Synthesis
The general procedure for the synthesis of 5-nitropyridine-2-carbaldehyde using 2-methyl-5-nitropyridine as starting material was as follows: 2-methyl-5-nitropyridine (3.0 g, 0.021 mol, 1 eq.) was dissolved in 1,4-dioxane (30 mL) at room temperature and selenium dioxide (2.9 g, 0.026 mol, 1.2 eq.) was added with stirring. The reaction mixture was heated to reflux and stirred continuously for 16 hours. Upon completion of the reaction, the mixture was cooled to room temperature and filtered to remove insoluble material. The filtrate was concentrated under reduced pressure and diluted with ethyl acetate (50 mL) and subsequently washed with water (50 mL). The organic phase was dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give 5-nitropyridine-2-carbaldehyde (3.12 g, 94% yield).
References
[1] Patent: WO2013/13815, 2013, A1. Location in patent: Page/Page column 230; 231
[2] Patent: US2013/29962, 2013, A1. Location in patent: Paragraph 1110
[3] Journal of Organic Chemistry, 2012, vol. 77, # 20, p. 8968 - 8979,12
[4] Journal of Medicinal Chemistry, 1992, vol. 35, # 20, p. 3672 - 3677
[5] Patent: WO2005/97752, 2005, A1. Location in patent: Page/Page column 42
