transition-metal-free one-pot sequence for the synthesis of 3-peroxy-substituted oxindoles from readily prepared 2-cyano-2-diazo-acetamides is reported. The two-step tandem process includes a highly efficient thermal intramolecular C–H-carbene insertion followed by a tetrabutylammonium iodide (TBAI) catalyzed radical C3-peroxy-functionalization. The protocol provides easy access to a new class of 3-cyano-3-
α-Dimethylaminomethylenation-induced Houben–Hoesch-type cyclization of cyanoacetanilides: a practical synthesis of 3-formyl-4-hydroxyquinolin-2(1H)-ones
The tandem reaction of cyanoacetanilides with triflic anhydride in DMF proceeded at room temperature to afford 3-formyl-4-hydroxyquinolin-2(1H)-ones in good to high yields. A detailed mechanistic study revealed that the tandem reaction proceeded via alpha-dimethylaminomethylenation, which promoted the subsequent Houben-Hoesch-type cyclization. Both alpha-functionalization and the cyclization steps were optimized, and a multi-gram scale synthesis of 3-formyl-4-hydroxyquinolin-2(1H)-one was achieved. (C) 2011 Elsevier Ltd. All rights reserved.
Triflic anhydride-mediated tandem formylation/cyclization of cyanoacetanilides: a concise synthesis of glycocitlone alkaloids
作者:Yusuke Kobayashi、Takashi Harayama
DOI:10.1016/j.tetlet.2009.09.073
日期:2009.12
A method is presented for the concise synthesis of 3-formyl-4-hydroxyquinolin-2(1H)-ones through triflic anhydride-mediated tandem formylation/cyclization of cyanoacetanilides. This tandem process was successfully used for the rapid syntheses of glycocitlones A and C. (C) 2009 Elsevier Ltd. All rights reserved.
Trifluoroacetylation-Induced Houben−Hoesch-Type Cyclization of Cyanoacetanilides: Increased Nucleophilicity of CN Groups
Trifluoroacetic anhydride-mediated tandem trifluoroacetylation/cyclization of cyanoacetanilides proceeded efficiently under mild conditions to give 4-hydroxy-3-trifluoroacetylquinolin-2(1H)-ones in good yields. Isolation and direct observation of the reaction intermediates revealed that alpha-trifluoroacetylation resulted in the shortening of C N bonds and that the electron density of CN groups was high. A plausible reaction mechanism based on the results is also described.
[EN] RARE EARTH COMPLEX<br/>[FR] COMPLEXE DE TERRE RARE<br/>[JA] 希土類錯体