Synthesis and biological evaluation of new analogues of the active fungal metabolites N-(2-methyl-3-oxodecanoyl)-2-pyrroline and N-(2-methyl-3-oxodec-8-enoyl)-2-pyrroline (II)

New analogues of the bioactive enamides isolated from P. brevicompactum (2 and 3) have been synthesized to improve the biological activities. Two different structural modifications have been introduced: substitution of the aliphatic side chain present in the natural products (1-4) by other groups frequently found in other active compounds and use of other nitrogen-containing five-membered rings with different degrees of oxidation. In this way, the insecticidal and fungicidal activities have been improved. Thus, compound 9, which possess a 3-pyrroline ring, exhibited important insecticidal activity against third-instar nymphs of Oncopeltus fasciatus Dallas (100% mortality at 7.5 microg/cm(2)). Remarkable fungicidal activity was also found, and preliminary structure-activity relationships could be established.