Download (3249Kb) - D-Scholarship@Pitt - University of Pittsburgh

Scheme 4.47 Comparison of the stability between alkyl-pyrrole 298a and acyl-pyrrole 308a.
H
BzN
MeO2C Bn
H
N
O
N
acyl pyrrole (308a)
H
BzN
MeO2C Bn
H
initial ratio 4.9 1.9
ratio after 4.8 3.8
60 days a
N
alkyl pyrrole (298a)
CO 2Et
CO 2Et
standard
a The ratios shown are standard / compound. The sample was kept in an NMR tube in d 6 DMSO at rt under N2 atmosphere.
Since compounds 308a-p represent a new class of angularly fused tricyclic pyrroles with high
molecular complexity, we became interested in synthesizing a discovery library for biological
evaluation. To obtain a better understanding of the three-dimensional structure of the pyrroles,
energy minimization was performed on the simplest pyrrole member 308n (Figure 4.1). x
Figure 4.1 Two different stereoviews (top and bottom) of the energy-minimized model of 308n.
x Energy minimization was performed with Cache Worksystem Pro. version 6.1.10. First, global minimum search
was performed using MM3 parameters, followed by energy minimization using AM1 paramaters.
120