phase at 500" gave
20(7%) -
(13)
226
Their
formatiomcan
be rationalized
of the siloxycarbene
as shown
products, Er -19 and the silene, to produce 20. Pyrolysis of triethylsilyl
which
unidentified
which
but very
polymeric
strong
styrene
reacts
ketone,=,
with
to Ffive
ketone
afforded
had no carbonyl -I at 1003-1100 cm .
absorption
and trans,4%),
of isomerization
then decomposes
again
phenyl
products,
Si-O-C
(cis,3%,
in terms
to a si'laoxetane which
allylbenzene(4%)
-17
mainly
absorption, Some P-methyl-
and benzaldehyde
(4%)
Since
also were obtained as minor products. -methylstyrene ? did not isomerize to allylbenzene under the reaction conditions, the Ia.tter may have been formed via cleavage of the Si-C bond of
silaoxetane
the
cleavage. have
been
followed
A long-range expected
Et3SiCOPh
from
5000 UZflow>
by 1,3 hydrogen
insertion
product
the siloxycarbene
Et3SiO=&Ph
migration
and C-O
such as 24, which
, was not obtained(eq.14).
+3 Ph
Et2Si, Y- 0
-21
-24
?
? 1
Me
/L
Et2Si f 0X
?
polymer
might
.e Et Sk 2l 0L
Ph
l
-
PhCEi=CEMe
(14)
22 -
Ph
0
Et2Si=CH2
+
1,3 hydrogen J PhCH2CH=CH2
PhCHO
migration
-23
Experl"menta1 General: Nmr data were
obtained
spectra
were
obtained
using
sPectra
were
obtained
either
at 7OeV.
Preparative
Separation
stainless
with
columns
10% P_piezon Grease
JEOL
GLC was
chromatography. with
on a Varian a Hitachi
A-60D
EP-l-G3
JNF-07
or Hitachi
accomplished
was
15% SF-96 on Celite
spectrometer.
Infrared
spectrometer_
using
RMU-7M
a Ohkura
Mass spectromete: gas
done by 2 m X5 mm or 30 cm X5 mm and 1.5 my5 545.
Yields
mm stainless were
column
done by.GLC.
227 A known
amount
and used
of standard
to calculate
sample
was
added
to the reaction
mixture
yield.
Reagents: Silyl
ketones
were
dibromide
with
the Brook
methodlo)
Me3SiCOPh:
prepared
acetate
m-p. m-p.
in 97% yield
51-53O'in
97-99O
67% yield
in 88% yield
b-p.
Et3SiCOPht
106-1G9°/4mmHg
14G"/2mmHg
system
(lit. b.p.
(lit. m.p.
{lit. m.p.
in 57% yield
61°/lmmHg1G)); 10) 1;
103Oll));
(lit. 113°/0.1mmHg12));
in 61% yield.
Nmr(CC14):
The pyrolyses diameter,3
cm;
of a 28 cmX1 by syringe,
were
performed
length,33 cm Pyrex was
of the appratus
cm).
at a rate
with
The pyrolysate
with
was
Trimethylsilyl at 500".
trapped
The sample
was
phenyl
cooling.
benzaldehyde(l2%)
ice-acetone
was passed
Separation
by comparison
of their
nmr,
through
identified
by its nmr,
mixture
5-57 and
Irtneat): M+ 176(relresolution
3050, iat. mass:
5.78(2H,d,J=3Hz,C=CH2) 2950,
1490,
1410,
162(15),
801, m,?e Calcd
tube
as
by GLC
styrene(33%),
and retention
spectra.
in the gas phase
the reaction
were
times 14)
d-Trimethylsilylstyrene
ir and mass
nitrogen
GLC.
was pyrolyzed
of the product
ir spectra
the Pyrex
was 1.4 sec.
x-trimethylsilylstyrene(24%). 13) , styrene and benzaldehyde
of authentic*samples.
in using
or a liquid
hexamethylcyclotrisiloxane(25%), and
(inside
of the oven was measured
time of the sample
ketoneiG.486g)
H,9.16.
consisted
through
Hexamethylcyclotrisiloxane
SiMe),
Calcd
oven
dripped
passing
The temperature
in a dry
One ml of benzene
after
four products,
those
2950,
chips.
and then separated by preparative trap, concentrated, Pyrolysis of Trimethylsilyl phenyl ketone:
gave
G-7-1.2
The upper end cap for sample introduction
of nitrogen
The residence
tube
apparatus
Pyrex
a rubber
inlet.
a stream
of 30 ml/min.
by a thermocouple.
a vertical
The pyrolysis
equipped
with
using
tube packed
and a nitrogen
a one ml syringe
a wash
x
fr(neat):
2875, 1612 (C=O), 1590, 1578 and 1210 cm-'. Anal. for C13H2001Sil: C,70.85; H.9.15: Found: C,70.79; Pyrolysis Procedure:
General
using
54-55"
7.2-7.9(5H,m,ArH).
(15R,m,SiCH2CH3),
tube
of the corresponding
rll).
2-ClGH,COSiMe3: b-p.
by hydrolysis
in water-acetone-ethanol
61-65°/lmmHg
b.p.
PhMe2SFCOPh: Ph3SiCOPh:
silver
identified
with was
Nmr(CC14):g0.15(9H,s,
and 6.9-7.4(5H,m,ArH).
1249 and
161(1OG),
for C11H16Silz
932 cm-l,
135(30)
and
176.1021;
Mass: 73163);
Found:
m/e, high
176.1009.
.
228 Pyrolysis
of Dimethylphenylsilyl
Dimethylphenylsilyl The products
were
phenyl
phenyl
analyzed
x
Calcd
for
is, mass
Ir(neat)r
3055,
C16H18Sil:
2945,
C,80.29;
elemental
1250,
1135,
MT 240(100), mass:
m/e
8 was
analyses.
