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
annulation between 2-aminobiphenyls and activated olefins is disclosed for succinct synthesis of valuable phenanthridine scaffolds. The protocol avails a common organic functional group, free amine, as a directing group and represents a unique combination of C–Hactivation/annulation/C–C bond cleavage cascade that bodes well in the production of bioactive alkaloids including trisphaeridine and bicolorine
Catalytic Oxidative Cyclization of 2′-Arylbenzaldehyde Oxime Ethers under Photoinduced Electron Transfer Conditions
作者:Julie L. Hofstra、Brittany R. Grassbaugh、Quan M. Tran、Nicholas R. Armada、H. J. Peter de Lijser
DOI:10.1021/jo502324z
日期:2015.1.2
sequence is initiated by an electron transfer step followed by nucleophilicattack of the aryl ring onto the nitrogen of the oxime ether. A concave downward Hammett plot is presumably the result of a change in charge distribution in the radical cation species with strongly electron-donating substituents that yields a less electrophilic nitrogenatom and a decreased amount of cyclized product. The reaction
An I2-mediated synthesis of phenanthridines via intramolecular sp3 C-H amination of readily accessible aniline precursors is reported. The present synthetic process is straightforward and applicable to a broad variety of unprotected aniline substrates, and provides facile and efficient access to phenanthridine derivatives. This C-H amination protocol does not use transition metals, is operationally
with diazo compounds has been achieved, giving rise to two types of prevalent phenanthridines via highly selective C–C cleavage. Compared to the simple N–H insertion manipulation of diazo, this method elegantly accomplishes a tandem N–H insertion/SEAr/C–C cleavage/aromatization reaction, and the synthetic utility of this new transformation is exemplified by the succinct syntheses of trisphaeridine and