H. Propose a synthesis method to show how you will prepare or make an aldehyde starting from an ester.

To prepare an aldehyde from an ester, we can use the following steps:

1. Hydrolysis of the ester:
The ester will be hydrolyzed under acidic or basic conditions to form a carboxylic acid and an alcohol. The acid will further be reduced to an aldehyde by LiAlH4 or NaBH4.

2. Reduction of carboxylic acid to aldehyde:
The carboxylic acid formed from the hydrolysis of the ester can be reduced to the aldehyde using a reducing agent such as LiAlH4 or NaBH4.

Therefore, the synthesis method involves the hydrolysis of the ester followed by reduction of the resulting carboxylic acid to obtain the aldehyde.

\textbf{Answer:}
The aldehyde can be prepared starting from an ester by first hydrolyzing the ester to obtain a carboxylic acid and an alcohol, followed by the reduction of the carboxylic acid to the aldehyde.