Copper Catalysts for Aerobic Oxidation of Alcohols - Transition Metal Catalysis in Aerobic Alcohol Oxidation - page 61

OH

t -Bu

t -Bu

N

N

d n 4 r 4 n g | 0

t -Bu H

t -Bu

HO

OH N

N OH

OH

A

C

"

"

HO R

R

OH

R'

R'

B

R' = R" = -Bu

t

or
R' = S- i -Pr, SPh; R" = t -Bu

t -Bu

t -Bu

t -Bu NH t -Bu

HN

t -Bu Se

t -Bu

t -Bu

t -Bu

OH

OH

OH HO

F

t -Bu

D

t -Bu

t -Bu S

t -Bu

OH

OH

t -Bu NO 2

E

HO

t -Bu NH HN

t -Bu

MeO

N

OH

HO F 3 C CF 3

N

OH

.

-Bu

t -Bu

t

G t -Bu

I

t-Bu NH

OH

t -Bu

H

Figure 2.27 Ligands used to prepare functional models of GO.

(bpy)Cu(PR 3 )X (R ¼ Me, Et, nBu, Ph; X ¼ Cl, Br, I), have been reported to
catalyze the oxidation of ethanol to acetaldehyde under O 2 pressure (30 psi)
at 25 1C. 121 Kitajima et al. used a copper complex of N,N 0 -(2-hydroxypropane-
1,3-diyl)bis(salicylaldiminato) (A in Figure 2.27) for the oxidation of ethanol
to acetaldehyde using the substrate as solvent under O 2 at 40 1C. 122 A strong
base such as KOH was used for catalytic activity. The catalyst could oxidize
propanol and hydroxyacetone to their corresponding carbonyl compounds.
In 1998, Stack and co-workers reported the first ecient biomimetic
copper catalysts for the aerobic oxidation of alcohols. 123 The ligands used for
this study were salen-type compounds with a binaphthyl backbone and
thioether functions (B in Figure 2.27). The ligands form a non-square-planar