Radical addition of R_FI to alkenylsuccinic anhydrides and gem-substituted alkenyl triesters: Zinc and radical induced, or spontaneous radical cyclization, of the δ-iodoalkanoic esters to γ-lactones

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• 作者：Brace ; Neal O.
• 关键词：R_FI free radical addition reactions ; R_F-substituted anhydrides ; Perfluoroalkyl lactones ; Acid catalyzed lactonization ; Homolytic (S_Hi) lactonization ; gem-Dialkyl induced lactonization ; Peroxide induced lactonization
• 刊名：Journal of Fluorine Chemistry
• 出版年：2003
• 出版时间：October 1, 2003
• 年：2003
• 卷：123
• 期：2
• 页码：237-248
• 全文大小：366 K

文摘

Radical addition of R_FI to alkenylsuccinic anhydrides affords ω-(perfluoroalkyl)-δ-iodoalkyl-2-butane-1,4-dioc acid anhydrides, and these adducts are reductively dehalogenated and esterified by zinc and acid in ethanol without lactonization. However, the R_FI adducts react with KOH in ethanol to give the alkenyl half esters (but no γ-lactone), which convert to the γ-lactones by acid catalysis. When treated with water, ethanol, Zn and 48 % HBr, the R_FI adduct from but-3-en-2-yl-succinic anhydride converts to the iodo half ester, R_FCH₂CHICH(CH₃)CH(CO₂H)CH₂CO₂Et, which undergoes Zn induced (S_Hi) conversion to γ-lactone. R_FI (AIBN) and the triester CH₂CHCH₂C(CO₂Et)₂CH₂CO₂Et yield R_FCH₂CHICH₂C(CO₂Et)₂CH₂CO₂Et (95 % ). When heated to 140°C, the adduct loses iodoethane.and cyclizes to diester γ-lactones (94 % ). With benzoyl peroxide, R_FI and the triester at 99°C, spontaneous radical cyclization of the adduct to lactone occurs. Evidently, the gem-disubstituted triester readily forms a five-membered lactone as a consequence of steric compression in the open chain form.