Chemistry Reference
In-Depth Information
O
O
H
3
CO
2
C
CO
2
CH
3
HO
NH
O
NH
F
F
F
b
/
l
= 99:1,
92% ee (93%)
(-)-Paroxetine
Scheme 8B.82.
A formal synthesis of (
−
) - paroxetine.
MeO
2
C
CO
2
Me
[Ir(COD)Cl]
2
/
L60/
TBD
CH(CO
2
CH
3
)
2
()
MeO
2
CO
()
n
n
n
= 1/2:
Salt-free-10/50°C
97/98% ee (56/65%)
n
= 3/4:
Via lithiomalonate
96/97% ee (77/79%)
-78°C
rt
Scheme 8B.83.
Intramolecular allylic substitutions.
R
1
NO
2
R
2
OCO
2
Me
R
1
R
2
CH-NO
2
NO
2
+
R
R
R
[Ir(COD)Cl]
2
/
L60
/TBD
THF, rt
R
1
R
2
b
l
R
1
=R
2
=CH
3
b
/
l
= 96:4, 99% ee (84%)
(base: Cs
2
CO
3
):
R=Ph
R
1
=H, R
2
=CO
2
Et
( no base):
R=Ph
b
/
l
= 99:1, 98% ee (90%)
R=PhCH
2
CH
2
b
/
l
= 78:22, 98% ee (86%)
R=
n
-Pr
b
/
l
= 90:10, 99% ee (92%)
Scheme 8B.84.
Aliphatic nitro compounds as pronucleophiles in asymmetric allylic alkylations.
8B.7.2.1.4. Substitutions with Aliphatic Nitro Compounds as Pronucleophiles
Allylic
substitutions with nitromethane as pronucleophile furnished mixtures of mono- and
dialkylation products. Good results were obtained with primary and secondary nitro
compounds [323]. Nitronates were generated with cesium carbonate as base (Schemes
8B.84 and 8B.85). Ethyl nitroacetate served as the synthetic equivalent of nitromethane.
An additional base was not required (salt-free conditions). Mixtures of epimers were
formed as a consequence of the high acidity of the chirality center α to N. For the
removal of the ethoxycarbonyl group, a new variant of the Krapcho reaction was
developed.
