Erlenmeyer synthesis reagent

The classical experimental conditions of the Erlenmeyer synthesis use anhydrous sodium acetate and acetic anhydride to effect cyclodehydration. However, many other reagent combinations have been used to improve the yield and the stereoselectivity of the reaction. With these aims in mind, zinc acetate,... 

Modification of the Erlenmeyer reaction has been developed using imines of the carbonyl compounds, obtained with aniline," benzylamine or n-butylamine. Ivanova has also shown that an A-methylketimine is an effective reagent in the Erlenmeyer azlactone synthesis. Quantitative yield of 19 is generated by treatment of 3 equivalents of 2-phenyl-5(4ff)-oxazolone (2) (freshly prepared in benzene) with 1 equivalent of iV-methyl-diphenylmethanimine (18) in benzene. Products resulting from aminolysis (20), alkali-catalyzed hydrolysis (21), and alcoholysis (22) were also described. 

A 25-mL Erlenmeyer flask, a standard Pyrex watch glass and a 1000-W micro-wave are used to carry out the microwave synthesis. 0.43 mL of benzaldehyde 1 and 0.3 mL of pyrrole 2 are mixed in the flask. Once the reactants are thoroughly mixed 0.63 g of silica gel is added, the flask stoppered, and the reagents mixed well until the silica gel is evenly and completely covered with the reactant mixture. The flask containing the reaction mixture is then placed in the micro-wave oven, covered with the watch glass and heated for 10 min in five 2-min intervals. Once the reaction is complete, it is allowed to cool to room temperature and ca. 15 mL of ethyl acetate added. The solution is filtered to remove the silica gel and then the ethyl acetate is removed using a rotary evaporator. Prior to... 

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