Parallel Synthesis of a Library of Acylsemicarbazides Using a Solution-Phase One-Pot Method and Their Evaluation as Crop-Protection Agents

Abstract

A solution-phase one-pot synthesis of a 40-member acylsemicarbazide library is outlined. The acylsemicarbazides were prepared by reacting various hydrazides with N,N¢-carbonyldiimidazole (CDI) to generate 1,3,4-oxadiazole-2-one intermediates, which were then opened in situ with amines. Purification in the majority of cases was accomplished through filtration of the precipitated product in generally good yields and with ≥ 95% purities. An analogous synthesis of acylthiosemicarbazides was accomplished using N,N¢-thiocarbonyldiimidazole (TCDI). The library was then assayed for herbicidal, insecticidal, fungicidal and plant growth regulatory behavior.