Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:


(e) 3-methyl-1-phenylbutane

Verified step by step guidance

1. Identify the target compound structure: 3-methyl-1-phenylbutane is a branched alkane with a phenyl group attached to the first carbon and a methyl group on the third carbon of the butane chain.
2. Consider using Friedel–Crafts acylation to introduce an acyl group onto a benzene ring. Start with benzene and react it with an appropriate acyl chloride (e.g., butanoyl chloride) in the presence of a Lewis acid catalyst like AlCl₃ to form a ketone intermediate.
3. Perform a Clemmensen reduction on the ketone intermediate to reduce the carbonyl group to a methylene group, converting the ketone into an alkane. This step will yield 1-phenylbutane.
4. Introduce the methyl group at the 3-position of the butane chain. This can be achieved by a free radical halogenation (e.g., using NBS) followed by a nucleophilic substitution with a methyl group donor (e.g., methyl magnesium bromide in a Grignard reaction).
5. Verify the structure of the final product to ensure it matches 3-methyl-1-phenylbutane, confirming the correct placement of the phenyl and methyl groups.

Key Concepts

Friedel–Crafts Acylation

Friedel–Crafts acylation is an electrophilic aromatic substitution reaction that introduces an acyl group into an aromatic ring. This reaction typically involves the use of an acyl chloride and a Lewis acid catalyst, such as aluminum chloride. The result is a ketone that can serve as a precursor for further transformations, making it a valuable method for synthesizing substituted aromatic compounds.

Clemmensen Reduction

The Clemmensen reduction is a chemical reaction that reduces carbonyl groups (aldehydes or ketones) to alkanes using zinc amalgam and hydrochloric acid. This method is particularly useful for converting aromatic ketones into their corresponding alkanes, allowing for the simplification of complex organic molecules. It is essential for synthesizing hydrocarbons from more functionalized precursors.

Gatterman–Koch Synthesis

The Gatterman–Koch synthesis is a method for synthesizing aromatic aldehydes through the formylation of aromatic compounds using carbon monoxide and hydrochloric acid in the presence of a Lewis acid catalyst. This reaction is significant for introducing formyl groups into aromatic systems, which can then be further manipulated to create various substituted aromatic compounds, including those needed for complex organic syntheses.