A NIS mediated sequential procedure involving oxidation and electrophilic cycloisomerization ofN-(2-trifluoromethyl-3-alkynyl) hydroxylamines for 4-trifluoromethyl-5-acylisoxazole synthesis is developed.
Divergent access to <i>N</i>-hydroxypyrroles and isoxazoles <i>via</i> the gold(<scp>i</scp>)- or Brønsted acid-catalysed regioselective cyclization of <i>N</i>-(2-trifluoromethyl-3-alkynyl) oximes
作者:Qin Zeng、Li Zhang、Yuanjing Xiao、Junliang Zhang
DOI:10.1039/c7ob03107f
日期:——
The divergent regioselective cyclization of N-(2-trifluoromethyl-3-alkynyl) oximes by a suitable choice of a gold(I) or a Brønsted acid catalyst, leading to 4-trifluoromethyl-N-hydroxypyrroles or 4-trifluoromethyl-5-alkylisoxazoles was developed. In order to avoid the tedious separation of unstable N-(2-trifluoromethyl-3-alkynyl) oximes, an easy two-step, one-pot synthesis of 4-trifluoromethyl-5-alkylisoxazoles
的发散区域选择性环化ñ - (2-三氟甲基-3-炔基)由一个金的合适选择肟(我)或布朗斯台德酸催化剂,导致4-三氟甲基- ñ -hydroxypyrroles或4-三氟甲基-5- alkylisoxazoles发展了。为了避免不稳定的N-(2-三氟甲基-3-炔基)肟的繁琐分离,通过顺序氧化相应的羟胺,实现了简单的两步一锅合成4-三氟甲基-5-烷基异恶唑然后用还原剂硫代硫酸钠(Na 2 S 2 O 3)处理。这种两步一锅法是从那些不稳定的N-(2-三氟甲基-3-炔基)肟合成4-三氟甲基-5-烷基异恶唑的补充方法。