Solvent/Oxidant-Switchable Synthesis of Multisubstituted Quinazolines and Benzimidazoles via Metal-Free Selective Oxidative Annulation of Arylamidines
摘要:
A fast and simple divergent synthesis of multisubstituted quinazolines and benzimidazoles was developed from readily available amidines, via iodine(III)-promoted oxidative C(sp(3))-C(sp(2)) and C(sp(2))-N bond formation in nonpolar and polar solvents, respectively. Further selective synthesis of quinazolines in polar solvent was realized by TEMPO-catalyzed sp(3)C-H/sp(2)C-H direct coupling of the amidine with K2S2O8 as the oxidant. No metal, base, or other additives were needed.
Solvent/Oxidant-Switchable Synthesis of Multisubstituted Quinazolines and Benzimidazoles via Metal-Free Selective Oxidative Annulation of Arylamidines
摘要:
A fast and simple divergent synthesis of multisubstituted quinazolines and benzimidazoles was developed from readily available amidines, via iodine(III)-promoted oxidative C(sp(3))-C(sp(2)) and C(sp(2))-N bond formation in nonpolar and polar solvents, respectively. Further selective synthesis of quinazolines in polar solvent was realized by TEMPO-catalyzed sp(3)C-H/sp(2)C-H direct coupling of the amidine with K2S2O8 as the oxidant. No metal, base, or other additives were needed.
Electron Transfer Chain Reactions in the Alkylation of Isonitriles by Alkylmercury Halides.
作者:Glen A. Russell、Ragine Rajaratnam、Ping Chen、Olle Matsson、Jadwiga Trocha-Grimshaw、Ole Hammerich、Inger Søtofte、Bengt Långström
DOI:10.3891/acta.chem.scand.52-0528
日期:——
Imidoyl (PhN=CR.) or acyl (RCO.) radicals undergo electron transfer to alkylmercury halides in Me2SO or PhH solution. Addition of t-Bu-. or i-Pr-. to isonitriles followed by electron transfer forms the nitrilium ion which is converted into the amide in Me2SO; into the imidoyl halide in PhH, and into the amidine in PhH solution containing primary or secondary amines.
Transition Metal-Free Visible Light-Driven Photoredox Oxidative Annulation of Arylamidines
作者:Zi-chao Shen、Pan Yang、Yu Tang
DOI:10.1021/acs.joc.5b02366
日期:2016.1.4
A fast catalytic synthesis of multisubstituted quinazolines from readily available amidines via visible light-mediated oxidative C(sp(3))-C(sp(2)) bond formation has been established. This reaction is a metal-free oxidative coupling catalyzed by a photoredox organocatalyst. The protocol features low catalyst loading (1 mol %).