[H-].C([Al+]CC(C)C)C(C)C.[SH:11][C:12]1[O:13][C:14]2[C:20]([C:21](OC)=[O:22])=[CH:19][CH:18]=[CH:17][C:15]=2[N:16]=1.Cl>C1(C)C=CC=CC=1.C1COCC1>[OH:22][CH2:21][C:20]1[C:14]2[O:13][C:12]([SH:11])=[N:16][C:15]=2[CH:17]=[CH:18][CH:19]=1A 1.0M solution of diisobutyl aluminum hydride in toluene (10 ml) was slowly dropped, under argon atmosphere at −78° C., into a solution of 2-mercapto-7-methoxycarbonylbenzoxazole (1.1 g, 5.0 mmol) in THF (20 ml) followed by stirring for 30 minutes. At that temperature, a 1.0M solution of diisobutyl aluminum hydride in toluene (5 ml) was slowly dropped thereinto followed by stirring for 30 minutes. After cooling, diluted hydrochloric acid was added to the reaction mixture to decompose the excessive diisobutyl aluminum hydride, after then extracted with ethyl acetate. The organic layer was washed with diluted hydrochloric acid solution and a saturated sodium chloride solution, dried over sodium sulfate and the solvent was evaporated therefrom. The resulting crude product was recrystallized from hexane-acetone-methanol to provide 848 mg (yield 94%) of 7-hydroxymethyl-2-mercaptobenzooxazole as colorless needles.
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