Site selectivity, regioselectivity and stereoselectivity of [2 + 3] cycloaddition of 4-trifluoromethylbenzonitrile oxide to polyunsaturated medium size rings including 1,5,9-cyclododecatriene, 11-membered sesquiterpenes, 1,3-cyclooctadiene and 5-vinyl-2-norbornene were examined. Site selectivity was correlated with electron charges of alkenyl carbon atoms. Structure of the products has been established by an extensive application of 1D and 2D 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization mass spectrometry. Some of the obtained products showed moderate fungicidal activities.

A series of new 3-substituted isoxazolecarboxamides have been prepared from aldehydes. The key step was a 1,3-dipolar cycloaddition reaction of nitrile oxides to α,β-unsaturated esters and amides. The cycloadditions to amides were mediated by chiral ligands and several products displayed excellent enantioselectivities. Some of the title compounds exhibited good fungicidal activities against Alternaria alternata, Botrytis cinerea, Fusarium culmorum, Phytophthora cactorum, and Rhizoctonia solani strains.

Una serie de nuevas isoxazolcarboxamidas 3-sustituidas se prepararon a partir de aldehídos. El paso clave fue la reacción de cicloadición dipolar-1,3 de óxidos de nitrilo con ésteres o amidas α,β-insaturados. Las cicloadiciones con amidas fueron llevadas a cabo en presencia de ligantes quirales, y varios productos mostraron excelentes enantioselectividades. Algunos de los compuestos preparados mostraron buena actividad fungicida contra las cepas de Alternaria alternata, Botrytis cinerea, Fusarium culmorum, Phytophthora cactorum y Rhizoctonia solani.