Chemistry Reference
In-Depth Information
(10 mL) was added dropwise over a period of 10 min. As the reaction was exother-
mic, the reaction temperature gradually increased to 50
C and the mixture was
kept at this temperature for 2 h. After standard work-up as described above, the
products 1379 obtained were purified by passage through a short silica gel column
followed by distillation or recrystallization from benzene/petroleum ether.
Phenyl chloroformate
A mild and general synthetic method for the facile conversion of alkyl, benzylic,
aryl, and heteroaryl primary amides to the corresponding nitriles in high yields of
80-95% uses phenyl chloroformate in the presence of pyridine at room tempera-
ture [1057].
PhOCOCl
O
R
R
N
NH
2
pyridine
CH
2
Cl
2
rt, 8-10 h
80-95 %
1379
1377
General procedure. Cyanides 1379 from carboxamides 1377 [1057]: Phenyl chloro-
formate (5.5 mmol) was added dropwise to a stirred, ice-cooled solution (or sus-
pension) of the amide/thioamide (5.0 mmol) in dry dichloromethane (25 mL) and
anhydrous pyridine (10.0 mmol) at such a rate that the temperature remained be-
low 5
C. The reaction mixture was allowed to warm to room temperature and was
stirred for 8-10 h (completion of the reaction was verified by TLC). It was then
quenched with water (8 mL) and extracted with dichloromethane (2
25 mL). The
combined organic phases were washed with brine, dried (Na
2
SO
4
), and the sol-
vent was removed in vacuo to afford the crude product, which was purified by col-
umn chromatography on silica gel. Pure cyanides 1379 were obtained in yields of
80-95%.
Oxalyl chloride
Oxalyl chloride has been used as a dehydration reagent in the preparation of 2,9-
dicarbonitrile-1,10-phenanthroline 1391, which serves as a starting material in the
synthesis of macrocyclic compounds [1058].
Typical procedure. 2,9-Dicyano-1,10-phenanthroline 1391 [1058]: To DMF (200 mL),
oxalyl chloride (5.7 mL, 0.066 mol) was added with stirring at 0
C under argon
atmosphere. A white precipitate formed immediately, which was accompanied by
gas evolution. When the gas evolution had ceased, a solution of the diamide 1390
(7.0 g, 0.026 mol) in DMF (150 mL) was added to the reaction flask. The resulting
yellow mixture was stirred for 6 h at 0
C. Pyridine (9.4 mL, 0.116 mol) was then
added and, after stirring for a further 30 min, the mixture was neutralized with
saturated aq. Na
2
CO
3
solution (500 mL). Some precipitate was formed, and pre-
cipitation was completed by adding water (700 mL). After filtration, the pale-yellow
