150
R
H
N
R
3
R 1 R 2
O
O
HP
2.0 equiv K 2 S 2 O 8
CH 3 CN, 90 °C
R
N
R
1
O
R
2
R
3
O
P
N
Me
O
P
Ph 2
90%
R
4
R
5
+
R 4
R
5
O
N
Bn
O
P
Ph 2
92%
O
N
Ts
O
P
Ph 2
66%
O
N
H
O
P
Ph 2
0%
O
N
Me
O
P
Ph 2
87%
O
N
Me
O
P
Ph 2
95%
O
N
Me
O
P
Ph 2
78%
O
N
O
P
Ph 2
95%
O
F
Cl
Me
Ph
Scheme 4.72 Transition-metal-free synthesis of phosphorylated oxindoles
Oxidative C-P radical coupling between diphenylphosphine and cinnamamides
toward 2-Phosphinoyl-3H-pyrrolo[1,2-a]indoles can be performed [57]. This reaction leads to the simultaneous formation of C-C and C-P bonds in one step using
AgNO 3 as catalyst and Zn(NO 3 ) 2 as oxidant. A possible reaction pathway is presented in Scheme  4.74. Firstly, Ag(I)-catalyzed oxidation of diphenylphosphine
oxide affords the phosphorus-centered radical. Then, the addition of phosphoruscentered radical on a C-C double bond in cinnamamide produces the radical intermediate, which is further transformed to the radical intermediate via intramolecular
cyclization on C2 of the indole. After oxidation and deprotonation process, final
product is obtained.
W. Liu