202 Lcvcl 2 - Case 30
Scheme30.6
NHAc
0.59~ "...--..,...
N " N 0.6501,
11
1
N~N 0.580
0.538 1 .......___., Ph
SCH 3
LUMO
HOMO
!
~şPh
SCH 3
8
major
Answer to Question 2
NHAc
0.59~ ,.......-..... Ph
~ "~ 0.580111
N~N 0.650
0.5381 ~
SCH3
LUMO
HOMO
!
NHAc
~JyPh
N'(
SCH3
9
minor
Compound 10 has a diene (1 ,2,4,5-tetrazine) tethered to a dienophile (C- C triple
bond), so it is reasonable to fonnulate an intramolecular [4+2] cycloaddition in the
first place, leading to adduct 11. The next step would bea retro-Diels-Alder process with N 2 extrusion, to obtain the bicyclic diazine 12 (Scheme 30.7).
10
Scheme30.7
Additional Comments
N
11
N
11
12
This problem is based on the work by Boger DL, Schaum RP, Garbaccio RM
(1998).!. Org. Chem. 63:6329-6337.
Subjects of Revision
Diels-Alder reactions: regioselectivity, reactivity.