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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This is a simple, symmetrical ether incorporating two moles of our starting material. Simple ethers such as this can be prepared from the alcohol using an SN2 reaction; since the starting material is an alkyl halide, it can be converted to a Grignard reagent and reacted with a carbonyl compound to give the intermediate secondary alcohol. First, give the structure of the intermediate alcohol and give the reagents and conditions necessary to complete the last conversion.
This is a simple, symmetrical aliphatic alcohol which can be prepared using a Grignard reaction with an ester. The carbon bearing the hydroxyl group is attached to the alkyl chains (which would come from the Grignard reagent) and to a hydrogen; we therefore need to use a formate ester. You should recall that esters add two moles of Grignard reagent to form secondary or tertiary alcohols. Give the reaction conditions and the ester which would be required for this conversion.
Benzyl bromide is converted to a Grignard reagent and reacted with a simple formate ester (any formate ester will do since the alcohol portion is lost in the reaction; you should recall that esters add two moles of Grignard reagent to form secondary or tertiary alcohols). The alcohol is then converted to the anion with butyl lithium and methylated using bromomethane.