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Mobile App Chapter 21: 21P (page 817)
Show two methods to synthesize each alkene: a one-step method using a Wittig reagent, and a two-step method that forms a carbon–carbon bond with an organometallic reagent in one of the steps.
a.
b.
Short Answer
a.
b.
Step by step solution
Synthesis of alkenes
Wittig reaction would convert an aldehyde or ketone into alkene using a triphenyl phosphonium ylide. Similarly, organometallic compounds, such as Grignard reagent, are good nucleophiles that would attack carbonyl carbon.
The hydrolysis followed by dehydration would yield a mixture of corresponding alkenes.
Synthesis of given compounds
a. 2-methylpent-3-one would give a single alkene with the Wittig reagent while forming a mixture of alkenes using an organometallic reagent.
The mixture of alkenes would include a tri-substituted major product and a di-substituted minor product.
Conversion to alkene
b. Cyclopentanone reacts with triphenyl phosphonium ylide to give an alkene while reacting with ethyl phenyl magnesium bromide. This is followed by a dehydrating agent such as sulfuric acid to form a mixture of alkenes.
Synthesis of alkenes via two methods
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