RR_ Y^ R RR

(VA–061)(
:EPHP)(CTAB)—
(Scheme 1) 1) ✔—
R 1
X
R 5
O
R 2
R 4
R 3
(Highly Hydrophobic)
VA–061 a
EPHP b
cat. CTAB
H2O, 80 °C
O R 4
N
N
H
Me Me N
NN
Me Me N
H
b
EPHP: 1-ethylpiperidine
hypophosphite
✔
R 1
(1a)(2)
(2a) VA–044
CTAB (3a)
(Scheme 2)
VA–044 CTAB
(2a)(1)
(3)(Scheme 3)
R 5
High Yield
R2
R 3
a VA–061:
Scheme 1. Radical cyclization reactions of hydrophobic compounds in water
O
initiator
Ph H
+ RS SR
additive
solvent
1a
conditions
2
initiator: VA–044, VA–061, AIBN, Et3B, ...
additive: CATB, CTAC, SDS, Triton X–100, ...
solvent: H2O, benzene, neat
disullfide: R = C6F5 (2a), Ph (2b), Bn (2c)
O
Ph SR
3
Best condition:
2a, VA–044 a , CTAB, H2O,
50 °C, 18 h: 73%
a VA–044:
Scheme 2. Radical thioesterification of 1a with various conditions
O
VA–044
R
1
H
+ C6F5S SC6F5 2a
CTAB
H2O, 50 °C
aldehyde: various aliphatic and
aromatic aldehydes
Scheme 3. Application to various aldehydes
O
R SC6F5 3
47~95%
N Me Me
NN
N Me Me
H
N N
H
• HCl

Scheme 4
(2) VA–044
(A)
(1)
R
(B)
(2)(A)
(3)
(2’)(A)
(3)
(1)
2 S SR 2 initiator
R
Scheme 4. The plausible thioesterification mechanism
2 S
R 1
R O
1
R
O
H
2 SH
R 2 S SR 2
R1 O
SR2 R 2 R
S
2 initiator
2
(VA–044)
A
(VA–044)
2'
3
1
B
S
2
A
or A
(3)
Pd Zn
3
(1)(2)(VA–044CTAB
)(3)(4) 3
(5)(Scheme 5)
R 1
O
C6F5SSC6F5 H H2O, 50 °C H2O, 50 °C R 1
NR 2 R 3
VA–044, CTAB
R
O
8~24 h
2 R 3 2a NH 4
(3 equiv.)
1
30 min
5
amine (4): cyclohexyl amine, pyrrolidine
70~93%
Scheme 5. Direct amidation of aldehydes in water
VA–044 CTAB —
2)
one–pot
References
1) Kita, Y.; Nambu, H.; Ramesh, N. G.; Anilkumar, G.; Matsugi, M. Org. Lett. 2001, 3, 1157–1160; Nambu, H.;
Anilkumar, G.; Matsugi, M.; Kita, Y. Tetrahedron 2003, 59, 77–85.
2) Nambu, H.; Hata, K.; Matsugi, M.; Kita, Y. Chem. Commun. 2002, 1082–1083.