Scaffold Hopping in Agrochemical Research: Discovery of Insecticidal 4-Pyridyl Isobenzofurans

The insecticidal activity of pyridine compounds substituted at the 4-position with lipophilic groups has been reported in recent agrochemical patent applications. Encouraged by these reports, 4-pyridyl dihydroisobenzofuran(one)s were designed to test scaffold-hopping hypotheses with the goal of discovering new insecticidally active areas of chemistry. A series of 4-pyridyl dihydroisobenzofuran(one)s were synthesized, and their activity against key sap-feeding insect pests (silverleaf whitefly, Bemisia tabaci; green peach aphid, Myzus persicae) was assessed. Many of these compounds showed strong activity (comparable to commercial standards) against B. tabaci and were also active against M. persicae, although activity on this pest was somewhat weaker. Investigative biology studies indicated that these compounds were active on early life stages of B. tabaci but lacked significant activity on adults.