Radical annulations with nitriles: Novel cascade reactions of cyano-substituted alkyl and sulfanyl radicals with isonitriles

Synthesis of Fused Quinoline and Quinoxaline Derivatives Enabled by Domino Radical Triple Bond Insertions

“…Control experiments verified the necessity of the base, photocatalyst and irradiation (entries 5-7). Solvent screening showed that DMA was the best solvent in terms of selectivity for 5 a (entries [8][9][10][11][12][13][14]. The yield for the desired product 5 a was further increased to 69 % by increasing the reaction temperature to 50 8C and a 26 % yield of byproduct 6 a was isolated (entry 15).…”

“…Curran and coworkers demonstrated beautiful domino radical isocyanide/ alkyne insertions to deliver fused quinoline derivatives, [7] and Nanni and co-workers reported elegant domino radical isocyanide/cyanide insertions to provide quinoxalines. [8] All these classic works are mediated by toxic tin and assisted by harmful ultraviolet irradiation or elevated temperature, which restrains their synthetic applications. Based on our previous findings, we believe that these disadvantages could be addressed by using a visible-light-mediated photoredox technique.…”

A Novel Tin‐Free Procedure for Alkyl Radical Reactions

“…Evaporation of the final reaction mixtures removes simultaneously solvent, excess isocyanide, by‐product isothiocyanate, and excess olefin giving the pure adducts 8 . Chromatography is sometimes needed to further purify compounds 8 and remove trace amounts of side products 20…”

“…[b] This compound is an important intermediate for the synthesis of crop protection agents; see Supporting Information, ref. 20. [c] Partial or total decomposition of product was observed by column chromatography.…”

Light-Induced Iminyl Radicals: Generation and Synthetic Applications

“…The formation of a tetracyclic heteroarene initiated by irradiation of an aromatic disulfide, with cleavage of an S-S bond, is shown in Scheme 23. The intermolecular addition of the sulfanyl radical to isonitriles gave an imidoyl radical, which was able to add to a nitrile to provide an iminyl radical that cyclizes to complete the cascade reaction (Camaggi et al, 1998;Nanni et al, 2000). The preparation of rings A-D of the alkaloids camptothecin and mappicine has been achieved in good yield using this protocol (Bowman et al, 2001;.…”