Chemistry Reference
In-Depth Information
CH
3
CH
3
CH
3
FV
T
CH
3
N
R
N
N
N
3
R
R
R
31
R = H or CH
3
R
N
32
FVT
N
N
N
CH
N
N
CHN
2
N
1
3
33T
33D
SCHEME 8.6.
they can be directly observed only when generated by matrix photolysis of the
diazo/triazole precursors.
3-Phenyl-2-pyridyl carbenes
35
rearrange to 2-biphenylyl nitrenes
36
and hence
in virtually quantitative yields on FVT (Scheme 8.7).
16b,18
afford carbazoles
9
2-Pyridyl nitrene
37
undergoes degenerate ring expansion to the cyclic carbo-
.
26,27
This has been demonstrated by
15
N- as well as substituent labeling
(Scheme 8.8).
18,26
This reaction, too, can be carried out either thermally or photo-
chemically, in the former case usually by FVT. The triplet nitrenes
diimide
38
can be
observed directly by ESR, IR, and UV spectroscopy by isolation of the FVT products
in noble gas matrices, typically Ar, 10 K. The seven-membered ring carbodiimides
37
FVT
Ph
N
N
N
N
CPh
N
2
N
35
34T
34D
Ph
Ph
N
N
H
9
36
SCHEME 8.7.
