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Vapour phase pyrolysis of benzoxazinones
TotmhedronI&ten Ao. 16, pp 1361- 1362,1973. Per#bmmIProm.
PrintodiaQwtBr~t8ia
VAPOUB PlusB PTROLYSIS OP mUmtAgmOtm8 U.P.
David and J.F.H.
llcC*lio
School of Chemistry, University Bristol (Reoefved in UR 23 Pbbruuy
The Comunicrtions
of Bees -et
by the vepour phase pyrolysis related
studies.
phthelic
of grist01
BSS ITS
1973;eooopted for publiortlu8 Muoh 1973)
al. on the formtioa
of 2-phenylbensuete’
of 4-phenylbenxo-1,2,3-triaeiae
By analogy with our work on the synthesis
anhydrides
we expected that benzoxarinones
bensynes and thence biphenylenas. lE-2,3-Renzoxazin-1-onea
Our preliminary
prmts
end biphenylene2
us to record our closely
of biphenylenes
by the pyrolysis
uuuld undergo theme1 fragmentetion
resultr
(1) but not with ?-substituted
rhov that this
is so vith
4E-3,1-Banroxezin-4-ones
of
to give
I-substituted
(2).
(1) -Ph;
a, -R3=H
a.
e.
Rl
b.
R1 - -cH3; RR - R3 - H
c.
RI - -Ph;
Rg - H, RR - Cl
d.
R1 - -Ph;
R,
=
-
colppound (lb)
Similarly
the dichloro
and the tetrachloro
at g40-g60°/0.01 derivative
derivative
occurs stepwise,
bensyne which dimerises benronitrile tation
first
(lc)
(ld)
P
RI
C.
RI - -Ph;
a, - H RR - Cl
gave biphenylene
at 700-720°/0.01 II
in 35% and 25% yields
and of the
respectively.
at 700°/0.01 m gave 2.3,6,7-tetrachlorobiphenylene
at 700°/0.05 PPLgave octachlorobiphenylene
by extrusion
to a biphenylene.
was detected
b.
of the 4-phenyl compound (la)
temperature0 quoted are those which gave optimum yields probably
a, -E
- -clIj;
R3 - Cl
We have found that pyrolysis 4lluthyl
R1 - -Ph;
in the pyrolysate.
which occurs in the suss-spectroamter,
of
products.
of carbon dioxide In the pyrolysis
and then by 10~s of RCR to give a
of compoundr
for compound (la):
1361
The
The thermal decqosition
(la),
The thermal decolaposition parallels e.g.
(6%).
(4%)
(lc),and
(Id)
the fragmen-
1362
No. 16
h/e 223 (100%) In contrart benuaete
to 4-phenylbenz.o-1,2,3-triozine
and above 500’ to give biphenylene,’
quantitatively
after
recovered
m/e 76 (14.4%)
which decomposes et 420-450’ to give 2-phenyl the benroxanin-l-one
(2) are even more stable.
in over 90% yield
assumed that in the pyrolysis
after
pyrolysis
of benrotriasines
and benroxazinones
x R
(4a)
and (4b)
at 600’ gave,
Presumably fragmentation benaonitrile,
analogue
shown that pyrolysis
thiophen analogues
(4a)
is
bond to be broken
I 0
b. B-Cl
R-U;
from benzoxarin-l-ones
product,
to the
The thia compounds
trace amounts of biphenyleue. with loss
of carbon dioxide
and
thiophynes underwent decomposition or rearrangement rather
(3) or its
tetrachloro
derivative.
(la-ld)
In separate
amounts of biphenylene.
at 600’ yields-trace
The benroxazin-l-ones
it
N
of biphenylene were unsuccessful.
of chlorobenxene at 690’ likewise
benxoic acid by reaction
a.
of the oxaxinone ring hed occurred,
to give
found that benxonitrile
of biphenylenes
as the only identifiable
but the resulting
than dixeriration
(3)
aud (SC)
0
(4)
0)
the first
If
The
94
Ii
of the dithiophen
(2b),
almost
agrees with the order of the bond
s’/
syxthesir
up to 560’.
at temperatures up to 800’.
N-R 4 N-O ( C-O.
Our attempts to extend the synthesis
ves recovered
Thus the compounds (2a),
is that between atoms 2 and 3 then the order of stability energies
(la)
being passed through the apparatus at temeratures
iroxmric benroxarin-4-oner were all
m/e 179 (15.5%)
yields
traces
Previously
and cyclisation
it had been
of biphenylene.
were prepared from the appropriate
with hydroxylanine
experiments it was
o_benzoyl
of the resultant
4
(or asetyl)
oximes.
The
and (4b) were prepared similarly. RRFRRRNCBS
1.
B.&l. Adger, M. Rearing,
2.
S. Bradbury, 1. Keating.
3.
R.F.C.
4.
E.K.
C.W. Bees, and R.C. Storr, C.W. Rees, and R.C. Storr,
Brown, D.V. Gardner,
Fields
J.F.W. McOrnie, and R.K.
and S. Meyerson. J. Amer. Chem. Sot.,
J.C.S.
Chem. Comm., 1973, 19.
Chem. Comm., 1971, 827. Solly, 1966. E,
Austral. 3388.
