Chenopodolans E and F, two new furopyrans produced by Phoma chenopodiicola and absolute configuration determination of chenopodolan B

Two new furopyrans, named chenopodolans E and F (1 and 2), were isolated from the liquid culture of Phoma chenopodiicola, a fungal pathogen proposed for the biological control of Chenopodium album, a common worldwide weed of arable crops. They were characterized using spectroscopic methods as 3-(3-methoxy-2,6-dimethyl-7aH-furo[2,3b]pyran-4-yl)-but-2-enoic acid methyl ester and 1-(3-methoxy-2,6-dimethyl-7aH-furo[2,3b]pyran-4-yl)-ethanone, respectively. Furthermore, the absolute configuration of chenopodolan B (3) was established to be (7aR,9S) by a combined application of the advanced Mosher's method and of quantum mechanical calculations of chiroptical (ECD and ORD) properties. When 1 and 2 were assayed on punctured leaves at 2 μg/μL, only 2 was active on Sonchus arvensis while 1 caused around 75% larval mortality on Artemia salina larvae at 0.1 μg/μL.