α-Trifluoroacetyl-δ-valerolactone: synthesis, acyl-lactone rearrangement and unexpected easy decarboxylation of the rearranged product

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• 作者：Sevenard ; Dmitri V. ; Lork ; Enno
• 关键词：Fluorinated 1 ; 3-ketoesters ; Lactones ; Enol ; Acyl-lactone rearrangement ; Pyrans ; X-ray analysis
• 刊名：Journal of Fluorine Chemistry
• 出版年：2004
• 出版时间：January 1, 2004
• 年：2004
• 卷：125
• 期：1
• 页码：125-128
• 全文大小：115 K

文摘

Claisen condensation of δ-valerolactone and ethyl trifluoroacetate leads to α-trifluoroacetyl-δ-valerolactone, existing completely in CDCl₃ solution as an enol. Upon treatment of this cyclic 1,3-ketoester with aqueous HCl, an acyl-lactone rearrangement takes place. The structure of the resulting pyran was confirmed by an X-ray analysis. The ability of the rearrangement product to lose its carboxylic group under unexpected mild conditions was used for the synthesis of the corresponding 3-unsubstituted cyclic hemi-ketal.