5lB
M. CHEM Taagepera
PRACTICE QUIZ 4
WINTER'08
Ch. 12: Oxidation and Reduction
1. SYNTHESIS (similar to #56, 58, 59 and 61) Starting with acetylene devise a synthesis of the following compounds. Indicate your strategy or do a retrosynthetic analysis. a) Retrosynthetic analysis
HC CH
----------------------------------------------------------------------------------------------------------------------Synthesis:
HC CH 1. NaNH2 2. CH3Br 1. NaNH2 2. CH3Br H2 Lindlar's catalyst
_______________________________________________________________________________ b) Retrosynthetic analysis
HC CH
----------------------------------------------------------------------------------------------------------------------Synthesis
HC CH 1. NaNH2 2. CH3Br 1. NaNH2 2. CH3Br Na, NH3
_______________________________________________________________________________ c) Retrosynthetic analysis
HC CH O
OH
OH
OH
----------------------------------------------------------------------------------------------------------------------Synthesis
HC CH 1. NaNH2 2. CH3CH2Br 1. NaNH2 2. O 3. H2O OH H2 Lindlar's catalyst OH
___________________________________________________________________
d) Devise two ways of synthesizing the given epoxide. You can start an with already prepared compound. Retrosynthetic analysis:
H O H H3C CH3 HC CH
HO H H3C
H CH3 Br
HC CH
Synthesis:
HC CH 1. NaNH2 2. CH3Br 1. NaNH2 2. CH3Br H2 Lindlar's catalyst mCPBA H O H H3C CH3
Or, by bromohydrin route: HC CH Br2, H2O HO H H3C H CH3 Br NaH H O H H3C CH3
2. PREDICT PRODUCTS (similar to #37-44)
ozononolysis 1. O3 2. Zn, H2O mCPBA 1. RCO3H 2. H2O, HO KMnO4 H2O, HO OH OH syn-dihydroxylation O epoxidation
O O
OH OH anti-dihydroxylation
3. IDENTIFY UNKNOWN COMPOUND (similar to #44, 46, 47, 48, 49, 50, 51, 52) Compound A has a molecular formula of C8H12 and reacts with two equivalents of H2. A gives HCOCH2CH2CHO as the only compound of oxidative cleavage with O3 followed by CH3SCH3.
Unknown A C8H12
Unsaturation number = 3 Reacts with 2 eq of H2: Thus, has either two alkenes or one triple bond, which accounts for 2 degrees of unsaturation. Last unit of unsaturation must be attributed to a ring.
Unknown A C8H12
1. O3 2. CH3SCH3
O O exclusive product (2eq)
Unknown A
4. SYNTHESIS (similar to #57 and 63) Devise the synthesis of Disparlure from acetylene.
O
Retrosynthesis:
O cis Disparlure HC CH + Br
Br
+
Synthesis:
HC CH 1. NaNH2 2. Br 1. NaNH2 2. Br H2 Lindlar's catalyst O Disparlure mCPBA