Chemistry Reference
In-Depth Information
Table 8.2
Asymmetric conjugate addition reaction of thiol
R-SH
R
Proton Sponge™ (
1
)
(10 mol%)
O
O
O
O
S
O
N
Me
O
N
Me
(
R
,
R
)-DBFOX/Ph -Ni(ClO
4
)
2
6H
2
O
(10 mol%)
0 °C, CH
2
Cl
2
-THF
(
R
,
R
)-DBFOX/Ph
R
yield (%)
ee (%)
phenyl
84
94
O
o
-tolyl
99
95
O
O
2-naphthyl
89
91
N
N
Ph
Ph
(Table 8.6). In this synthesis, a slight excess of Proton Sponge (1) is indispensable for high
selectivity.
Enantioselective nitroaldol reaction (Henry reaction) of simple trifluoromethyl
ketone was reported by Tur and Saa [27] (Table 8.7). Reaction of trifluoromethyl
ketones with nitromethane in the presence of lanthanum (III) triflate salt complex and
Proton Sponge (1) (0.25 equiv. each) gave tertiary nitroaldols in 50-93% yields with
67-98% ee.
O
O
C
N
NH
2
Cl
OCCl
3
Me
Me
Proton Sponge™ (
1
)
(2 equiv.)
81%
CH
2
Cl
2
, 0 °C
O
O
Cl
OCCl
3
C
NH
2
N
N
3
N
3
Proton Sponge™ (
1
)
(2 equiv.)
88%
CH
2
Cl
2
,rt
Scheme 8.8
Synthesis of isocyanates
