Yield:-

Reaction Conditions:

with toluene-4-sulfonic acid at 130; for 1 h;

Steps:

A1
Example A1; 6-Bromo-2-methyl-oxazolo[4,5-b]pyridine; A solution of 20 g (106 mmol) 2-amino-6-bromo-3-hydroxy-pyridine and 0.05 g p-toluenesulfonic acid monohydrate in 22 ml triethyl orthoacetate is stirred at 13O⁰C for 1 h. After cooling to room temperature the reaction solution is diluted with ethyl acetate (150 ml) and extracted with water (3 x 150 ml). The combined organic phases are dried over MgSO₄, filtered and concentrated in vacuo. Subsequent purification by crystallization from ethanol affords the title compound (19 g) as yellow-orange crystals. The mass spectrum shows the molecular peak MH⁺ at 213.2 and 215.2 Da.

References:

ALTANA Pharma AG WO2007/45622, 2007, A1 Location in patent:Page/Page column 32