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 diff erent structural modifications have been introduced: substitution of the al iphatic side chain present in the natural products (1-4) by other groups fr equently found in other active compounds and use of other nitrogen-containi ng five-membered rings with different degrees of oxidation. In this way, th e insecticidal and fungicidal activities have been improved. Thus, compound 9, which posseses a 3-pyrroline ring, exhibited important insecticidal act ivity against third-instar nymphs of Oncopeltus fasciatus Dallas (100% mort ality at 7.5 mu g/cm(2)). Remarkable fungicidal activity was also found, an d preliminary structure-activity relationships could be established.