4 dimethyl 4 5 dihydro oxazole in 4 ml nitromethane was added 0 78 ml 12 mmol methyl iodide and the mixture heated in a sealed tube to 60 u00b0 c for 18 h the brown solution was diluted with tert butyl methyl ether the suspension filtered and the precipitate washed with tert butyl methyl ether and dried 2 2 methoxy 3 methyl 4 trifluoromethyl phenyl 3 4 4 trimethyl 4 5 dihydro oxazol 3 ium iodide was obtained as off white powder ms isp 302 1 m a solution of 515 mg 1 2 mmol 2 2 methoxy 3 methyl 4 trifluoromethyl phenyl 3 4 4 trimethyl 4 5 dihydro oxazol 3 ium iodide in 5 ml methanol and 5 ml 20 naoh was heated to 70 u00b0 c for 17 h the yellow solution was cooled to rt methanol was distilled off the residue acidified with conc hcl to ph 1 and extracted three times with tert butyl methyl ether the combined organic phases were washed twice with brine dried over na 2 so 4 filtered and evaporated 2 methoxy 3 methyl 4 trifluoromethyl benzoic acid was obtained as yellow solid ms isn 233 04 m u2212 h u2212 to u2212 75 u00b0 c cooled thf 70 ml was added dropwise 36 ml 50 0 mmol of a 1 4 m sec buli solution in cyclohexane within 5 minutes keeping the temperature below u2212 70 u00b0.