Trifluoroacetic acid → 2-Amino-5-bromo-3-hydroxypyridine

Participants

Reaction Steps

In another example, 6-bromooxazolo[4,5-b]pyridine can be subjected to palladium-catalyzed coupling and deprotection of the resulting intermediate with trifluoroacetic acid. 6-Bromooxazolo[4,5-b]pyridine can be produced from 2-amino-5-bromo-3-pyridinol by condensation with formic acid or a trialkyl orthoformate, using methodology similar to that of Viaud et al., Heterocycles 41: 2799 (1995). The use of other carboxylic acids produces 2-substituted-6-bromooxazolo[4,5-b]pyridines, which are also substrates for the Heck and Sonogashira reactions. The synthesis of 2-amino-5-bromo-3-pyridinol proceeds from furfurylamine (Aldrich Chemical Company). Thus, 5-bromo-3-pyridinol (produced from furfurylamine according to U.S. Pat. No. 4,192,946) can be chlorinated, using methods described by Koch et al., Synthesis, 499 (1990), to give 2-chloro-5-bromo-3-pyridinol, which in turn can be converted to 2-amino-5-bromo-3-pyridinol by treatment with ammonia.

Provenance & Evidence