Abstract
The synthesis and enantioselective α-deprotonation—double ring opening of 6,7-epoxy-8-azabicyclo[3.2.1]octanes 5 using organolithiums in the presence of (−)-sparteine or (4 S)-2,2′-(1-ethylpropylidene)bis-4-(1-methylethyl)-4,5-dihydrooxazole, giving amino cycloheptenols in up to 85% yield and 82% ee is described. The impact of different reaction variables on reaction profiles has been studied, including the nature of organolithium, solvent, ligand, temperature and epoxide structure. The reactions proved to be dependent on all these variables, in particular on the structure of substrate. A mixed organolithium system (Pr iLi/TMSCH 2Li) has been successfully used to introduce potentially versatile allylsilane functionality.
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