A complementary and general strategy for the oxidative generation of iminyl radicals from the readily available α-imino-oxy acids has been established through silver-catalyzed decarboxylation. To demonstrate its synthesis utility, the direct C–H cyanoalkylation of heterocycles and quinones with cyclic α-imino-oxy acids via the iminyl radical-mediated C–C bond cleavage is developed. This cost-effective method takes place under mild reaction conditions and exhibits a broad substrate scope.

A new method for the iodocyclization of olefinic dicarbonyl compounds with t-butyl hydroperoxide (TBHP) and I 2 was developed. The in situ generated hypoiodous acid and t BuOI were used as active iodine cation reagents. This method allowed the synthesis of polysubstituted 5-iodomethyldihydrofurans under mild reaction conditions with cheap reagents and high atom economy. Keywords iodocyclization; olefinic dicarbonyl compounds; dihydrofurans; TBHP; I 2 烯烃的碘环化反应是构建碘代环状化合物的重要 策略 [1,2] , 由于碘取代基可进一步发生各种官能团化, 因 此, 该反应被广泛应用于生物活性物质和天然产物的合 成 [3～6] . 烯烃的碘环化反应可通过自由基机理 [7] 和离子 型机理 [8] 进行, 其中离子型碘环化反应由于底物适用范 围广, 应用更加广泛. 离子型碘环化机理首先是碳-碳 双键被碘正离子试剂活化, 再与分子内的亲核官能团发 生亲核加成 [1,8] . 常用的碘正离子试剂有 Barluenga 试剂 (I(Py) 2 BF 4 ) [9] 、一氯化碘(ICl) [10] 、N-碘代丁二酰亚胺 (NIS) [11] 等. 最近, 还有通过碘苯二乙酯(PhI(OAc) 2 )氧化 碘代三甲基硅烷(TMSI)原位形成 I ＋ 并应用于碘环化反 应的报道(图 1a) [12] . 但这些碘试剂均存在原子经济性 差、成本较高的缺点.单 质 碘 (I 2 ) 是 一 种 用 途 广 泛 、 廉 价 易 得 的 碘 试 剂 [13,14] . 尽管可以通过 I 2 -π 复合物活化烯烃进行碘环化 反应, 但理论上只有一半的碘原子可被利用. 更重要的 是, 由于活性较低, 往往需要添加大大过量的单质碘, 而且需要加入碱来中和产生的碘化氢(图 1a) [15～17] . 因 此, 近年来通过在单质碘参与的反应中加入环境友好的 氧化剂, 如叔丁基过氧化氢(TBHP)或双氧水来提高单 质 I 2 的碘原子利用率或反应活性受到人们的广泛关 注 [18～22] . 例如我们课题组最近基于 I 2 /TBHP 体系发展了 一种不饱和肟的碘环化合成碘代异噁唑啉的反应, 该反 应的碘原子理论利用率为 100%(图 1b) [8] . 为了进一步拓 展这一方法的适用范围, 本文报道了 I 2 /TBHP 体系介导 烯基化二羰基化合物的碘环化反应, 合成了 5-碘甲基二 氢呋喃衍生物(图 1b).

A radical-mediated approach to alkene oxyallylation using allylic oximes is described. The reaction proceeds under copper-catalytic redox-neutral conditions and tolerates various functional groups. This protocol thus enables the synthesis of structurally valuable isoxazolines and the introduction of a versatile olefin motif in a single step.

An iminyl-radical-mediated cyanoalkylarylation of α,β-unsaturated imides with cyclic α-imino oxy acids leading to isoquinoline-1,3(2H,4H)-dione derivatives has been developed. The procedure involves the generation of iminyl radicals through silver-catalyzed oxidative decarboxylation, followed by a C–C bond cleavage, cyanoalkylation, and C–H-functionalization cascade.