Level 1 – Case 15
106
N
Me
Me
O
Me
HOMO (-8.51 eV)
HOMO
HOMO (-8.41 eV)
LUMO
LUMO
LUMO
10
11
dipolarophile
O
N
Me
Me
O
Me
Figure 15.3
energy compared to nitrone 11. The effect of the substituents on the FMO energies
has been established
2 and it is known that adding an extra conjugation to the double bond generally produces a reduction of the HOMO-LUMO energy gap.
HOMO
HOMO
HOMO
LUMO (+0.69 eV)
LUMO (+0.59 eV)
LUMO
10
11
dipolarophile
N
Me
Me
O
Me
O
N
Me
Me
O
Me
Figure 15.4
A Ad dd di it ti io on na al l C Co om mm me en nt ts s
This problem is based on the work by Kouklovsky C, Dirat O, Berranger T, Langlois Y, Tran-Huu-Dau ME, Riche C (1998) J. Org. Chem. 63:5123-5128.
S Su ub bj je ec ct ts s o of f R Re ev vi is si io on n
FMO theory. Cycloaddition processes: Reactivity, regioselectivity and stereoselectivity.
2 For a study of the effect of substituents on the energies of the frontier orbitals of dienes
and dienophiles see: I. Fleming, Frontier Orbitals and Organic Chemical Reactions
Wiley, Chichester, 1976, p. 114.