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588 Chapter 17
Copyright © 2017 Pearson Education, Inc.
79.
CH
3
CH CHCH
3
H Br
CH
3
CH CHCH
3
Br
HO
−
O
CH
3
CH
3
CH
3
CH
3
CHCH OH
CH
3
CH
3
CH
2
CH O
−
−
−
CH
3
HO
HO
−
−
H
C
O
C
O
C
O
C
O
CH
3
OH O
−
Release of strain
in the three-membered
ring causes a ring bond
to be the most likely
bond to break.
O H
80.
O
LDA/THF
O
Se Br
−
O
Se
HO OH
O
Se
OH
+
O
Se
O
+
SeOH
O
+
H
+
H
+
−
81.
The compound that gives the
1
H NMR spectrum is 4-phenyl-3-buten-2-one. The singlet at 2.3 ppm
that integrates to 3 protons is the methyl group. Because the benzene ring protons that show signals
between 7 and 8 ppm apparently integrate to 6 protons, we know that the signals include one of the vinylic
protons of the double bond. The other vinyl proton is the doublet (6.7 ppm) that integrates to 1 proton. The
compounds that would form this compound (via an aldol condensation) are benzaldehyde and acetone.
CH
O
CH
3
CCH
3
O
CH CHCCH
4-phenyl-3-buten-2-one
3
O
HO
−
+
H
2
O
+