Synthesis and Fungicidal Activity of Lansiumamide A and B and Their Derivatives.

A efficient 2-step protocol has been applied for the synthesis of Lansiumamide B (-methyl---styryl-cinnamamide, ) derivatives by various substitution on the amide nitrogen with alkyl, allyl, propargyl, benzyl or ester groups. The structures of nine new compounds were characterized by HRMS, ¹H NMR, and C NMR spectra. These compounds were tested in vitro against 10 strains of phytopathogenic fungi and showed a wide antifungal spectrum. The relationship between different substituents on the amide nitrogen and antifungal activity of Lansiumamide B derivatives were compared and analyzed. The result indicates that the length and steric hindrance of -substitution have a significant impact on biological activities. It is noteworthy that the methyl or ethyl substituent on the amide nitrogen is critical for the antifungal activities.