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Carbonyl Homologation Via Α-Trimethylsilyl Β-Lactone Rearrangement: A Nonbasic Wittig Alternative, Yong Zhang

Masters Theses

Our research group has been interested in β-lactones as useful synthetic intermediates. Transformations of β-lactones, generally ring expansion/opening processes initiated by Lewis acids via ionization/cation-rearrangement or elimination mechanisms, provide efficient protocols for the syntheses of biologically important butyrolactones, β,γ-unsaturated carboxylic acids, or butenolides.

α-Trimethylsilyl β-lactones, synthesized via the BF₃- catalyzed [2+2] cycloaddition of trimethylsilylketene to carbonyl compounds, spontaneously undergo ionization and trimethylsilyl group migration to form α,β-unsaturated trimethylsilyl esters. The trimethylsilyl moiety facilitates the ionization process because of its β-cation stabilizing ability. The two-carbon homologated α,β-unsaturated acids are formed in yields from moderate to high (41-99%) upon aqueous …