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Difficulty with maleic anhydride compound


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I’m having a little trouble with a reaction and was hoping someone could help me. I’m trying to make a maleic anhydride compound,  but the compound is not there in the final step. My procedure is as follows:

To a clean and dry RBF fitted with a reflux condenser and a 1” stir bar, 20mL of dry ether and 0.004mol maleic anhydride are added. The mixture reflexes at room temperature under argon until the maleic anhydride is dissolved, at which point 0.004mol 4-aminopiperidine in 8mL dry ether is added. A white solid immediately precipitated, and the mixture stirs for an additional hour before being evaporated under reduced pressure. The resulting white powder was determined by LCMS to be the correct mass for a mono-substituted piperidine (thought the position is merely assumed to be at the primary amine). 

Next, the product is dissolved in 20mL acetic anhydride and 0.004mol sodium acetate is added along with a 1” stir bar. The reaction mixture stirs in a 105°C oil bath for 30mins, over which time is adopts a dark brown color. The mixture then cools in a water bath for 30 minutes before be evaporated under reduced pressure. The resulting brown powder is dissolved in 20mL acetonitrile and 0.004mol 9-bromofluorene is added along with 0.0048mol DBU and 0.02mol Sodium Bicarbonate. The reaction mixture reflexes at 90°C in an oil bath for 40h and is evaporated under reduced pressure. 

The LCMS for the final crude is included. As you can see, the product did not form and it just appears that there is a lot of DBU. Does anyone have any ideas for a better path to take for this reaction?



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