J. Chem., 1967, g,
139
PrintodiaQwtBr~t8ia
VAPOUB PlusB PTROLYSIS OP mUmtAgmOtm8 U.P.
David and J.F.H.
llcC*lio
School of Chemistry, University Bristol (Reoefved in UR 23 Pbbruuy
The Comunicrtions
of Bees -et
by the vepour phase pyrolysis related
studies.
phthelic
of grist01
BSS ITS
1973;eooopted for publiortlu8 Muoh 1973)
al. on the formtioa
of 2-phenylbensuete’
of 4-phenylbenxo-1,2,3-triaeiae
By analogy with our work on the synthesis
anhydrides
we expected that benzoxarinones
bensynes and thence biphenylenas. lE-2,3-Renzoxazin-1-onea
Our preliminary
prmts
end biphenylene2
us to record our closely
of biphenylenes
by the pyrolysis
uuuld undergo theme1 fragmentetion
resultr
(1) but not with ?-substituted
rhov that this
is so vith
4E-3,1-Banroxezin-4-ones
of
to give
I-substituted
(2).
(1) -Ph;
a, -R3=H
a.
e.
Rl
b.
R1 - -cH3; RR - R3 - H
c.
RI - -Ph;
Rg - H, RR - Cl
d.
R1 - -Ph;
R,
=
-
colppound (lb)
Similarly
the dichloro
and the tetrachloro
at g40-g60°/0.01 derivative
derivative
occurs stepwise,
bensyne which dimerises benronitrile tation
first
(lc)
(ld)
P
RI
C.
RI - -Ph;
a, - H RR - Cl
gave biphenylene
at 700-720°/0.01 II
in 35% and 25% yields
and of the
respectively.
at 700°/0.01 m gave 2.3,6,7-tetrachlorobiphenylene
at 700°/0.05 PPLgave octachlorobiphenylene
by extrusion
to a biphenylene.
was detected
b.
of the 4-phenyl compound (la)
temperature0 quoted are those which gave optimum yields probably
a, -E
- -clIj;
R3 - Cl
We have found that pyrolysis 4lluthyl
R1 - -Ph;
in the pyrolysate.
which occurs in the suss-spectroamter,
of
products.
of carbon dioxide In the pyrolysis
and then by 10~s of RCR to give a
of compoundr
for compound (la):
1361
The
The thermal decqosition
(la),
The thermal decolaposition parallels e.g.
(6%).
(4%)
(lc),and
(Id)
the fragmen-
1362
No. 16
h/e 223 (100%) In contrart benuaete
to 4-phenylbenz.o-1,2,3-triozine
and above 500’ to give biphenylene,’
quantitatively
after
recovered
m/e 76 (14.4%)
which decomposes et 420-450’ to give 2-phenyl the benroxanin-l-one
(2) are even more stable.
in over 90% yield
assumed that in the pyrolysis
after
pyrolysis
of benrotriasines
and benroxazinones
x R
(4a)
and (4b)
at 600’ gave,
Presumably fragmentation benaonitrile,
analogue
shown that pyrolysis
thiophen analogues
(4a)
is
bond to be broken
I 0
b. B-Cl
R-U;
from benzoxarin-l-ones
product,
to the
The thia compounds
trace amounts of biphenyleue. with loss
of carbon dioxide
and
thiophynes underwent decomposition or rearrangement rather
(3) or its
tetrachloro
derivative.
(la-ld)
In separate
amounts of biphenylene.
at 600’ yields-trace
The benroxazin-l-ones
it
N
of biphenylene were unsuccessful.
of chlorobenxene at 690’ likewise
benxoic acid by reaction
a.
of the oxaxinone ring hed occurred,
to give
found that benxonitrile
of biphenylenes
as the only identifiable
but the resulting
than dixeriration
(3)
aud (SC)
0
(4)
0)
the first
If
The
94
Ii
of the dithiophen
(2b),
almost
agrees with the order of the bond
s’/
syxthesir
up to 560’.
at temperatures up to 800’.
N-R 4 N-O ( C-O.
Our attempts to extend the synthesis
ves recovered
Thus the compounds (2a),
is that between atoms 2 and 3 then the order of stability energies
(la)
being passed through the apparatus at temeratures
iroxmric benroxarin-4-oner were all
m/e 179 (15.5%)
yields
traces
Previously
and cyclisation
it had been
of biphenylene.
were prepared from the appropriate
with hydroxylanine
experiments it was
o_benzoyl
of the resultant
4
(or asetyl)
oximes.
The
and (4b) were prepared similarly. RRFRRRNCBS
1.
B.&l. Adger, M. Rearing,
2.
S. Bradbury, 1. Keating.
3.
R.F.C.
4.
E.K.
C.W. Bees, and R.C. Storr, C.W. Rees, and R.C. Storr,
Brown, D.V. Gardner,
Fields
J.F.W. McOrnie, and R.K.
and S. Meyerson. J. Amer. Chem. Sot.,
J.C.S.
Chem. Comm., 1973, 19.
Chem. Comm., 1971, 827. Solly, 1966. E,
Austral. 3388.
J. Chem., 1967, g,
139