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Chapter 17 587
Copyright © 2017 Pearson Education, Inc.
77.
At low temperatures
1
-
78
°
C
2
, the proton will be more apt to be removed from the methyl group, because
its hydrogens are the most accessible and are slightly more acidic (that is, the kinetically controlled
product will be formed).
CH
3
C
Br
O
CH
2
C
Br
O
LDA/THF
−
−
78
°
C
O
At higher temperatures
1
0
°
C
2
, the proton will be more apt to be removed from the more substituted
a
-carbon because in that way, the more stable enolate is formed (the one with the more stable double
bond). Therefore, the thermodynamically controlled product is formed.
CH
3
C
Br
O
CH
3
C
Br
O
−
C
O CH
3
CH
3
C
Br
O
−
LDA/THF
0
°
C
78.
HCH
O
HN
CH
3
CH
3
OCH
2
N
H
H C1
H
CH
3
CH
3
−
+
HOCH
2
N
H
1
CH
3
CH
3
+
HOCH
2
N
CH
3
CH
3
+
HB
HB
+
+
N
CH
3
CH
3
N
CH
3
CH
3
CH
2
HO
H
+
CH
2
+
OH
O
CH
2
N
CH
3
CH
3
O
CH
2
N
CH
3
CH
3
+
B
B
+