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0 °C

Prepared by a procedure similar to Example 9, where sodium hydride (60% dispersion in mineral oil 56 mg, 1.4 mmol) and propionamidoxime (123 mg, 1.4 mmol) were suspended in dry THF in an oven dried round bottom flask with stirring under nitrogen at 0° C. After 15 minutes stirring the ice bath was removed and the grey suspension refluxed 45 minutes to give a white suspension. 1-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (540 mg, 1.4 mmol) was added, dissolved in dry THF and reflux continued 18 hours. The solvents were evaporated in vacno and the residue was chromatographed (silica, chloroform/methanol 9:1) to yield 1-triphenylmethyl-1,4,5,6-tetrahydro-5-(3-ethyl-1,2,4-oxadiazol-5-yl)pyrimidine 420 mg (70%). This product was dissolved in trifluoroacetic acid (2 mL), with stirring at room temperature for 24 hours. The yellow solution was then evaporated in vacuo, and the residue recrystallized from methanol/ether to yield 144 mg (49%) white crystals, mp 116°-118° C. identified by 300 MHz nmr.

1. customdried round bottom flask
2. stirringAfter 15 minutes stirring the ice bath
3. customwas removed
4. temperaturethe grey suspension refluxed 45 minutes
5. customto give a white suspension
6. temperaturereflux
7. customThe solvents were evaporated in vacno
8. customthe residue was chromatographed (silica, chloroform/methanol 9:1)