Two different selective ways in the deprotonation of β-bromopropionanilides: β-lactams or acrylanilides formation

The reactivity of 3-bromo-N-(p-bromophenyl)propanamide with different bases in an ionic liquid (BMImBF4) and in acetonitrile (ACN) was studied. Two possible deprotonation sites are present in this molecule, leading to different products. When the NH group is deprotonated, a β-lactam is obtained after internal halide displacement; when the CH2 in alpha to the carbonyl is deprotonated, the corresponding acrylanilide is formed. This study allowed determining the experimental conditions to obtain selectively and in high yields both products starting from the same molecule. In particular, to obtain the acrylanilide Et3N in ACN is to be used, while to obtain selectively the β-lactam ring the base must be generated by cathodic reduction of a DMF or ACN-Et4NBF4 solution. These reactions were extended to other β-bromopropionanilides, allowing to easily synthesize both β-lactams and acrylanilides, molecules having noteworthy biological activities.