Maculosin (cyclo-Pro-Tyr), a host-specific phytotoxin produced by Alternaria alternata on spotted knapweed (Centaurea maculosa), is an ideal prototype for creating a safe and an environmentally friendly antiknapweed herbicide. To evaluate this possibility, a series of 18 maculosin analogs was synthesized and tested in the greenhouse on whole knapweed plants by spray or brush application. Interestingly, many of the maculosin analogs have significant potential as natural herbicides against spotted knapweed. Even the simplest analog, cyclo-Pro-Phe, destroys two thirds of the spotted knapweed foliage at a concentration of 6 × 10-2 mol/L within 15 days. Structure−activity relationships are discussed. Keywords: Cyclodipeptides; herbicides; maculosin; spotted knapweed

A number of substituted 2,2‐dimethyl‐6‐arylidene‐1‐triazol‐1‐ylmethylcyclohexanols and 2,2‐dimethyl‐6‐arylidene‐1‐imidazol‐1‐ylmethylcyclohexanols were prepared from 2‐methylcyclohexanone in four steps: Claisen–Schmidt condensation with substituted benzaldehydes, methylation of the resulting 2‐methyl‐6‐benzylidenecyclohexanones, conversion to the oxiranes by interaction with dimethylsulfonium methylide and reaction of the oxiranes with triazole or imidazole. The compounds obtained were tested for antifungal activity against five phytopathogenic fungi of different taxonomic classes. EC50 values were determined for all compounds. Structure–activity relationships are discussed in broad terms. Some of triazolymethyl‐substituted cyclohexanols obtained are more active than triadimenol. © 1997 SCI.

: A number of substituted 2,2-dimethyl-6-arylidene-1-triazol-1-ylmethylcyclohexanols and 2,2-dimethyl-6-arylidene-1-imidazol-1-ylmethylcyclohexanols were prepared from 2-methylcyclohexanone in four steps : ClaisenÈ Schmidt condensation with substituted benzaldehydes, methylation of the resulting 2-methyl-6-benzylidenecyclohexanones, conversion to the oxiranes by interaction with dimethylsulfonium methylide and reaction of the oxiranes with triazole or imidazole. The compounds obtained were tested for antifungal activity against Ðve phytopathogenic fungi of di †erent taxonomic classes. values EC 50 were determined for all compounds. StructureÈactivity relationships are discussed in broad terms. Some of triazolymethyl-substituted cyclohexanols obtained are more active than triadimenol.

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