反应详情

Commercially available 3-pyridinealdoxime (61) is converted to its chlorohydroxyimino derivative (US 2004/0157900) which is converted to nicotinonitrile oxide (Tetrahedron, 61, 2005, 4363-4371) “in situ” and reacted with 1,2-bis-trimethylsilanyl-ethyne (Chem. Ber., 107, 1974, 3717-3722) to afford the 1,3-dipolar cycloaddition product 3-(4,5-bis-trimethylsilanyl-isoxazol-3-yl)-pyridine (62). Halogen-induced ipso desilylation resulted in the 4-bromo-5-trimethylsilanyl derivative (63). Subsequent desilylation with NH4OH (Chem. Ber., 112, 1979, 2829-2836) generates 3-(4-bromo-isoxazol-3-yl)-pyridine (64).