5-Substituted-3-(substituted)phenyl-1,3,4-oxadiazolin-2(3<i>H</i>)-ones. Synthesis and reactions with nucleophilic reagents
作者:Kurt H. Pilgram
DOI:10.1002/jhet.5570190423
日期:1982.7
A new synthesis of 4,4-dialkyl-2-(substituted)phenylsemicarbazides has been developed. The procedure begins with a 5-substituted-3-(substituted)phenyl-1,3,4-oxadiazolin-2(3H)-one, 3, which is treated with dialkylamine to give a 1-acyl-4,4-dialkyl-2-(substituted)phenylsemicarbazide, 7. Subsequent base-catalyzed hydrolysis of 7 gives 4,4-dialkyl-2-(substituted)phenylsemicarbazides, 14, in high yield
2-Phenylsemicarbazides are prepared by a multi-step process involving: (a) treating a phenylhydrazine, or salt thereof, with a chloroformate; (b) adding phosgene; (c) treating the resulting product with an amine; and (d) hydrolyzing the resulting acylated semicarbazide. The reaction can proceed through a .DELTA..sup.2 -1,3,4-oxadiazolin-5-one intermediate formed with heating in step (b). Certain of the products are novel compounds.