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Solutions for Alkynes
CH C Na+C CH H
C C
OH
Br
O
C C
OH
C CH H
CH2CH3H3C
H H
C HCH3C
CH3I
CH2CH3H3C
H H
H2O
NaNH2NaNH2
Na+
CH3CH2Br
CH2I2
Zn, CuCl
CCH
C C
H2
NaNH2
HH
H3C CH2CH3
C CH3C CH2CH3
+ NaNH2
(a) analysis of target
25 When proposing syntheses, begin by analyzing the target molecule, looking for smaller pieces that 
can be combined to make the desired compound. This is especially true for targets that have more carbons 
than the starting materials; immediately, you will know that a carbon-carbon bond forming reaction will be 
necessary.
 People who succeed at synthesis know the reactions—there is no shortcut. Practice the reactions for 
each functional group until they become automatic. See Appendix 3 in this Manual for a suggestion on 
how to organize reactions.
from
acetylene
from alkylation 
of acetylide3° acetylenic alcohols made
from acetylide plus ketones
forward direction:
Put on less reactive
group first.
Lindlar's
catalyst
(b) Analysis of target: cyclopropanes are made by carbene insertion into alkenes.
To get cis substitution around cyclopropane, stereochemistry of the alkene 
precursor must be cis. Cis alkenes come from catalytic hydrogenation of an 
alkyne using Lindlar's catalyst.
C CH H
CH2CH2CH3H
CH3CH2 H
HCH3CH2
H CH2CH2CH3
O
C HCCH3CH2
Na
NH3HCH3CH2
H CH2CH2CH3
O
NaNH2NaNH2 CH3CH2Br
MCPBA
CH3CH2CH2Br
C CCH3CH2 CH2CH2CH3
(c) Analysis of target: epoxides are made by direct epoxidation of 
alkenes. To get trans substitution around the epoxide, 
stereochemistry of the alkene precursor must be trans. Trans 
alkenes come from sodium/ammonia reduction of an alkyne.
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