Alcohols: Multi-Step Synthesis
Suggest a synthetic scheme for the conversion shown on the left using the starting materials shown below. Work each problem backwards, and draw the structures of the intermediates required for the conversion, and the reaction conditions necessary for each step.
Click the mouse on the buttons to view the synthetic logic for each step, the structures of the intermediates and the solution to the problem.
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Working backwards, this molecule is an aryl ketone. We can make aryl ketones by Friedel-Crafts acylation, or by oxidation of the corresponding alcohol. Since the starting material has the correct carbon skeleton, the simplest route would involve oxidation of the alcohol. The alcohol could be formed by hydration of the starting alkene.
Working backwards, this molecule is an aryl ketone. We can make aryl ketones by Friedel-Crafts acylation, or by oxidation of the corresponding alcohol. Since the starting material has the correct carbon skeleton, the simplest route would involve oxidation of the alcohol using something like PCC in CH2Cl2. The required alcohol has the hydroxyl group bonded to the benzylic carbon (the carbon in the side-chain which would form the most stable carbocation) and is therefore a "Markovnikov" alcohol. Next, suggest a synthesis of this alcohol, beginning with the alkene.
Styrene (ethenylbenzene) undergoes simple acid-catalyzed hydration on the benzyl carbon (the carbon which would form the most stable carbocation) to give 1-phenylethanol. Simple oxidation using PCC in CH2Cl2 gives the aryl ketone.