Chemistry Reference
In-Depth Information
The same end products,
103
on photolysis and
105
on FVT, were obtained from
4-quinazolinyl carbene
108
, generated from triazoloquinazoline
106
, which under-
goes ring opening to the valence isomer 4-diazomethylquinazoline
108
was directly observed via its ESR and IR spectra. The rearrangement of
4-quinazolinyl carbene
107
. Carbene
108
100
is a carbene-nitrene
rearrangement, but DFT calculations indicate that the putative seven-membered
ring intermediate
to 3-quinolyl nitrene
(observed by a weak absorption at 1910 cm
1
)ismorelikely
to ring-open directly to the nitrile ylide
110
101
, which then gives rise to the final
products (Scheme 8.19).
23
In the case of 2-phenyl-3-azidoquinoline
111
,a
blue ylide
114
was formed rapidly
300 nm (observed IR 2220, 2154 cm
1
; calculated
(B3LYL/6-31G
) 2233, 2171 cm
1
; UV-Vis 400 and 680 nm).
40
on matrix photolysis
>
It could be con-
verted into the seven-membered ring ketenimine
113
(IR: 1920; calculated:
1921 cm
1
) on photolysis above 550 nm. The ketenimine
113
was again converted
on photolysis at 310-390 nm. Similar to 2-biphenylyl nitrene
9
described in Scheme 8.2, nitrene
into ylide
114
112
inserts in the
o
-phenyl group, leading to
the indoloquinoline
116
, which is the main product (52-60%) on FVT of the azide
at 400-800
C;
111
116
was isolated together with a small amount of amine
117
and
the ring contraction product, 2-phenyl-3-cyanoindole
118
(21-15%). Formation of
CH
N
CHN
2
N
Δ
N
N
N
or hν
N
N
N
106
107
108
(Z-isomer,
1
A 36.8 kcal/mol)
N
N
109TS
46.7
N
:
N
N
N
N
N
100
(S
1
14.3 kcal/mol)
110
5.3
TS
33.8
TS
25.9
CN
C
CN
N
H
N
NC
C
H
103
105
-45
101
22.5
SCHEME 8.19.
