Studies on Plenolic Lactones

Part V. General Route to Substituted β-Benzyl-γ-butyrolactones and an Alternate Synthesis of (±) Hibalactone

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Substituted β-benzyl-γ-butyrolactones were synthesized. Hydrolysis and decarboxylation of ethyl α-allyl-α-benzyl malonate gave α-allyl-α-benzyl acetic acid. Esterification of the acid and subsequent reduction with lithium aluminum hydride afforded β-benzyl-β-allyl ethanol. Oxidation of the double bonds with potassium permanganate followed by periodate treatment, silver oxide oxidation and lactonization yielded β-benzyl butyrolactones. Thus β-benzyl-, β-piperonly-, β-3, 4, 5-trimethoxybenzyl- butyrolactone were prepared.
Condensation of piperonal and β-piperonyl-γ-butyrolactone with sodium ethylate afforded (±) hibalactone