Well you don't say which amine you will use. However, you can go from the methyl or ethyl ester directly to the amide. Depending upon the amine you are using.
It happens that in the laboratory initially tried to prepare amides using DCC and EDC ( carbodiimide ) , but did not succeed . In Mexico the sale of thionyl chloride is prohibited to make an acid chloride .
So we decided to change the carboxylic acid to ester, then reduce the ester to alcohol, then oxidize the alcohol to aldehyde, and the aldehyde would react with primary amines to form imines, these imines would be reduced to form primary amines.
In theory , it is easy to prepare amines by reaction with aldehyde in basic or acidic medium , and then make a reductive amination .
I found some methods in the literature , but I have few milligrams of sample so I would like to know if anyone has experience in this type of reactions.