Palladium-Catalyzed Four-Component Cascade Imidoyl-Carbamoylation of Unactivated Alkenes

Abstract

A 1,2-difunctionalization of an unactivated alkene, imidoyl-carbamoylation, has been developed through a palladium-catalyzed four-component cascade reaction involving aryl iodide, alkenyl isocyanide, CO, and amine. Continuous migratory insertion of three different functionalities to the Pd­(II) intermediate generated from the previous step takes place in a well-defined sequence. Four chemical bonds, including three C–C bonds and one C–N bond, are formed in this cascade process, leading to a convenient and convergent access to acetamides substituted with five- to seven-membered cyclic ketoimines. In addition, an extra C–N bond is formed through in situ or postreaction cyclization of the amido NH to the ketoimine moiety, providing a facile one-pot access to pyrrolo-fused heterocycles.

MOF-based Pd catalysts: a controllable and efficient platform towards cyclization reactions of isonitriles

“…Pd-catalyzed transformations of C-N triple bonds have been regarded as a powerful method for the construction of various functionalized N-containing skeletons. [43][44][45][46][47][48][49][50][51][52] Generally, (sub) stoichiometric amounts of alkali and other additives are critical for improving the reaction turnover and selectivity, [53][54][55] which might result in low atom economy and a complex environment of Pd species. Herein, we report the heterogeneous catalyst Pd(II) x -UiO-67-bpy as a controllable and efficient platform to achieve the "homogenization of heterogeneous catalysis" in the cyclization reactions of isonitriles and N-acyl-o-alkynylanilines (Scheme 1b).…”

Synthesis of 7-Arylthiomethyl Dibenzo[b,d]azepines through Imidoylative Heck Cyclization and CPA-Catalyzed Thio-Michael Addition/Enantioselective Protonation

“…In a similar CoCl 2 -catalyzed [5+2] cyclization strategy reported by Zhong, terminal aryl alkynes in addition to symmetric diaryl alkynes also could be used as coupling partners . Very recently, we expanded the C7 substituents on type III dibenzo­[ b , d ]­azepines to acetic amides and esters through a Pd-catalyzed four-component cascade reaction involving aryl iodide, 2-isocyano-2′-vinyl-1,1′-biphenyl, CO, and an amine/alcohol . Although this approach is efficient in creating diversity on this scaffold, an enantioselective version of this reaction was unsuccessful.…”

“…Nevertheless, the benzylic substituents were mainly limited to aryls, and the only alkylated example gave poor enantioselectivity. Continuing our interest in the synthesis of N-heterocycles through Pd-catalyzed cascade reaction involving imidoylation/alkene insertion using alkene-substituted isocyanides, , we envisage that 7-methylene-6-aryl-7 H -dibenzo­[ b,d ]­azepine 2 will be readily accessible via imidoylative Heck reaction by applying 2-isocyano-2′-vinyl-1,1′-biphenyl 1 (Scheme b). Then, α,β-unsaturated cyclic imine 2 can serve as an ideal substrate for Michael addition to generate a stereogenic center.…”

“…7 Very recently, we expanded the C7 substituents on type III dibenzo [b,d]azepines to acetic amides and esters through a Pd-catalyzed fourcomponent cascade reaction involving aryl iodide, 2-isocyano-2′-vinyl-1,1′-biphenyl, CO, and an amine/alcohol. 8 Although this approach is efficient in creating diversity on this scaffold, an enantioselective version of this reaction was unsuccessful. The only successful synthesis of enantioenriched imino dibenzo- [b,d] phosphoric acid (CPA)-catalyzed enamine to imine tautomerization, in which both a stereogenic center and an axis were established simultaneously (Scheme 1a).…”

Switchable Radical Carbonylation by Philicity Regulation

“…基于一氧化碳(CO)作为廉价且丰富的 C1 源的羰基 化反应已成为合成羰基化合物的最有效方法之一, 在工 业和学术界备受关注, 并取得了令人瞩目的进展 [1] . 其 中过渡金属催化烯烃的羰基化反应是一个重要的策略 用于合成包括 β-内酰胺 [2] 、醛 [3] 、烷基羧酸及其衍生 物 [4][5] 等羰基化合物; 另外, 过渡金属催化芳基卤化物 环化羰基化也能用于合成含氮杂环酰胺 [6] 和含氮杂环 酮 [7] . 然而对于过渡金属催化的烯烃及烷基卤化物的羰 基化反应, 通常会遇到金属缓慢的氧化加成和烷基金属 (M-C(sp 3 ))中间体的 β-H 消除反应, 从而得不到目标的 羰基化反应产物.…”