protocol for direct C–H alkylation and acylation of N-heterocycles, using readily accessible carboxylic acids as radical precursors under visible-light irradiation without a photocatalyst and an additional acid additive, has been developed. This protocol provides expedient access to substituted N-heterocycles under mild and metal-free conditions. Mechanistic experiments indicate that this reaction proceeds
Synthesis of 6-aroyl phenanthridines by Fe-catalyzed oxidative radical cyclization of 2-isocyanobiphenyls with benzylic alcohols
作者:Ziyi Nie、Qiuping Ding、Yiyuan Peng
DOI:10.1016/j.tet.2016.11.010
日期:2016.12
A practical method for the synthesis of 6-aroyl phenanthridine derivatives by Fe-catalyzed oxidative radicalcyclization of 2-isocyanobiphenyls with benzylic alcohols is described. In addition, this cyclization could be occurred by using toluene as aroyl source. The procedure tolerates various functional groups under simple conditions. A single-electron-transfer pathway is proposed according to mechanistic
type of Minisci reaction for regiospecificacylation of phenanthridine has been developed based on cross dehydrogenative coupling (CDC) strategy. Using substoichiometric amount of TBAB (tetrabutylammonium bromide, 30 mol %) and K2S2O8 as an oxidant, acyl radicals generate from aldehyde substrates under thermal conditions followed by a regiospecific intermolecular acylation with phenanthridine. Furthermore
在这项研究中,基于交叉脱氢偶联(CDC)策略,已开发出一种新型的Minisci反应,用于菲啶的区域特异性酰化。使用亚化学计量的TBAB(四丁基溴化铵,30摩尔%)和K 2 S 2 O 8作为氧化剂,在热条件下由醛底物生成酰基,然后用菲啶进行区域特异性的分子间酰化。此外,初步研究表明,当K 2 S 2 O 8 / TBAB被(NH 4)2 S 2 O 8取代时,酰化反应可以在室温下进行。在可见光照射下,将另外的5mol%的fac- Ir(ppy)3用作光催化剂。该分子间酰化反应提供了容易获得6-酰化菲啶衍生物的途径。
Metal-Free Generation of Acyl Radical via Photoinduced Single-Electron Transfer from Lewis Base to Acyl Chloride
作者:Lei Bao、Zhi-Xiang Wang、Xiang-Yu Chen
DOI:10.1021/acs.orglett.2c03339
日期:2022.11.11
We herein describe a simple approach for generating acyl radical from acyl chloride via photoinduced single-electron transfer. It has been demonstrated that the generated acyl radicals could react with various substrates, including isocyanides, methacrylamides, alkenes, alkynes, and enynes, to afford diverse heterocycles (>10 classes). Mechanistic analyses show that a photoactive charge transfer complex
Photoinduced N-Heterocyclic Nitrenium-Catalyzed Single Electron Reduction of Acyl Fluorides for Phenanthridine Synthesis
作者:Lei Bao、Zhi-Xiang Wang、Xiang-Yu Chen
DOI:10.1021/acs.orglett.3c00049
日期:2023.1.27
Acylfluorides are versatile reagents in organic synthesis. However, there is no precedent to employ acylfluorides as acyl radical precursors. We herein report an N-heterocyclic nitrenium iodide salt-catalyzed photoreduction of acylfluorides to produce acyl radicals, which could react with 2-isocyanobiaryls to afford various carbonyl phenanthridines.