Hydrochloric Acid → 5-(Benzoxazol-2-yl)-2-(tetrahydropyran-4-yl)aminoaniline

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Reaction Steps

To a suspension of 2-fluoro-5-(4-methylbenzoxazol-2-yl)nitrobenzene (see Working Example 46-1) (0.50 g, 1.8 mmol) in ethanol (10 mL) was added triethylamine (0.22 g, 2.17 mmol) and aminotetrahydropyran (0.20 g, 1.9 mmol), and this was heated to reflux for 3 hours. After the reaction was complete, this was cooled to room temperature and then the mixture was poured into dilute hydrochloric acid (1 M, 10 mL), this was extracted with chloroform (50 mL), and washed with saturated sodium hydrogen carbonate (approx. 50 mL) and then with brine (approx. 50 mL). The organic layer was dried over anhydrous magnesium sulfate, and then the solvent was distilled away at reduced pressure to give crystals, which were added to palladium-carbon (Pd: 10%, 0.06 g) and a solvent mixture of ethyl acetate/methanol (1:1, 20 mL), hydrogen was substituted in by successively reducing the pressure and purging with hydrogen gas 3 times, and this was stirred at room temperature for 2.5 hours. After substituting in nitrogen, the insoluble material was filtered off through a Celite layer (20 mm thickness), and this same layer was washed with methanol (20 mL, 3 times). The filtrate and wash solutions were combined and the solvent was distilled away under reduced pressure to yield the title compound (0.56 g, 94.3% yield) as a blackish brown solid.

Provenance & Evidence