Water → 5-Chloro-3-nitropicolinaldehyde

Beteiligte Stoffe

Reaktionsschritte

2-Amino-3-(6-chloro-3-methoxy-2H-pyrazolo[4,3-b]pyridin-2-yl)-2-methylpropionitrile (39 mg) was prepared quantitatively using a procedure similar to that described in Example 1, part b, except starting from 1-(6-chloro-3-methoxy-2H-pyrazolo[4,3-b]pyridin-2-yl)propan-2-one (32 mg). 1-(6-Chloro-3-methoxy-2H-pyrazolo[4,3-b]pyridin-2-yl)propan-2-one was prepared using a procedure similar to that described in Example 105 part a to d except using 5-chloro-3-nitropyridine-2-carboxaldehyde (1.2 g) and decaborane in part a to yield [2-(tert-butyldimethylsilanyloxy)propyl]-(5-chloro-3-nitropyridin-2-yl-methyl)amine (0.4 g, 17%). 5-Chloro-3-nitropyridine-2-carboxaldehyde was prepared using a procedure similar to that described in Example 136 part a to c except starting from 2-amino-5-chloro-3-nitropyridine in part a or using commercially available 2-bromo-5-chloro-3-nitropyridine in part b. Alternatively, oxidative cleavage using a 4% solution of osmium tetroxide in water (2 mL) and sodium periodate (1.2 g) was carried out in a mixture of THF and water (10:1, 20 mL) in part c instead of ozonolysis following a procedure similar to that described in Example 61 to afford 5-chloro-3-nitropyridine-2-carboxaldehyde (0.72 g, 72%) from 5-chloro-3-nitro-2-vinylpyridine (1 g).

Herkunft & Nachweise