1
2
34
5
N
H
NH2
R
R
N
H
R2
R1
indol
R2
R1
O
CH3
O
O
H
R2
R1
OH
N
H
N
R
R1
OH
R2
H
H
CH3
O
O
CH3
O
O
CH3
O
O
H
N
H
N
R
R1
O
R2
H
H
H
N
H
N
R
H
R1
R2
H
H
O
H
H
CH3
O
O
N
H
NH
R
R1
R2
N
NH
R
R1
R2
H3C
O
O
H
H H
proton transfer
N
NH
R
R1
R2
H H
HH3C
O
O
N
NH
R
R1
R2
H H
CH3
O
O
H3C
O
O
H
N
NH2
R
R1
R2
H H
R
N
R1
R1
NH2
H H
proton transfer
CH3
O
O
CH3
O
O
H
R
N
H
R1
R1
NH3
R
N
H
R1
R1
NH3
H
6
7
[3,3]
3,3-sigmatropní přesmyk
Fischerova syntéza indolů
‐ mechanismus