The author of 《Metal Catalyzed Synthesis of Dihydropyridobenzodiazepines》 were Maddess, Matthew L.; Li, Chaomin. And the article was published in Organometallics in 2019. Quality Control of 2-Bromonicotinaldehyde The author mentioned the following in the article:
A versatile synthesis of dihydropyridobenzodiazepines that proceeds via a palladium-catalyzed C-N coupling and catalytic hydrogenation cascade is reported. The intermediate 2-anilinonicotinaldehydes may be efficiently protected to ultimately afford N6 differentiated dihydropyridobenzodiazepines, which facilitates further elaboration. The experimental process involved the reaction of 2-Bromonicotinaldehyde(cas: 128071-75-0Quality Control of 2-Bromonicotinaldehyde)
2-Bromonicotinaldehyde(cas: 128071-75-0) belongs to pyridine. Pyridine is a relatively complex molecule and exhibits a number of different bands in IR spectra. Among others, the bands characterizing the ν8a and ν19b modes have been found to be sensitive to the coordination or protonation of the molecule. Note that the band that is diagnostic for the PyH+ ion at about 1545 cm− 1 (ν19b mode) does not overlap with any of the other bands.Quality Control of 2-Bromonicotinaldehyde