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Solutions for Condensations and Alpha Substitutions of Carbonyl Compounds
73 continued
OMe
O
H
H
C
H
O O
H
H
PhC
O O
OCH3
PhC
O
OCH3
C Ph
OO
H HA
(b)
– CH3O
(c) Robinson annulations are explained most easily by remembering that the first step is a Michael 
addition, followed by aldol cyclization with dehydration.
OH
OH
OH
OMe
O
H
C
O
CH3
H
H
H
C
H
O
OMe
O
H OH
H OH
H
CH3
O
HO
OMe
OMe
O
HH
H
C
H
CH3
O
H
O
OMe
H
OMe
O
O
CH3
H
two rapid
proton transfers
plus one other 
resonance form
plus other
resonance forms
(Michael addition)
(aldol)
plus one other 
resonance form
mechanism continued on next page
587