6.08(lH,s,_Ar-CH-0) 1490,
and
1249,
1110
Found:
of
and
and
934
by
6.8-7.6(10H, an
its
nmr,
for C15H1601Sil:
fr(neat):
Found:
Anal.
_
ir,
mass
3045,
1590,
Mass:
m/e,
high resolution
and 105(18);
240.0970;
-1
0.48(3H,s,SiMe),
and 1015 cm -'(Si-O-C). 165(30)
Nmr(CC14):
H,6.99.
7 0.42(3H,s,SiMe),
6.8-7.7(9H,m,ArH).
225(43),
!
and
analyses.
C,80.02;
identified
?Znr(&14):
104O(Si-O-C)
239(88),
Calcd
1427, H,7.19:
l-Sila-2-oxa-cyclopent-Gene ans
and elemental
5.62 and 5_92(2H,d,J=3Hz,C=CH2)
0.38(6H,s,SiMe),
at 500".
the formation
$-Dimethylphenylsilylstyrene
g(l?%).
by its nmr,
was pyrolyzed
showed
d-dimethylphenylsilylstyrene(8%)
I-sila-2-oxa-cyclopent-4-ene
rn,&H).
ketone(0.956g)
by GLC, which
s_;yrene(5%), benzaldehyde(8%), spas identified
ketone:
240.0945.
Anal.
Calcd.: C,74_95; H,6.71: Found: C,74.72; H,6.85. Pyrolysis of Triphenylsilyl phenyl ketone: A benzene pyrolyzed
solution
at 500".
GLC as resinous and
of triphenylsilyl
phenyl
ketone(0.550g)
1-Sila-2-oxa-cyclopent-4-ene
liquid
in 40% yield.
6.9-7.9(19H,m,ArH)-
Ir(CC14):
1122 and 1010 cm -'(Si-O-C); 364.1283;
high
Found:
Nmr(CC14): 3060,
1590,
resolution
364.1296.
C25H2001Sil' H,5.53: Found: C,82.12; H,5.37. Copyrolyses of Trimethylsilyl phenyl
1430,
mass:
Anal.
ketone
was
-10 was obtained by p 5-27(J_H,s,Zz-CH-0) 1267,
m/e Calcd
Calcd.:
with
1185, for
C,82.38;
Benzophenone
and
2,3-Dimethyl-1,3-butadiene: A mixture and 2.54g(14m
of 0.435g(2.44m
mol)
l,l-Diphenylethylene
mol)
of benzophenone was obtained
hexamethylcyclotrisiloxane(l4%), l,l-Diphenylethylene
was
of trimethylsilyl
was pyrolyzed in 17% yield styrene(32%)
identified
together
were
identical
with
also was
those
done
of the pyrolysis
ketone
of its nmr,
at 500°.
an excess
Products
of trimethylsilyl
of
-l-(
2_naphthyl)ethylene(7%)
were
obtained
phenyl
4 1 1 2
at 5OOO.
and I-trimethylsilyl
by GLC-
1
and yield7
ketone.
2_naphthaldehyde(25%)
i
ir spectr i
Pyrolysis of Trimethylsilyl 2-naphthyl ketone: Trimethylsilyl 2-naphthyl ketone(O-22g) was Pyrolyzed 2_Vinylnaphthalene(20%),
’
with
and benzaldehyde(27%).
by comparison
and retention time with tho'se of an authentic sample, Copyrolysis of trimethylsily phenyl ketone with 2,3-dimethyl-1,3-butadiene
phenyl
at 500'.
2-Vinylnaphthalenej
[ ]
229
1it.l') 60-62O)
(m-p. 61-6Z", lit.16) 59-62O) with
those
were
of
-ethylene
identified
authentic
was
m/e,
5.63
m/e
has
only
the
small
Calcd been
of
were
the
by
and
and
mass
930
nmr
152(52)
226-1178:
the
above
and
ir
Nmr(CC14):
and 890
and
7.1-8.1(7H,-
cm-'.
Mass:
73(100);
Found:
high
226.1181.
spectroscopic
resolution
The
means
.
spectra
2 -naphthyl)
spectra.
and
product
because
of
reaction of
pyrolyzed
P_methylstyrene(cis,3%, The
material
which
p-Methylstyrene
Trimethylsilyl
cm
high
GLC;
was
had
strong not
500".
and
major
did
at
trans,d%),
product
Si-O-C
Four
was
an
absorption
isomerize
to
allylbenzene
conditions.
Trimethylsilyl 8 mm ~30
ketone:
ketone(0.569g)
benzaldehyde(4S).
polymeric -1 cm .
1000-1100
Photolysis
in
ir
1250,
phenyl
phenyl
found
unidentified
a 4OOW
their
5.87(2H,d,J=3Hz,C=CH2) 2950,
by
Triethylsilyl
allylbenzene(4%)
under
nmr,
153(23),
identified
of
I-Trimethylsilyl-l-(
C15H18Sil:
Triethylsilyl
at
comparison
yield,
Pyrolysis products
and
211(27), for
by
its
3050,
Ir(CC14):
M + 2266613,
mss:
by
(m.p. 58-60",
2-naphthaldehyde
samples.
identified
0.25(9H,s,SiMe),
s
m,Np-H).
and
phenyl
phenyl
Pyrex
and
tube,
pressure
mercury
of
trimethylsilyl
phenyl
1.
W.Ando,
T.Hagiwara
W.Ando,
A.Sekiguchi,
ketone
in Benzene:
ketone(0.199g) then
lamp
and
the
for
ketone(868)
3 ml
mixture
24 hr. and
of
was GLC
benzene
was
irradiated
showed
the
placed
with presence
benzaldehyde(g%).
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