A metal-free cyclization of olefinic dicarbonyl compounds for the synthesis of various 5-halomethyl-4,5-dihydrofurans is presented. Using (diacetoxyiodo)benzene as the reaction promoter and halotrimethylsilane as the halogen source, the intramolecular haloenolcyclization of the 2-allyl-1,3-dicarbonyl compounds smoothly proceeded, leading to the corresponding 5-halomethyl-4,5-dihydrofurans in good to excellent isolated yields. Moreover, the resulting 5-iodomethyl products could be converted to functionalized furans in almost quantitative yields by treatment with DBU followed by acid-catalyzed rearrangement. The reactions could be carried out on a gram scale and did not require harsh reaction conditions. The good isolated yields, mild conditions, and operational simplicity make this reaction a viable method for the construction of different dihydrofuran and furan structures.

中文翻译：

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通过PhI（OAc）₂促进烯烃二羰基化合物的卤烯醇环化制备多取代的二氢呋喃

提出了用于合成各种5-卤代甲基-4,5-二氢呋喃的烯烃二羰基化合物的无金属环化。使用（二乙酰氧基碘）苯作为反应促进剂和卤代三甲基硅烷作为卤素源，2-烯丙基-1,3-二羰基化合物的分子内卤代烯醇环化反应顺利进行，得到了相应的5-卤代甲基-4,5-二氢呋喃。优良的孤立产量。此外，通过用DBU处理然后酸催化的重排，可以以几乎定量的产率将所得的5-碘甲基产物转化为官能化的呋喃。反应可以以克为单位进行，并且不需要苛刻的反应条件。良好的单产，温和的条件，