Esterification of Carboxylic Acids with Dimethyl Carbonate and DBU

Esterification of Carboxylic Acids with Dimethyl Carbonate and DBU 

Why does the reaction work with DBU and not with the rest of the amines studied  

This question was a subject of debate and led to different speculations about the role of DBU diuing the process. The following mechanistic proposals were raised  

Undoubtedly a carbamate intermediate is formed, but the reaction proceeds by attack of the benzoate anion to the carbamate carbonyl group to form an anhy- 

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