Alcohols & Ethers: 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.
Click the mouse on the molecule to reset this frame.
Working backwards, this molecule is an ether and two carbons have been added to the parent chain of the 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 an aldehyde 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.
Working backwards, this molecule is an ether and two carbons have been added to the parent chain of the starting material. Simple ethers such as this can be prepared from the alcohol using an SN2 reaction; n-butyl lithium is utilized to form the alcohol anion, which is then methylated with bromomethane. Next, suggest a synthesis of the intermediate alcohol, beginning with benzyl bromide.
Benzyl bromide is first converted to a Grignard reagent by reaction with Mg in ether; this is then reacted with acetaldehyde (ethanal) to give the intermediate alcohol. This is converted to the anion with n-butyl lithium and alkylated with bromomethane to give the final product.