2298-07-9Relevant articles and documents
Direct cyanation of picolinamides using K4[Fe(CN)6] as the cyanide source
Guan, Dinghui,Han, Lu,Wang, Lulu,Song, He,Chu, Wenyi,Sun, Zhizhong
, p. 743 - 745 (2015)
The efficient, simple, and environment-friendly route of direct cyanation of picolinamides has been developed with nontoxic K4[Fe(CN)6] as the cyanide source through Pdcatalyzed C-H bond activation. A series of N-(naphthalene-1- yl)picolinamide derivatives were successfully transformed to the corresponding cyanation products. The cyanation mechanism has also been speculated.
Mild and Selective Method of Bromination of Flavonoids
Hurtová, Martina,Biedermann, David,Kuzma, Marek,K?en, Vladimír
, p. 3324 - 3331 (2020/11/30)
A new method was developed for the mild and selective bromination of simple aromatic compounds and flavonoids in good yields using α,β-dibromohydrocinnamic acid in the presence of a base. This procedure enables selective mono- or dibromination of compounds highly sensitive to oxidative or radical attack. New brominated derivatives of silymarin flavonolignans and related flavonoids were prepared. These brominated derivatives can be used as valuable synthetic intermediates in further synthesis.
Making endo-cyclizations favorable again: A conceptually new synthetic approach to benzotriazoles via azide group directed lithiation/cyclization of 2-azidoaryl bromides
Ageshina, Alexandra A.,Chesnokov, Gleb A.,Topchiy, Maxim A.,Alabugin, Igor V.,Nechaev, Mikhail S.,Asachenko, Andrey F.
supporting information, p. 4523 - 4534 (2019/05/17)
Although benzotriazoles are important and ubiquitous, currently there is only one conceptual approach to their synthesis: bridging the two ortho-amino groups with an electrophilic nitrogen atom. Herein, we disclose a new practical alternative-the endo-cyclization of 2-azidoaryl lithiums obtained in situ from 2-azido-aryl bromides. The scope of the reaction is illustrated using twenty-four examples with a variety of alkyl, alkoxy, perfluoroalkyl, and halogen substituents. We found that the directing effect of the azide group allows selective metal-halogen exchange in aryl azides containing several bromine atoms. Furthermore, (2-bromophenyl)diazomethane undergoes similar cyclization to give an indazole. Thus, cyclizations of aryl lithiums containing an ortho-X = Y = Z group emerge as a new general approach for the synthesis of aromatic heterocycles. DFT computations suggested that the observed endo-selectivity applies to the anionic cyclizations of other functionalities that undergo "1,1-additions" (i.e., azides, diazo compounds, and isonitriles). In contrast, cyclizations with the heteroatomic functionalities that follow the "1,2-addition" pattern (cyanates, thiocyanates, isocyanates, isothiocyanates, and nitriles) prefer the exo-cyclization path. Hence, such reactions expand the current understanding of stereoelectronic factors in anionic cyclizations.
