In his most famous namesake reaction, water must be removed to prevent the product from reverting to its alcohol and carboxylic acid reactants.  
In one synthesis named for this man, cyanohydrins and aldehydes react in the presence of anhydrous hydrochloric acid to form oxazole.  He discovered phenylhydrazine, which when reacted with an aldehyde or ketone, forms enamine, imine, and aminal intermediates in his namesake indole synthesis.  In his most famous namesake reaction, water must be removed to prevent the product from reverting to its alcohol and carboxylic acid reactants.  Known for that esterification, FTP name this chemist perhaps most famous for depicting complex sugars with straight backbones and 90? bond angles in his eponymous projections.
In one synthesis named for this man, cyanohydrins and aldehydes react in the presence of anhydrous hydrochloric acid to form oxazole.  
(Hermann) Emil Fischer