摘要:
2-Substituted oxetan-3-ones can be prepared in good yields and enantioselectivities (up to 84% cc) by the metalation of the SAMP/RAMP hydrazones of oxetan-3-one, followed by reaction with a range of electrophiles that include alkyl, ally!, and benzyl halides. Additionally, both chiral 2,2- and 2,4-disubstituted oxetan-3-ones can be made in high ee (86-90%) by repetition of this lithiation/allcylation sequence under appropriately controlled conditions. Hydrolysis of the resultant hydrazones with aqueous oxalic acid provides the 2-substituted oxetan-3-ones without detectable racemization.