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Fluoride Ion‐Promoted α‐Ketol Rearrangement during Unmasking of Silyl‐Protected Medium‐Ring Dihydroxy Ketones
Author(s) -
Hartung Ryan E.,
Hilmey David G.,
Paquette Leo A.
Publication year - 2004
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200404002
Subject(s) - chemistry , steric effects , isomerization , fluoride , alkoxide , silylation , ion , ring (chemistry) , cleavage (geology) , medicinal chemistry , photochemistry , stereochemistry , catalysis , organic chemistry , inorganic chemistry , fracture (geology) , engineering , geotechnical engineering
A new strategy for implementing α‐ketol rearrangements under mild conditions is presented. The reactants are mono‐ and disilylated stereoisomers of α,α′‐ and α,β‐dihydroxycycloheptanones and ‐cyclooctanones. Compounds of this class experience ready deprotection upon treatment with tetrabutylammonium fluoride. In certain examples, this process is accompanied by structural isomerization. Since the product diols are stable to the reaction conditions, these chemical changes have been attributed to kinetically controlled events following transient alkoxide generation resulting from cleavage of the OSi bond proximal to the carbonyl group. The experimental findings are evaluated against a backdrop of calculated (MM3) steric energies of the silicon‐free products and their response to equilibration under strongly basic conditions.