C(NC(C)C)(C)C.C([Li])CCC.[C:13]([NH:17][S:18]([CH3:21])(=[O:20])=[O:19])([CH3:16])([CH3:15])[CH3:14].[CH:22]([C:24]1[CH:29]=[CH:28][N:27]=[CH:26][CH:25]=1)=[O:23]>O1CCCC1.CCCCCC.O>[C:13]([NH:17][S:18]([CH2:21][CH:22]([OH:23])[C:24]1[CH:29]=[CH:28][N:27]=[CH:26][CH:25]=1)(=[O:20])=[O:19])([CH3:16])([CH3:15])[CH3:14]To a solution of diisopropylamine (7.4 ml) in tetrahydrofuran (36 ml) was added dropwise a 1.6 M solution (30 ml) of 1-butyllithium in n-hexane under a nitrogen atmosphere at an inside temperature of from −62° C. to −48° C. over 5 minutes. After stirring for 30 min under ice-cooling, a solution of N-tert-butylmethanesulfonamide (3.63 g) in tetrahydrofuran (15 ml) was added dropwise at an inside temperature of from −60° C. to −50° C. over 5 minutes. After stirring for 1 hr under ice-cooling, the mixture was cooled to an inner temperature of −60° C. again. 4-Formylpyridine (2.74 ml) was added dropwise and after stirring at room temperature for 5 hr, the mixture was left standing overnight. Water (250 ml) was gradually added to the reaction mixture under ice-cooling, and the mixture was extracted 4 times with ethyl acetate. The organic layers were combined and dried over magnesium sulfate and concentrated to dryness under reduced pressure to give N-tert-butyl-2-hydroxy-2-(4-pyridyl)ethanesulfonamide (7.02 g) as a brown oil.
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