Broadhurst, Michael and Brown, Samantha J and Percy, Jonathan and Prime, Michael E (2000) Synthesis of α-hydroxy-β,β-difluoro-γ-ketoesters via [3,3]sigmatropic rearrangements. Journal of the Chemical Society, Perkin Transactions 1, 2000 (19). pp. 3217-3226. ISSN 1472-7781
Readily available γ,γ-difluorinated allylic alcohols obtained from trifluoroethanol were esterified efficiently. Exposure to strong base (LDA) afforded the ester enolates, in which chelation both controlled configuration and stabilised against fragmentation, which were trapped as their silyl ketene acetals. Rearrangement occurred to afford base-sensitive acid products. Esterification under mild conditions afforded the purifiable methyl esters in which the masked ketone had been released. Educts with either a benzyloxy or an allyloxy group at the α-position could be deprotected releasing the alcohols.
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