Chemistry Reference
In-Depth Information
(+)-Troger's base
68
(30 mol
%)
CsOH•H
2
O (3.0 equiv.)
¨
H
O
O
O O
N
S
+
ONH
2
CH
3
CN/CH
2
Cl
2
, 0°C, 5 h
Cl
Cl
50%, 62% ee
N
N
(+)-Troger's base
68
¨
Scheme 11.80.
69
(1.05 equiv.)
NaH,
i
PrOH
O
O
H
O
N
OMe
P
+
Ph
ONH
2
CH
2
Cl
2
Ph
Ph
Ph
Ph
Ph
N
64%, 56% ee
OH
N
69
Scheme 11.81.
R'
70
(20 mol
%)
R'
OAc
N
+
H
CHO
CHO
CHCl
3
R
R
R' = Cbz or Boc
84-99% ee
Ph
OTMS
H
Ph
Boc
Cbz
Cbz
70
N
N
N
CHO
CHO
CHO
Et
nPr
54%, 90% ee
5:1 dr
60%, 97% ee
5:1 dr
62%, 99% ee
10:1 dr
Scheme 11.82.
pathway to that of the epoxidation [156]: iminium ion formation, conjugate addition of
hydroxylamine to the iminium ion, enamine attack on the electrophilic nitrogen atom
and hydrolysis of the iminium ion. Chiral pyrrolidine
70
promotes the reaction of enals
bearing β-alkyl substituents to give the
N
- Boc - or
N
- Cbz - protected 2 - formylaziridines
with good diastereo- and high enantioselectivity (Scheme 11.82). The product 2-
formylaziridines are rather unstable under the reaction conditions due to the high
reactivity. Thus, short reaction time at elevated temperature is recommended for
obtaining 2 - formylaziridines in higher yield.
