Regioselective synthesis of isoxazole and 1,2,4-oxadiazole-derived phosphonates <i>via</i> [3 + 2] cycloaddition
作者:Bohdan A. Chalyk、Alona S. Sosedko、Dmitriy M. Volochnyuk、Andrey A. Tolmachev、Konstantin S. Gavrilenko、Oleksandr S. Liashuk、Oleksandr O. Grygorenko
DOI:10.1039/c8ob02257g
日期:——
results of the study on reactions of halogenoximes bearing (protected) functional groups or fluorinated substituents with various phosphorus-containing dipolarophiles are described. To control the regioselectivity of the reaction, vinylphosphonates bearing a leaving group (i.e. bromine or dialkylamino group) in the α or β position were used; 3,5- and 3,4-disubstituted isoxazoles were obtained in 47–80%
描述了带有(保护的)官能团或氟化取代基的卤代肟与各种含磷的双亲性试剂反应的研究结果。为了控制反应的区域选择性,使用了在α或β位置带有离去基团(即溴或二烷基氨基)的乙烯基膦酸酯;3,5-和3,4-二取代异恶唑的产率分别为47-80%和63-75%。该反应对于母体膦酸乙烯基酯和氰基膦酸酯也是有效的。在这种情况下,分离出相应的异恶唑啉和1,2,4-恶二唑衍生的膦酸酯,产率分别为55-69%和34-73%。通过制备磷酸组氨酸的直接构象受限的类似物证明了所获得产物的实用性。