Fluorination and chlorination of nitroalkyl groups
摘要:
Heterocycles substituted with a nitromethyl (CH2NO2) or phenyl-nitromethyl (CHPhNO2) group were prepared by reaction of a methyl- or phenylmethyl-substituted heterocycle, respectively, with lithium di-isopropylamide followed by quenching the intermediate carbanion with methyl nitrate. Conversion of CH2NO2 attached to an alkyl or aryl moiety into a dichloronitromethyl (CCl2NO2) group was achieved using N-chlorosuccinimide and 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU) in dichloromethane. Similarly, CH2NO2 attached to an alkyl or aryl group was converted into difluoronitromethyl (CF2NO2) using either 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis( tetrafluoroborate) (Selectfluor (TM)) or N-fluorobenzenesulfonimide with DBU as base and dichloromethane as solvent. Reaction of omega-nitroacetophenone with Selectfluor/DBU in dimethylformamide followed by acidification and distillation gave the parent difluoronitromethane in a useful 'one-pot' procedure. (c) 2007 Elsevier Ltd. All rights reserved.
An efficient palladium-catalyzed nucleophilic substitution/C–H activation/aromatization cascade reaction between readily available 2-halo-N-Ms-arylamines (Ms = methanesulfonyl) and benzyl halides/sulfonates has been described. A wide variety of phenanthridines were synthesized in a one-pot fashion in moderate to high yields (37–86 %). Notably, this method provides a straightforward, facile approach
transformation. This reaction features ambient air as the sole oxidant and oxygen source, a broad substrate scope, and excellent functional-group tolerance and proceeds under mild reaction conditions. Furthermore, a highly efficient synthesis of bioactive molecules and natural products including N-methylcrinasiadine, N-isopentylcrinasiadine, N-phenethylcrinasiadine, isoindolo[2,1-b]isoquinolin-5(7H)-one, PJ-34,
Expeditious synthesis of phenanthridines through a Pd/MnO<sub>2</sub>-mediated C–H arylation/oxidative annulation cascade from aldehydes, aryl iodides and amino acids
作者:Jian Fan、Li Li、Jitan Zhang、Meihua Xie
DOI:10.1039/d0cc00300j
日期:——
The expeditious construction of phenanthridine scaffolds via a Pd/MnO2-mediated C-H arylation/oxidative annulationcascade involving aldehydes, aryl iodides and amino acids is disclosed. This reaction proceeds smoothly involving the formation of multiple chemical bonds with the tolerance of a wide range of functional groups. The control experiments suggest a radical mechanism for C-N bond formation
Photocyclization synthesis of phenanthridine and its derivatives under direct dehydrogenation conditions
作者:Wen-Qing Zhu、Jin Zhang、Pan Fan、Lan-Ting Shi、Hong Li、Min-Ge Yang、Yang Li
DOI:10.1016/j.tetlet.2020.152734
日期:2021.2
synthesizing phenanthridines by photocyclization has been established. This method does not require inert gas protection, does not require transition metal catalysts and is environmentally friendly, efficient and convenient. It is proposed to use (E)-N,1-diphenylformimines as substrates to synthesize phenanthridine and its derivatives by ultraviolet light, which provides a new synthesis route for further research