Synthesis and herbicidal activity of 3-substituted toxoflavin analogs

Abstract

We investigated the synthesis and herbicidal activity of 23 toxoflavin analogs, 1a-w, in which aromatic rings (R) were introduced into the C-3 position. In paddy field conditions, 1k (R=2-CF 3 -C 6 H 4 ) and 1w (R=2-thienyl) showed excellent herbicidal activity. Under upland field conditions, we found that toxoflavin analogs 1a (R=C 6 H 5 ), 1n (R=2-CH 3 O-C 6 H 4 ), and 1p (R=4-CH 3 O-C 6 H 4 ) exhibited wide herbicidal spectrum against Echinochloa crus-galli (L) var. crus-galli (ECHCG), Chenopodium album, and Amaranthus viridis (AMAVI). The analog with the 2-fluoro group on benzene ring 1b also showed high herbicidal activity against both ECHCG and AMAVI.