Schmeda-Hirschmann, G.; Astudillo L. Instituto de Química de Recursos Naturales, Universidad de Talca, Casilla Talca, 747, Chile. Sandoval, C. Laboratorio de Fitopatologi­a, Facultad de Ciencias Agrarias, Universidad de Talca, Talca, ChileThe novel acetophenone derivative 2′,4′-dihydroxy-3′-methoxymethyl-5′-methylacetophenone and the known 2′,4′-dihydroxy-3′,5′-dimethylacetophenone (clavatol) were isolated from the culture filtrate of a Chilean strain of Trichoderma pseudokoningii.