Silica-supported ceric ammonium nitrate catalyzed chemoselective formylation of indoles
摘要:
Selective formylation of free (N-H) indoles at C3 can be achieved by using formylating species generated from hexamethylenetetramine (HMTA) and silica-supported ceric ammonium nitrate (CAN-SiO2). The use of a catalytic amount of this solid-supported reagent was found to be compatible with a range of substituents on the indoles and generated the corresponding products with good yields. A plausible mechanism for the formylation involving an electron transfer process is discussed. (C) 2014 Elsevier Ltd. All rights reserved.
A copper(<scp>ii</scp>)-catalyzed annulative formylation of <i>o</i>-alkynylanilines with DMF: a single-step strategy for 3-formyl indoles
作者:Balaji Ganesan、Gopal Chandru Senadi、Bing-Chun Guo、Min-Yuan Hung、Wei-Yu Lin
DOI:10.1039/c8ra09214a
日期:——
developed for synthesizing multisubstituted 3-formyl indole scaffolds. This one-pot reaction proceeds through a cascade 5-endo-dig cyclization followed by formylation to construct 1,2-disubstituted 3-formyl indoles. The key aspects of this synthesis method are the broad substrate scope (with 38 examples), and well tolerating various functional groups. In addition, a detailed mechanism has been proposed, where
Selective formylation of free (N-H) indoles at C3 can be achieved by using formylating species generated from hexamethylenetetramine (HMTA) and silica-supported ceric ammonium nitrate (CAN-SiO2). The use of a catalytic amount of this solid-supported reagent was found to be compatible with a range of substituents on the indoles and generated the corresponding products with good yields. A plausible mechanism for the formylation involving an electron transfer process is discussed. (C) 2014 Elsevier Ltd. All rights reserved.