30
2 Results and Discussion
Table 2.5: Screening of the C–H acetoxylation of chlorolactone O -methyloxime
29a. All reactions were carried out on a 0.1 mmol scale (1.0 equiv
of O -methyloxime 29a, 0.2 equiv of Pd(OAc)2 and 1.2 equiv of
PhI(OAc)2) at 75 °C for 8 h.
MeON
H
H
O
H
Cl
O
H
AcO
H
O
H
Cl
O
MeON
Solvent, 75 °C
Pd(OAc) 2 (20 mol-%),
PhI(OAc) 2 (1.2 equiv),
Ac 2 O (26 equiv)
29a
30a
Entry Solvent
V (Solvent)
/ml
Ac 2 O
/equiv
Note
1
AcOH
0.25
26.5
No target molecule
2
DCE
0.50
10.0
No target molecule
Due to the issues described later in Section 2.3.4, it was thereafter switched
to the respective bromolactone 6b. Berger slightly modified the C–H acetoxylation conditions described in Table 2.3.
[33] C–H Acetoxylation of broH
AcOH, 40 °C
(48 %)
H
O
H
Br
O
(2a)
(b)
H
H
O
H
Br
O
HON
AcON
AcO
Ac 2 O (26 equiv)
Pd(OAc) 2 (15 mol-%),
PhI(OAc) 2 (1.6 equiv)
6b
7b
(dr 75:25)
Scheme 2.18: Synthesis of 7b. Reagents and conditions: See Scheme 2.25 on
Page 37.