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。
Regioselective synthesis of 1-methyl-3-hydroxy-5-perfluoroalkylpyrazoles by the addition of methylhydrazine to perfluoroalkylacetylenic esters
作者:Bruce C. Hamper
DOI:10.1016/s0022-1139(00)82607-x
日期:1990.6
1H,3H)pyrazoles has been developed. Treatment of perfluoroalkylacetylenic esters with methylhydrazine in methanol-water at 0° or in methylene chloride at low temperature leads to 1-methyl-3-hydroxy-5-perfluoroalkyl(1H,3H)pyrazoles in a regioselective manner. Structuralassignments of the regioisomers are based on 13C nmr chemical shifts, long range carbon-fluorine and carbon-proton coupling. The effect
已开发出对1-甲基-3-羟基-5-全氟烷基(1H,3H)吡唑的区域选择性途径。在甲醇-水中于0°或在二氯甲烷中于低温下用甲基肼处理全氟烷基炔属酸酯会以区域选择性方式生成1-甲基-3-羟基-5-全氟烷基(1H,3H)吡唑。区域异构体的结构分配基于13 C nmr化学位移,远距离碳氟和碳质子偶合。讨论了乙炔结构对反应区域选择性的影响。
Substituted 3-hydroxy pyrazoles
申请人:Monsanto Company
公开号:US04855442A1
公开(公告)日:1989-08-08
The present invention relates to a class of 5-haloalkyl-3-hydroxy-1-(C.sub.1-2 alkyl)pyrazoles useful as precursors for an active class of phenoxypyrazole herbicides.
Synthesis and Herbicidal Activity of 3-Aryl-5-(haloalkyl)-4-isoxazolecarboxamides and Their Derivatives
作者:Bruce C. Hamper、Kindrick L. Leschinsky、Steven S. Massey、Crystal L. Bell、Lawrence H. Brannigan、S. Douglas Prosch
DOI:10.1021/jf00049a040
日期:1995.1
A series of unique 3-aryl-5-(haloalkyl)-4-isoxazolecarboxamides have been prepared which exhibit, in both greenhouse and field studies, significant preemergent and postemergent herbicidal activity in the grams per hectare range against broadleaf and narrowleaf weeds. The key step in the formation of the fully substituted isoxazole ring 2 is 1,3 dipolar cycloaddition of a haloalkyl-substituted acetylenic ester and a nitrile oxide intermediate. The 3-aryl-5-(halo alkyl)-4-isoxazolecarboxylate esters 2 are converted to isoxazole-4-carboxamide herbicides 5 and 6, secondary amides 7, and amino acid derivatives 8. Greatest activity was observed with compounds having a combination of three substituents: a substituted phenyl ring in the 3-position, a primary or secondary carboxamide in the 4-position, and a difluorochloromethyl group in the, 5-position of the isoxazole ring.
Diels-Alder reactions of polyfluoro-2-alkynoic acids