Synthesis of substituted 3-arylpiperidines and 3-arylpyrrolidines by radical 1,4 and 1,2-aryl migrations
作者:Alexandru Gheorghe、Béatrice Quiclet-Sire、Xavier Vila、Samir Z. Zard
DOI:10.1016/j.tet.2007.04.091
日期:2007.7
A route to 3-arylpiperidines and 3-arylpyrrolidines involving radical 1,4- and 1,2-aryl migrations has been explored. For the piperidines, the first route requires a xanthate addition to an N-allylarylsulfonamide, followed by acetylation and treatment with lauroyl peroxide to give the corresponding 1,4-aryl transfer product. This compound can be converted into the desired piperidine derivative following
xanthate-based radicaladdition/cyclization reaction cascade toward 2-biphenylisocyanides is described as a practical and modular approach to 6-alkylated phenanthridines. The use of xanthates as radical precursors allowed the synthesis of diversely 6-substituted phenanthridines. Electrophilicradicals derived from nitriles, aromatic and aliphatic ketones, malonates, and amide derivatives, as well as radicals
A simple and efficient method to obtain α-xanthylmethyl ketones from α-diazo ketones is described. The reaction proceeds through a protonation/nucleophilic substitution sequence in the presence of p-toluenesulfonic acid and potassium ethyl xanthogenate as the nucleophile. As α-diazo ketones can be readily synthesized from ubiquitous carboxylic acids, a broad variety of xanthates can be obtained, including