Reaction of benzohydroximinoyl chlorides and β-(trifluoromethyl)-acetylenic esters: Synthesis of regioisomeric (trifluoromethyl)-isoxazolecarboxylate esters and oxime addition products
作者:Bruce C. Hamper、Kindrick L. Leschinsky
DOI:10.1002/jhet.5570400404
日期:2003.7
triethylamine induced reaction of benzohydroximinoyl chlorides, precursors of nitrile oxides, with β-trifluoromethylacetylenic esters gives rise to three products: 5-trifluoromethyl-4-isoxozolecarboxylate esters, regioisomeric 4-trifluoromethyl-5-isoxazolecarboxylate esters and an unexpected oxime 1,4-addition adduct. Product distribution is rationalized in terms of two competing reaction modes, either 1
由三乙胺引起的苯甲酰氢氧甲烷酰氯(腈的前体)与β-三氟甲基乙炔酸酯的反应产生三种产物:5-三氟甲基-4-异恶唑羧酸酯,区域异构的4-三氟甲基-5-异恶唑羧酸酯和意外的1,4-肟另外的加合物。根据两种竞争反应模式合理化了产品分布,可以是在乙炔酸酯中1,4加入肟阴离子,或在形成腈氧化物之后再进行1,3偶极环氧化。在低温下,优选将氧亚氨基酰氯与炔属酸酯进行阴离子1,4-加成,而在高于0°C的温度下,优选先形成氧化腈,然后进行环加成。13 C NMR。