Chemistry Reference
In-Depth Information
R
1
O
OH
H
O
R
1
O
O
OH
29
Planetary Ball-Mill
O
H
R
1
R
1
8 examples
68-100%
or
1) K
2
CO
3
(1.0 equiv), NaCl
500 rpm, 2 h (Continuous)
O
2), 3)
O
-
K
+
OH
30
H
2
N
H
2
N
12 examples
70-100%
R
1
24-50 balls 5 mm O
O
O
O
Inox or WC
OH
27
28
O
H
O
Conditions:
2) - Boc
2
O (1.0 equiv) / NaCl, 300 rpm, 3 h (Cycled)
-
ZOSu (1.0 equiv) / NaCl, 500 rpm, 2 h (Continuous)
-
FmocOSu (1.0 equiv) / NaCl, 500-750 rpm, 2-3 h (Continuous or Cycled)
31
5 examples
63-95%
or
or
3) Aqueous acidic work-up, then filtration/precipitation
E
-factor for the synthesis of
32
PG
In Solution
Solvent-free
CH
2
Ph
O
H
2
O
2 KCl
Waste
OH
Boc
62
265
PG-NH
CO
2
NOH
Z
20
8
NaCl
CO
2
O
Fmoc
288
6
(HOSu)
t-BuOH
32
O
from Boc
2
O
from ZOSu
or FmocOSu
Scheme 6.8 Two step/one-pot N-protection of amino acids in a planetary ball-mill.
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