[C:1](=[N:4][NH2:5])([CH3:3])[CH3:2].C([O-])([O-])=O.[K+].[K+].[C:12](Cl)(=[N:19][OH:20])[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1.C(OCC)(=O)C>C(Cl)(Cl)Cl.C(Cl)Cl.O>[CH3:2][C:1]1([CH3:3])[O:20][N:19]=[C:12]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[N:4]1[NH2:5]A solution of isopropylidene-hydrazine (0.59 g, 8 mmol) in 15 mL of chloroform and an aqueous solution of K2CO3 (0.5 g in 3 mL of water) were mixed and cooled in a 50 mL round-bottom flask chilled with ice water. A solution of benzohydroximoyl chloride (0.51 g, 3.2 mmol) in 10 mL of chloroform was added slowly with vigorous magnetic stirring. The ice batch was replaced with a 40° C. water bath and the mixture was stirred at 40° C. for 2 hours and then monitored by TLC (1:1 ethyl acetate:hexanes). When progression of the reaction began to significantly decelerate, the mixture was worked up by the addition of 10 mL of water and 60 mL of chloroform or methylene chloride. The organic layer was removed in a separatory funnel, dried over MgSO4, and the solvent removed on a rotary evaporator to yield a semi-solid. The crude product was triturated with 2% ether in hexanes (30 mL), by magnetic stirring in a round bottom flask or manipulating the material with a spatula. Filtration and air-drying provided 5,5-dimethyl-3-phenyl-[1,2,4]oxadiazol-4-ylamine in ca. 40% yield. 1H-NMR (300 MHz, CDCl3) δ (ppm): 7.77 (m, 2H), 7.48 (m, 3H), 3.4 (br), 1.55 (s, 6H).
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