Iodine → 5-Bromo-4-methyl-3-nitropyridine-2-carboxaldehyde

Beteiligte Stoffe

Reaktionsschritte

2-Amino-3-(6-bromo-3-methoxy-7-methyl-2H-pyrazolo[4,3-b]pyridin-2-yl)-2-methylpropionitrile (20 mg) was prepared using a procedure similar to that described in Example 1, part b, except starting from 1-(6-bromo-3-methoxy-7-methyl-2H-pyrazolo[4,3-b]pyridin-2-yl)propan-2-one (117 mg). 1-(6-Bromo-3-methoxy-7-methyl-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-bromo-4-methyl-3-nitropyridine-2-carboxaldehyde (5.5 g) in part a to yield [2-(tert-butyldimethylsilanyloxy)propyl]-(5-bromo-4-methyl-3-nitropyridin-2-yl-methyl)amine (6 g, 67%). 5-Bromo-4-methyl-3-nitro-pyridine-2-carboxaldehyde was prepared using a procedure similar to that described in Example 136 part a to c except starting from 2-amino-5-bromo-4-methyl-3-nitropyridine (58.6 g) and using iodine (64 g) in part a instead of copper bromide to generate 5-bromo-2-iodo-4-methyl-3-nitropyridine (28.7 g, 33%). Oxidative cleavage using a 4% solution of osmium tetroxide in water (3 mL) and sodium periodate (23.1 g) was carried out in a mixture of THF and water (10:1, 330 mL) in part c instead of ozonolysis following a procedure similar to that described in Example 61 to afford 5-bromo-4-methyl-3-nitropyridine-2-carboxaldehyde (11.7 g, 59%) from 5-bromo-4-methyl-3-nitro-2-vinylpyridine (18.8 g). 2-Amino-5-bromo-4-methyl-3-nitropyridine (120.2 g, 85%) was prepared using a procedure similar to that described in Example 38 part a except starting from 2-amino-4-methyl-3-nitropyridine (101.5 g).

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