1,3-Dipolar cycloaddition synthesis of 3-bromo-5-substituted isoxazoles, useful intermediates for the preparation of pharmacologically active compounds
作者:D. Chiarino、M. Napoletano、A. Sala
DOI:10.1002/jhet.5570240109
日期:1987.1
monosubstituted acetylenic derivatives 4 to give 3-bromo-5-substituted isoxazoles 5 in high yield. The experimental conditions necessary to overcome difficulties such as the low reactivity of acetylenic dipolarophiles and the high tendency to dimerization of bromonitrile oxide 2, are discussed; the regioselectivity of this 1,3-dipolar cycloaddition is also studied. The obtained improvements in the synthesis of
Bromonitrile氧化物2,从容易获得的二溴甲醛肟生成1,与单取代的炔属衍生物进行反应4,得到3-溴-5-异恶唑取代的5以高收率。讨论了克服困难的条件,例如乙炔双极性亲和剂的低反应性和溴代腈氧化物2的二聚化趋势高。还研究了这种1,3-偶极环加成反应的区域选择性。据报道在某些药理活性化合物的合成中获得的改进。