3 - Pericyclic Reactions 2018

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re
la
tiv
e
 e
n
e
rg
y 
(k
ca
l/m
o
l)
C=C-C=C dihedral angle (degrees)slightlytwisted
s-cis
s-trans
bisected
s-trans:
S = 0.22
estimated energy/
interaction: 14.9 kcal/mol
s-cis:
S = 0.20
estimated energy/
interaction: 12.8 kcal/mol
-0.25
-0.41 -0.22
-0.23
+0.21 +0.23
-0.10
-0.24
-0.20
-0.40
large
small
-0.77
+0.22
+0.16
-0.41
HOMO (nitrile oxide, top) +
LUMO (propyne, bottom)
LUMO (nitrile ox., top) +
HOMO (propyne, bottom)
Mg
Br
2.17 A