[CH2:1]([C:3]1([CH3:14])[CH:8]([CH3:9])[CH:7]([OH:10])[CH2:6][C:5]([CH2:12][CH3:13])([CH3:11])[NH:4]1)[CH3:2].[CH3:15][N:16]=[C:17]=[O:18]>C1(C)C(C)=CC=CC=1>[CH3:15][NH:16][C:17](=[O:18])[O:10][CH:7]1[CH2:6][C:5]([CH2:12][CH3:13])([CH3:11])[NH:4][C:3]([CH2:1][CH3:2])([CH3:14])[CH:8]1[CH3:9]4.0 g of 2,6-diethyl-2,3,6-trimethyl-4-piperidinol (Compound 1) and 1.7 g of methyl isocyanate were dissolved in 6 ml of xylene and the solution was refluxed by heating for 3.5 hours. Xylene and excess methyl isocyanate were distilled off under reduced pressure. The residue was purified by column chromatography on silica gel ("60F 254", available from Merck & Co.) using a 4 : 1 by volume mixture of chloroform and methanol as eluent. The product was then distilled under reduced pressure, giving 5.0 g of Compound 66 as a pale yellow liquid (bp 145° - 149° C/1.4 mmHg).
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