Chemistry Reference
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CAN (2 eq)
MX (2 eq)
X
(69-91%)
m.m. (12 Hz)
r.t.; 4 h
R
2
COOH
R
1
MX = LiCl, LiBr, KBr
H
R
1
O
R
2
CAN (2 eq)
(20-60%)
m.m. (12 Hz)
r.t.; 4 h
R
2
R
1
Scheme 3.11
Solid-state ball mill oxidation of cinnamic, 4-methoxy- and 3,4-
dimethoxycinnamic acid.
(a)
OCH
3
OCH
3
O
CH
3
O
CH
3
OCH
3
HO
H
O
OCH
3
O
H
3
C
H
3
C
3-Cl-PBA, Al
2
O
3
m.m. (14.6 Hz)
r.t.; 60 min
N
N
(57%)
OH
OH
O
O
O
O
NHAc
NHAc
O
(b)
OH
O
O
O
R
O
O
ROCl
TEA/Al
2
O
3
m.m.
H
N
H
H
H
N
m.m.
N
N
N
S
S
S
O
O
O
O
O
O
R=
p
-C
6
H
4
NO
7
Scheme 3.12 General scheme of mechanochemical reactions of lappaconitine
(a) and piroxicam-4-nitrobenzoate mechanochemical synthesis (b).
Reaction condition: Vibratory mill SPEX-8000 (CertiPrep Inc., USA)
with 60 mL steel vials 3 mm diameter grinding balls.
acylation of the anti-inflammatory drug piroxicam to improve its therapeutic
properties. Consequently, piroxicam 4-nitrobenzoate was obtained in solvent-
free reaction conditions, giving a moderate yield as a result of the mechanical
activation of the reaction between piroxicam and 4-nitrobenzoyl chloride in
the presence of triethylamine (TEA) impregnated aluminium oxide.
12
Mal et al. have investigated the potential use of IBX (2-iodoxybenzoic acid,
an oxidant whose extensive use is impeded by its explosiveness at high
temperature and poor solubility in common organic solvents except DMSO)
in solvent free, milling conditions at room temperature in the following
reactions: the oxidation of primary/secondary alcohols to corresponding
carbonyl compounds, amine to imine; the conversion of olefins to a-bromo/
iodoketones, sulfide to sulfoxide; dithiane deprotection and the synthesis of
benzimidazoles from primary alcohols.
13
This methodology has been
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