Chemistry Reference
In-Depth Information
H
3
C
O
O
O
O
O
O
O
O
O
2
2
2
2
Cl
O
2
N
98%
95 %
64 %
65 %
H
3
C
O
O
O
O
H
3
CO
O
O
O
O
2
2
2
2
O
H
3
CO
H
3
CO
OCH
3
62 %
73 %
79 %
72 %
O
O
O
O
O
O
O
H
3
C
O
2
7
2
88 %
89 %
85 %
Typical procedure. o-Anisic anhydride [1042]:
A solution of o-anisic acid (500 mg, 1.8
mmol) and distilled triethylamine (0.25 mL, 1.8 mmol) in ethyl acetate (35 mL)
was stirred in an ice bath. Triphosgene (90 mg, 0.3 mmol) was then added in one
portion, whereupon the immediate precipitation of Et
3
N
HCl was observed. The
reaction mixture was kept in the ice bath for 10 min, and then stirred for a further
15 min at room temperature. The solid (Et
3
N
HCl) was filtered off and washed
with ethyl acetate (10 mL). The combined filtrate and washings were concentrated
to dryness, and the residue obtained was recrystallized from ethyl acetate and hex-
ane at room temperature to give the title compound as clear crystals (330 mg,
65%).
Typical procedure. Succinic anhydride [1042]:
A solution of succinic acid (500 mg, 42
mmol) and triethylamine (1.23 mL, 42 mmol) in anhydrous THF (120 mL) was
allowed to react with triphosgene (42 mg, 7.0 mmol) at ice-water temperature for
10 min. The reaction mixture was subsequently stirred for a further 15 min at
room temperature. The solution was then filtered, and the filtrate was concentrated
to dryness. The residue was crystallized from ethyl acetate to afford the desired
product as white crystals (370 mg, 85%).
A similar activation method using triphosgene has recently been applied for the
esterification of monocarboxylic acids and amino acids [1043].
R
O
Cl
R
O
RH
O
(CCl
3
O)
2
CO
R'OH
R'
-5 to 40°C, CH
2
Cl
2
O
O
O
O
1375
1376
