Adapted from PLTL
Names: ___________________
Chem 227/ Dr. Rusay
Enolate Chemistry Continued
Synthesis and Reactions of β-Dicarbonyl Compounds
1.
Give a reasonable mechanism for the following reaction, clearly showing all
important intermediates and resonance structures. Use curved arrows to show the
movement of electron pairs.
O
2 PhCH 2C
O
O
PhCH 2C
C
1. NaOEt (1 equiv.)
OEt
2. H3O
OEt
CH
Ph
2.
When compound C in ethanol is stirred with one molar equivalent of NaOC2H5
and one equivalent of CH3CH2CH2Br, a new compound D is formed. When D is
refluxed with 3M H2SO4, the ketone E is formed. Propose a structure for D, and
give a stepwise electron-pushing mechanism leading from C to D to E.
O
O
COC2H 5
O
NaOC2H5
CH2 CH2CH 2Br
C
D
Δ
H3O+
E
3.
Provide structures for the major products of each of the following reactions. In
each case, circle the nucleophile in the carbon-carbon bond-forming steps.
O
1.
N
a.
Cl
2. H3 O, H2O
O
O
Et2 NH
PhCH + CH 3CCH 2CO2Et
b.
EtOH
O
Ph
O
c.
OC2H5
(C 15H17NO3)
NaOC2H5 (cat.)
d.
3.
N
C
1 (Me2 CH)2 N
CH3 CH2CO2 Et
Li
2 CH3 CH2I
Disconnect the following compounds into components that would condense
(assemble) to give the designated compounds. Use the electron-pushing
formalism to show the condensation steps.
e.g.,
O
O
CH2 CH2
COEt
O
O
O
+
H 2C
CH
O
O
a.
O
C6H 5CCH 2COEt
(two ways)
O
Ph
Ph
b.
(Hint: MA says Robinson.)
C2H 5
O
c.
CH3 CCHCH2CH=CH2
CH3
COEt
4.
Having available ethyl acetoacetate, diethyl malonate, benzene, any compounds
with three carbons or fewer, and any inorganic reagents, show how to synthesize
the following compounds.
O
CH 3C
O
CHCH2Ph
CH3 CH2CH2CH2 COH
CH3
O
CH3 CH2CCH2CCH3
O
O
PhCCH
CH2 COH
CH3
O
HO2CCH2CH 2CH2CH2CO2H
CCH 3