A Method to Access Symmetrical Tetrasubstituted Pyridines via Iodine and Ammonium Persulfate Mediated [2+2+1+1]-Cycloaddition Reaction
作者:Weibing Liu、Hua Tan、Cui Chen、Yupeng Pan
DOI:10.1002/adsc.201601225
日期:2017.5.2
productive preparation of symmetrical 2,3,5,6‐tetrasubstituted pyridines has been developed from α‐substituted arones and N,N‐dimethyl formamide (DMF) using iodine (I2) and ammonium persulfate ((NH4)2S2O8) as mediators. In this process, both DMF and (NH4)2S2O8 play a dual role for the formation of pyridines. DMF acts as the reaction medium and the C4 source (the methyl group of DMF), while (NH4)2S2O8 serves
由α-取代的芳烃和N,N-二甲基甲酰胺开发了一种新颖的无金属[2 + 2 + 1 + 1]-环加成方法,用于快速,高效地制备对称的2,3,5,6-四取代吡啶(使用碘(I 2)和过硫酸铵((NH 4)2 S 2 O 8)作为介体。在这个过程中,DMF和(NH 4)2 S 2 O 8都对吡啶的形成起双重作用。DMF用作反应介质和C4源(DMF的甲基),而(NH 4)2 S 2 O 8用作氧化剂和氮源。值得注意的是,该转化对多种不同的芳族化合物显示出较宽的底物范围,从而以中等至优异的产率得到相应的四取代的吡啶。
Ruthenium-Catalyzed Cyclization of Ketoxime Acetates with DMF for Synthesis of Symmetrical Pyridines
A novel ruthenium-catalyzed cyclization of ketoxime carboxylates with N,N-dimethylformamide (DMF) for the synthesis of tetrasubstituted symmetrical pyridines has been developed. A methyl carbon on DMF performed as a source of a one carbon synthon. And NaHSO3 plays a role in the reaction.
A Pd-catalyzed highly selective direct diarylation of pyridines has been developed using a transient activator strategy. Both (MeO)2SO2 and Cu2O are required for this transformation. The in situ generated N-methylpyridinium salt can be arylated at both 2- and 6-positions under the cooperative Pd/Cu catalysis. A subsequent N-demethylation then gives the 2,6-diarylpyridines. This protocol provides a
已使用瞬态活化剂策略开发了Pd催化的吡啶的高选择性直接二芳基化反应。两者(MEO)2 SO 2和Cu 2需要用于该转化O操作。原位生成的N-甲基吡啶盐可以在Pd / Cu协同催化下在2-位和6-位芳基化。然后,随后的N-去甲基化得到2,6-二芳基吡啶。该协议为对称的2,6-二芳基吡啶提供了一种新颖的合成途径。
Simple Selective Synthesis of 2,4- and 2,6-Diarylpyridines through Metal-Free Cyclocondensation of Aromatic Ketones with Ammonium Acetate
A simple and selective one-pot synthesis of 2,4- and 2,6-diarylpyridines through the cyclocondensation reaction of aromatic ketones with ammonium acetate has been developed. The procedure is metal-free, convenient, and efficient, and the substrates are readily available.