Abstract
Gold nanoclusters stabilized by poly(N -vinyl-2-pyrrolidone)
(Au:PVP) are active and selective catalysts under aerobic conditions
for oxidation of cyclic secondary amines at the α-position
of the nitrogen atom. The catalyst accelerates the formation of the
imines by oxidation of the amines in aqueous solvent to afford the
corresponding lactams.
Key words
gold nanoclusters - amine - oxidation - amide
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Typical Procedure
for the Oxidation of 1a Catalyzed by Au:PVP under NaOH/H
2
O-EtOH
Conditions
1a (13.3 mg, 0.10 mmol),
NaOH (8 mg, 0.20 mmol), and EtOH (5 mL). The aq solution of Au:PVP
(1 mM, 10 mL = 10 atom%) was
added, and the reaction mixture was stirred vigorously (1300 rpm) at
27 ˚C or 50 ˚C for 24 h. The reaction mixture
was extracted with EtOAc (3 × 10 mL),
and then washed the organic layers with brine, dried over Na2 SO4 ,
and concen-trated in vacuo. The crude products were separated by preparative
TLC.
