A unique transition-metal-free C(sp3)–H/C(sp3)–H dehydrocoupling of N-benzylimines with saturated heterocycles is presented using 2-azaallyl anions as super electron donors to initiate the generation of hydrogen atom abstracting aryl radicals.

Benzofurans are among the most popular structural units in bioactive natural products,h owever,t he synthesis of such structures by radical cyclization cascade reactions is rare. Herein, we report am ild and broadly applicable method for the construction of complex benzofurylethylamine derivatives through au nique radical cyclization cascade mechanism. Single-electron transfer (SET) from 2-azaallyl anions to 2-iodo aryl allenyl ethers initiates aradical cyclization that is followed by intermolecular radical-radical coupling. This expedient approach enables the synthesis of ar ange of polycyclic benzofurans that would otherwise be difficult to prepare.

The synthesis of a series of novel N-substituted tetrahydro-β-carboline-imidazolium salt derivatives is presented. The biological properties of the compounds were evaluated in vitro against a panel of human tumor cell lines. The results suggest that the benzimidazole ring and 1-(naphthalen-2-yl)ethan-1-one or 2-naphthylmethyl substituent at the imidazolyl-3-position were vital for modulating cytotoxic activity. Compound 41 was observed as a potent derivative with IC values of 3.24-8.78 μM and exhibited cytotoxic activity selectively against HL-60, A-549 and MCF-7 cell lines. Meanwhile, high inhibitory activities selectively against HL-60 and MCF-7 cell lines were observed for compound 51. Moreover, compound 51 was able to induce G1 phase cell cycle arrest and apoptosis in MCF-7 cells. The cytotoxicity of compound 51 against human normal lung epithelial cell line BEAS-2B was further evaluated.

Isochromenes are important pharmacophores present in biologically active molecules and natural products. Their synthesis is generally limited to cyclization of phenyl propargyl ether precursors under transition metal catalyzed conditions. Herein, we present a novel disconnection that rapidly constructs isochromene derivatives through a cascade radical cyclization strategy. Generation of aryl radicals by SET reduction of 2-iodo benzyl allenyl ethers is followed by radical cyclization to construct the isochromene core with formation of an allylic radical. The allylic radical then undergoes coupling with the azaallyl radical to give products in good to excellent yields. The elaborated 2-iodo phenyl propargyl ether precursors can be used to construct isochromenes bearing various functional groups.