Chemistry Reference
In-Depth Information
N
3
N
hν
hν
N
N
N
N
3 NCN
13 K
N
3
N
N
3
N
N
N
272
Me
Me
Me
N
N
3
N
3
NC
CN
+
>300
n
m
N
273
N
3
N
CN
hν
CN
N
3
N
274
N
N
3
F
F
F
F
F
F
I
hν
-N
2
, -I
C
I
F
F
F
I
F
F
F
275
SCHEME 8.43.
alternative ring-opening analogous to that of 2-pyrimidinyl nitrene described in
Scheme 8.39, and the structures of the final products need to be investigated. Ring
expansion and ring opening of pyridine-2,6-dinitrenes have also been proposed.
65
The photo-fragmentation of septet 1,3,5-triazine-2,4,6-trinitrene
to three
molecules of NCN was established by matrix ESR and IR spectroscopy
66
(Scheme 8.43). Several triplet pyridylnitrenes, quinted pyridyldinitrenes, and septet
pyridyltrinitrenes have been investigated by IR
31a
and ESR
67
spectroscopy. Ring
opening on matrix photolysis of
p
- and
m
-diazidobenzene (e.g.,
272
273
) and 1,5-
) have been reported by Tomioka et al.
68,69
Sander et al.
reported ring opening of 3-dehydrophenyl nitrenes, for example,
diazidonaphthalene
(274
.
29c
275
8.5 CONCLUSIONS AND OUTLOOK
Aryl- and heteroaryl nitrenes undergo cyclization to observable azirenes in many
cases, but the parent azirenes derived from phenyl nitrene, 2-pyridyl nitrene, and so
on, have not been observed (e.g.,
276
, Scheme 8.44). They are predicted to exist in
