Chemistry Reference
In-Depth Information
The approach of Martin et al. centered on a series of model reactions of various piperi-
dine or piperidone enynes to provide azabridged bicyclic cyclopentenones. As shown in
Scheme 8.12, the appropriately functionalized series of piperidones related to
73
were
synthesized from pyridine
69
. A number of Pauson-Khand promoters were studied with
TMS
R
Cbz
MgBr
CuCN, MeLi, (1:1:1
)
THF, -78
°
C
96% (17:1 dr)
Cbz
N
Br
N
N
TMS
Zn, HgCl
2
, THF
Cbz-Cl, 10% HCl
77%
OMe
O
O
70
71
: R=TMS
72
: R=H
69
TBAF
THF
89%
R
m
n
n
Co
2
(CO)
8
[1.2 eq]
then DMSO [6 eq]
THF, 65
°
C
N
NR
O
O
m
O
74
73
Entry
Product
Yield (%)
Substrate
O
Cbz
H
N
1
N
89
Cbz
O
75
O
76
O
Cbz
2
N
H
N
91
Cbz
O
O
77
78
O
Cbz
3
33 (3:1 dr)
N
H
N
Cbz
O
79
O
80
Scheme 8.12
Model studies of the Pauson-Khand reaction toward azabridged bicyclic
enones.
