The behaviour of a series of N-substituted 3,4-pyridinedicarboximides under electron impact at 70 eV is analyzed. Compounds under study were divided into three groups: 3,4-pyridinedicarboximidoacetic, beta-3,4-pyridinedicarboximidopropionic and gamma-3,4-pyridinedicarboximidobutyric acid derivatives (compounds 1, 2 and 3 respectively), which in turn determine the dominant fragmentations. The proposed fragmentation patterns are supported by HRMS and tandem mass spectrometry. Results are in some cases compared to data from the related 2,3-pyridinedicarboximides 4.
Efficient Cesium Carbonate Promoted N-Alkylations of Aromatic Cyclic Imides Under Microwave Irradiation
We present here an efficient and simple method for the N-alkylation of aromatic cyclic imides employing cesium carbonate as the base in anhydrous N,N-dimethylformamide at low temperatures (20-70 ËC). The employment of microwave irradiation presents noteworthy advantages over conventional heating. The method is compatible with base labile functional groups.