Preparation of substituted 3-aryl-5-trifluoromethyl-1,2,4-oxadiazoles

A process for preparing an oxadiazole compound of formula I,

• wherein
• A is phenyl or a 5- or 6-membered aromatic heterocycle;
• wherein the ring member atoms of the aromatic heterocycle include besides carbon atoms 1, 2, 3, or 4 heteroatoms selected from N, O, and S as ring member atoms with the provision that the heterocycle cannot contain 2 contiguous atoms selected from O and S;
• and wherein A is further unsubstituted or further substituted with additional n identical or different radicals RA;
• wherein
• n is 0,1, 2, 3, or 4;
• RA is independently selected from the group consisting of halogen, cyano, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, and C1-C6-haloalkoxy;
• R is methyl, which is further unsubstituted or further substituted with additional 1, 2, or 3 identical or different radicals RX;
• wherein
• RX is hydrogen, halogen, oxo, or OH;
• the process comprising reacting an amidoxime compound of formula II,
• wherein the variables A and R are as defined above for compounds of formula I, with a haloacetic ester of formula II.a,
• wherein R5 is C1-C6-alkyl;
• in the presence of a base;
• wherein the process is conducted in the absence of an auxiliary solvent.