Design, synthesis and antifungal activities of novel pyrrole alkaloid analogs

A series of novel analogs of pyrrole alkaloid were designed and synthesized by a facile method and their structures were characterized by 1H NMR, 13C NMR and high-resolution mass spectrometry (HRMS). The structure of compound 2a was identified by 2D NMR including heteronuclear multiple-quantum coherence (HMQC), heteronuclear multiple-bond correlation (HMBC) and H–H correlation spectrometry (H–H COSY) spectra. Their antifungal activities against five fungi were evaluated, and the results indicated that some of the title compounds showed moderate fungicidal activities in vitro against Alternaria solani, Cercospora arachidicola, Fusarium omysporum, Gibberella zeae and Physalospora piricola at the dosage of 50 μg mL −1. Compound 2a and 3a exhibited good activities against P. piricola at low dosage. A series of new pyrrole alkaloid analoes were designed, synthesized and tested against fungi in vitro. Their possible structure–activity relationships (SAR) of antifungal activities were discussed. [Display omitted] ► Twenty-nine pyrrole alkaloid analogues were designed and synthesized with a new and facile procedure. ► The results of bioassay showed that the fungicidal activities of most target compounds exhibited moderate activities against Alternaria solani, Cercospora arachidicola, Fusarium omysporum, Gibberella zeae and Physalospora piricola at the dosage of 50 μg mL −1. ► The possible SAR of those target compounds was discussed. ► Compound 2a and 3a exhibited good activities against P. piricola at low dosage.