Synthesis, Anti‐oomycete and Anti‐fungal Activities of Novel Eugenol/Dihydroeugenol Derivatives Bearing Carbamate Moiety

Eugenol is the main component of clove basil oil extracted from plants such as Syzygium aromaticum and Ocimum gratissimum. To discover biorational natural product-based pesticides, a series of eugenol/dihydroeugenol derivatives containing carbamate moiety were prepared by introducing an active aminooyloxy group at its C1 hydroxy position, and their structures were well characterized by proton nuclear magnetic resonance (¹H NMR), carbon-13 NMR (¹³C NMR), high-resolution mass spectrometry, and melting point. Bioactivities of these target compounds as anti-oomycete and anti-fungal agents against two serious agricultural pests, Phytophthora capsici and Fusarium graminearum were evaluated. Among assessed compounds: (1) Title compounds 1b and 2b showed significant anti-fungal against F. graminearum, with half maximal effective concentration values of 29.13 and 35.04 mg/L, respectively. (2) The title compounds have obvious selectivity, and their anti-fungal activity is significantly better than their anti-oomycete activity. (3) The anti-oomycete and anti-fungal activities of introducing the aminoalkyloyloxy group at the C1 hydroxyl position of eugenol or dihydroeugenol are significantly better than that of introducing the aminoaryloyloxy group. (4) The presence of a double bond is beneficial for increasing anti-fungal activity, and the reduction of a double bond is beneficial for increasing anti-oomycete activity.