Synthesis and X‐ray study of hexahydro‐ and tetrahydrophospholo‐[2,3‐<i>d</i>]isoxazoles, a new class of heterocycles of potential fungicidal activity

Abstract

Abstract Hexahydro‐, 5b‐1 and 6a,f,1 and tetrahydrophospholo[2,3‐ d ]isoxazoles 8, 9 and 10 were synthesized by 1,3‐dipolar cycloaddition of nitrones 3b‐1 and benzonitrile oxide ( 4 ) to 2,3‐dihydro‐1‐phenyl‐1 H ‐phosphole 1‐oxide ( 1 ) and 2,3‐dihydro‐1‐ethoxy‐1 H ‐phosphole 1‐oxide ( 2 ). The structural assignment to the compounds was confirmed by an X‐ray study of two compounds of the series 5a and 5m . The compounds show a good activity as fungicides against Plasmopara viticola on vines and against Botrytis cinerea on apples. Compounds 5a‐d showed weak to moderate activity as herbicides.