2-(5-BroMopyridin-3-yl)oxazole synthesis

Yield:342600-96-8 100%

Reaction Conditions:

Stage #1: C₁₀H₁₃BrN₂O₂with sulfuric acid;phosphorus pentoxide at 20 - 100;
Stage #2: with ammonia in water at 0; pH=8;

Steps:

43.B

To the acetal obtained in Step A (361.0 mg; 1.32 mmol) was added with cooling to 0° C. concentrated H₂SO₄ (7 mL). Next, P₂O₅ (487.0 mg; 1.72 mmol) was added as a solid and the whole was heated to 100° C. for 30 minutes. The reaction mixture was allowed to reach ambient temperature and stirred overnight. The next day, the contents of the reaction were poured onto ice and concentrated NH₄OH was added with cooling to 0° C. until the reaction mixture was approximately pH=8. The aqueous layer was extracted several times with CHCl₃. The organic layer was then washed with brine. Drying (MgSO₄), filtration and removal of the solvent in vacuo provided quantitative yield of the desired oxazole.

References:

US6642237,2003,B1 Location in patent:Page/Page column 152-153