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 acetylenicdipolarophiles 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