Microwave-assisted synthesis and antifungal activity of novel fused Osthole derivatives

Based on the microwave-assisted synthetic protocol developed in our previous work, we have synthesized a series of novel furo[3,2-c]coumarins as fused Osthole derivatives, via the reaction of 4-hydroxycoumarins and beta-ketoesters catalyzed by DMAP. All the target compounds were evaluated in vitro for their antifungal activity against six phytopathogenic fungi, some compounds exhibited potential activity in the primary assays. Especially compounds 6c, 7b, 813 and 8c (shown in Fig. 1) were the most active ones, EC50 values of these four compounds against Colletotrichum capsica, Botrytis cinerea and Rhizoctonia solani were further investigated. 6c was identified as the most promising candidate with the EC50 value at 0.110 mu M against Botrytis cinerea and 0.040 mu M against Colletotrichum capsica, respectively, representing better antifungal activity than that of the commonly used fungicide Azoxystrobin. (C) 2016 Elsevier Masson SAS. All rights reserved.