[CH3:1][N:2]([CH3:8])[CH2:3][CH2:4][C:5](=[O:7])[CH3:6].[N:9](OC(C)C)=[O:10].C(OCC)C.[ClH:20]>C(O)(C)C>[ClH:20].[OH:10][N:9]=[C:4]([C:5](=[O:7])[CH3:6])[CH2:3][N:2]([CH3:8])[CH3:1]To a solution of 4-dimethylamino-2-butanone[34.5 g, 0.3 moles, described by E. C. du Feu et al., J. Chem. Soc., 56 (1937)] in dry isopropanol (120 ml), gaseous hydrogen chloride is introduced at 0° C. until the solution is acidic to congo red (ca. pH=4). Isopropanol saturated with hydrogen chloride (2 ml) is added. Isopropyl nitrite (29.4 g, 0.33 moles) is added dropwise with stirring while maintaining the reaction temperature at 30° to 35° C. After 30 min, diethyl ether (100 ml) is added and the mixture is stirred for 30 min. The precipitate is collected to obtain 47 g of the title compound, mp 188°-199° C. The latter precipitate is crystallized from ethanol-diethyl ether to obtain 32 g of title compound; mp 205°-206° C., nmr(DMSO-d6) δ 2.4(s), 2.75(s), 4.07(s) and 12.35(broad singlet).
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