The fungicidal activity of substituted 1, 4-naphthoquinones. Part II: Alkoxy,phenoxy and acyloxy derivatives

A representative group of 1, 4-naphthoquinone derivatives, bearing alkoxy, phenoxy and acyloxy substitutents in the 2-position, has been synthesised and assayed against Botrytis cinerea, Cladosporium fulvum and Venturia inaequalis. The alkoxy compounds exhibited moderate activity, which was enhanced by the presence of a 3-chloro and, to a lesser extent, a 3-bromo substituent. 2-Chloro-3-phenoxy derivatives were highly active, but diphenoxy compounds were inactive. Acyloxy derivatives possessed only weak activity unless a halogen atom was present in the 3-position; benzoyloxy compounds, however, were generally poor fungicides.